Improvement of massive human islet isolation techniques and their quality evaluation

Objective To obtain massive human pancreatic islets with modified techniques and to evaluate the function of the isolated islets. Methods Twenty-eight adult human islets of pancreas were isolated and purified with classic and modified automated techniques respectively. The islet yield was counted as islet equivalent (IEQ). The function of the isolated islets was evaluated by measuring DNA/ insulin ratio, static glucose stimulating test (SGS) in vitro and transplanting the islets into diabetic nude mice followed by abdominal glucose tolerance test and C peptide measurement. Results The first 13 isolations with the classic method yielded 49 123 IEQs/pancreas, 846 IEQs/g and, purity 87 % in average. The remained 15 isolations after the modifications yielded 501 813 IEQs/pancreas, 7 003 IEQ/g and, purity 89% in average. The results of in vitro SGS showed good response to the different glucose concentrations. Thirty-four diabetic nude mice were transplanted with the freshly isolated islets with 29 obtained normoglycemia within 12 h and the glucose tolerance tests were near normal. Serum C peptide level of transplanted mice was close to that of the control group. Conclusion Massive human islets with normal function can be isolated with the modified techniques.