Stanford Advisors

Lab Affiliations

All Publications

  • Bioengineering Cell Therapy for Treatment of Peripheral Artery Disease. Arteriosclerosis, thrombosis, and vascular biology Huang, N. F., Stern, B., Oropeza, B. P., Zaitseva, T. S., Paukshto, M. V., Zoldan, J. 2024


    Peripheral artery disease is an atherosclerotic disease associated with limb ischemia that necessitates limb amputation in severe cases. Cell therapies comprised of adult mononuclear or stromal cells have been clinically tested and show moderate benefits. Bioengineering strategies can be applied to modify cell behavior and function in a controllable fashion. Using mechanically tunable or spatially controllable biomaterials, we highlight examples in which biomaterials can increase the survival and function of the transplanted cells to improve their revascularization efficacy in preclinical models. Biomaterials can be used in conjunction with soluble factors or genetic approaches to further modulate the behavior of transplanted cells and the locally implanted tissue environment in vivo. We critically assess the advances in bioengineering strategies such as 3-dimensional bioprinting and immunomodulatory biomaterials that can be applied to the treatment of peripheral artery disease and then discuss the current challenges and future directions in the implementation of bioengineering strategies.

    View details for DOI 10.1161/ATVBAHA.123.318126

    View details for PubMedID 38174560

  • Cardiovascular human organ-on-a-chip platform for disease modeling, drug development, and personalized therapy. Journal of biomedical materials research. Part A Khanna, A., Oropeza, B. P., Huang, N. F. 2023


    Cardiovascular organ-on-a-chip (OoC) devices are composed of engineered or native functional tissues that are cultured under controlled microenvironments inside microchips. These systems employ microfabrication and tissue engineering techniques to recapitulate human physiology. This review focuses on human OoC systems to model cardiovascular diseases, to perform drug screening, and to advance personalized medicine. We also address the challenges in the generation of organ chips that can revolutionize the large-scale application of these systems for drug development and personalized therapy.

    View details for DOI 10.1002/jbm.a.37602

    View details for PubMedID 37668192

  • Combinatorial extracellular matrix cues with mechanical strain induce differential effects on myogenesis in vitro. Biomaterials science Chan, A. H., Jain, I., Oropeza, B. P., Zhou, T., Nelsen, B., Geisse, N. A., Huang, N. F. 2023


    Skeletal muscle regeneration remains a clinical unmet need for volumetric muscle loss and atrophy where muscle function cannot be restored to prior capacity. Current experimental approaches do not account for the complex microenvironmental factors that modulate myogenesis. In this study we developed a biomimetic tissue chip platform to systematically study the combined effects of the extracellular matrix (ECM) microenvironment and mechanical strain on myogenesis of murine myoblasts. Using stretchable tissue chips composed of collagen I (C), fibronectin (F) and laminin (L), as well as their combinations thereof, we tested the addition of mechanical strain regimens on myogenesis at the transcriptomic and translational levels. Our results show that ECMs have a significant effect on myotube formation in C2C12 murine myoblasts. Under static conditions, laminin substrates induced the longest myotubes, whereas fibronectin produced the widest myotubes. Combinatorial ECMs showed non-intuitive effects on myotube formation. Genome-wide analysis revealed the upregulation in actin cytoskeletal related genes that are suggestive of myogenesis. When mechanical strain was introduced to C + F + L combinatorial ECM substrates in the form of constant or intermittent uniaxial strain at low (5%) and high (15%) levels, we observed synergistic enhancements in myotube width, along with transcriptomic upregulation in myosin heavy chain genes. Together, these studies highlight the complex role of microenvironmental factors such as ECM interactions and strain on myotube formation and the underlying signaling pathways.

    View details for DOI 10.1039/d3bm00448a

    View details for PubMedID 37477446

  • β-Glucan-Mediated Oral Codelivery of 5FU and Bcl2 siRNA Attenuates Stomach Cancer. ACS applied materials & interfaces Afrin, H., Esquivel, S. V., Kumar, R., Zahid, M. I., Oporeza, B., Rahman, M. F., Boland, T., Nurunnabi, M. 2023; 15 (27): 32188-32200


