2024-25 Courses
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Independent Studies (3)
- Graduate Research
IMMUNOL 399 (Aut, Win, Spr) - Graduate Research
STEMREM 399 (Aut, Win, Spr) - Teaching in Immunology
IMMUNOL 290 (Aut, Win, Spr)
- Graduate Research
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Prior Year Courses
2023-24 Courses
- Advanced Immunology I
IMMUNOL 201 (Win)
2022-23 Courses
- Advanced Immunology I
IMMUNOL 201 (Win)
2021-22 Courses
- Advanced Immunology I
IMMUNOL 201 (Win)
- Advanced Immunology I
Stanford Advisees
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Doctoral Dissertation Reader (AC)
Sarah Sackey, Brenda Velasco -
Postdoctoral Faculty Sponsor
Eri Takematsu, Yuting Wang, Liming Zhao -
Postdoctoral Research Mentor
Chao Ma, Eri Takematsu, Yuting Wang, Liming Zhao
All Publications
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Combination of Distinct Vascular Stem/Progenitor Cells for Neovascularization and Ischemic Rescue.
Arteriosclerosis, thrombosis, and vascular biology
2023
Abstract
Peripheral vascular disease remains a leading cause of vascular morbidity and mortality worldwide despite advances in medical and surgical therapy. Besides traditional approaches, which can only restore blood flow to native arteries, an alternative approach is to enhance the growth of new vessels, thereby facilitating the physiological response to ischemia.The ActinCreER/R26VT2/GK3 Rainbow reporter mouse was used for unbiased in vivo survey of injury-responsive vasculogenic clonal formation. Prospective isolation and transplantation were used to determine vessel-forming capacity of different populations. Single-cell RNA-sequencing was used to characterize distinct vessel-forming populations and their interactions.Two populations of distinct vascular stem/progenitor cells (VSPCs) were identified from adipose-derived mesenchymal stromal cells: VSPC1 is CD45-Ter119-Tie2+PDGFRa-CD31+CD105highSca1low, which gives rise to stunted vessels (incomplete tubular structures) in a transplant setting, and VSPC2 which is CD45-Ter119-Tie2+PDGFRa+CD31-CD105lowSca1high and forms stunted vessels and fat. Interestingly, cotransplantation of VSPC1 and VSPC2 is required to form functional vessels that improve perfusion in the mouse hindlimb ischemia model. Similarly, VSPC1 and VSPC2 populations isolated from human adipose tissue could rescue the ischemic condition in mice.These findings suggest that autologous cotransplantation of synergistic VSPCs from nonessential adipose tissue can promote neovascularization and represents a promising treatment for ischemic disease.
View details for DOI 10.1161/ATVBAHA.122.317943
View details for PubMedID 37051932
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Denervation during mandibular distraction osteogenesis results in impaired bone formation.
Scientific reports
2023; 13 (1): 2097
Abstract
Mandibular distraction osteogenesis (DO) is mediated by skeletal stem cells (SSCs) in mice, which enact bone regeneration via neural crest re-activation. As peripheral nerves are essential to progenitor function during development and in response to injury, we questioned if denervation impairs mandibular DO. C57Bl6 mice were divided into two groups: DO with a segmental defect in the inferior alveolar nerve (IAN) at the time of mandibular osteotomy ("DO Den") and DO with IAN intact ("DO Inn"). DO Den demonstrated significantly reduced histological and radiological osteogenesis relative to DO Inn. Denervation preceding DO results in reduced SSC amplification and osteogenic potential in mice. Single cell RNA sequencing analysis revealed that there was a predominance of innervated SSCs in clusters dominated by pathways related to bone formation. A rare human patient specimen was also analyzed and suggested that histological, radiological, and transcriptional alterations seen in mouse DO may be conserved in the setting of denervated human mandible distraction. Fibromodulin (FMOD) transcriptional and protein expression were reduced in denervated relative to innervated mouse and human mandible regenerate. Finally, when exogenous FMOD was added to DO-Den and DO-Inn SSCs undergoing in vitro osteogenic differentiation, the osteogenic potential of DO-Den SSCs was increased in comparison to control untreated DO-Den SSCs, modeling the superior osteogenic potential of DO-Inn SSCs.
View details for DOI 10.1038/s41598-023-27921-9
View details for PubMedID 36747028
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A seed-and-soil theory for blood ageing.
Nature cell biology
2023
View details for DOI 10.1038/s41556-022-01062-z
View details for PubMedID 36650380
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Development and systematic characterization of GelMA/alginate/PEGDMA/xanthan gum hydrogel bioink system for extrusion bioprinting.
Biomaterials
2022; 293: 121969
Abstract
Gelatin methacryloyl (GelMA)/alginate-based hydrogels have shown great promise in bioprinting, but their printability is limited at room temperature. In this paper, we present our development of a room temperature printable hydrogel bioink by introducing polyethylene glycol dimethacrylate (PEGDMA) and xanthan gum into the GelMA/alginate system. The inclusion of PEGDMA facilitates tuning of the hydrogel's mechanical property, while xanthan gum improves the viscosity of the hydrogel system and allows easy extrusion at room temperature. To fine-tune the mechanical and degradation properties, methacrylated xanthan gum was synthesized and chemically crosslinked to the system. We systematically characterized this hydrogel with attention to printability, strut size, mechanical property, degradation and cytocompatibility, and achieved a broad range of compression modulus (∼10-100 kPa) and degradation profile (100% degradation by 24 h-40% by 2 weeks). Moreover, xanthan gum demonstrated solubility in ionic solutions such as cell culture medium, which is essential for biocompatibility. Live/dead staining showed that cell viability in the printed hydrogels was over 90% for 7 days. Metabolic activity analysis demonstrated excellent cell proliferation and survival within 4 weeks of incubation. In summary, the newly developed hydrogel system has demonstrated distinct features including extrusion printability, widely tunable mechanical property and degradation, ionic solubility, and cytocompatibility. It offers great flexibility in bioprinting and tissue engineering.
View details for DOI 10.1016/j.biomaterials.2022.121969
View details for PubMedID 36566553
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Sexually dimorphic estrogen sensing in skeletal stem cells controls skeletal regeneration.
Nature communications
2022; 13 (1): 6491
Abstract
Sexually dimorphic tissues are formed by cells that are regulated by sex hormones. While a number of systemic hormones and transcription factors are known to regulate proliferation and differentiation of osteoblasts and osteoclasts, the mechanisms that determine sexually dimorphic differences in bone regeneration are unclear. To explore how sex hormones regulate bone regeneration, we compared bone fracture repair between adult male and female mice. We found that skeletal stem cell (SSC) mediated regeneration in female mice is dependent on estrogen signaling but SSCs from male mice do not exhibit similar estrogen responsiveness. Mechanistically, we found that estrogen acts directly on the SSC lineage in mice and humans by up-regulating multiple skeletogenic pathways and is necessary for the stem cell's ability to self- renew and differentiate. Our results also suggest a clinically applicable strategy to accelerate bone healing using localized estrogen hormone therapy.
View details for DOI 10.1038/s41467-022-34063-5
View details for PubMedID 36310174
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Glucocorticoids Affect Bone Mass and Strength by Inhibiting Osteoprogenitor Cell Maturation
WILEY. 2022: 2569
View details for Web of Science ID 000877386503054
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Partial Tendon Injury at the Tendon-to-Bone Enthesis Activates Skeletal Stem Cells.
Stem cells translational medicine
2022
Abstract
The tendon enthesis plays a critical role in facilitating movement and reducing stress within joints. Partial enthesis injuries heal in a mechanically inferior manner and never achieve healthy tissue function. The cells responsible for tendon-to-bone healing remain incompletely characterized and their origin is unknown. Here, we evaluated the putative role of mouse skeletal stem cells (mSSCs) in the enthesis after partial-injury. We found that mSSCs were present at elevated levels within the enthesis following injury and that these cells downregulated TGFβ signaling pathway elements at both the RNA and protein levels. Exogenous application of TGFβ post-injury led to a reduced mSSC response and impaired healing, whereas treatment with a TGFβ inhibitor (SB43154) resulted in a more robust mSSC response. Collectively, these data suggest that mSSCs may augment tendon-to-bone healing by dampening the effects of TGFβ signaling within the mSSC niche.
View details for DOI 10.1093/stcltm/szac027
View details for PubMedID 35640155
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The Tabula Sapiens: A multiple-organ, single-cell transcriptomic atlas of humans.
Science (New York, N.Y.)
2022; 376 (6594): eabl4896
Abstract
Molecular characterization of cell types using single-cell transcriptome sequencing is revolutionizing cell biology and enabling new insights into the physiology of human organs. We created a human reference atlas comprising nearly 500,000 cells from 24 different tissues and organs, many from the same donor. This atlas enabled molecular characterization of more than 400 cell types, their distribution across tissues, and tissue-specific variation in gene expression. Using multiple tissues from a single donor enabled identification of the clonal distribution of T cells between tissues, identification of the tissue-specific mutation rate in B cells, and analysis of the cell cycle state and proliferative potential of shared cell types across tissues. Cell type-specific RNA splicing was discovered and analyzed across tissues within an individual.
View details for DOI 10.1126/science.abl4896
View details for PubMedID 35549404
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Human Coronary Plaque T Cells Are Clonal and Cross-React to Virus and Self.
Circulation research
2022: 101161CIRCRESAHA121320090
Abstract
Once considered primarily a disorder of lipid deposition, coronary artery disease is an incurable, life-threatening disease that is now also characterized by chronic inflammation notable for the buildup of atherosclerotic plaques containing immune cells in various states of activation and differentiation. Understanding how these immune cells contribute to disease progression may lead to the development of novel therapeutic strategies.We used single-cell technology and in vitro assays to interrogate the immune microenvironment of human coronary atherosclerotic plaque at different stages of maturity.In addition to macrophages, we found a high proportion of αβ T cells in the coronary plaques. Most of these T cells lack high expression of CCR7 and L-selectin, indicating that they are primarily antigen-experienced, memory cells. Notably, nearly one-third of these cells express the HLA-DRA surface marker, signifying activation through their TCRs (T-cell receptors). Consistent with this, TCR repertoire analysis confirmed the presence of activated αβ T cells (CD4
View details for DOI 10.1161/CIRCRESAHA.121.320090
View details for PubMedID 35430876
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REGENERATION OF CARTILAGE THOUGH ACTIVATION OF TISSUE RESIDENT SKELETAL STEM CELLS AND AUGMENTATION OF THE NICHE
MARY ANN LIEBERT, INC. 2022: S375
View details for Web of Science ID 000821187301490
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Publisher Correction: Cell types of origin of the cell-free transcriptome.
