Objective
Our objective is to establish an improved strategy for beta cell replacement therapy by studying key genes and pathways that are likely to compromise the survival and fitness of replacement islets/beta cells. Our preliminary work implicates specific enzymes that promote autoimmune recognition of human islets. We will evaluate the activity of those enzymes and pathways in stem cells as they mature into replacement beta cells and test a gene editing strategy to eliminate the negative effects of those pathways. We hypothesize that stem cells engineered to lack expression of these stress activated enzymes will have improved resilience, function and survival.
Background Rationale
Type I diabetes is an disease in which the insulin-producing cells of the pancreas are recognized and destroyed by immune cells due to inappropriate recognition of self-proteins. At the time of clinical diagnosis, individuals with T1D have a significant reduction in functional beta cell mass and are dependent on exogenous. Engraftment of insulin-producing replacement beta cells or islets is almost certain to be a key element of any effective strategy to restore and maintain glycemic control. Recent studies demonstrate that cellular stress impairs beta cell function and negatively impacts beta cell survival. In addition, stress in the beta cell increases the activity of modifying enzyme, triggering immune recognition. Therefore, eliminating these pathways by gene editing could be a means of developing improved replacement bata cells that have increased resilience and function and are less vulnerable to immune attack. Out team has combined expertise about islet biology and stem cell differentiation and about T cell recognition of beta cells. This combined knowledge positions us to develop novel strategies to create improved replacement beta cells.
Description of Project
Type 1 diabetes (T1D) results from destruction of pancreatic beta cells by autoreactive T cells. At the time of clinical diagnosis, individuals with T1D have a significant reduction in functional beta cell mass and are dependent on exogenous insulin for survival. Transplantation or engraftment of insulin-producing beta cells or islets is a promising strategy to restore and maintain glycemic control. Recent efforts to develop renewable sources of insulin producing cells by differentiating human pluripotent stem cells into islets have the potential to revolutionize the treatment of T1D. However, additional discovery work is needed to assess the vulnerability of replacement islets/beta cells to mechanisms of beta cell stress and recurrence of the autoimmune process. This project will investigate key pathways that, based on our preliminary findings, are likely to play an important role in compromising the survival and fitness of replacement islets/beta cells. Specifically, we will investigate changes in the stress response of human beta cells and their visibility to immune cells as they differentiate from endocrine precursors into mature beta cells. We will utilize culture based assays to assess the effects of stress on beta cell survival and activity, biochemical measures and co-cultures of differentiated islets and self-reactive T cells to assess changes in the immune recognition of maturing beta cells, and genetic editing to test the feasibility of deleting specific genes to decrease immune recognition and increase the resilience of replacement beta cells. Based on those findings we will identify lead candidates to advance toward the development of improved beta cell replacement therapies.
Anticipated Outcome
We expect to show that specific stress related pathways emerge in beta cells as they differentiate from stem cell precursors. We also expect these pathways to generate neo-epitopes that increase T cell recognition of islets. We further expect that deleting enzymes at the center of these pathways will allow us to generate replacement beta cells that are more resilient to stress and less vulnerable to immune attack. The end result of this work will be the establishment of new strategies to improve the resilience and function of replacement beta cells to more effectively treat type 1 diabetes.
Relevance to T1D
Cellular stress and self-destructive immune responses are key contributors to the development and pathogenesis of Type 1 Diabetes. Beta cell function and identity decline and immune responses accelerate over time, eventually leading to insulin dependence. The proposed research would generate knowledge that can be used to develop improved replacement beta cells. A successful outcome would confirm that targeted editing of stem cells to eliminate at least one of these pathways would improve beta cell resilience without compromising function. The ultimate goal would be to translate this idea into clinical practice to improve the efficacy of beta cell replacement, resulting in a long term restoration of insulin secretion.