I am a Physician-Engineer with multidisciplinary training in diverse fields. In my doctoral research, I developed robust technologies of stem cell differentiation and cellular reprogramming for cardiovascular and neural tissue engineering and regenerative medicine applications. My current research combines genome engineering, systems biology, cell biology, molecular biology and engineering principles to investigate organelle (i.e., melanosome and lysosomes) biogenesis in order to understand how organelle level perturbations influence stem cell, tissue and organismal pathophysiology with the aim to engineer novel therapeutics.
Honors & Awards
Mansour Award, poster prize winner, Chemical and Systems Biology, Stanford University (2018)
Peer Reviewed Cancer Research Program (PRCRP) Horizon Award ($235, 500), U.S. Army Medical Research and Materiel Command (USAMRMC) (2017)
Research work received IMPACT Award ($32,800), SUNY at Buffalo (2014)
Education & Certifications
PhD, University at Buffalo-SUNY, Chemical and Biological Engineering (2015)
Master of Technology, Indian Institute of Technology, Kanpur, India, Bioengineering (2008)
MBBS, Maharani Laxmi Bai Medical College, Jhansi, India, Medicine (2005)
Professional Affiliations and Activities
Member, Biomedical Engineering Society (BMES) (2011 - Present)
Member, American Institute of Chemical Engineers (AIChE) (2011 - Present)
Member, International Society for Stem Cell Research (ISSCR) (2015 - Present)
A genome-wide genetic screen uncovers novel determinants of human pigmentation
bioRxiv Cold Spring Harbor Laboratory
View details for DOI 10.1101/2021.09.29.462413
Human-chimpanzee fused cells reveal cis-regulatory divergence underlying skeletal evolution.
Gene regulatory divergence is thought to play a central role in determining human-specific traits. However, our ability to link divergent regulation to divergent phenotypes is limited. Here, we utilized human-chimpanzee hybrid induced pluripotent stem cells to study gene expression separating these species. The tetraploid hybrid cells allowed us to separate cis- from trans-regulatory effects, and to control for nongenetic confounding factors. We differentiated these cells into cranial neural crest cells, the primary cell type giving rise to the face. We discovered evidence of lineage-specific selection on the hedgehog signaling pathway, including a human-specific sixfold down-regulation of EVC2 (LIMBIN), a key hedgehog gene. Inducing a similar down-regulation of EVC2 substantially reduced hedgehog signaling output. Mice and humans lacking functional EVC2 show striking phenotypic parallels to human-chimpanzee craniofacial differences, suggesting that the regulatory divergence of hedgehog signaling may have contributed to the unique craniofacial morphology of humans.
View details for DOI 10.1038/s41588-021-00804-3
View details for PubMedID 33731941
A microfluidic cell-migration assay for the prediction of progression-free survival and recurrence time of patients with glioblastoma.
Nature biomedical engineering
Clinical scores, molecular markers and cellular phenotypes have been used to predict the clinical outcomes of patients with glioblastoma. However, their clinical use has been hampered by confounders such as patient co-morbidities, by the tumoral heterogeneity of molecular and cellular markers, and by the complexity and cost of high-throughput single-cell analysis. Here, we show that a microfluidic assay for the quantification of cell migration and proliferation can categorize patients with glioblastoma according to progression-free survival. We quantified with a composite score the ability of primary glioblastoma cells to proliferate (via the protein biomarker Ki-67) and to squeeze through microfluidic channels, mimicking aspects of the tight perivascular conduits and white-matter tracts in brain parenchyma. The assay retrospectively categorized 28 patients according to progression-free survival (short-term or long-term) with an accuracy of 86%, predicted time to recurrence and correctly categorized five additional patients on the basis of survival prospectively. RNA sequencing of the highly motile cells revealed differentially expressed genes that correlated with poor prognosis. Our findings suggest that cell-migration and proliferation levels can predict patient-specific clinical outcomes.
View details for DOI 10.1038/s41551-020-00621-9
View details for PubMedID 32989283
Neural crest stem cells from human epidermis of aged donors maintain their multipotency in vitro and in vivo.
