LOCALIZATION OF ENDOCRINE PANCREATIC-ISLETS

Transplantation of whole pancreas or pancreatic islets remains a promi sing approach to treatment of diabetes mellitus. Because at present th ere is no efficient method for in vivo early diagnosis of pancreatic i slet rejection or for disorders of pancreatic endocrine function, we e xamined if dithizone (DTZ) and a synthetic iodo-derivative of DTZ (I-D TZ) can he used as a potential radioactive marker for monitoring viabl e transplanted pancreatic islets. Human pancreatic islets harvested fr om multiorgan donors were tested ex vivo after intraductal injection o f DTZ solution for islet staining. Lewis rats Irere used in the in viv o experiments for localizing pancreatic islets in situ after intraveno us injection of various concentrations of DTZ or I-DTZ. Fresh rat isle ts were transplanted into streptozotocin-induced diabetic recipients, either underneath the kidney capsule or intraperitoneally. Intravenous DTZ or I-DTZ was then used for macroscopic and microscopic identifica tion of viable transplanted islets. These studies indicate that DTZ an d I-DTZ solutions specifically stain pancreatic islets in vivo after i ntravenous injection without damage to their endocrine function as ass essed by plasma insulin and glucose levels. Human islets stain red in in vitro studies similar to the DTZ (I-DTZ) effect in rats. We conclud e that DTZ and I-DTZ are effective in the in vivo and in vitro identif ication of pancreatic islets and may have potential clinical applicati on in the detection of pancreatic islet tumors (insulinomas) and in th e diagnosis of rejection of pancreatic organ allografts or islets.