Deciphering transcriptional control of pancreatic beta-cell maturation in vitro

Deciphering transcriptional control of pancreatic beta-cell maturation in vitro

Funding Type: 
Basic Biology IV
Grant Number: 
RB4-06144
Award Value: 
$1,258,560
Disease Focus: 
Diabetes
Stem Cell Use: 
Embryonic Stem Cell
Status: 
Active
Public Abstract: 
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. By comprehensively comparing the molecular profiles of mature, functional beta-cells and malfunctioning insulin-producing cells generated in vitro, we have identified molecular cues that are not appropriately induced under current culture conditions. These studies have led to short list of candidate regulators of beta-cell maturation. We propose to manipulate these candidate factors in stem cell-derived beta-cell precursors in culture, with the goal of forcing them to adopt a mature phenotype. We will first characterize these cells in vitro and then test functionality in diabetic animal models.
Statement of Benefit to California: 
Diabetes is a metabolic disorder that affects 8.3% of the U.S. population. Average medical expenditures among people with diabetes are 2.3 times higher than those of people without diabetes. The disease is characterized by either absolute insulin deficiency due to the autoimmune destruction of pancreatic insulin-producing beta-cells [Type 1 diabetes], or relative insulin deficiency due to defective insulin secretion or insulin sensitivity [Type 2 diabetes]. The resulting elevated blood glucose levels eventually lead to damage of the blood vessels followed by kidney failure, blindness, neuropathy, heart disease, and stroke. Despite current treatment regimens of several insulin injections per day, blood glucose levels still fluctuate significantly in diabetic patients, making diabetes the seventh leading cause of death in the United States. Alternative approaches to insulin injections include attempts to develop a cell therapy by producing transplantable beta-cells from stem cells. A cell therapy would lead to better blood glucose control and therefore ameliorate long-term complications. This proposal seeks to identify factors that force stem cell-derived beta-cells to functionally mature in culture with the goal to produce an unlimited source of transplantable beta-cells. Given the high prevalence of diabetes in California, we believe that the proposed research will have tremendous benefit to the State of California and its citizens.
Progress Report: 

Year 1

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.

Year 2

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.

© 2013 California Institute for Regenerative Medicine