2019; 9 (1): 9750
Neural crest (NC) cells are multipotent stem cells that arise from the embryonic ectoderm, delaminate from the neural tube in early vertebrate development and migrate throughout the developing embryo, where they differentiate into various cell lineages. Here we show that multipotent and functional NC cells can be derived by induction with a growth factor cocktail containing FGF2 and IGF1 from cultures of human inter-follicular keratinocytes (KC) isolated from elderly donors. Adult NC cells exhibited longer doubling times as compared to neonatal NC cells, but showed limited signs of cellular senescence despite the advanced age of the donors and exhibited significantly younger epigenetic age as compared to KC. They also maintained their multipotency, as evidenced by their ability to differentiate into all NC-specific lineages including neurons, Schwann cells, melanocytes, and smooth muscle cells (SMC). Notably, upon implantation into chick embryos, adult NC cells behaved similar to their embryonic counterparts, migrated along stereotypical pathways and contributed to multiple NC derivatives in ovo. These results suggest that KC-derived NC cells may provide an easily accessible, autologous source of stem cells that can be used for treatment of neurodegenerative diseases or as a model system for studying disease pathophysiology and drug development.
View details for DOI 10.1038/s41598-019-46140-9
View details for PubMedID 31278326
- A microfluidic assay for the quantification of the metastatic propensity of breast cancer specimens NATURE BIOMEDICAL ENGINEERING 2019; 3 (6): 452–65
Cross-species blastocyst chimerism between nonhuman primates using iPSCs
bioRxiv Cold Spring Harbor Laboratory
View details for DOI 10.1101/635250
Derivation of neural crest stem cells from human epidermal keratinocytes requires FGF-2, IGF-1, and inhibition of TGF-beta 1
BIOENGINEERING & TRANSLATIONAL MEDICINE
2018; 3 (3): 256–64
Neural crest (NC) cells play a central role in forming the peripheral nervous system, the craniofacial skeleton, and the pigmentation of the skin during development due to their broad multilineage differentiation potential into neurons, Schwann cells, melanocytes, and mesenchymal stem cells. Recently, we identified an easily accessible source of pluripotent NC stem cells from human inter-follicular keratinocyte (KC) cultures (KC-NC). In this work, we examined specific conditions for the derivation of NC from KC cultures. More specifically, we examined the role of two growth factors, FGF2 and IGF1, in NC proliferation and in expression of two potent NC transcription factors, Sox10 and FoxD3. Using specific chemical inhibitors, we uncovered that the downstream regulatory pathways AKT/PI3K, MEK/ERK, and JNK/cJun may be critical in Sox10 and FoxD3 regulation in KC-NC. The TGF-β1 pathway was also implicated in suppressing Sox10 expression and NC proliferation. In summary, our study shed light into the role of FGF2, IGF1, and TGF-β1 on the induction of NC from KC cultures and the pathways that regulate Sox10 and FoxD3. We also established culture conditions for sustaining KC-NC multipotency and, therefore, the potential of these cells for regenerative medicine and cellular therapies.
View details for DOI 10.1002/btm2.10109
View details for Web of Science ID 000447808300009
View details for PubMedID 30377664
View details for PubMedCentralID PMC6195909
Reprogramming Postnatal Human Epidermal Keratinocytes Toward Functional Neural Crest Fates
2017; 35 (5): 1402-1415
During development, neural crest (NC) cells are induced by signaling events at the neural plate border of all vertebrate embryos. Initially arising within the central nervous system, NC cells subsequently undergo an epithelial to mesenchymal transition to migrate into the periphery, where they differentiate into diverse cell types. Here we provide evidence that postnatal human epidermal keratinocytes (KC), in response to fibroblast growth factor 2 and insulin like growth factor 1 signals, can be reprogrammed toward a NC fate. Genome-wide transcriptome analyses show that keratinocyte-derived NC cells are similar to those derived from human embryonic stem cells. Moreover, they give rise in vitro and in vivo to NC derivatives such as peripheral neurons, melanocytes, Schwann cells and mesenchymal cells (osteocytes, chondrocytes, adipocytes, and smooth muscle cells). By demonstrating that human keratin-14+ KC can form NC cells, even from clones of single cells, our results have important implications in stem cell biology and regenerative medicine. Stem Cells 2017;35:1402-1415.
