Effectiveness of hydroxyethyl starch (HES) on purification of pancreatic islets

Background. The isolation of large-scale and high-quality islets from the pancreas is essential for a successful islet transplantation. We developed a hydroxyethyl starch (HES)-Collins solution as the purification medium and evaluated its usefulness on islet isolation from the pancreas of beagle dogs. Materials and methods. The pancreas of beagle dog was digested using our original 2-step automated technique. Islets were purified by discontinuous purification method on HES-Collins solution (group 1, n = 10) or Euro-Ficoll solution (group 2, n = 16) with a COBE2991 cell processor. Islet yield and purity, changes in islet number during 3-day cultures, static incubation, perifusion study, and insulin content were examined. In addition, the islets were autotransplanted into the liver via the portal vein. Results. Although no significant differences were detected, yield and purity were higher in group 1. After 3 days of culture, the islet number decreased less in group 1. Both under static incubation and in the perifusion study, stimulation indices were 4.50 ± 1.82 and 6.02 ± 1.05, which were significantly higher than the 2.18 ± 0.67 and 3.32 ± 1.46 observed in group 2. Also, insulin content of the islets was significantly higher in group 1 than in group 2. Fasting blood glucose levels were maintained at values below 100 mg/dl for 100 days in group 1 and around 200 mg/dl in group 2. Conclusions. The use of HES-Collins solution was associated with an improvement of islet yield and purity. Also, islet viability and function were preserved longer during culture. Accordingly, islet purification using HES-Collins solution might be recommended for clinical islet transplantation.