Nature biotechnology
2022
View details for DOI 10.1038/s41587-022-01293-3
View details for PubMedID 35347330
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Molecular hallmarks of heterochronic parabiosis at single-cell resolution.
Nature
2022
Abstract
The ability to slow or reverse biological ageing would have major implications for mitigating disease risk and maintaining vitality1. Although an increasing number of interventions show promise for rejuvenation2, their effectiveness on disparate cell types across the body and the molecular pathways susceptible to rejuvenation remain largely unexplored. Here we performed single-cell RNA sequencing on 20 organs to reveal cell-type-specific responses to young and aged blood in heterochronic parabiosis. Adipose mesenchymal stromal cells, haematopoietic stem cells and hepatocytes are among those cell types that are especially responsive. On the pathway level, young blood invokes new gene sets in addition to reversing established ageing patterns, with the global rescue of genes encoding electron transport chain subunits pinpointing a prominent role of mitochondrial function in parabiosis-mediated rejuvenation. We observed an almost universal loss of gene expression with age that is largely mimicked by parabiosis: aged blood reduces global gene expression, and young blood restores it in select cell types. Together, these data lay the groundwork for a systemic understanding of the interplay between blood-borne factors and cellular integrity.
View details for DOI 10.1038/s41586-022-04461-2
View details for PubMedID 35236985
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Cell types of origin of the cell-free transcriptome.
Nature biotechnology
2022
Abstract
Cell-free RNA from liquid biopsies can be analyzed to determine disease tissue of origin. We extend this concept to identify cell types of origin using the Tabula Sapiens transcriptomic cell atlas as well as individual tissue transcriptomic cell atlases in combination with the Human Protein Atlas RNA consensus dataset. We define cell type signature scores, which allow the inference of cell types that contribute to cell-free RNA for a variety of diseases.
View details for DOI 10.1038/s41587-021-01188-9
View details for PubMedID 35132263
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A Brain Dependent Osteogenic Factor Controls Peak Bone Mass
WILEY. 2022: 191
View details for Web of Science ID 000778074501002
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Tractable Human Skeletal Stem Cell Diversity Shapes Bone Development and Regeneration
WILEY. 2022: 266-267
View details for Web of Science ID 000778074501234
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Cross-species comparisons reveal resistance of human skeletal stem cells to inhibition by non-steroidal anti-inflammatory drugs.
Frontiers in endocrinology
2022; 13: 924927
Abstract
Fracture healing is highly dependent on an early inflammatory response in which prostaglandin production by cyclo-oxygenases (COX) plays a crucial role. Current patient analgesia regimens favor opioids over Non-Steroidal Anti-Inflammatory Drugs (NSAIDs) since the latter have been implicated in delayed fracture healing. While animal studies broadly support a deleterious role of NSAID treatment to bone-regenerative processes, data for human fracture healing remains contradictory. In this study, we prospectively isolated mouse and human skeletal stem cells (SSCs) from fractures and compared the effect of various NSAIDs on their function. We found that osteochondrogenic differentiation of COX2-expressing mouse SSCs was impaired by NSAID treatment. In contrast, human SSCs (hSSC) downregulated COX2 expression during differentiation and showed impaired osteogenic capacity if COX2 was lentivirally overexpressed. Accordingly, short- and long-term treatment of hSSCs with non-selective and selective COX2 inhibitors did not affect colony forming ability, chondrogenic, and osteogenic differentiation potential in vitro. When hSSCs were transplanted ectopically into NSG mice treated with Indomethacin, graft mineralization was unaltered compared to vehicle injected mice. Thus, our results might contribute to understanding species-specific differences in NSAID sensitivity during fracture healing and support emerging clinical data which conflicts with other earlier observations that NSAID administration for post-operative analgesia for treatment of bone fractures are unsafe for patients.
View details for DOI 10.3389/fendo.2022.924927
View details for PubMedID 36093067
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Aging of Skeletal Stem Cells.
Advances in geriatric medicine and research
2022; 4 (2)
Abstract
The skeletal system is generated and maintained by its progenitors, skeletal stem cells (SSCs), across the duration of life. Gradual changes associated with aging result in significant differences in functionality of SSCs. Declines in bone and cartilage production, increase of bone marrow adipose tissue, compositional changes of cellular microenvironments, and subsequent deterioration of external and internal structures culminate in the aged and weakened skeleton. The features and mechanisms of skeletal aging, and of its stem and progenitor cells in particular, are topics of recent investigation. The discovery of functionally homogeneous SSC populations with a defined cell surface phenotype has allowed for closer inspection of aging in terms of its effects on transcriptional regulation, cell function, and identity. Here, we review the aspects of SSC aging on both micro- and macroscopic levels. Up-to-date knowledge of SSC biology and aging is presented, and directions for future research and potential therapies are discussed. The realm of SSC-mediated bone aging remains an important component of global health and a necessary facet in our understanding of human aging.
View details for DOI 10.20900/agmr20220006
View details for PubMedID 36037035
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Denervation During Mandibular Distraction Osteogenesis Results in Impaired Osteogenesis
ELSEVIER SCIENCE INC. 2021: S196-S197
View details for Web of Science ID 000718303100369
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Acellular Dermal Matrix Modulation of the Peri-Prosthetic Breast Microenvironment During Breast Reconstruction
ELSEVIER SCIENCE INC. 2021: S195-S196
View details for Web of Science ID 000718303100367
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RNA splicing programs define tissue compartments and cell types at single-cell resolution
ELIFE
2021; 10
View details for DOI 10.7554/eLife.70692.sa2
View details for Web of Science ID 000715795700001
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Skeletal stem and progenitor cells maintain cranial suture patency and prevent craniosynostosis.
Nature communications
2021; 12 (1): 4640
Abstract
Cranial sutures are major growth centers for the calvarial vault, and their premature fusion leads to a pathologic condition called craniosynostosis. This study investigates whether skeletal stem/progenitor cells are resident in the cranial sutures. Prospective isolation by FACS identifies this population with a significant difference in spatio-temporal representation between fusing versus patent sutures. Transcriptomic analysis highlights a distinct signature in cellsderived from the physiological closing PF suture, and scRNA sequencing identifies transcriptional heterogeneity among sutures. Wnt-signaling activation increases skeletal stem/progenitor cells in sutures, whereas its inhibition decreases. Crossing Axin2LacZ/+ mouse, endowing enhanced Wnt activation, to a Twist1+/- mouse model of coronal craniosynostosis enriches skeletal stem/progenitor cells in sutures restoring patency. Co-transplantation of these cells with Wnt3a prevents resynostosis following suturectomy in Twist1+/- mice. Our study reveals that decrease and/or imbalance of skeletal stem/progenitor cells representation within sutures may underlie craniosynostosis. These findings have translational implications toward therapeutic approaches for craniosynostosis.
View details for DOI 10.1038/s41467-021-24801-6
View details for PubMedID 34330896
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Distinct skeletal stem cell types orchestrate long bone skeletogenesis.
eLife
2021; 10
Abstract
Skeletal stem and progenitor cell populations are crucial for bone physiology. Characterization of these cell types remains restricted to heterogenous bulk populations with limited information on whether they are unique or overlap with previously characterized cell types. Here we show, through comprehensive functional and single-cell transcriptomic analyses, that postnatal long bones of mice contain at least two types of bone progenitors with bona fide skeletal stem cell (SSC) characteristics. An early osteochondral SSC (ocSSC) facilitates long bone growth and repair, while a second type, a perivascular SSC (pvSSC), co-emerges with long bone marrow and contributes to shape the hematopoietic stem cell niche and regenerative demand. We establish that pvSSCs, but not ocSSCs, are the origin of bone marrow adipose tissue. Lastly, we also provide insight into residual SSC heterogeneity as well as potential crosstalk between the two spatially distinct cell populations. These findings comprehensively address previously unappreciated shortcomings of SSC research.
View details for DOI 10.7554/eLife.66063
View details for PubMedID 34280086
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Aged skeletal stem cells generate an inflammatory degenerative niche.
Nature
2021
Abstract
Loss of skeletal integrity during ageing and disease is associated with an imbalance in the opposing actions of osteoblasts and osteoclasts1. Here we show that intrinsic ageing of skeletal stem cells (SSCs)2 in mice alters signalling in the bone marrow niche and skews the differentiation of bone and blood lineages, leading to fragile bones that regenerate poorly. Functionally, aged SSCs have a decreased bone- and cartilage-forming potential but produce more stromal lineages that express high levels of pro-inflammatory and pro-resorptive cytokines. Single-cell RNA-sequencing studies link the functional loss to a diminished transcriptomic diversity of SSCs in aged mice, which thereby contributes to the transformation of the bone marrow niche. Exposure to a youthful circulation through heterochronic parabiosis or systemic reconstitution with young haematopoietic stem cells did not reverse the diminished osteochondrogenic activity of aged SSCs, or improve bone mass or skeletal healing parameters in aged mice. Conversely, the aged SSC lineage promoted osteoclastic activity and myeloid skewing by haematopoietic stem and progenitor cells, suggesting that the ageing of SSCs is a driver of haematopoietic ageing. Deficient bone regeneration in aged mice could only be returned to youthful levels by applying a combinatorial treatment of BMP2 and a CSF1 antagonist locally to fractures, which reactivated aged SSCs and simultaneously ablated the inflammatory, pro-osteoclastic milieu. Our findings provide mechanistic insights into the complex, multifactorial mechanisms that underlie skeletal ageing and offer prospects for rejuvenating the aged skeletal system.
View details for DOI 10.1038/s41586-021-03795-7
View details for PubMedID 34381212
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Skeletal Stem Cells as the Developmental Origin of Cellular Niches for Hematopoietic Stem and Progenitor Cells.