View details for DOI 10.1002/stem.2583
View details for Web of Science ID 000400017200024
View details for PubMedID 28142205
NANOG Reverses the Myogenic Differentiation Potential of Senescent Stem Cells by Restoring ACTIN Filamentous Organization and SRF-Dependent Gene Expression
2017; 35 (1): 207-221
Cellular senescence as a result of organismal aging or progeroid diseases leads to stem cell pool exhaustion hindering tissue regeneration and contributing to the progression of age related disorders. Here we discovered that ectopic expression of the pluripotent factor NANOG in senescent or progeroid myogenic progenitors reversed cellular aging and restored completely the ability to generate contractile force. To elicit its effects, NANOG enabled reactivation of the ROCK and Transforming Growth Factor (TGF)-β pathways-both of which were impaired in senescent cells-leading to ACTIN polymerization, MRTF-A translocation into the nucleus and serum response factor (SRF)-dependent myogenic gene expression. Collectively our data reveal that cellular senescence can be reversed and provide a novel strategy to regain the lost function of aged stem cells without reprogramming to the pluripotent state. Stem Cells 2017;35:207-221.
View details for DOI 10.1002/stem.2452
View details for Web of Science ID 000391966700022
View details for PubMedID 27350449
Flow induced adherens junction remodeling driven by cytoskeletal forces.
Experimental cell research
Adherens junctions (AJs) are a key structural component for tissue organization and function. Under fluid shear stress, AJs exhibit dynamic assembly/disassembly, but how shear stress couples to AJs is unclear. In MDCK cells we measured simultaneously the forces in cytoskeletal α-actinin and the density and length of AJs using a genetically coded optical force sensor, actinin-sstFRET, and fluorescently labeled E-cadherin (E-cad). We found that shear stress of 0.74dyn/cm(2) for 3h significantly enhanced E-cad expression at cell-cell contacts and this phenomenon has two phases. The initial formation of segregated AJ plaques coincided with a decrease in cytoskeletal tension, but an increase in tension was necessary for expansion of the plaques and the formation of continuous AJs in the later phase. The changes in cytoskeletal tension and reorganization appear to be an upstream process in response to flow since it occurred in both wild type and dominant negative E-cad cells. Disruption of F-actin with a Rho-ROCK inhibitor eliminated AJ growth under flow. These results delineate the shear stress transduction paths in cultured cells, which helps to understand pathology of a range of diseases that involve dysfunction of E-cadherin.
View details for DOI 10.1016/j.yexcr.2017.08.009
View details for PubMedID 28803065
Heart Regeneration with Engineered Myocardial Tissue
ANNUAL REVIEW OF BIOMEDICAL ENGINEERING, VOL 16
2014; 16: 1-28
Heart disease is the leading cause of morbidity and mortality worldwide, and regenerative therapies that replace damaged myocardium could benefit millions of patients annually. The many cell types in the heart, including cardiomyocytes, endothelial cells, vascular smooth muscle cells, pericytes, and cardiac fibroblasts, communicate via intercellular signaling and modulate each other's function. Although much progress has been made in generating cells of the cardiovascular lineage from human pluripotent stem cells, a major challenge now is creating the tissue architecture to integrate a microvascular circulation and afferent arterioles into such an engineered tissue. Recent advances in cardiac and vascular tissue engineering will move us closer to the goal of generating functionally mature tissue. Using the biology of the myocardium as the foundation for designing engineered tissue and addressing the challenges to implantation and integration, we can bridge the gap from bench to bedside for a clinically tractable engineered cardiac tissue.
View details for DOI 10.1146/annurev-bioeng-071812-152344
View details for Web of Science ID 000348433000001
View details for PubMedID 24819474
View details for PubMedCentralID PMC4213953
Functional vascular smooth muscle cells derived from human induced pluripotent stem cells via mesenchymal stem cell intermediates
2012; 96 (3): 391-400
Smooth muscle cells (SMC) play an important role in vascular homeostasis and disease. Although adult mesenchymal stem cells (MSC) have been used as a source of contractile SMC, they suffer from limited proliferation potential and culture senescence, particularly when originating from older donors. By comparison, human induced pluripotent stem cells (hiPSC) can provide an unlimited source of functional SMC for autologous cell-based therapies and for creating models of vascular disease. Our goal was to develop an efficient strategy to derive functional, contractile SMC from hiPSC.We developed a robust, stage-wise, feeder-free strategy for hiPSC differentiation into functional SMC through an intermediate stage of multipotent MSC, which could be coaxed to differentiate into fat, bone, cartilage, and muscle. At this stage, the cells were highly proliferative and displayed higher clonogenic potential and reduced senescence when compared with parental hair follicle mesenchymal stem cells. In addition, when exposed to differentiation medium, the myogenic proteins such as α-smooth muscle actin, calponin, and myosin heavy chain were significantly upregulated and displayed robust fibrillar organization, suggesting the development of a contractile phenotype. Indeed, tissue constructs prepared from these cells exhibited high levels of contractility in response to receptor- and non-receptor-mediated agonists.We developed an efficient stage-wise strategy that enabled hiPSC differentiation into contractile SMC through an intermediate population of clonogenic and multipotent MSC. The high yield of MSC and SMC derivation suggests that our strategy may facilitate an acquisition of the large numbers of cells required for regenerative medicine or for studying vascular disease pathophysiology.