    Based on cancer-related deaths, stomach cancer is ranked fifth, and first among Hispanics. Lack of technologies for early diagnosis and unavailability of target-specific therapeutics are largely the causes of the poor therapeutic outcomes from existing chemotherapeutics. Currently available therapeutic modalities are invasive and require systemic delivery, although the cancer is localized in the stomach at its early stage. Therefore, we hypothesize that an oral local delivery approach can extend the retention duration of the therapeutics modalities within the stomach and thereby enhance therapeutic efficacy. To accomplish this, we have developed a ß-glucan (BG)-based oral delivery vehicle that can adhere to the mucus lining of the stomach for an extended period while controlling the release of Bcl2 siRNA and 5-fluorouracil (5FU) payload for over 6 h. We found that Bcl2 siRNA selectively knocked down the Bcl2 gene in a C57BL/6 stomach cancer mouse model followed by upregulation of apoptosis and remission of cancer. BG was found to be very effective in maintaining the stability of siRNA for at least 6 h, when submerged in simulated gastric juice tested in vitro. To investigate the potential therapeutic effects in vivo, we used a stomach cancer mouse model, where C57BL/6 mice were treated with 5FU, BG/5FU, siRNA, BG/siRNA, and BG/5FU/siRNA. Higher inhibition of Bcl2 and therapeutic efficacy were observed in mice treated with BG/5FU/siRNA confirmed with Western blotting and a TUNEL assay. Significant reduction in the tumor region was observed with histology (H&E) and immunohistochemistry (Ki67, TUNEL, and Bcl2) analyses. Overall, the oral formulation shows improved efficacy with nonsignificant side effects compared to the conventional treatment tested in the gastric cancer mouse model.

    View details for DOI 10.1021/acsami.3c03528

    View details for PubMedID 37350332

    View details for PubMedCentralID PMC10787598

  • Multiomics Analyses of Peripheral Artery Disease Muscle Biopsies. Circulation research Jain, I., Oropeza, B. P., Huang, N. F. 2023; 132 (11): 1444-1446

    View details for DOI 10.1161/CIRCRESAHA.123.322913

    View details for PubMedID 37228238

  • Elastin-like protein hydrogels with controllable stress relaxation rate and stiffness modulate endothelial cell function. Journal of biomedical materials research. Part A Shayan, M., Huang, M. S., Navarro, R., Chiang, G., Hu, C., Oropeza, B. P., Johansson, P. K., Suhar, R. A., Foster, A. A., LeSavage, B. L., Zamani, M., Enejder, A., Roth, J. G., Heilshorn, S. C., Huang, N. F. 2023


    Mechanical cues from the extracellular matrix (ECM) regulate vascular endothelial cell (EC) morphology and function. Since naturally derived ECMs are viscoelastic, cells respond to viscoelastic matrices that exhibit stress relaxation, in which a cell-applied force results in matrix remodeling. To decouple the effects of stress relaxation rate from substrate stiffness on EC behavior, we engineered elastin-like protein (ELP) hydrogels in which dynamic covalent chemistry (DCC) was used to crosslink hydrazine-modified ELP (ELP-HYD) and aldehyde/benzaldehyde-modified polyethylene glycol (PEG-ALD/PEG-BZA). The reversible DCC crosslinks in ELP-PEG hydrogels create a matrix with independently tunable stiffness and stress relaxation rate. By formulating fast-relaxing or slow-relaxing hydrogels with a range of stiffness (500-3300Pa), we examined the effect of these mechanical properties on EC spreading, proliferation, vascular sprouting, and vascularization. The results show that both stress relaxation rate and stiffness modulate endothelial spreading on two-dimensional substrates, on which ECs exhibited greater cell spreading on fast-relaxing hydrogels up through 3days, compared with slow-relaxing hydrogels at the same stiffness. In three-dimensional hydrogels encapsulating ECs and fibroblasts in coculture, the fast-relaxing, low-stiffness hydrogels produced the widest vascular sprouts, a measure of vessel maturity. This finding was validated in a murine subcutaneous implantation model, in which the fast-relaxing, low-stiffness hydrogel produced significantly more vascularization compared with the slow-relaxing, low-stiffness hydrogel. Together, these results suggest that both stress relaxation rate and stiffness modulate endothelial behavior, and that the fast-relaxing, low-stiffness hydrogels supported the highest capillary density in vivo.

    View details for DOI 10.1002/jbm.a.37520

    View details for PubMedID 36861665

  • Engineering Spatiotemporal Control in Vascularized Tissues. Bioengineering (Basel, Switzerland) Khanna, A., Oropeza, B. P., Huang, N. F. 2022; 9 (10)


    A major challenge in engineering scalable three-dimensional tissues is the generation of a functional and developed microvascular network for adequate perfusion of oxygen and growth factors. Current biological approaches to creating vascularized tissues include the use of vascular cells, soluble factors, and instructive biomaterials. Angiogenesis and the subsequent generation of a functional vascular bed within engineered tissues has gained attention and is actively being studied through combinations of physical and chemical signals, specifically through the presentation of topographical growth factor signals. The spatiotemporal control of angiogenic signals can generate vascular networks in large and dense engineered tissues. This review highlights the developments and studies in the spatiotemporal control of these biological approaches through the coordinated orchestration of angiogenic factors, differentiation of vascular cells, and microfabrication of complex vascular networks. Fabrication strategies to achieve spatiotemporal control of vascularization involves the incorporation or encapsulation of growth factors, topographical engineering approaches, and 3D bioprinting techniques. In this article, we highlight the vascularization of engineered tissues, with a focus on vascularized cardiac patches that are clinically scalable for myocardial repair. Finally, we discuss the present challenges for successful clinical translation of engineered tissues and biomaterials.