Current topics in microbiology and immunology
2021; 434: 1-31
Abstract
The skeletal system is a highly complex network of mesenchymal, hematopoietic, and vasculogenic stem cell lineages that coordinate the development and maintenance of defined microenvironments, so-called niches. Technological advancements in recent years have allowed for the dissection of crucial cell types as well as their autocrine and paracrine signals that regulate these niches during development, homeostasis, regeneration, and disease. Ingress of blood vessels and bone marrow hematopoiesis are initiated by skeletal stem cells (SSCs) and their more committed downstream lineage cell types that direct shape and form of skeletal elements. In this chapter, we focus on the role of SSCs as the developmental origin of niches for hematopoietic stem and progenitor cells. We discuss latest updates in the definition of SSCs, cellular processes establishing and maintaining niches, as well as alterations of stem cell microenvironments promoting malignancies. We conclude with an outlook on future studies that could take advantage of SSC-niche engineering as a basis for the development of new therapeutic tools to not only treat bone-related diseases but also maladies stemming from derailed niche dynamics altering hematopoietic output.
View details for DOI 10.1007/978-3-030-86016-5_1
View details for PubMedID 34850280
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Prrx1 Fibroblasts Represent a Pro-fibrotic Lineage in the Mouse Ventral Dermis.
Cell reports
2020; 33 (6): 108356
Abstract
Fibroblast heterogeneity has been shown within the unwounded mouse dorsal dermis, with fibroblast subpopulations being identified according to anatomical location and embryonic lineage. Using lineage tracing, we demonstrate that paired related homeobox 1 (Prrx1)-expressing fibroblasts are responsible for acute and chronic fibroses in the ventral dermis. Single-cell transcriptomics further corroborated the inherent fibrotic characteristics of Prrx1 fibroblasts during wound repair. In summary, we identify and characterize a fibroblast subpopulation in the mouse ventral dermis with intrinsic scar-forming potential.
View details for DOI 10.1016/j.celrep.2020.108356
View details for PubMedID 33176144
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Delayed Union of a Diaphyseal Forearm Fracture Associated With Impaired Osteogenic Differentiation of Prospectively Isolated Human Skeletal Stem Cells.
JBMR plus
2020; 4 (10): e10398
Abstract
Delayed union or nonunion are relatively rare complications after fracture surgery, but when they do occur, they can result in substantial morbidity for the patient. In many cases, the etiology of impaired fracture healing is uncertain and attempts to determine the molecular basis for delayed union and nonunion formation have been limited. Prospectively isolating skeletal stem cells (SSCs) from fracture tissue samples at the time of surgical intervention represent a feasible methodology to determine a patient's biologic risk for compromised fracture healing. This report details a case in which functional in vitro readouts of SSCs derived from human fracture tissue at time of injury predicted a poor fracture healing outcome. This case suggests that it may be feasible to stratify a patient's fracture healing capacity and predict compromised fracture healing by prospectively isolating and analyzing SSCs during the index fracture surgery. © 2020 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.
View details for DOI 10.1002/jbm4.10398
View details for PubMedID 33103027
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Human skeletal stem cell aging
AGING-US
2020; 12 (17): 16669–71
View details for Web of Science ID 000572850000003
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Human skeletal stem cell aging.
Aging
2020
View details for DOI 10.18632/aging.104034
View details for PubMedID 32929053
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Articular cartilage regeneration by activated skeletal stem cells.
Nature medicine
2020
Abstract
Osteoarthritis (OA) is a degenerative disease resulting in irreversible, progressive destruction of articular cartilage1. The etiology of OA is complex and involves a variety of factors, including genetic predisposition, acute injury and chronic inflammation2-4. Here we investigate the ability of resident skeletal stem-cell (SSC) populations to regenerate cartilage in relation to age, a possible contributor to the development of osteoarthritis5-7. We demonstrate that aging is associated with progressive loss of SSCs and diminished chondrogenesis in the joints of both mice and humans. However, a local expansion of SSCs could still be triggered in the chondral surface of adult limb joints in mice by stimulating a regenerative response using microfracture (MF) surgery. Although MF-activated SSCs tended to form fibrous tissues, localized co-delivery of BMP2 and soluble VEGFR1 (sVEGFR1), a VEGF receptor antagonist, in a hydrogel skewed differentiation of MF-activated SSCs toward articular cartilage. These data indicate that following MF, a resident stem-cell population can be induced to generate cartilage for treatment of localized chondral disease in OA.
View details for DOI 10.1038/s41591-020-1013-2
View details for PubMedID 32807933
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Geriatric fragility fractures are associated with a human skeletal stem cell defect.
Aging cell
2020: e13164
Abstract
Fragility fractures have a limited capacity to regenerate, and impaired fracture healing is a leading cause of morbidity in the elderly. The recent identification of a highly purified bona fide human skeletal stem cell (hSSC) and its committed downstream progenitor cell populations provides an opportunity for understanding the mechanism of age-related compromised fracture healing from the stem cell perspective. In this study, we tested whether hSSCs isolated from geriatric fractures demonstrate intrinsic functional defects that drive impaired healing. Using flow cytometry, we analyzed and isolated hSSCs from callus tissue of five different skeletal sites (n=61) of patients ranging from 13 to 94years of age for functional and molecular studies. We observed that fracture-activated amplification of hSSC populations was comparable at all ages. However, functional analysis of isolated stem cells revealed that advanced age significantly correlated with reduced osteochondrogenic potential but was not associated with decreased in vitro clonogenicity. hSSCs derived from women displayed an exacerbated functional decline with age relative to those of aged men. Transcriptomic comparisons revealed downregulation of skeletogenic pathways such as WNT and upregulation of senescence-related pathways in young versus older hSSCs. Strikingly, loss of Sirtuin1 expression played a major role in hSSC dysfunction but re-activation by trans-resveratrol or a small molecule compound restored in vitro differentiation potential. These are the first findings that characterize age-related defects in purified hSSCs from geriatric fractures. Our results provide a foundation for future investigations into the mechanism and reversibility of skeletal stem cell aging in humans.
View details for DOI 10.1111/acel.13164
View details for PubMedID 32537886
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Therapeutic modulation of phagocytosis in glioblastoma can activate both innate and adaptive antitumour immunity.
Nature communications
2020; 11 (1): 1508
Abstract
Tumour cell phagocytosis by antigen presenting cells (APCs) is critical to the generation of antitumour immunity. However, cancer cells can evade phagocytosis by upregulating anti-phagocytosis molecule CD47. Here, we show that CD47 blockade alone is inefficient in stimulating glioma cell phagocytosis. However, combining CD47 blockade with temozolomide results in a significant pro-phagocytosis effect due to the latter's ability to induce endoplasmic reticulum stress response. Increased tumour cell phagocytosis subsequently enhances antigen cross-presentation and activation of cyclic GMP-AMP synthase-stimulator of interferon genes (cGAS-STING) in APCs, resulting in more efficient T cell priming. This bridging of innate and adaptive responses inhibits glioma growth, but also activates immune checkpoint. Sequential administration of an anti-PD1 antibody overcomes this potential adaptive resistance. Together, these findings reveal a dynamic relationship between innate and adaptive immune regulation in tumours and support further investigation of phagocytosis modulation as a strategy to enhance cancer immunotherapy responses.
View details for DOI 10.1038/s41467-020-15129-8
View details for PubMedID 32198351
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Expansion of Bone Precursors through Jun as a Novel Treatment for Osteoporosis-Associated Fractures.
Stem cell reports
2020
Abstract
Osteoporosis and osteoporotic fractures lead to decreased life quality and high healthcare costs. Current treatments prevent losses in bone mass and fractures to some extent but have side effects. Therefore, better therapies are needed. This study investigated whether the transcriptionfactor Jun has a specific pro-osteogenic potency and whether modulating Jun could serve as a novel treatment for osteoporosis-associated fractures. We demonstrate that ectopically transplanted whole bones and distinct osteoprogenitors increase bone formation. Perinatal Jun induction disturbs growth plate architecture, causing a striking phenotype with shortened and thickened bones. Molecularly, Jun induces hedgehog signaling in skeletal stem cells. Therapeutically, Jun accelerates bone growth and healing in a drilling-defect model. Altogether, these results demonstrate that Jun drives bone formation by expanding osteoprogenitor populations and forcing them into the bone fate, providing a rationale for future clinical applications.
View details for DOI 10.1016/j.stemcr.2020.02.009
View details for PubMedID 32197115
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A single-cell transcriptomic atlas characterizes ageing tissues in the mouse.
Nature
2020
Abstract
Ageing is characterized by a progressive loss of physiological integrity, leading to impaired function and increased vulnerability to death1. Despite rapid advances over recent years, many of the molecular and cellular processes that underlie the progressive loss of healthy physiology are poorly understood2. To gain a better insight into these processes, here we generate a single-cell transcriptomic atlas across the lifespan of Mus musculus that includes data from 23 tissues and organs. We found cell-specific changes occurring across multiple cell types and organs, as well as age-related changes in the cellular composition of different organs. Using single-cell transcriptomic data, we assessed cell-type-specific manifestations of different hallmarks of ageing-such as senescence3, genomic instability4 and changes in the immune system2. This transcriptomic atlas-which we denote Tabula Muris Senis, or 'Mouse Ageing Cell Atlas'-provides molecular information about how the most important hallmarks of ageing are reflected in a broad range of tissues and cell types.
View details for DOI 10.1038/s41586-020-2496-1
View details for PubMedID 32669714
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Ageing hallmarks exhibit organ-specific temporal signatures.
