A two-step digestion process and LAP-I cold preservation solution for human islet isolation

Pancreatic islet transplantation has a high potential for treating diabetes mellitus, but long-lasting insulin independence has not been achieved in type I diabetic patients. In order to obtain better results, improvement is needed in many areas. The first area is the islet isolation process. The requirements for an islet isolation method are: 1) to produce a maximum number of healthy islets without demanding a high quality of donor pancreas; 2) to be able to perform the procedure with fewer numbers of personnel who may be without extensive skills and expertise; and 3) to lower isolation costs. In order to achieve these objectives, we have made two important modifications to the isolation process. One is the development of a new preservation solution, LAP-I and the other is the use of a two-step process for pancreas digestion, involving a short warm collagenase digestion, followed by cold mechanical digestion without collagenase. We also use a clear plastic digestion chamber in order to visualize the process. The chamber cover is designed to facilitate frequent removal of digested tissue fragments. The overall procedure is simple and straightforward, requires less manpower and is cost effective. Our procedure is described in detail, and its advantages are discussed.