Long-term preservation of the pig pancreas by a one-layer method for successful islet isolation

Pancreas preservation by two-layer method (TLM) was recently established for clinical islet transplantation. The extensive use of TLM would require enormous efforts to solve logistical and technical problems. Omitting University of Wisconsin solution (UW) as second layer would facilitate the regular application of oxygenated perfluorocarbon; (PFC). To clarify whether long-term pancreas preservation is feasible by this simplified procedure, pancreases from retired breeder pigs were subjected to 7-hour preservation utilizing PFC alone in a one-layer method (OLM, n = 8) or in combination with UW (TLM, n = 10).

Resected pancreata were intraductally flushed with cold UW. Subsequently, pancreata were promptly processed (n = 6) as previously described or stored by TLM or OLM.

Compared to unstored (429200 +/- 86700 IEQ) and OLM-stored pancreases (338600 +/- 42100 IEQ), (P = ns vs unstored) postpurification islet yield decreased after TLM storage (238000 +/- 26600 IEQ, P < .05). No significant differences were found regarding purity (>90%), adenosine triphosphate (ATP) content, and viability as determined by formazan production and trypan-blue exclusion (>95%). Glucose stimulation index of freshly isolated islets (2.5 +/- 0.4) was significantly decreased after TLM storage (1.8 +/- 0.2, P < .05) but not after OLM storage (2.3 +/- 0.6). Islet transplantation in diabetic nude mice demonstrated sustained graft function in all experimental groups.

This study demonstrates that viable pig islets can be successfully isolated after prolonged ischemia utilizing PFC alone for oxygenation of cold-stored pig pancreases. The easy handling of OLM could facilitate the regular application of PFC as pancreas preservation solution.