    View details for DOI 10.3390/bioengineering9100555

    View details for PubMedID 36290523

  • Detection of Anticancer Drug-Induced Cardiotoxicity Using VCAM1-Targeted Nanoprobes ACS APPLIED MATERIALS & INTERFACES Afrin, H., Huda, M., Islam, T., Oropeza, B. P., Alvidrez, E., Abir, M. I., Boland, T., Turbay, D., Nurunnabi, M. 2022; 14 (33): 37566-37576


    Chemotherapy-induced cardiac toxicity is an undesirable yet very common effect that increases the risk of death and reduce the quality of life of individuals undergoing chemotherapy. However, no feasible methods and techniques are available to monitor and detect the degree of cardiotoxicity at an early stage. Therefore, in this project, we aim to develop a fluorescent nanoprobe to image the toxicity within the cardiac tissue induced by an anticancer drug. We have observed that vascular cell adhesion molecule 1 (VCAM1) protein alone with collagen was overly expressed within the heart, when an animal was treated with doxorubicin (DOX), because of inflammation in the epithelial cells. We hypothesize that developing a VCAM1-targeted peptide-based (VHPKQHRGGSKGC) fluorescent nanoprobe can detect and visualize the affected heart. In this regard, we prepared a poly(lactic-co-glycolic acid) (PLGA) nanoparticle linked with VCAM1 peptide and rhodamine B (PLGA-VCAM1-RhB). Selective binding and higher accumulation of the PLGA-VCAM1-RhB nanoprobes were detected in DOX-treated human cardiomyocyte cells (HCMs) compared to the untreated cells. For in vivo studies, DOX (5 mg/kg) was injected via the tail vein once in two weeks for 6 weeks (3 injection total). PLGA-VCAM1-RhB and PLGA-RhB were injected via the tail vein after 1 week of the last dose of DOX, and images were taken 4 h after administration. A higher fluorescent signal of PLGA-RhB-VCAM-1 (48.62% ± 12.79%) was observed in DOX-treated animals compared to the untreated control PLGA-RhB (10.61% ± 4.90) within the heart, indicating the specificity and targeting ability of PLGA-VCAM1-RhB to the inflamed tissues. The quantified fluorescence intensity of the homogenized cardiac tissue of PLGA-RhB-VCAM1 showed 156% higher intensity than the healthy control group. We conclude that PLGA-VCAM1-RhB has the potential to bind inflamed cardiac cells, thereby detecting DOX-induced cardiotoxicity and damaged heart at an early stage.

    View details for DOI 10.1021/acsami.2c13019

    View details for Web of Science ID 000840787400001

    View details for PubMedID 35939041

    View details for PubMedCentralID PMC9994100

  • Assessment of Angiogenesis and Cell Survivability of an Inkjet Bioprinted Biological Implant in an Animal Model MATERIALS Oropeza, B. P., Serna, C., Furth, M. E., Solis, L. H., Gonzalez, C. E., Altamirano, V., Alvarado, D. C., Castor, J. A., Cedeno, J. A., Vega, D., Cordova, O., Deaguero, I. G., Delgado, E., Duarte, M., Favela, M., Marquez, A., Loera, E. S., Lopez, G., Lugo, F., Miramontes, T. G., Munoz, E., Rodriguez, P. A., Subia, L. M., Herrera, A., Boland, T. 2022; 15 (13)


    The rapidly growing field of tissue engineering hopes to soon address the shortage of transplantable tissues, allowing for precise control and fabrication that could be made for each specific patient. The protocols currently in place to print large-scale tissues have yet to address the main challenge of nutritional deficiencies in the central areas of the engineered tissue, causing necrosis deep within and rendering it ineffective. Bioprinted microvasculature has been proposed to encourage angiogenesis and facilitate the mobility of oxygen and nutrients throughout the engineered tissue. An implant made via an inkjet printing process containing human microvascular endothelial cells was placed in both B17-SCID and NSG-SGM3 animal models to determine the rate of angiogenesis and degree of cell survival. The implantable tissues were made using a combination of alginate and gelatin type B; all implants were printed via previously published procedures using a modified HP inkjet printer. Histopathological results show a dramatic increase in the average microvasculature formation for mice that received the printed constructs within the implant area when compared to the manual and control implants, indicating inkjet bioprinting technology can be effectively used for vascularization of engineered tissues.

