Approximately 285 million people worldwide suffer from diabetes, with insulin supplementation as the most common treatment measure. Regenerative medicine approaches such as a bioengineered pancreas has been proposed as potential therapeutic alternatives. A bioengineered pancreas will benefit from the development of a bioscaffold that supports and enhances cellular function and tissue development. Perfusion-decellularized organs are a likely candidate for use in such scaffolds since they mimic compositional, architectural and biomechanical nature of a native organ. In this study, we investigate perfusion-decellularization of whole pancreas and the feasibility to recellularize the whole pancreas scaffold with pancreatic cell types. Our result demonstrates that perfusion-decellularization of whole pancreas effectively removes cellular and nuclear material while retaining intricate three-dimensional microarchitecture with perfusable vasculature and ductal network and crucial extracellular matrix (ECM) components. To mimic pancreatic cell composition, we recellularized the whole pancreas scaffold with acinar and beta cell lines and cultured up to 5 days. Our result shows successful cellular engraftment within the decellularized pancreas, and the resulting graft gave rise to strong up-regulation of insulin gene expression. These findings support biological utility of whole pancreas ECM as a biomaterials scaffold for supporting and enhancing pancreatic cell functionality and represent a step toward bioengineered pancreas using regenerative medicine approaches.
Adequate cell-based repair of adult myocardium remains an elusive goal because most cells that are used cannot generate mature myocardium sufficient to promote large functional improvements. Embryonic stem cells can generate both mature cardiocytes and vasculature, but their use is hampered by associated teratoma formation and the need for an allogeneic source. The detection of sca-1(+), c-kit(+), or isl-1(+) cardiac precursors and the creation of cardiospheres from adult heart tissues suggest that a persistent population of immature progenitor cells is present in the mature myocardium. These cell populations probably represent stages along a continuum of cardiac stem cell development and differentiation. We report isolation from ventricle of uncommitted cardiac progenitor cells, which appear to resemble the more immature, common pool of embryonic lateral plate mesoderm progenitors that yield both myocardial and endocardial cells during normal cardiac development. Under controlled in vitro conditions and in vivo, these cells can differentiate into endothelial, smooth muscle, and cardiomyocyte lineages and can be isolated and expanded to clinically relevant numbers from adult rat myocardial tissue. In this article, we discuss the potential for autologous repair or even cardiac regeneration with cells that follow a developmental pathway similar to embryonic cardiac precursors but without the inherent limitations associated with undifferentiated embryonic stem cells.
Background: The investigation of molecular mechanisms underlying transcriptional regulation, particularly in embryonic stem cells, has received increasing attention and involves the systematic identification of target genes and the analysis of promoter co-occupancy. High-throughput approaches based on chromatin immunoprecipitation (ChIP) have been widely used for this purpose. However, these approaches remain time-consuming, expensive, labor-intensive, involve multiple steps, and require complex statistical analysis. Advances in this field will greatly benefit from the development and use of simple, fast, sensitive and straightforward ChIP assay and analysis methodologies.
Whole organ engineering has emerged as a promising alternative avenue to fill the gap of donor organ shortage in organ transplantation. Recent breakthroughs in the decellularization of solid organs and repopulation with desired cell populations have generated neo-organ constructs with promising functional outcomes. The realization of this goal requires engineering advancement in the perfusion-based bioreactors to (i) efficiently deliver decellularization agents, followed by (ii) its reconstruction with relevant cell types and (iii) maintenance of viability and function of the repopulated organ. In this study, we report the development and assembly of a perfusion bioreactor with the potential to enable regenerative reconstruction of pancreas. The assembled bioreactor is versatile to efficiently decellularize multiple organs, as demonstrated by complete decellularization of pancreas, liver and heart in the same set-up. Further, the same system is amenable to support organ repopulation with diverse cell types. Using our in-house bioreactor system, we demonstrate pancreas repopulation with both immortalized MIN-6 beta cells and differentiating human pluripotent stem cells. Importantly, we show the significant advantage of perfusion culture over static culture in enhancing cell engraftment, viability and phenotypic maintenance of the repopulated pancreas. In addition, this study is a significant step forward for whole organ engineering as it will facilitate cost-effective and easy assembly of perfusion bioreactors to enable rapid advancement in regenerative organ reconstruction.
Type 1 diabetes affects more than a million people in the United States and many more across the world. While pharmaceutical interventions and insulin supplementation are the most commonplace treatment of diabetes, these are not essentially cures and can potentially lead to long-term complications. Transplantation of insulin-producing Islets of Langerhans from donor pancreas has been established as a promising alternative to diabetes therapy. While successful islet transplantation has the potential of providing a cure, the primary hurdles to be overcome for it to be clinically viable are the scarcity of donor islets and immune rejection of transplanted islets. Recent advances in stem cell culture and differentiation techniques have established stem cells as a likely source of transplantable islets. Different stem cell sources have been induced toward pancreatic differentiation using specific chemical perturbations along with use of specific substrates. An approach to overcoming the second hurdle of immune rejection of transplantable islets is to encapsulate the islets in specific biomaterials. In this review, we discuss the extensive use of various substrates for pancreatic differentiation of different stem cell sources, along with different biomaterial designs used for islet transplantation.
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