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Investigation of long-term preservation of pancreatic islets.

OBJECTIVE
To develop a method for maintaining viability and function of islets of Langerhans during the long-term preservation.


METHODS
We encapsulated Wistar Furth (WF) rat islets in hydrophilic macrobeads (diameter 6-8 mm) made with agarose and collagen, then preserved them at 37 degrees C in a humidified atmosphere of air and 5% CO2 for different time, and compared unencapsulated islets with encapsulated islets for their insulin secretion capability in vitro. At the same time, we have investigated their viability and insulin secreting function in vivo.


RESULTS
Initially, there was no statistically significant difference in the insulin secretion values between the encapsulated and unencapsulated WF rat islets. While the unencapsulated islet insulin secretion decreased significantly within 2 weeks, the preserved and encapsulated islets maintained their viability and ability of insulin secretion for 40 weeks. In the in vivo study, the diabetic state was reversed in 92.8% of recipients transplanted with preserved macroencapsulated islets. The mice maintained normoglycemia for 157.6 +/- 49.3 days, at which point these macrobeads were retrieved. Glucose tolerance curves in the recipient mice were similar to those of normal mice.


CONCLUSIONS
These results indicate that it is a good method for long-term preservation of islets by encapsulating islets in agarose and collagen, and then culturing them at 37 degrees C in a humidified atmosphere of air and 5% CO2 before transplantation.