Pig Pancreas Oxygenation at 20°C Increases Islet ATP Generation but Deteriorates Islet Function

Abstract

Successful pancreas preservation during storage in oxygenated perfluorodecalin (PFD) is mainly related to oxidative ATP generation during storage. Increasing the storage temperature would accelerate this process essential for resuscitation of ischemically damaged pancreatic tissue. The present study aimed at comparing islet isolation outcome from adult pig pancreata preserved in oxygenated PFD by means of a one-layer method during storage on ice or at 20 degrees C. Resected pancreata were intraductally flushed with cold UW solution and promptly processed (n = 6) or stored for 3 h in continuously oxygenated PFD at 4 degrees C (n = 5) or 20 degrees C (n = 7). Prior to digestion-filtration pancreata were intraductally injected with UW supplemented with Serva collagenase NB8 and neutral protease. Islet quality assessment determined viability, glucose stimulation index, mitochondrial activity, intracellular ATP content, and transplant function in diabetic nude mice. Pancreata oxygenated for 3 h at 20 degrees C yielded islet numbers similar to organs oxygenated at 4 degrees C. Compared to a storage temperature of 20 degrees C, preservation at 4 degrees C reduced islet ATP content (p < 0.05) as well as islet viability (p < 0.05). Nevertheless, PFD storage at 20 degrees C decreased insulin response to glucose compared to unstored pancreata (p < 0.05). In contrast to unstored pancreata or cold-stored organs, transplantation of islets isolated after oxygenation at 20 degrees C was characterized by an early loss of transplant function in 50% of recipients (p < 0.05). The present study demonstrates that PFD storage at 20 degrees C enhances islet ATP synthesis within a short period of oxygenation but deteriorates islet function. We conclude that the present data reflect an equilibration between reduced depression of metabolic activity resulting in damage of islets and temperature-stimulated acceleration of ATP synthesis. Future studies are required to adjust the optimum storage temperature for pancreas oxygenation in different species.

Oxygenation of islets and its role in transplantation

“…This finding may at least in part be explained by the fact that perfluorohexyloctane has nearly the same oxygen solubility as perfluorodecalins but is characterized by a lower specific density (1.33 vs. 1.93 g/cm 3 ) and better lipophilic qualities to penetrate into the core of donor pancreata [16]. Storage of pig pancreata with perfluorodecalins at 208C enhanced islet ATP synthesis but decreased islet posttransplant function when compared with conventional cold storage at 48C during preservation [17 ].…”

Implication of Mitochondrial Cytoprotection in Human Islet Isolation and Transplantation

“…In the pig pancreas model, oxygenated perfluorodecalin (PFD) was used at various temperatures showing that pig pancreas oxygenation at 20°C increases islet ATP generation; however, the islets were found to have compromised insulin secretion in response to glucose stimulation [43]. In a human islet study, F6H8S5, a newly developed oxygen carrier composed of F6H8 (perfluorohexyloctane) and silicone oil polydimethylsiloxane 5, was compared to PFD, showing comparable results linking the optimization of ATP production during the cold storage period [44].…”

Chemical Oxygenation of Pancreatic Tissue Prior to Islet Isolation and Transplantation

“…This modification bears the potential of increased flexibility in the logistics of pancreas procurement and subsequent islet isolation by facilitating short-term oxygenation after pancreas arrival in the isolation facility prior to initiating the isolation procedure. Experiments in pig pancreases revealed that determinants of successful islet isolation such as islet yield, viability, and morphological integrity were not reduced compared to nonstored pancreases when the oxygenation temperature was increased to 20°C (Iken et al, 2009). Nevertheless, in spite of an ATP generation that was enormously increased when compared to freshly isolated islets or to oxygenation at 4°C, islets isolated after oxygenation at 20°C were characterized by reduced in vitro function and posttransplant outcome after transplantation into diabetic nude mice (Fig.…”

“…Initial experiments in rats clearly demonstrated that pancreas oxygenation utilizing the lipophilic compound F6H8 for 24 hours of cold storage significantly improved islet isolation outcome in terms of yield, viability and functional integrity of isolated islets as well as transplant function in diabetic nude mice when compared to PFD (Brandhorst et al, 2009). In agreement with the postulation of Avgoustiniatos (Avgoustiniatos et al, 2006), small organs like rat pancreases can efficently be provided with oxygen regardless of the chemical characteristics of the oxygen carrier used.…”