Cold preservation of rat pancreatic islets just above the freezing point using University of Wisconsin solution

Preservation of pancreatic islets in cold UW solution before transplantation

Culture of islets prior to transplantation needs to be revisited for maintaining functional islet capacity. This study was conducted to compare cold UW (University of Wisconsin) preservation with conventional culture based on insulin secretory capacity in vitro and in vivo. Islets isolated from Wistar rats were either cultured for 24 h at 37°C in RPMI1640 medium or DMEM containing various concentrations of glucose or preserved for the same period in UW solution or in DMEM solution at 4°C. The islet yield in UW group, but not in other groups, was maintained as comparable with that of fresh islets. Insulin secretory capacity in response to glucose was maintained only in the islets of UW group, but not in other groups. SCID mice given 300 IEQ islets of UW group showed gradual restoration of normoglycemia as found in the mice given freshly isolated islets. Meanwhile, those mice given cultured islets for 24 h at 37°C in RPMI1640 medium showed rapid decrease of blood glucose levels on day 1 followed by relatively elevated levels on day 2, suggesting unstable insulin secretory capacity of islets.   Morphological staining with anti-HMGB1 (high mobility group B1) antibody revealed central damage of islets in all culture groups regardless of glucose concentration and in islets of cold DMEM group, whereas those in the UW group were quite intact. These results suggest that cold preservation in UW solution is simple and beneficial in protecting islets morphologically and functionally before transplantation.

Real-Time Direct Measurement of Human Liver Allograft Temperature from Recovery to Transplantation

Temperature is a key parameter in organ preservation that has been consistently linked to primary nonfunction (PNF). In this communication, and for the first time anywhere, continued and direct measurements of human liver intraparenchymal temperatures are reported in six clinical cases of orthotopic liver transplantations (OLT). These measurements cover the entire transplantation procedure and include the full transport phase. In contrast with long-held beliefs, these data demonstrate that liver allograft temperatures reach and stabilize at near 0 degrees C, instead of 4 degrees C, during transport using standard protocols. Furthermore, these low temperatures do not appear to contribute to graft failure when negative factors such as long preservation, the presence of hepatic steatosis, or advanced donor age are present. The clinical and experimental implications of these findings, together with other relevant elements derived from the direct and continuous monitoring of human liver allograft intraparenchymal temperatures, are discussed.

Cold preservation of islets in UW solution--with special reference to apoptosis

BACKGROUND

Apoptosis progresses in cultured islets. Little is known with regard to apoptosis under cold preservation. We examined viability and function of islets in University of Wisconsin (UW) solution.

MATERIALS AND METHODS

Isolated rat islets were cultured overnight (overnight group) and further treated with 7-day culture in RPMI 1640 medium at 37 degrees C (culture group) or 7-day preservation in UW solution at 4 degrees C (preservation group). They were evaluated by glucose-stimulated insulin secretion test. Apoptosis was examined by TdT-mediated dUTP-biotin nick end-labeling (TUNEL) assay. Expression of caspase mRNA and the ratio of Bax to Bcl-2 were evaluated by reverse-transcriptase polymerase chain reaction (RT-PCR).

RESULTS

Islet recovery after 7 days was significantly lower in culture group than in preservation group (44.0 +/- 3.7% versus 75.0 +/- 4.9%, P < 0.05). The stimulation index in the culture group was significantly lower than in the overnight group (2.1 +/- 0.2 versus 4.1 +/- 0.4, P < 0.05). The apoptotic index in the culture group was significantly higher than both in the overnight group and in the preservation group (38.0 +/- 3.0% versus 10.8 +/- 2.0 and 27.0 +/- 4.0%, P < 0.05). Caspase 3, 8, and 9 mRNA in the culture group expressed more than in the other groups. Bax/Bcl-2 in the culture group was significantly lower than in the overnight group (3.2 +/- 0.66 versus 8.1 +/- 0.95, P < 0.05), suggesting that apoptosis had been already destined early after isolation.

CONCLUSIONS

The preservation group showed better recovery and function than the culture group. Apoptosis contributed to islet loss under culture and it was significantly suppressed under cold preservation.

Preservation of pancreas tissue during cold storage assessed by X-ray microanalysis

Clinical transplantation requires cold storage of tissue for several hours. We have examined the elemental content in exocrine and endocrine cells in mouse pancreas after cold storage by X-ray microanalysis, and in parallel carried out morphological studies. Tissue was stored at 4 degrees C for 4-12 h in Normal Krebs-Ringer's (high Na+/K+ ratio), Modified Krebs-Ringer's (low Na+/K+ ratio), Euro-Collins, University of Wisconsin (UW) solution, and seven modified version of UW solution. Incubation in Normal Krebs-Ringer's solution caused significantly increased Na and decreased K concentrations in contrast to incubation in other solutions. The cellular concentration of Na and Cl followed the concentration in the storage solution. Changes in the endocrine cells were similar to, but less pronounced than those in exocrine cells. Calcium was retained best in UW and some variants of UW, and least in Euro-Collins. This may indicate differences in preservation of secretory granules. Also, morphological studies showed that endocrine cells were less affected than exocrine cells. In conclusion, the only factor determining the intracellular concentration of diffusible ions after cold tissue storage is the ionic composition of the extracellular medium. X-ray microanalysis provides an objective method to assess whether the intracellular ionic composition of tissue is maintained during storage.