OPTIMIZATION OF HUMAN FETAL PANCREAS FOR TRANSPLANTATION

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Human fetal pancreas (HFP) has the unique capacity for further growth and differentiation following transplantation to a diabetic recipient. The objective of our funded application was to determine the parameters required for the procurement, processing, storage, HLA typing, and testing for bacterial and viral contamination of HFP. We have achieved these goals and have established protocols for obtaining high quality tissue with good function. Our studies have advanced the field of HFP transplantation to the point where clinical trials can be, initiated. Three problems remain which limit the potential of HFP for successful clinical transplantation: 1) HFP requires up to three months following transplantation before acquisition of glucose responsiveness during which time it is not possible to monitor graft rejection, 2) HFP has a small mass of tissue and may require 20 or more pancreata for successful transplantation, and 3) HFP transplantation is subject to both allograft and autoimmune responses. Our long-term goal is to achieve successful HFP transplantation. Thus the objectives of this application are to: 1) Characterize both the allograft and autoimmune response to HFP and cellular subsets of HFP tissue. We will use mixed lymphocyte islet cell culture and specific lymphoid depletion to determine 1) the contribution of cellular and cytokine responses and 2) the role of direct and indirect antigen presentation to HFP graft loss. We will use this knowledge to design clinically relevant strategies for immunosuppressive therapy, 2) Accelerate the differentiation of HFP glucose responsiveness. We will use short-term culture and adenoviral-mediated gene transfer of specific growth and transcription factors to accelerate HFP differentiation and maturation, and 3) Demonstrate the potential to increase HFP beta cell mass in vitro with transient transformation of HFP with SV40-T antigen while maintaining beta cell function. We will use beta cell enriched HFP subpopulations infected with replication- defective adenovirus expressing SV40-T antigen to demonstrate the potential to increase beta cell mass without loss of HFP function. The results of these studies will provide a sufficient source of HFP tissue for clinical transplantation which responds to glucose challenge and requires minimal immunosuppressive therapy.