Description: Long-term pancreatic cold ischemia contributes to decreased islet number and viability after isolation and culture, leading to poor islet transplantation outcome in patients with type 1 diabetes. In this study, we examined mechanisms of pancreatic cold preservation and rewarming-induced injury by interrogating the proapoptotic gene BBC3/Bbc3, also known as Puma (p53 upregulated modulator of apoptosis), using three experimental models: 1 ) bioluminescence imaging of isolated luciferase-transgenic ("Firefly") Lewis rat islets, 2 ) cold preservation of en bloc-harvested pancreata from Bbc3-knockout (KO) mice, and 3 ) cold preservation and rewarming of human pancreata and isolated islets. Cold preservation-mediated islet injury occurred during rewarming in "Firefly" islets. Silencing Bbc3 by transfecting Bbc3 siRNA into islets in vitro prior to cold preservation improved postpreservation mitochondrial viability. Cold preservation resulted in decreased postisolation islet yield in both wild-type and Bbc3 KO pancreata. However, after culture, the islet viability was significantly higher in Bbc3-KO islets, suggesting that different mechanisms are involved in islet damage/loss during isolation and culture. Furthermore, Bbc3-KO islets from cold-preserved pancreata showed reduced HMGB1 (high-mobility group box 1 protein) expression and decreased levels of 4-hydroxynonenal (4-HNE) protein adducts, which was indicative of reduced oxidative stress. During human islet isolation, BBC3 protein was upregulated in digested tissue from cold-preserved pancreata. Hypoxia in cold preservation increased BBC3 mRNA and protein in isolated human islets after rewarming in culture and reduced islet viability. These results demonstrated the involvement of BBC3/Bbc3 in cold preservation/rewarming-mediated islet injury, possibly through modulating HMGB1- and oxidative stress-mediated injury to islets.

Description: Organs from hypernatremia (elevated Na + ) donors when used for transplantation have had dismal outcomes. However, islet isolation from hypernatremic donors for both transplantation and research applications has not yet been investigated. A retrospective analysis of in vivo and in vitro islet function studies was performed on islets isolated from hypernatremic (serum sodium levels ≥ 160 meq/l) and normal control (serum sodium levels ≤ 155 meq/l) donors. Twelve isolations from 32 hypernatremic and 53 isolations from 222 normal donors were randomly transplanted into diabetic NOD Scid mice. Sodium levels upon pancreas procurement were significantly elevated in the hypernatremia group (163.5 ± 0.6 meq/l) compared with the normal control group (145.9 ± 0.4 meq/l) ( P 〈 0.001). The postculture islet recovery rate was significantly lower in the hypernatremia (59.1 ± 3.8%) group compared with the normal (73.6 ± 1.8%) group ( P = 0.005). The duration of hypernatremia was inversely correlated with the recovery rate ( r 2 = 0.370, P 〈 0.001). Furthermore, the percentage of successful graft function when transplanted into diabetic NOD Scid mice was significantly lower in the hypernatremia (42%) group compared with the normal control (85%) group ( P 〈 0.001). The ability to predict islet graft function posttransplantation using donor sodium levels and duration of hypernatremia was significant (ROC analysis, P = 0.022 and 0.042, respectively). In conclusion, duration of donor hypernatremia is associated with reduced islet recovery postculture. The efficacy of islets from hypernatremia donors diminished when transplanted into diabetic recipients.