    View details for DOI 10.3390/ma15134468

    View details for Web of Science ID 000824221800001

    View details for PubMedID 35806588

    View details for PubMedCentralID PMC9267737

  • Bioprinting of Decellularized Porcine Cardiac Tissue for Large-Scale Aortic Models FRONTIERS IN BIOENGINEERING AND BIOTECHNOLOGY Oropeza, B. P., Adams, J. R., Furth, M. E., Chessa, J., Boland, T. 2022; 10: 855186


    Bioprinting is an emerging technique used to layer extrudable materials and cells into simple constructs to engineer tissue or arrive at in vitro organ models. Although many examples of bioprinted tissues exist, many lack the biochemical complexity found in the native extracellular matrix. Therefore, the resulting tissues may be less competent than native tissues-this can be especially problematic for tissues that need strong mechanical properties, such as cardiac or those found in the great vessels. Decellularization of native tissues combined with processing for bioprinting may improve the cellular environment for proliferation, biochemical signaling, and improved mechanical characteristics for better outcomes. Whole porcine hearts were decellularized using a series of detergents, followed by lyophilization and mechanical grinding in order to produce a fine powder. Temperature-controlled enzymatic digestion was done to allow for the resuspension of the decellularized extracellular matrix into a pre-gel solution. Using a commercial extrusion bioprinter with a temperature-controlled printhead, a 1:1 scale model of a human ascending aorta and dog bone shaped structures were printed into a reservoir of alginate and xanthium gum then allowed to crosslink at 37C. The bioengineered aortic construct was monitored for cell adhesion, survival, and proliferation through fluorescent microscopy. The dog bone structure was subjected to tensile mechanical testing in order to determine structural and mechanical patterns for comparison to native tissue structures. The stability of the engineered structure was maintained throughout the printing process, allowing for a final structure that upheld the dimensions of the original Computer-Aided Design model. The decellularized ECM (Ē = 920 kPa) exhibited almost three times greater elasticity than the porcine cardiac tissue (Ē = 330 kPa). Similarly, the porcine cardiac tissue displayed two times the deformation than that of the printed decellularized ECM. Cell proliferation and attachment were observed during the in vitro cell survivability assessment of human aortic smooth muscle cells within the extracellular matrix, along with no morphological abnormalities to the cell structure. These observations allow us to report the ability to bioprint mechanically stable, cell-laden structures that serve as a bridge in the current knowledge gap, which could lead to future work involving complex, large-scale tissue models.

    View details for DOI 10.3389/fbioe.2022.855186

    View details for Web of Science ID 000778367700001

    View details for PubMedID 35360395

    View details for PubMedCentralID PMC8960451

  • Kinetics of collagen microneedle drug delivery system JOURNAL OF DRUG DELIVERY SCIENCE AND TECHNOLOGY Aditya, A., Kim, B., Koyani, R. D., Oropeza, B., Furth, M., Kim, J., Kim, N. 2019; 52: 618-623
  • Whole genome comparison of a large collection of mycobacteriophages reveals a continuum of phage genetic diversity. eLife Pope, W. H., Bowman, C. A., Russell, D. A., Jacobs-Sera, D., Asai, D. J., Cresawn, S. G., Jacobs, W. R., Hendrix, R. W., Lawrence, J. G., Hatfull, G. F. 2015; 4: e06416


    The bacteriophage population is large, dynamic, ancient, and genetically diverse. Limited genomic information shows that phage genomes are mosaic, and the genetic architecture of phage populations remains ill-defined. To understand the population structure of phages infecting a single host strain, we isolated, sequenced, and compared 627 phages of Mycobacterium smegmatis. Their genetic diversity is considerable, and there are 28 distinct genomic types (clusters) with related nucleotide sequences. However, amino acid sequence comparisons show pervasive genomic mosaicism, and quantification of inter-cluster and intra-cluster relatedness reveals a continuum of genetic diversity, albeit with uneven representation of different phages. Furthermore, rarefaction analysis shows that the mycobacteriophage population is not closed, and there is a constant influx of genes from other sources. Phage isolation and analysis was performed by a large consortium of academic institutions, illustrating the substantial benefits of a disseminated, structured program involving large numbers of freshman undergraduates in scientific discovery.

    View details for DOI 10.7554/eLife.06416

    View details for PubMedID 25919952

    View details for PubMedCentralID PMC4408529