Twenty-four hour hypothermic machine perfusion preservation of porcine pancreas facilitates processing for islet isolation

Abstract

Procurement of donor pancreata for islet isolation and transplantation is not yet widely practiced due to concerns about the impact of postmortem ischemia on functional islet yields. Perfusion/preservation technology may help to circumvent ischemic injury as applied in this study of porcine pancreata prior to islet isolation. Pancreata harvested from adult pigs were assigned to 1 of 3 preservation treatment groups: G1, fresh controls, processed immediately with minimum cold ischemia (<1 hour); G2, static cold storage, flushed with cold UW-Viaspan and stored at 2 degrees -4 degrees C for 24 hours; and G3, hypothermic machine perfusion (HMP) on a pulsatile LifePort machine Organ Recovery Systems, Inc., Des Plaines, Ill, United States with KPS1 solution at 4-7 degrees C and low pressure (10 mm Hg) for 24 hours. Islet isolation was then accomplished using conventional methods. Product release criteria were used to assess islet yield and function. Islet yield was markedly different between the treatment groups. There was a statistically significant increased yield in the HMP group over static cold storage in UW-Viaspan (P < .05). Functionally, the islets from each experimental group were equivalent and not significantly different from fresh controls (G1). Dithizone staining of islets showed consistently more uniform digestion of pancreata from G3 compared with G1 and G2, with greater separation of the tissue and fewer entrapped islets. HMP for 24 hours was well tolerated, leading to moderate edema but no loss of function of the harvested islets. The edema appeared to aid in enzymatic digestion, producing a greater yield and purity of islets compared with pancreata subjected to 24 hours of static cold storage.

Figure 1

Islet retrieval data (Mean ± SEM) expressed as both Islet Equivalents (IE) per unit weight of digested pancreas (UPPER GRAPH) and total islet yield per pancreas (LOWER GRAPH). Group 1: Fresh Control Pancreases (N=7); Group 2: Preservation controls cold stored in UW solution (N=9); Group 3: Hypothermic Machine Perfused (HMP) with KPS1 solution (N=7).