View details for DOI 10.1093/cvr/cvs253
View details for Web of Science ID 000311306800010
View details for PubMedID 22941255
View details for PubMedCentralID PMC3584971
Stem Cell Sources for Vascular Tissue Engineering and Regeneration
TISSUE ENGINEERING PART B-REVIEWS
2012; 18 (5): 405-425
This review focuses on the stem cell sources with the potential to be used in vascular tissue engineering and to promote vascular regeneration. The first clinical studies using tissue-engineered vascular grafts are already under way, supporting the potential of this technology in the treatment of cardiovascular and other diseases. Despite progress in engineering biomaterials with the appropriate mechanical properties and biological cues as well as bioreactors for generating the correct tissue microenvironment, the source of cells that make up the vascular tissues remains a major challenge for tissue engineers and physicians. Mature cells from the tissue of origin may be difficult to obtain and suffer from limited proliferative capacity, which may further decline as a function of donor age. On the other hand, multipotent and pluripotent stem cells have great potential to provide large numbers of autologous cells with a great differentiation capacity. Here, we discuss the adult multipotent as well as embryonic and induced pluripotent stem cells, their differentiation potential toward vascular lineages, and their use in engineering functional and implantable vascular tissues. We also discuss the associated challenges that need to be addressed in order to facilitate the transition of this technology from the bench to the bedside.
View details for DOI 10.1089/ten.teb.2011.0264
View details for Web of Science ID 000309516500006
View details for PubMedID 22571595
View details for PubMedCentralID PMC3458622
Clonal multipotency and effect of long-term in vitro expansion on differentiation potential of human hair follicle derived mesenchymal stem cells
STEM CELL RESEARCH
2012; 8 (1): 74-84
Hair follicle harbors a rich stem cell pool with mesenchymal lineage differentiation potential. Although previous studies with rodent cells demonstrated that hair follicle sheath and papilla cells possess multi-lineage differentiation potential, human hair follicle derived mesenchymal stem cells (hHF-MSCs) have not been characterized in detail in terms of their multipotency. In addition, it is not clear whether these cells are true stem cells that can differentiate along multiple lineages or whether they represent a collection of progenitor cells with restricted differentiation potential. Here we report that hHF-MSCs are highly proliferative cells that can be maintained in culture for ~45 population doublings before they start to show signs of cellular senescence. Under appropriate culture conditions, hHF-MSCs differentiated along the myogenic, osteogenic, adipogenic and chondrogenic lineages, as demonstrated by kinetic gene expression profiling and functional assays. Interestingly, the differentiation potential decreased with time in culture in a lineage-specific manner. Specifically, myogenesis and chondrogenesis showed a moderate decrease over time; osteogenesis was maximum at intermediate passages and adipogenesis was highly sensitive to long-term culture and was diminished at late passages. Finally, hHF-MSCs were clonally multipotent as the majority of hHF-MSCs clones (73%) demonstrated bi- or tri-lineage differentiation potential. These results suggest that hHF-MSCs may present as an alternative source of easily accessible, autologous stem cells for tissue engineering and regenerative medicine.
View details for DOI 10.1016/j.scr.2011.07.003
View details for Web of Science ID 000300129000007
View details for PubMedID 22099022
View details for PubMedCentralID PMC3222855
- Cation-pi interaction: to stack or to spread MOLECULAR PHYSICS 2008; 106 (12-13): 1557-1566