Hypothermic perfusion preservation of pancreas for islet grafts: validation using a split lobe porcine model

B.P. Weegman¹, M.J. Taylor², S.C. Baicu², W.E. Scott III¹, K.R. Mueller¹, J.P. Kitzmann¹, M.D. Rizzari¹, K.K. Papas^1
1 University of Minnesota, Department of Surgery, Minneapolis, MN, USA; ² Cell and Tissue Systems Inc., N. Charleston, SC, USA

The demand for high quality islets of Langerhans for transplantation in Type I diabetics will increase as the current clinical trials transition into standard of care. The mode of preservation of donor pancreata is therefore critical to this mission since islets are very sensitive to ischemic injury. Hypothermic perfusion preservation (HPP) is currently being investigated for extended pancreas preservation in light of the beneficial effects recently reported for other organs. The present study reports on a pilot study to validate the in vivo function of porcine islets isolated from pancreata stored for 24h at 4-8°C. The study design included a split-lobe pancreas model that permitted paired comparisons of batches of islets isolated from 24h HPP splenic lobes with non-perfused, fresh control duodenal/connecting lobes stored at 4°C for <3h. Prior to transplantation, islet viability was assessed in vitro using the ratio of oxygen consumption rate to DNA (OCR/DNA) assay and correlated with subsequent in vivo function by transplantation in diabetic immunocompromised mice. The OCR/DNA (mean ±SD) measured after 7 days culture and immediately prior to transplantation for islets from the 24h HPP group was 269± 19 nmol/min/mg DNA, which was higher but not statistically different to the mean of 236 ± 43 for the counterpart control group. All four nude mice transplanted with islets from the 24h HPP group showed diabetes reversal, compared with 5 of 6 transplants from the control group. In conclusion, islets isolated from adult porcine pancreata after 24h HPP exhibited high viability as measured by OCR/DNA and were able to consistently reverse diabetes in a nude mouse bioassay.