Nature
2020
Abstract
Ageing is the single greatest cause of disease and death worldwide, and understanding the associated processes could vastly improve quality of life. Although major categories of ageing damage have been identified-such as altered intercellular communication, loss of proteostasis and eroded mitochondrial function1-these deleterious processes interact with extraordinary complexity within and between organs, and a comprehensive, whole-organism analysis of ageing dynamics has been lacking. Here we performed bulk RNA sequencing of 17 organs and plasma proteomics at 10 ages across the lifespan of Mus musculus, and integrated these findings with data from the accompanying Tabula Muris Senis2-or 'Mouse Ageing Cell Atlas'-which follows on from the original Tabula Muris3. We reveal linear and nonlinear shifts in gene expression during ageing, with the associated genes clustered in consistent trajectory groups with coherent biological functions-including extracellular matrix regulation, unfolded protein binding, mitochondrial function, and inflammatory and immune response. Notably, these gene sets show similar expression across tissues, differing only in the amplitude and the age of onset of expression. Widespread activation of immune cells is especially pronounced, and is first detectable in white adipose depots during middle age. Single-cell RNA sequencing confirms the accumulation of T cells and B cells in adipose tissue-including plasma cells that express immunoglobulin J-which also accrue concurrently across diverse organs. Finally, we show how gene expression shifts in distinct tissues are highly correlated with corresponding protein levels in plasma, thus potentially contributing to the ageing of the systemic circulation. Together, these data demonstrate a similar yet asynchronous inter- and intra-organ progression of ageing, providing a foundation from which to track systemic sources of declining health at old age.
View details for DOI 10.1038/s41586-020-2499-y
View details for PubMedID 32669715
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A Brain-Dependent Osteogenic Factor Dramatically Enhances the Capacity of Skeletal Stem Cells to form Bone in Female Mice
WILEY. 2019: 57
View details for Web of Science ID 000508614700162
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A Brain-Dependent Osteogenic Factor Dramatically Enhances the Capacity of Skeletal Stem Cells to form Bone in Female Mice
WILEY. 2019: 57
View details for Web of Science ID 000508356600162
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Role of the Skeletal Stem Cell in Achilles Tendon to Bone Interface Healing
ELSEVIER SCIENCE INC. 2019: S228–S229
View details for Web of Science ID 000492740900438
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A Revised Perspective of Skeletal Stem Cell Biology.
Frontiers in cell and developmental biology
2019; 7: 189
Abstract
Bone-related maladies are a major health burden on modern society. Loss of skeletal integrity and regeneration capacity through aging, obesity, and disease follows from a detrimental shift in bone formation and resorption dynamics. Targeting tissue-resident adult stem cells offers a potentially innovative paradigm in the development of therapeutic strategies against organ dysfunction. While the essential role of skeletal stem cells (SSCs) for development, growth, and maintenance of the skeleton has been generally established, a common consensus on the exact identity and definition of a pure bona fide SSC population remains elusive. The controversies stem from conflicting results between different approaches and criteria for isolation, detection, and functional evaluation; along with the interchangeable usage of the terms SSC and "mesenchymal stromal/stem cell (MSC)". A great number of prospective bone-forming stem cell populations have been reported with various characteristic markers, often describing overlapping cell populations with widely unexplored heterogeneity, species specificity, and distribution at distinct skeletal sites, bone regions, and microenvironments, thereby creating confusion that may complicate future advances in the field. In this review, we examine the state-of-the-art knowledge of SSC biology and try to establish a common ground for the definition and terminology of specific bone-resident stem cells. We also discuss recent advances in the identification of highly purified SSCs, which will allow detailed interrogation of SSC diversity and regulation at the single-cell level.
View details for DOI 10.3389/fcell.2019.00189
View details for PubMedID 31572721
View details for PubMedCentralID PMC6753172
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A Revised Perspective of Skeletal Stem Cell Biology
FRONTIERS IN CELL AND DEVELOPMENTAL BIOLOGY
2019; 7
View details for DOI 10.3389/fcell.2019.00189
View details for Web of Science ID 000485330300001
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THERAPEUTIC MODULATION OF THE PHAGOCYTIC AXIS SPARKS ANTI-TUMOR CD8 T CELL RESPONSES IN GLIOBLASTOMA
OXFORD UNIV PRESS INC. 2018: 124
View details for Web of Science ID 000460646300519
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Mechanoresponsive stem cells acquire neural crest fate in jaw regeneration.
Nature
2018
Abstract
During both embryonic development and adult tissue regeneration, changes in chromatin structure driven by master transcription factors lead to stimulus-responsive transcriptional programs. A thorough understanding of how stem cells in the skeleton interpret mechanical stimuli and enact regeneration would shed light on how forces are transduced to the nucleus in regenerative processes. Here we develop a genetically dissectible mouse model of mandibular distraction osteogenesis-which isa process that is used in humans to correct an undersized lower jawthat involves surgically separating the jaw bone, whichelicits new bone growth in the gap. We use this model to show that regions of newly formed bone are clonally derived from stem cells that reside in the skeleton. Using chromatin and transcriptional profiling, we show that these stem-cell populations gain activity within the focal adhesion kinase (FAK) signalling pathway, and that inhibiting FAK abolishes new bone formation. Mechanotransduction via FAK in skeletal stem cells during distraction activates a gene-regulatory program and retrotransposons that are normally active in primitive neural crest cells, from which skeletal stem cells arise during development. This reversion to a developmental state underlies the robust tissue growth that facilitates stem-cell-based regeneration of adult skeletal tissue.
View details for PubMedID 30356216
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Method of Isolating and Transplanting the Hematopoietic Stem Cell with Its Microenvironment Which Improves Functional Hematopoietic Engraftment
ELSEVIER SCIENCE INC. 2018: E224
View details for DOI 10.1016/j.jamcollsurg.2018.08.605
View details for Web of Science ID 000447772500541
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Translational Approach Using Trimodal Manipulation of Resident Skeletal Stem Cells for Articular Cartilage Repair
ELSEVIER SCIENCE INC. 2018: S213–S214
View details for DOI 10.1016/j.jamcollsurg.2018.07.457
View details for Web of Science ID 000447760600420
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Identification of the Human Skeletal Stem Cell.
Cell
2018; 175 (1): 43
Abstract
Stem cell regulation and hierarchical organization ofhuman skeletal progenitors remain largely unexplored. Here, we report the isolation of a self-renewing and multipotent human skeletal stem cell (hSSC) that generates progenitors of bone, cartilage, and stroma, but not fat. Self-renewing and multipotent hSSCs are present in fetal and adult bones and can also be derived from BMP2-treated human adipose stroma (B-HAS) and induced pluripotent stem cells (iPSCs). Gene expression analysis of individual hSSCs reveals overall similarity between hSSCs obtained from different sources and partially explains skewed differentiation toward cartilage in fetal and iPSC-derived hSSCs. hSSCs undergo local expansion in response to acute skeletal injury. In addition, hSSC-derived stroma can maintain human hematopoietic stem cells (hHSCs) in serum-free culture conditions. Finally, we combine gene expression and epigenetic data of mouse skeletal stem cells (mSSCs) and hSSCs to identify evolutionarily conserved and divergent pathways driving SSC-mediated skeletogenesis. VIDEO ABSTRACT.
View details for PubMedID 30241615
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Isolation and functional assessment of mouse skeletal stem cell lineage
NATURE PROTOCOLS
2018; 13 (6): 1294–1309
Abstract
There are limited methods available to study skeletal stem, progenitor, and progeny cell activity in normal and diseased contexts. Most protocols for skeletal stem cell isolation are based on the extent to which cells adhere to plastic or whether they express a limited repertoire of surface markers. Here, we describe a flow cytometry-based approach that does not require in vitro selection and that uses eight surface markers to distinguish and isolate mouse skeletal stem cells (mSSCs); bone, cartilage, and stromal progenitors (mBCSPs); and five downstream differentiated subtypes, including chondroprogenitors, two types of osteoprogenitors, and two types of hematopoiesis-supportive stroma. We provide instructions for the optimal mechanical and chemical digestion of bone and bone marrow, as well as the subsequent flow-cytometry-activated cell sorting (FACS) gating schemes required to maximally yield viable skeletal-lineage cells. We also describe a methodology for renal subcapsular transplantation and in vitro colony-formation assays on the isolated mSSCs. The isolation of mSSCs can be completed in 9 h, with at least 1 h more required for transplantation. Experience with flow cytometry and mouse surgical procedures is recommended before attempting the protocol. Our system has wide applications and has already been used to study skeletal response to fracture, diabetes, and osteoarthritis, as well as hematopoietic stem cell-niche interactions in the bone marrow.
View details for PubMedID 29748647
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Improving immune-vascular crosstalk for cancer immunotherapy
NATURE REVIEWS IMMUNOLOGY
2018; 18 (3): 195–203
Abstract
The vasculature of tumours is highly abnormal and dysfunctional. Consequently, immune effector cells have an impaired ability to penetrate solid tumours and often exhibit compromised functions. Normalization of the tumour vasculature can enhance tissue perfusion and improve immune effector cell infiltration, leading to immunotherapy potentiation. However, recent studies have demonstrated that the stimulation of immune cell functions can also help to normalize tumour vessels. In this Opinion article, we propose that the reciprocal regulation between tumour vascular normalization and immune reprogramming forms a reinforcing loop that reconditions the tumour immune microenvironment to induce durable antitumour immunity. A deeper understanding of these pathways could pave the way for identifying new biomarkers and developing more effective combination treatment strategies for patients with cancer.
View details for PubMedID 29332937
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Prolonged survival of transplanted stem cells after ischaemic injury via the slow release of pro-survival peptides from a collagen matrix.
Nature biomedical engineering
2018; 2 (2): 104-113
Abstract
Stem-cell-based therapies hold considerable promise for regenerative medicine. However, acute donor-cell death within several weeks after cell delivery remains a critical hurdle for clinical translation. Co-transplantation of stem cells with pro-survival factors can improve cell engraftment, but this strategy has been hampered by the typically short half-lives of the factors and by the use of Matrigel and other scaffolds that are not chemically defined. Here, we report a collagen-dendrimer biomaterial crosslinked with pro-survival peptide analogues that adheres to the extracellular matrix and slowly releases the peptides, significantly prolonging stem cell survival in mouse models of ischaemic injury. The biomaterial can serve as a generic delivery system to improve functional outcomes in cell-replacement therapy.
