Sophisticated mesh filtration technique of a large-scale isolation of islets and their function.

A large-scale isolation of islets is required for islet transplantation. We improved our conventional method, and could obtain about three times more islets than by the conventional methods. Pancreata of adult Wistar rats were inflated by injection of buffer with (A) or without 1.3 mg/ml collagenase (B). The rats were bled from the inferior vena cava and the aorta in (A) simultaneously with the inflation. They were further digested with collagenase and filtered through two different meshes (pore size: 1190 and 590 microns) (A1) or three different meshes (pore size: 1190, 590 120 microns) (A2) in order. Insulin released from islets isolated in this manner was determined by 1-h incubation with 3.3 and 16.7 mM glucose. Besides, 600 islets each were transplanted into the liver of streptozotocin-induced diabetic Wistar rats and their fasting plasma glucose was measured at weekly intervals. (1) With these methods more numerous islets were harvested by A1 (mean: 554) and A2 (mean: 746) than B (mean: 224). (2) Insulin released at both glucose concentrations was similar among islets obtained by A1, A2 and B. (3) The plasma glucose-lowering effect was similar among the islets obtained by these methods. (4) A more selected range of islet sizes was obtained by A2 than A1. These observations indicate that the present techniques (A1 and A2) are less time-consuming and simpler for a large-scale isolation of islets.