Sertoli cells are immune-privileged cells that have the ability to survive long-term without the use of immunosuppressive drugs when transplanted across allogeneic or xenogeneic barriers. The ability of Sertoli cells to survive transplantation when most other cells are immunologically rejected suggests Sertoli cells could be engineered as a vehicle for gene therapy. The long-term goal of my research is to use genetically engineered, immune-privileged Sertoli cells as an unlimited source of tissue that can be used as a vehicle to deliver therapeutically relevant proteins as a means to treat multiple disorders. Therefore, the objective of this application is to evaluate the feasibility of using Sertoli cells engineered to produce functional levels of insulin as an effective long-term, therapeutic strategy in diabetic mice. It is hypothesized that immune- privileged Sertoli cells can be genetically engineered to stably express basal levels of insulin, and that these cells can survive transplantation as allografts or xenografts in diabetic mice without the need for immunosuppression. This hypothesis is based on our preliminary data, which demonstrated unmodified Sertoli cells survive long-term when transplanted as allografts and xenografts without the use of immunosuppressive drugs and that Sertoli cells stably expressing GFP survive allogeneic transplantation while continuing to express GFP.
The specific aims are designed to test this hypothesis.
In Aim 1, the function of insulin expressing Sertoli cells will be examined. Mouse and porcine Sertoli cells stably expressing insulin will be examined for production and secretion of functional levels of insulin in vitro and after transplantation into diabetic immunodeficient SCID mice in vivo.
In Aim 2, the ability of these insulin-expressing Sertoli cells to survive (remain immune-privileged) when transplanted across immunological barriers will be examined. Insulin-expressing Sertoli cells will be transplanted into diabetic, immune-competent C3H mice as allografts (mouse Sertoli cells) or xenografts (porcine Sertoli cells). The production of functional insulin and Sertoli cell survival will be examined. It is expected that Sertoli cells engineered to stably deliver basal levels of insulin are capable of lowering blood glucose levels long-term after transplantation into diabetic mice. This contribution is significant because it will provide evidence that genetically engineered, immune-privileged Sertoli cells can be used as an unlimited supply of tissue for transplantation.
There are many disorders that have the potential to be treated by gene therapy;for example, delivery of factor VIII for the treatment of hemophilia. However, an efficient and safe delivery system has not yet been developed. We will explore the novel and innovative concept that immune-privileged Sertoli cells can be engineered to deliver therapeutic proteins. In the long-term these cells could provide an unlimited supply of genetically modified tissue that could be transplanted without the use of chronic immunosuppression as a means of treatment for multiple disorders.
