System to analyze factors affecting human islet yield

DESCRIPTION (provided by applicant): The Edmonton Protocol is a breakthrough in the treatment of adult, type 1 diabetic patients and heralds a new era in transplantation medicine. Edmonton's success rate, as measured by insulin independence > 1 year post transplant, is comparable to whole organ pancreas transplantation. The major barrier for routine clinical adoption of the Protocol is the poor recovery of islets from human pancreata. Typically, 2 or more organs are usually required to recover a sufficient number of islets for successful transplantation. A combination of enzymatic & mechanical techniques are used to free islets from the pancreas. Improvements to the islet isolation procedure have been made incrementally since no laboratory has had the resources or expertise to critically evaluate the interaction of three factors that affect islet yield: histochemical composition of the organ, quality and composition of the tissue dissociation enzymes (TDEs), and the amount of endogenous pancreatic proteolytic enzymes generated during the tissue dissociation procedure. This grant focuses on evaluating the feasibility for developing a tissue test system (TTS) that will fill this gap. The TTS is similar to a biochemical enzyme assay: purified proteolytic enzymes are used to digest minced porcine pancreatic tissue (substrate) with free islet volume expressed as an islet equivalent number as the product of this interaction. We believe that the TTS will allow systematic evaluation of factors that affect islet yield and with this information we can rapidly assess modifications in the reagents and isolation process that can lead to improvements in the quality and yield of islets used in transplantation. The 3 goals of this grant will be to define the optimal experimental parameters for the TTS, compare the amount and quality of islets recovered from the TTS to those obtained from the established procedure, and develop a histochemical staining procedure to improve characterization of the tissue substrate. If successful, this project will be extended in a Phase II application to develop a human TTS. Development of a human TTS may be an innovative approach to improve knowledge of factors that affect islet yield. The ability to perform multiple analyses on tissue derived from an individual organ eliminates the problem of interpreting data between organs, enabling further research to develop improved TDE reagents and islet isolation procedures that will increase the recovery of islets from human pancreata.