Cryopreservation of microencapsulated rat islets / 南方医科大学学报

<p><b>OBJECTIVE</b>To investigate the role of alginate-polylysine-alginate (APA) microcapsules in protecting rat islet cells in cryopreservation.</p><p><b>METHOD</b>Purified rat islet cells microencapsulated with APA and free islet cells were cryopreserved for one month and then thawed for culture in RPMI 1640 overnight. The morphology of the cells was observed and their function assessed by stimulated insulin release test.</p><p><b>RESULT</b>APA microcapsulation protected the fragile islets from freezing damage by increasing the recovery rate of the cells from 68.6%+/-2.9% to 94.7%+/-1.4% (P<0.05). After incubation with high glucose (16.7 mmol/L) solution, the insulin release from the encapsulated cells after cryopreservation significantly increased in comparison with that of the nonencapsulated cells (22.6+/-1.8 mU/L vs 11.7+/-1.5 mU/L, P<0.05). In high glucose solution containing theophylline, the calculated stimulation index of the encapsulated cells was about 3 times that of the nonencapsulated cells.</p><p><b>CONCLUSION</b>APA microencapsulation may significantly increase the post-thaw recovery and improve the function for cryopreserved rat islets.</p>

Co-culture of cryopreserved rat islets with small intestinal submucosa / 南方医科大学学报

<p><b>OBJECTIVE</b>To investigate the feasibility and benefits of co-culture of cryopreserved islets with small intestinal submucosa (SIS).</p><p><b>METHODS</b>Purified rat islets cryopreserved for one month were divided into SIS group and control group, and after culture in standard islet culture media RPMI1640 for 1 week, the morphology and function of the islets were assessed.</p><p><b>RESULTS</b>The SIS protects the fragile islets from damage by cryopreservation, and increased the recovery from (60.6-/+3.3)% to (91.7-/+1.8) % (P<0.05). Compared with the control group, incubation of the islets of the SIS group in high-glucose (16.7 mmol/L) solution resulted in significantly enhanced insulin secretion (23.7-/+1.6 vs 12.5-/+1.1 mU/L, P<0.05). When the islets were incubated in high-glucose solution containing theophylline, the calculated stimulation index of SIS group was about 3-fold higher than that of the control group.</p><p><b>CONCLUSION</b>Co-culture of cryopreserved rat islets with SIS can increase the recovery of islet cells and improve their function.</p>