Transplantation of isolated pancreatic islets: current status and prospects

Complete and permanent reversal of diabetes by transplantation of isolated pancreatic islets has been repeatedly demonstrated experimentally, whereas islet isolation and transplantation in man are associated with largely unsolved problems: the standard isolation procedure including disruption of acini and collagenase digestion is ineffective. Improvement of the islet yield is currently obtained in animal and human trials by using substances selectively acting on exocrine tissue and others protecting the islets at the isolation as well as in tissue culture media. Islet tissue banks and repeated transplantations seem to be realistic also in man. Islets are advantageously implanted intraportally in the liver. They are rejected soon without protection or efficient immunosuppression. Intense research concerns islet-containing diffusion chambers, macrophage suppression, new immunosuppressive agents and induction of immunological tolerance. A successful solution of the technical and immunological problems will aggravate a shortage of donor tissue, already noticeable in the experimental work: this will make the recipient selection crucial.