New sources of pancreatic beta cells are urgently needed to enable more islet transplants to be carried out for serious cases of type 1 diabetes. A source of autologous beta cells would solve the tissue supply problem and also reduce the need for immunosuppression. This proposal describes a translational research project designed to optimize a protocol for making beta cells, or beta-like cells, from hepatocytes. The recent advent of induced pluripotential cell (iPS) technology has demonstrated the potential for using specific transcription factors to reprogram one cell type to another. The long term goal is to develop a reliable supply of beta cells for clinical transplantation. The objective of this application is to optimize methods for production of beta cells, or cells with a phenotype approaching that of the beta cell, starting from normal hepatocytes. The rationale for this study depends on the close developmental similarity of liver and pancreas, and on previous work showing that overexpression of Pdx1 in liver can provoke expression of beta cell genes. A three step process will be developed based on application of iPS technology, used here not to make embryonic stem cells but to transform one differentiated cell type into another. First, induction of de- differentiation. Second, introduction of specific transcription factors. Third, treatment with agents promoting beta cell differentiation. Preliminary results have already identified the best combination of transcription factors for inducing beta cell-specific gene expression, have shown the critical importance of prior morphological de-differentiation of the hepatocytes, and have identified some maturation-promoting factors. The overall goal will be met through achieving each of the following three specific aims, the results on chromatin changes informing the development of the main protocol: 1: To optimize the methods for producing beta-like cells from primary hepatocytes in vitro. 2: To determine the changes that occur at the chromatin level during hepatocyte de-differentiation. 3: To translate the findings to human hepatocytes. Beta-like cells produced by the optimized protocol will be characterized to establish their phenotype and their capacity to cure experimental diabetes. The approach is innovative because it is the first time that iPS technology and the three step design have been applied to this problem. Success in generating a working protocol will lead directly to studies on larger animals and eventually to clinical trials on human patients.
This project is designed to find a new way to make pancreatic beta cells, by reprogramming of hepatocytes. Islet (beta cell) transplantation is a successful method of cell therapy for treatment of severe type 1 diabetes, but the number of patients who can be treated is severely limited by cell supply. A new source of beta cells would enable many more transplants to be carried out.
