Critical mass of purified islets that induce normoglycemia after implantation into dogs.

Twenty grafts of highly purified islets of Langerhans (mean +/- SE vol 0.98 +/- 0.3 ml, islet diam 122 +/- 5 micron) were autoimplanted into the spleen or liver of totally pancreatectomized dogs. Portal venous pressure did not change significantly. Incremental doses of islets of 1000-3000 (n = 3), 3000-4000 (n = 6), 4000-5000 (n = 5), 5000-6000 (n = 3), and 6000-8000 (n = 3) per kilogram body weight resulted in corresponding fasting plasma glucose (PG) of 258 +/- 18, 163 +/- 13, 158 +/- 17, 138 +/- 15, and 108 +/- 6 mg/dl. In 3 apancreatic control dogs, PG was 338 +/- 9 mg/dl. One (normoglycemic) dog died of wound complications, and follow-up PG at 1 mo was 89 +/- 5 mg/dl in 6 of 10 dogs that received 3000-5000 islets/kg and 91 +/- 6 mg/dl in all 6 that received greater than 5000 islets/kg. K values 1 mo after surgery during glucose tolerance tests were 1.8 +/- 0.3 for 6 spleen dogs and 1.6 +/- 0.3 for 6 liver dogs. Six months after splenic implantation, PG was 75 +/- 4 mg/dl and rose to greater than 350 mg/dl after splenectomy. These data define the critical number of purified dog islets of known size that is necessary to induce prolonged normoglycemia. Sufficient pure islets can be collected from 1 dog pancreas to correct diabetes after autoimplantation into the liver or spleen.