Deciphering transcriptional control of pancreatic beta-cell maturation in vitro

The loss of pancreatic beta-cells in type 1 diabetes results in absence of insulin secreted by the pancreas, and consequently elevated blood sugar which leads to various long-term complications. Diabetic patients would benefit tremendously from availability of transplantable replacement beta-cells. Much of current research focuses on producing beta-cells from stem cells. Despite some progress, it is at present still not possible to generate functional beta-cells in culture. The beta-like cells generated with current protocols in vitro lack key features of normal beta-cells, most notably the ability to secrete insulin a regulated manner. However, when stem cell-derived beta-cell precursors are transplanted into mice, they acquire properties of functional beta-cells, indicating that the precursors have the potential to transition into a mature beta-cell state. This proposal explores strategies for maturing beta-cell precursors in the culture dish with the goal to produce fully functional insulin-producing beta-cells in vitro. Previous studies from our laboratory have resulted in a short list of candidate regulators of beta-cell maturation. We propose to manipulate these candidate regulators in vitro in order to force beta-cell precursors to adopt a mature phenotype. We have now established a robust in vitro system for culturing and manipulating beta-cell precursors. We have also generated and tested requisite reagents for manipulating precursors in the culture dish. Over the next year, we will obtain first results from these manipulations.

The potential to generate functional pancreatic beta cells from human embryonic stem cells provides a promising avenue for beta cell replacement therapy for treatment of diabetes mellitus. Despite the rapid advancements in the field, current protocols still do not produce fully functional beta cells and the production of these cells takes at least six weeks. Understanding the molecular cues that regulate how a beta cell develops and matures would be critical in improving current approaches to generate functional beta cells. In our lab, we found that hundreds of genes enriched in functional beta cells were not properly induced in the nonfunctional cells derived from embryonic stem cells, suggesting that manipulating critical regulators that can affect multiple beta cell genes simultaneously might be instrumental in directing beta cell differentiation and maturation in the culture dish. Our studies have identified several novel regulators of gene expression, including transcription factors and small non-coding RNAs, which we predict will have critical roles in beta cell maturation. These novel regulators are highly expressed in insulin-producing islets and have very low expression in non-functional beta-like cells. This suggests that forcing expression of these regulators could accelerate the formation of functional mature beta cells. Preliminary studies so far show that forced expression of select candidates in immature precursor cells can induce the expression of several genes critical for beta cell maturation. Over the next year, we will determine, by manipulating the expression of our candidate regulators, the optimal conditions required for inducing the production of mature beta cells in vitro.

The potential to generate functional pancreatic beta cells from human embryonic stem cells provides a promising avenue for beta cell replacement therapy for treatment of diabetes mellitus. Despite the rapid advancements in the field, current protocols still do not produce fully functional beta cells and the production of these cells takes at least six weeks. Understanding the molecular cues that regulate how a beta cell develops and matures would be critical in improving current approaches to generate functional beta cells. In our lab, we found that hundreds of genes enriched in functional beta cells were not properly induced in the nonfunctional cells derived from embryonic stem cells, suggesting that manipulating critical regulators that can affect multiple beta cell genes simultaneously might be instrumental in directing beta cell differentiation and maturation in the culture dish. Our studies have identified several novel regulators of gene expression, including transcription factors and small non-coding RNAs, which we predict will have critical roles in beta cell maturation. These novel regulators are highly expressed in insulin-producing islets and have very low expression in non-functional beta-like cells. This suggests that forcing expression of these regulators could accelerate the formation of functional mature beta cells. Our studies have shown that forced expression of these select candidates in immature precursor cells can induce the expression of several genes critical for beta cell maturation. Furthermore, we have used bioinformatic approaches to identify candidates with the highest potential to regulate beta cell-specific genes and promote beta cell differentiation. By identifying these critical regulators, our findings could lead to novel and improved strategies that allow for the production of unlimited numbers of functional human beta cells in the culture dish for regeneration therapy in type 1 diabetes.