IN-VIVO DEPLETION OF PANCREATIC ACINAR TISSUE SIMPLIFIES ISLET PREPARATION FOR TRANSPLANTATION

A copper deficient diet is reported to reduce acinar tissue in vivo, W e investigated the suitability of this method to reduce in vivo acinar tissue mass of a rat pancreas prior to transplantation of dispersed p ancreatic tissue, We also studied islet function in the acinar deplete d pancreas and the outcome of transplantation of islets from such panc reata, Eighty-two Wistar Furth rats were divided into two groups with 42 animals in the control group receiving regular diet, and 40 receivi ng copper deficient diets (Cudt) plus tetraethylenepentamine penta-hyd rochloride (TEPA) as a chelating agent, All animals in the control gro up and 34 (85%) in the Cudt group tolerated this diet and survived for 60 days or longer, At the end of 60 days, all experimental animals we re converted to a regular diet until the pancreata were harvested for islet transplantation. Eight rats in the Cudt group, which were conver ted to a regular diet for 2 weeks, and 2 in the control group were ran domly selected and sacrificed 60 study the pancreas for acinar depleti on and islet morphology, An intravenous glucose tolerance test (IVGTT) in the control group (n = 24) and the Cudt group (n = 25) showed K-va lues of 1.891 +/- 0.7 and 1.107 +/- 0.47, respectively (P = ns), Histo logy of pancreata showed normal acinar tissue in the control group and reduction of acinar tissue mass in the Cudt group, Furthermore, immun ohistochemistry for insulin, glucagon, and somatostatin showed positiv ely staining, while amylase was negative in the Cudt group, compared w ith the positive stain for cells in the control group, Standard collag enase digestion of the pancreas showed that islets were surrounded by scant amounts of acinar tissue in the Cudt group compared with the con trol group, The islet count in the control group was 523 +/- 126 and 6 11 +/- 52 in the Cudt group, The mean volumes of dispersed pancreatic tissue were 0.3875 +/- 0.14 and 0.0668 +/- 0.029 ml per rat in the con trol and Cudt groups, respectively (P < 0.05), Transplantation of disp ersed pancreatic tissue from the control group into the spleen of two diabetic Wister Furth rats resulted in the death of the recipients wit hin 24 hr, To avoid this complication, purified islets from the contro l group were used for transplantation. Purified islets from 5 donor pa ncreata from the control group and dispersed pancreatic tissue from 3 pancreata in the Cudt group were transplanted into each recipient, Isl et function was seen in 75% of the rats transplanted with purified isl ets from the control group, and in 67% receiving dispersed pancreatic tissue from the Cudt group, Rats with sustained islet function for 30 days following islet transplantation developed diabetes following sple nectomy, The islet cells were positively stained for insulin in these splenectomy specimens, This study demonstrates that rats maintained on a copper deficient diet for 60 days show depletion of pancreatic acin ar tissue, A significant reduction of collagenase digested volume of w hole pancreatic tissue occurred in the Cudt as compared with the contr ol group, Transplantation of dispersed pancreatic tissue from the acin ar depleted pancreas was successful in reversing diabetes, We conclude that Cudt containing TEPA depletes exocrine tissue and facilitates pa ncreas digestion for successful transplantation of islets into the por tal system.