View details for DOI 10.1038/s41551-018-0191-4
View details for PubMedID 29721363
View details for PubMedCentralID PMC5927627
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Where Hematopoietic Stem Cells Live: The Bone Marrow Niche
ANTIOXIDANTS & REDOX SIGNALING
2018
Abstract
Hematopoietic stem cells (HSCs) can sustain the production of blood throughout one's lifetime. However, for proper self-renewal of its own population and differentiation to blood, the HSC requires a specialized microenvironment called the "niche." Recent Advances: Recent studies using novel mouse models have shed new light on the cellular architecture and function of the HSC niche. Here, we review the different cells that constitute the HSC niche and the molecular mechanisms that underlie HSC and niche interaction. We discuss the evidence and potential features that distinguish the HSC niche from other microenvironments in the bone marrow. The relevance of the niche in malignant transformation of the HSCs and harboring cancer metastasis to the bone is also outlined. In addition, we address how the niche may regulate reactive oxygen species levels surrounding the HSCs. Critical Issues and Future Directions: We propose future directions and remaining challenges in investigating the niche of HSCs. We discuss how a better understanding of the HSC niche may help in restoring an aged hematopoietic system, fighting against malignancies, and transplanting purified HSCs safely and effectively into patients. Antioxid. Redox Signal. 00, 000-000.
View details for PubMedID 29113449
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Prrx1 Labels the Fibrogenic Fibroblast in the Ventral Dermis
WILEY. 2018: A4
View details for Web of Science ID 000430308600009
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Single-cell transcriptomics of 20 mouse organs creates a Tabula Muris.
Nature
2018; 562 (7727): 367–72
Abstract
Here we present a compendium of single-cell transcriptomic data from the model organism Mus musculus that comprises more than 100,000 cells from 20 organs and tissues. These data represent a new resource for cell biology, reveal gene expression in poorly characterized cell populations and enable the direct and controlled comparison of gene expression in cell types that are shared between tissues, such as T lymphocytes and endothelial cells from different anatomical locations. Two distinct technical approaches were used for most organs: one approach, microfluidic droplet-based 3'-end counting, enabled the survey of thousands of cells at relatively low coverage, whereas the other, full-length transcript analysis based on fluorescence-activated cell sorting, enabled the characterization of cell types with high sensitivity and coverage. The cumulative data provide the foundation for an atlas of transcriptomic cell biology.
View details for DOI 10.1038/s41586-018-0590-4
View details for PubMedID 30283141
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Prolonged survival of transplanted stem cells after ischaemic injury via the slow release of pro-survival peptides from a collagen matrix
Nature Biomedical Engineering
2018; 2 (2): 104–13
Abstract
Stem-cell-based therapies hold considerable promise for regenerative medicine. However, acute donor-cell death within several weeks after cell delivery remains a critical hurdle for clinical translation. Co-transplantation of stem cells with pro-survival factors can improve cell engraftment, but this strategy has been hampered by the typically short half-lives of the factors and by the use of Matrigel and other scaffolds that are not chemically defined. Here, we report a collagen-dendrimer biomaterial crosslinked with pro-survival peptide analogues that adheres to the extracellular matrix and slowly releases the peptides, significantly prolonging stem cell survival in mouse models of ischaemic injury. The biomaterial can serve as a generic delivery system to improve functional outcomes in cell-replacement therapy.
View details for DOI 10.1038/s41551-018-0191-4
View details for PubMedCentralID PMC5927627
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Lessons from immuno-oncology: a new era for cancer nanomedicine?
NATURE REVIEWS DRUG DISCOVERY
2017; 16 (6): 369–70
Abstract
Despite a decade of intensive preclinical research, the translation of cancer nanomedicine to the clinic has been slow. Here, we discuss how recent lessons learned from the successes with immuno-oncology therapies could be applied to cancer nanomedicine and how this may help to overcome some of the key technical challenges in this field.
View details for PubMedID 28303024
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Discussion: Regeneration of Vascularized Corticocancellous Bone and Diploic Space Using Muscle- Derived Stem Cells: A Translational Biologic Alternative for Healing Critical Bone Defects
PLASTIC AND RECONSTRUCTIVE SURGERY
2017; 139 (4): 906-907
View details for DOI 10.1097/PRS.0000000000003210
View details for PubMedID 28350669
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Fibroblasts become fat to reduce scarring.
Science
2017; 355 (6326): 693-694
View details for DOI 10.1126/science.aam6748
View details for PubMedID 28209860
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Breaking Down the Barriers to Precision Cancer Nanomedicine
TRENDS IN BIOTECHNOLOGY
2017; 35 (2): 159-171
Abstract
Nanomedicine offers unique advantages in treating human cancers. However, physiological and pathological barriers within normal and disease tissues, which are highly variable among individuals, often hinder its effectiveness. The body possesses specific innate responses to nanoparticles (NPs), which when combined with unique pathophysiological signatures in the tumor microenvironment, can severely limit the utility of nanomedicine in the oncological setting. Furthermore, with the successes of cancer immunotherapies, understanding nanoimmune interactions and developing immune-smart cancer nanomedicine that can take advantage of the body's immune functions will increasingly become clinically relevant. Therefore, a better understanding of the important native and acquired biological processes that dictate the fate of nanomedicine is integral to developing more effective individualized platforms for treating cancer patients.
View details for DOI 10.1016/j.tibtech.2016.07.006
View details for Web of Science ID 000393261300009
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Pharmacological rescue of diabetic skeletal stem cell niches.
Science translational medicine
2017; 9 (372)
Abstract
Diabetes mellitus (DM) is a metabolic disease frequently associated with impaired bone healing. Despite its increasing prevalence worldwide, the molecular etiology of DM-linked skeletal complications remains poorly defined. Using advanced stem cell characterization techniques, we analyzed intrinsic and extrinsic determinants of mouse skeletal stem cell (mSSC) function to identify specific mSSC niche-related abnormalities that could impair skeletal repair in diabetic (Db) mice. We discovered that high serum concentrations of tumor necrosis factor-α directly repressed the expression of Indian hedgehog (Ihh) in mSSCs and in their downstream skeletogenic progenitors in Db mice. When hedgehog signaling was inhibited during fracture repair, injury-induced mSSC expansion was suppressed, resulting in impaired healing. We reversed this deficiency by precise delivery of purified Ihh to the fracture site via a specially formulated, slow-release hydrogel. In the presence of exogenous Ihh, the injury-induced expansion and osteogenic potential of mSSCs were restored, culminating in the rescue of Db bone healing. Our results present a feasible strategy for precise treatment of molecular aberrations in stem and progenitor cell populations to correct skeletal manifestations of systemic disease.
View details for DOI 10.1126/scitranslmed.aag2809
View details for PubMedID 28077677
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Human Adipose-Derived Stromal Cell Isolation Methods and Use in Osteogenic and Adipogenic In Vivo Applications.
Current protocols in stem cell biology
2017; 43
Abstract
Adipose tissue represents an abundant and easily accessible source of multipotent cells, which may serve as excellent building blocks for tissue engineering. This article presents a newly described protocol for isolating adipose-derived stromal cells (ASCs) from human lipoaspirate, compared to the standard protocol for harvesting ASCs established in 2001. Human ASC isolation is performed using two methods, and resultant cells are compared through cell yield, cell viability, cell proliferation and regenerative potential. The osteogenic and adipogenic potential of ASCs isolated using both protocols are assessed invitro and gene expression analysis is performed. The focus of this series of protocols is the regenerative potential of both cell populations in vivo. As such, the two in vivo animal models described are fat graft retention (soft tissue reconstruction) and calvarial defect healing (bone regeneration). The techniques described comprise fat grafting with cell assisted lipotransfer, and calvarial defect creation healed with cell-seeded scaffolds. © 2017 by John Wiley & Sons, Inc.
View details for PubMedID 29140567
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The Role of Skeletal Stem Cells in the Reconstruction of Bone Defects.
The Journal of craniofacial surgery
2017; 28 (5): 1136–41
Abstract
Craniofacial surgery, since its inauguration, has been the culmination of collaborative efforts to solve complex congenital, dysplastic, oncological, and traumatic cranial bone defects. Now, 50 years on from the first craniofacial meeting, the collaborative efforts between surgeons, scientists, and bioengineers are further advancing craniofacial surgery with new discoveries in tissue regeneration. Recent advances in regenerative medicine and stem cell biology have transformed the authors' understanding of bone healing, the role of stem cells governing bone healing, and the effects of the niche environment and extracellular matrix on stem cell fate. This review aims at summarizing the advances within each of these fields.
View details for PubMedID 28665863
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External Beam Radiation Therapy for the Treatment of Human Pluripotent Stem Cell-Derived Teratomas.
Stem cells (Dayton, Ohio)
2017
Abstract
Human pluripotent stem cells (hPSCs), including embryonic stem cells (hESCs) and induced pluripotent stem cells (hiPSCs), have great potential as an unlimited donor source for cell-based therapeutics. The risk of teratoma formation from residual undifferentiated cells, however, remains a critical barrier to the clinical application of these cells. Herein we describe external beam radiation therapy (EBRT) as an attractive option for the treatment of this iatrogenic growth. We present the evidence that EBRT is effective in arresting growth of hESC-derived teratomas in vivo at day 28 post-implantation by utilizing a microCT irradiator capable of targeted treatment in small animals. Within several days of irradiation, teratomas derived from injection of undifferentiated hESCs and hiPSCs demonstrated complete growth arrest lasting several months. In addition, EBRT reduced re-seeding potential of teratoma cells during serial transplantation experiments, requiring irradiated teratomas to be seeded at 1x10(3) higher doses to form new teratomas. We demonstrate that radiation induces teratoma cell apoptosis, senescence, and growth arrest, similar to established radiobiology mechanisms. Taken together, these results provide proof of concept for the use of EBRT in the treatment of existing teratomas and highlight a strategy to increase the safety of stem cell-based therapies. This article is protected by copyright. All rights reserved.
View details for PubMedID 28600830
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Lectins bring benefits to bones
ELIFE
2016; 5
Abstract
The discovery that proteins called c-type lectins promote bone growth could lead to new treatments for age-related bone disorders.
