Cadaveric human islet transplantation has been shown to restore blood glucose concentrations to some extent in diabetic individuals; however it is limited, due to immune-mediated rejection and scarcity of donor islets. Adult stem cells are considered as a potential alternative to generate insulin-producing cells for transplantation. However, till date highly efficient differentiation of stem cells into insulin-producing cells has not been achieved. We believe that the inherent chromatin modifications associated with lineage specifications of stem cells are responsible for efficient differentiation. We therefore generated lineage committed progenitor cells from human pancreatic islet cells and employed different approaches to enhance their differentiation potential.
We have extensively characterized human islet-derived precursor cells (hIPCs) that are generated by epithelial-to-mesenchymal transition (EMT) of cadaveric human islets. hIPCs do not express any pancreatic hormones but retain active chromatin conformation at (pro)-hormone gene promoters, suggesting lineage commitment. We assessed 5 different approaches for differentiation of hIPCs. These include a previously optimized protocol in our lab, transient transfection of key pancreatic transcription factors & microRNAs as well as use of HDAC and DNMT inhibitors. In another approach we used specific growth and differentiation factors (GDFs) in a temporal fashion to mimic embryonic development of insulin-producing cells from their progenitors. We also present co-culture techniques to understand the effect of endothelial cells on endocrine cell lineage commitment. Preliminary results indicate increase in insulin transcript abundance after exposure to specific GDFs in majority of these methods. I will present a comparative profile for differentiation of hIPCs along with current studies on functional assessment of these insulin -producing cells in vitro and in vivo.
Our data reiterate that hIPCs are lineage committed cells with the ability to differentiate into insulin-producing cells for replacement therapy in diabetes.