View details for PubMedID 27960074
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A Novel Method of Human Adipose-Derived Stem Cell Isolation with Resultant Increased Cell Yield
PLASTIC AND RECONSTRUCTIVE SURGERY
2016; 138 (6): 983E-996E
Abstract
The authors have developed a novel protocol for isolating adipose-derived stem cells from human lipoaspirate. In this study, they compare their new method to a previously published standard protocol.Human adipose-derived stem cell isolation was performed using two methods to compare cell yield, cell viability, cell proliferation, and regenerative potential. The new and conventional isolation methods differ in two key areas: the collagenase digestion buffer constituents and the use of an orbital shaker. The osteogenic and adipogenic potential of adipose-derived stem cells isolated using both protocols was assessed in vitro, and gene expression analysis was performed. To assess the ability of the isolated cells to generate bone in vivo, the authors created critical-size calvarial defects in mice, which were treated with adipose-derived stem cells loaded onto hydroxyapatite-coated poly(lactic-co-glycolic acid) scaffolds. To test the ability of the isolated cells to enhance adipogenesis, the cells were added to lipoaspirate and placed beneath the scalp of immunocompromised mice. Fat graft volume retention was subsequently assessed by serial computed tomographic volumetric scanning.The new method resulted in a 10-fold increased yield of adipose-derived stem cells compared with the conventional method. Cells harvested using the new method demonstrated significantly increased cell viability and proliferation in vitro (p < 0.05). New method cells also demonstrated significantly enhanced osteogenic and adipogenic differentiation capacity in vitro (p < 0.05) in comparison with the conventional method cells. Both cell groups demonstrated equivalent osteogenic and adipogenic regenerative potential in mice.The authors have developed a protocol that maximizes the yield of adipose-derived stem cells derived from lipoaspirate. The new method cells have increased osteogenic and adipogenic potential in vitro and are not inferior to conventional method cells in terms of their ability to generate bone and fat in vivo.Therapeutic, V.
View details for DOI 10.1097/PRS.0000000000002790
View details for PubMedID 27537222
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Immune Priming of the Tumor Microenvironment by Radiation
TRENDS IN CANCER
2016; 2 (11): 638–45
Abstract
Ionizing irradiation can induce a multitude of alterations within the tumor microenvironment. Unlike targeted therapies, radiation delivered to the tumor bed can prompt phenotypic changes in both normal stromal and cancer cells, leading to molecular and physiological alterations within the tumor microenvironment. These environmental modulations directly influence the degree of immunogenicity of the tumor microenvironment and may ultimately affect tumor responsiveness to cancer immunotherapies. Here we review the preclinical evidence for tumor microenvironment-mediated immune suppression and how radiation can modulate immune properties within a tumor. We then discuss the therapeutic opportunities for combining radiation with molecular agents to enhance tumor immunogenicity and how this represents a potential exciting strategy to complement immunotherapies including immune checkpoint blockers in cancer treatment.
View details for PubMedID 28741502
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Enrichment of Adipose-Derived Stromal Cells for BMPR1A Facilitates Enhanced Adipogenesis
TISSUE ENGINEERING PART A
2016; 22 (3-4): 214-221
Abstract
Reconstruction of soft tissue defects has traditionally relied on the use of grafts and flaps, which may be associated with variable resorption and/or significant donor site morbidity. Cell-based strategies employing adipose-derived stromal cells (ASCs), found within the stromal vascular fraction (SVF) of adipose tissue, may offer an alternative strategy for soft tissue reconstruction. In this study, we investigated the potential of a bone morphogenetic protein receptor type 1A (BMPR1A)(+) subpopulation of ASCs to enhance de novo adipogenesis.Human lipoaspirate was enzymatically digested to isolate SVF and magnetic-activated cell separation was utilized to obtain BMPR1A(+) and BMPR1A(-) cells. These cells, along with unenriched cells, were expanded in culture and evaluated for adipogenic gene expression and in vitro adipocyte formation. Cells from each group were also labeled with a green fluorescent protein (GFP) lentivirus and transplanted into the inguinal fat pads, an adipogenic niche, of immunocompromised mice to determine their potential for de novo adipogenesis. Confocal microscopy along with staining of lipid droplets and vasculature was performed to evaluate the formation of mature adipocytes by transplanted cells.In comparison to BMPR1A(-) and unenriched ASCs, BMPR1A(+) cells demonstrated significantly enhanced adipogenesis when cultured in an adipogenic differentiation medium, as evidenced by increased staining with Oil Red O and increased expression of peroxisome proliferator-activating receptor gamma (PPAR-γ) and fatty acid-binding protein 4 (FABP4). BMPR1A(+) cells also formed significantly more adipocytes in vivo, as demonstrated by quantification of GFP+ adipocytes. Minimal formation of mature adipocytes was appreciated by BMPR1A(-) cells.BMPR1A(+) ASCs show an enhanced ability for adipogenesis in vitro, as shown by gene expression and histological staining. Furthermore, within an adipogenic niche, BMPR1A(+) cells possessed an increased capacity to generate de novo fat compared to BMPR1A(-) and unenriched cells. This suggests utility for the BMPR1A(+) subpopulation in cell-based strategies for soft tissue reconstruction.
View details for DOI 10.1089/ten.tea.2015.0278
View details for PubMedID 26585335
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Local and Circulating Endothelial Cells Undergo Endothelial to Mesenchymal Transition (EndMT) in Response to Musculoskeletal Injury.
Scientific reports
2016; 6: 32514-?
Abstract
Endothelial-to-mesenchymal transition (EndMT) has been implicated in a variety of aberrant wound healing conditions. However, unambiguous evidence of EndMT has been elusive due to limitations of in vitro experimental designs and animal models. In vitro experiments cannot account for the myriad ligands and cells which regulate differentiation, and in vivo tissue injury models may induce lineage-independent endothelial marker expression in mesenchymal cells. By using an inducible Cre model to mark mesenchymal cells (Scx-creERT/tdTomato + ) prior to injury, we demonstrate that musculoskeletal injury induces expression of CD31, VeCadherin, or Tie2 in mesenchymal cells. VeCadherin and Tie2 were expressed in non-endothelial cells (CD31-) present in marrow from uninjured adult mice, thereby limiting the specificity of these markers in inducible models (e.g. VeCadherin- or Tie2-creERT). However, cell transplantation assays confirmed that endothelial cells (ΔVeCadherin/CD31+/CD45-) isolated from uninjured hindlimb muscle tissue undergo in vivo EndMT when transplanted directly into the wound without intervening cell culture using PDGFRα, Osterix (OSX), SOX9, and Aggrecan (ACAN) as mesenchymal markers. These in vivo findings support EndMT in the presence of myriad ligands and cell types, using cell transplantation assays which can be applied for other pathologies implicated in EndMT including tissue fibrosis and atherosclerosis. Additionally, endothelial cell recruitment and trafficking are potential therapeutic targets to prevent EndMT.
View details for DOI 10.1038/srep32514
View details for PubMedID 27616463
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Identification and characterization of an injury-induced skeletal progenitor
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
2015; 112 (32): 9920-9925
Abstract
The postnatal skeleton undergoes growth, remodeling, and repair. We hypothesized that skeletal progenitor cells active during these disparate phases are genetically and phenotypically distinct. We identified a highly potent regenerative cell type that we term the fracture-induced bone, cartilage, stromal progenitor (f-BCSP) in the fracture callus of adult mice. The f-BCSP possesses significantly enhanced skeletogenic potential compared with BCSPs harvested from uninjured bone. It also recapitulates many gene expression patterns involved in perinatal skeletogenesis. Our results indicate that the skeletal progenitor population is functionally stratified, containing distinct subsets responsible for growth, regeneration, and repair. Furthermore, our findings suggest that injury-induced changes to the skeletal stem and progenitor microenvironments could activate these cells and enhance their regenerative potential.
View details for DOI 10.1073/pnas.1513066112
View details for PubMedID 26216955
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Assessment of the Radiation Effects of Cardiac CT Angiography Using Protein and Genetic Biomarkers
JACC-CARDIOVASCULAR IMAGING
2015; 8 (8): 873-884
View details for DOI 10.1016/j.jcmg.2015.04.016
View details for Web of Science ID 000359895400001
View details for PubMedID 26210695
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Assessment of the Radiation Effects of Cardiac CT Angiography Using Protein and Genetic Biomarkers.
JACC. Cardiovascular imaging
2015; 8 (8): 873-884
Abstract
The purpose of this study was to evaluate whether radiation exposure from cardiac computed tomographic angiography (CTA) is associated with deoxyribonucleic acid (DNA) damage and whether damage leads to programmed cell death and activation of genes involved in apoptosis and DNA repair.Exposure to radiation from medical imaging has become a public health concern, but whether it causes significant cell damage remains unclear.We conducted a prospective cohort study in 67 patients undergoing cardiac CTA between January 2012 and December 2013 in 2 U.S. medical centers. Median blood radiation exposure was estimated using phantom dosimetry. Biomarkers of DNA damage and apoptosis were measured by flow cytometry, whole genome sequencing, and single cell polymerase chain reaction.The median dose length product was 1,535.3 mGy•cm (969.7 to 2,674.0 mGy•cm). The median radiation dose to the blood was 29.8 mSv (18.8 to 48.8 mSv). Median DNA damage increased 3.39% (1.29% to 8.04%, p < 0.0001) and median apoptosis increased 3.1-fold (1.4- to 5.1-fold, p < 0.0001) post-radiation. Whole genome sequencing revealed changes in the expression of 39 transcription factors involved in the regulation of apoptosis, cell cycle, and DNA repair. Genes involved in mediating apoptosis and DNA repair were significantly changed post-radiation, including DDB2 (1.9-fold [1.5- to 3.0-fold], p < 0.001), XRCC4 (3.0-fold [1.1- to 5.4-fold], p = 0.005), and BAX (1.6-fold [0.9- to 2.6-fold], p < 0.001). Exposure to radiation was associated with DNA damage (odds ratio [OR]: 1.8 [1.2 to 2.6], p = 0.003). DNA damage was associated with apoptosis (OR: 1.9 [1.2 to 5.1], p < 0.0001) and gene activation (OR: 2.8 [1.2 to 6.2], p = 0.002).Patients exposed to >7.5 mSv of radiation from cardiac CTA had evidence of DNA damage, which was associated with programmed cell death and activation of genes involved in apoptosis and DNA repair.
View details for DOI 10.1016/j.jcmg.2015.04.016
View details for PubMedID 26210695
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The role and regulation of osteoclasts in normal bone homeostasis and in response to injury.
Plastic and reconstructive surgery
2015; 135 (3): 808-816
Abstract
Bone is a dynamic tissue, with a range of diverse functions, including locomotion, protection of internal organs, and hematopoiesis. Optimum treatment of fractures and/or bone defects requires knowledge of the complex cellular interactions involved with bone healing and remodeling. Emerging data have underscored the importance of osteoclasts in this process, playing a key role both in normal bone turnover and in facilitating bone regeneration. In this review, the authors discuss the basic principles of osteoclast biology, including its cellular origins, its function, and key regulatory mechanisms, in addition to conditions that arise when osteoclast function is altered.
View details for DOI 10.1097/PRS.0000000000000963
View details for PubMedID 25719699
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Identification and specification of the mouse skeletal stem cell.
Cell
2015; 160 (1-2): 285-298
Abstract
How are skeletal tissues derived from skeletal stem cells? Here, we map bone, cartilage, and stromal development from a population of highly pure, postnatal skeletal stem cells (mouse skeletal stem cells, mSSCs) to their downstream progenitors of bone, cartilage, and stromal tissue. We then investigated the transcriptome of the stem/progenitor cells for unique gene-expression patterns that would indicate potential regulators of mSSC lineage commitment. We demonstrate that mSSC niche factors can be potent inducers of osteogenesis, and several specific combinations of recombinant mSSC niche factors can activate mSSC genetic programs in situ, even in nonskeletal tissues, resulting in de novo formation of cartilage or bone and bone marrow stroma. Inducing mSSC formation with soluble factors and subsequently regulating the mSSC niche to specify its differentiation toward bone, cartilage, or stromal cells could represent a paradigm shift in the therapeutic regeneration of skeletal tissues.
View details for DOI 10.1016/j.cell.2014.12.002
View details for PubMedID 25594184
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Epigenetic and in vivo comparison of diverse MSC sources reveals an endochondral signature for human hematopoietic niche formation.
Blood
2015; 125 (2): 249-260
Abstract
In the last decade there has been a rapid expansion in clinical trials using mesenchymal stromal cells (MSCs) from a variety of tissues. However, despite similarities in morphology, immunophenotype and differentiation behavior in vitro, MSCs sourced from distinct tissues do not necessarily have equivalent biological properties. We performed a genome-wide methylation, transcription and in vivo evaluation of MSCs from human bone marrow (BM), white adipose tissue, umbilical cord and skin cultured in humanized media. Surprisingly, only BM-derived MSCs spontaneously formed a bone marrow cavity through a vascularized cartilage intermediate in vivo that was progressively replaced by hematopoietic tissue and bone. Only BM-derived MSCs exhibited a chondrogenic transcriptional program with hypomethylation and increased expression of RUNX3, RUNX2, BGLAP, MMP13 and ITGA10 consistent with a latent and primed skeletal developmental potential. The humanized MSC-derived microenvironment permitted homing and maintenance of long-term murine SLAM(+) hematopoietic stem cells (HSCs) as well as human CD34(+)/CD38(-)/CD90(+)/CD45RA(+) HSCs after cord blood transplantation. These studies underscore the profound differences in developmental potential between MSC sources independent of donor age with implications for their clinical use. We also demonstrate a tractable human niche model for studying homing and engraftment of human hematopoietic cells in normal and neoplastic states.
View details for DOI 10.1182/blood-2014-04-572255
View details for PubMedID 25406351
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Positive Selection for Bone Morphogenetic Protein Receptor Type-IB Promotes Differentiation and Specification of Human Adipose-Derived Stromal Cells Toward an Osteogenic Lineage
TISSUE ENGINEERING PART A
2014; 20 (21-22): 3031-3040
Abstract
Adipose tissue represents an abundant and easily accessible source of multipotent cells that may serve as an excellent building block for tissue engineering. However, adipose-derived stromal cells (ASCs) are a heterogeneous group and subpopulations may be identified with enhanced osteogenic potential.Human ASC subpopulations were prospectively isolated based on expression of bone morphogenetic protein receptor type-IB (BMPR-IB). Unsorted, BMPR-IB(+), and BMPR-IB(-) cells were analyzed for their osteogenic capacity through histological staining and gene expression. To evaluate their in vivo osteogenic potential, critical-sized calvarial defects were created in immunocompromised mice and treated with unsorted, BMPR-IB(+), or BMPR-IB(-) cells. Healing was assessed using microcomputed tomography and pentachrome staining of specimens at 8 weeks.Increased osteogenic differentiation was noted in the BMPR-IB(+) subpopulation, as demonstrated by alkaline phosphatase staining at day 7 and extracellular matrix mineralization with Alizarin red staining at day 14. This was also associated with increased expression for osteocalcin, a late marker of osteogenesis. Radiographic analysis demonstrated significantly enhanced healing of critical-sized calvarial defects treated with BMPR-IB(+) ASCs compared with unsorted or BMPR-IB(-) cells. This was confirmed through pentachrome staining, which revealed more robust bone regeneration in the BMPR-IB(+) group.BMPR-IB(+) human ASCs have an enhanced ability to form bone both in vitro and in vivo. These data suggest that positive selection for BMPR-IB(+) and manipulation of the BMP pathway in these cells may yield a highly osteogenic subpopulation of cells for bone tissue engineering.
View details for DOI 10.1089/ten.tea.2014.0101
View details for Web of Science ID 000344592600021
View details for PubMedCentralID PMC4229710
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Positive selection for bone morphogenetic protein receptor type-IB promotes differentiation and specification of human adipose-derived stromal cells toward an osteogenic lineage.
Tissue engineering. Part A
2014; 20 (21-22): 3031-3040
Abstract
Adipose tissue represents an abundant and easily accessible source of multipotent cells that may serve as an excellent building block for tissue engineering. However, adipose-derived stromal cells (ASCs) are a heterogeneous group and subpopulations may be identified with enhanced osteogenic potential.Human ASC subpopulations were prospectively isolated based on expression of bone morphogenetic protein receptor type-IB (BMPR-IB). Unsorted, BMPR-IB(+), and BMPR-IB(-) cells were analyzed for their osteogenic capacity through histological staining and gene expression. To evaluate their in vivo osteogenic potential, critical-sized calvarial defects were created in immunocompromised mice and treated with unsorted, BMPR-IB(+), or BMPR-IB(-) cells. Healing was assessed using microcomputed tomography and pentachrome staining of specimens at 8 weeks.Increased osteogenic differentiation was noted in the BMPR-IB(+) subpopulation, as demonstrated by alkaline phosphatase staining at day 7 and extracellular matrix mineralization with Alizarin red staining at day 14. This was also associated with increased expression for osteocalcin, a late marker of osteogenesis. Radiographic analysis demonstrated significantly enhanced healing of critical-sized calvarial defects treated with BMPR-IB(+) ASCs compared with unsorted or BMPR-IB(-) cells. This was confirmed through pentachrome staining, which revealed more robust bone regeneration in the BMPR-IB(+) group.BMPR-IB(+) human ASCs have an enhanced ability to form bone both in vitro and in vivo. These data suggest that positive selection for BMPR-IB(+) and manipulation of the BMP pathway in these cells may yield a highly osteogenic subpopulation of cells for bone tissue engineering.
View details for DOI 10.1089/ten.TEA.2014.0101
View details for PubMedID 24854876
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Abstract 161: identification of cell-intrinsic mechanisms and differentially regulated genetic pathways responsible for the age-related functional decline in aged skeletal stem cells.
Plastic and reconstructive surgery
2014; 133 (3): 178-?
View details for DOI 10.1097/01.prs.0000444990.75431.f1
View details for PubMedID 25942271
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Osteoclast derivation from mouse bone marrow.
Journal of visualized experiments : JoVE
2014
View details for DOI 10.3791/52056
View details for PubMedID 25407120
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Osteoclast derivation from mouse bone marrow.
Journal of visualized experiments : JoVE
2014
Abstract
Osteoclasts are highly specialized cells that are derived from the monocyte/macrophage lineage of the bone marrow. Their unique ability to resorb both the organic and inorganic matrices of bone means that they play a key role in regulating skeletal remodeling. Together, osteoblasts and osteoclasts are responsible for the dynamic coupling process that involves both bone resorption and bone formation acting together to maintain the normal skeleton during health and disease. As the principal bone-resorbing cell in the body, changes in osteoclast differentiation or function can result in profound effects in the body. Diseases associated with altered osteoclast function can range in severity from lethal neonatal disease due to failure to form a marrow space for hematopoiesis, to more commonly observed pathologies such as osteoporosis, in which excessive osteoclastic bone resorption predisposes to fracture formation. An ability to isolate osteoclasts in high numbers in vitro has allowed for significant advances in the understanding of the bone remodeling cycle and has paved the way for the discovery of novel therapeutic strategies that combat these diseases. Here, we describe a protocol to isolate and cultivate osteoclasts from mouse bone marrow that will yield large numbers of osteoclasts.
View details for DOI 10.3791/52056
View details for PubMedID 25407120
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BLT-humanized C57BL/6 Rag2(-/-)gamma(-/-)(c)CD47(-/-) mice are resistant to GVHD and develop B- and T-cell immunity to HIV infection
BLOOD
2013; 122 (25): 4013-4020
Abstract
The use of C57BL/6 Rag2(-/-)γc(-/-) mice as recipients for xenotransplantation with human immune systems (humanization) has been problematic because C57BL/6 SIRPα does not recognize human CD47, and such recognition is required to suppress macrophage-mediated phagocytosis of transplanted human hematopoietic stem cells (HSCs). We show that genetic inactivation of CD47 on the C57BL/6 Rag2(-/-)γc(-/-) background negates the requirement for CD47-signal recognition protein α (SIRPα) signaling and induces tolerance to transplanted human HSCs. These triple-knockout, bone marrow, liver, thymus (TKO-BLT) humanized mice develop organized lymphoid tissues including mesenteric lymph nodes, splenic follicles and gut-associated lymphoid tissue that demonstrate high levels of multilineage hematopoiesis. Importantly, these mice have an intact complement system and showed no signs of graft-versus-host disease (GVHD) out to 29 weeks after transplantation. Sustained, high-level HIV-1 infection was observed via either intrarectal or intraperitoneal inoculation. TKO-BLT mice exhibited hallmarks of human HIV infection including CD4(+) T-cell depletion, immune activation, and development of HIV-specific B- and T-cell responses. The lack of GVHD makes the TKO-BLT mouse a significantly improved model for long-term studies of pathogenesis, immune responses, therapeutics, and vaccines to human pathogens.
View details for DOI 10.1182/blood-2013-06-506949
View details for Web of Science ID 000329739100009
View details for PubMedID 24021673
View details for PubMedCentralID PMC3862274
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Clonal precursor of bone, cartilage, and hematopoietic niche stromal cells
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
2013; 110 (31): 12643-12648
Abstract
Organs are composites of tissue types with diverse developmental origins, and they rely on distinct stem and progenitor cells to meet physiological demands for cellular production and homeostasis. How diverse stem cell activity is coordinated within organs is not well understood. Here we describe a lineage-restricted, self-renewing common skeletal progenitor (bone, cartilage, stromal progenitor; BCSP) isolated from limb bones and bone marrow tissue of fetal, neonatal, and adult mice. The BCSP clonally produces chondrocytes (cartilage-forming) and osteogenic (bone-forming) cells and at least three subsets of stromal cells that exhibit differential expression of cell surface markers, including CD105 (or endoglin), Thy1 [or CD90 (cluster of differentiation 90)], and 6C3 [ENPEP glutamyl aminopeptidase (aminopeptidase A)]. These three stromal subsets exhibit differential capacities to support hematopoietic (blood-forming) stem and progenitor cells. Although the 6C3-expressing subset demonstrates functional stem cell niche activity by maintaining primitive hematopoietic stem cell (HSC) renewal in vitro, the other stromal populations promote HSC differentiation to more committed lines of hematopoiesis, such as the B-cell lineage. Gene expression analysis and microscopic studies further reveal a microenvironment in which CD105-, Thy1-, and 6C3-expressing marrow stroma collaborate to provide cytokine signaling to HSCs and more committed hematopoietic progenitors. As a result, within the context of bone as a blood-forming organ, the BCSP plays a critical role in supporting hematopoiesis through its generation of diverse osteogenic and hematopoietic-promoting stroma, including HSC supportive 6C3(+) niche cells.
View details for DOI 10.1073/pnas.1310212110
View details for PubMedID 23858471
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Do pluripotent stem cells exist in adult mice as very small embryonic stem cells?
Stem cell reports
2013; 1 (2): 198-208
Abstract
Very small embryonic-like stem cells (VSELs) isolated from bone marrow (BM) have been reported to be pluripotent. Given their nonembryonic source, they could replace blastocyst-derived embryonic stem cells in research and medicine. However, their multiple-germ-layer potential has been incompletely studied. Here, we show that we cannot find VSELs in mouse BM with any of the reported stem cell potentials, specifically for hematopoiesis. We found that: (1) most events within the "VSEL" flow-cytometry gate had little DNA and the cells corresponding to these events (2) could not form spheres, (3) did not express Oct4, and (4) could not differentiate into blood cells. These results provide a failure to confirm the existence of pluripotent VSELs.
View details for DOI 10.1016/j.stemcr.2013.07.001
View details for PubMedID 24052953
View details for PubMedCentralID PMC3757755
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Do pluripotent stem cells exist in adult mice as very small embryonic stem cells?
Stem cell reports
2013; 1 (2): 198-208
Abstract
Very small embryonic-like stem cells (VSELs) isolated from bone marrow (BM) have been reported to be pluripotent. Given their nonembryonic source, they could replace blastocyst-derived embryonic stem cells in research and medicine. However, their multiple-germ-layer potential has been incompletely studied. Here, we show that we cannot find VSELs in mouse BM with any of the reported stem cell potentials, specifically for hematopoiesis. We found that: (1) most events within the "VSEL" flow-cytometry gate had little DNA and the cells corresponding to these events (2) could not form spheres, (3) did not express Oct4, and (4) could not differentiate into blood cells. These results provide a failure to confirm the existence of pluripotent VSELs.
View details for DOI 10.1016/j.stemcr.2013.07.001
View details for PubMedID 24052953
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In vivo directed differentiation of pluripotent stem cells for skeletal regeneration
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
2012; 109 (50): 20379-20384
Abstract
Pluripotent cells represent a powerful tool for tissue regeneration, but their clinical utility is limited by their propensity to form teratomas. Little is known about their interaction with the surrounding niche following implantation and how this may be applied to promote survival and functional engraftment. In this study, we evaluated the ability of an osteogenic microniche consisting of a hydroxyapatite-coated, bone morphogenetic protein-2-releasing poly-L-lactic acid scaffold placed within the context of a macroenvironmental skeletal defect to guide in vivo differentiation of both embryonic and induced pluripotent stem cells. In this setting, we found de novo bone formation and participation by implanted cells in skeletal regeneration without the formation of a teratoma. This finding suggests that local cues from both the implanted scaffold/cell micro- and surrounding macroniche may act in concert to promote cellular survival and the in vivo acquisition of a terminal cell fate, thereby allowing for functional engraftment of pluripotent cells into regenerating tissue.
View details for DOI 10.1073/pnas.1218052109
View details for PubMedID 23169671
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VHL loss in renal cell carcinoma leads to up-regulation of CUB domain-containing protein 1 to stimulate PKC delta-driven migration
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
2011; 108 (5): 1931-1936
Abstract
A common genetic mutation found in clear cell renal cell carcinoma (CC-RCC) is the loss of the von Hippel-Lindau (VHL) gene, which results in stabilization of hypoxia-inducible factors (HIFs), and contributes to cancer progression and metastasis. CUB-domain-containing protein 1 (CDCP1) was shown to promote metastasis in scirrhous and lung adenocarcinomas as well as in prostate cancer. In this study, we established a molecular mechanism linking VHL loss to induction of the CDCP1 gene through the HIF-1/2 pathway in renal cancer. Also, we report that Fyn, which forms a complex with CDCP1 and mediates its signaling to PKCδ, is a HIF-1 target gene. Mechanistically, we found that CDCP1 specifically regulates phosphorylation of PKCδ, but not of focal adhesion kinase or Crk-associated substrate. Signal transduction from CDCP1 to PKCδ leads to its activation, increasing migration of CC-RCC. Furthermore, patient survival can be stratified by CDCP1 expression at the cell surface of the tumor. Taken together, our data indicates that CDCP1 protein might serve as a therapeutic target for CC-RCC.
View details for DOI 10.1073/pnas.1011777108
View details for PubMedID 21233420
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Anti-CD47 Antibody Synergizes with Rituximab to Promote Phagocytosis and Eradicate Non-Hodgkin Lymphoma
CELL
2010; 142 (5): 699-713
Abstract
Monoclonal antibodies are standard therapeutics for several cancers including the anti-CD20 antibody rituximab for B cell non-Hodgkin lymphoma (NHL). Rituximab and other antibodies are not curative and must be combined with cytotoxic chemotherapy for clinical benefit. Here we report the eradication of human NHL solely with a monoclonal antibody therapy combining rituximab with a blocking anti-CD47 antibody. We identified increased expression of CD47 on human NHL cells and determined that higher CD47 expression independently predicted adverse clinical outcomes in multiple NHL subtypes. Blocking anti-CD47 antibodies preferentially enabled phagocytosis of NHL cells and synergized with rituximab. Treatment of human NHL-engrafted mice with anti-CD47 antibody reduced lymphoma burden and improved survival, while combination treatment with rituximab led to elimination of lymphoma and cure. These antibodies synergized through a mechanism combining Fc receptor (FcR)-dependent and FcR-independent stimulation of phagocytosis that might be applicable to many other cancers.
View details for DOI 10.1016/j.cell.2010.07.044
View details for PubMedID 20813259
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Endochondral ossification is required for haematopoietic stem-cell niche formation
NATURE
2009; 457 (7228): 490-U9
Abstract
Little is known about the formation of niches, local micro-environments required for stem-cell maintenance. Here we develop an in vivo assay for adult haematopoietic stem-cell (HSC) niche formation. With this assay, we identified a population of progenitor cells with surface markers CD45(-)Tie2(-)alpha(V)(+)CD105(+)Thy1.1(-) (CD105(+)Thy1(-)) that, when sorted from 15.5 days post-coitum fetal bones and transplanted under the adult mouse kidney capsule, could recruit host-derived blood vessels, produce donor-derived ectopic bones through a cartilage intermediate and generate a marrow cavity populated by host-derived long-term reconstituting HSC (LT-HSC). In contrast, CD45(-)Tie2(-)alpha(V)(+)CD105(+)Thy1(+) (CD105(+)Thy1(+)) fetal bone progenitors form bone that does not contain a marrow cavity. Suppressing expression of factors involved in endochondral ossification, such as osterix and vascular endothelial growth factor (VEGF), inhibited niche generation. CD105(+)Thy1(-) progenitor populations derived from regions of the fetal mandible or calvaria that do not undergo endochondral ossification formed only bone without marrow in our assay. Collectively, our data implicate endochondral ossification, bone formation that proceeds through a cartilage intermediate, as a requirement for adult HSC niche formation.
View details for DOI 10.1038/nature07547
View details for PubMedID 19078959
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Elucidation of the phenotypic, functional, and molecular topography of a myeloerythroid progenitor cell hierarchy
CELL STEM CELL
2007; 1 (4): 428-442
Abstract
The major myeloid blood cell lineages are generated from hematopoietic stem cells by differentiation through a series of increasingly committed progenitor cells. Precise characterization of intermediate progenitors is important for understanding fundamental differentiation processes and a variety of disease states, including leukemia. Here, we evaluated the functional in vitro and in vivo potentials of a range of prospectively isolated myeloid precursors with differential expression of CD150, Endoglin, and CD41. Our studies revealed a hierarchy of myeloerythroid progenitors with distinct lineage potentials. The global gene expression signatures of these subsets were consistent with their functional capacities, and hierarchical clustering analysis suggested likely lineage relationships. These studies provide valuable tools for understanding myeloid lineage commitment, including isolation of an early erythroid-restricted precursor, and add to existing models of hematopoietic differentiation by suggesting that progenitors of the innate and adaptive immune system can separate late, following the divergence of megakaryocytic/erythroid potential.
View details for DOI 10.1016/j.stem.2007.07.005
View details for Web of Science ID 000251055300012
View details for PubMedID 18371379