P38alpha-selective mitogen-activated protein kinase inhibitor for improvement of cultured human islet recovery.

Objectives: We investigated whether the recovery of cultured human islets is improved through the addition of a p38alpha-selective mitogen-activated protein kinase inhibitor, SD-282, to clinically used serum-free culture medium.

Methods: Immediately after isolation, islets were cultured for 24 hours in medium alone (control) or medium containing dimethyl sulfoxide, 0.1 microM SD-282, or 0.3 microM SD-282. Cytokine expression, apoptotic beta-cell percentage, and islet function were assessed postculture.

Results: Expression of p38 and phosphorylated p38 in islets increased during culture. Interleukin 6 mRNA expression in cultured islets, as well as IL-6, IL-8, and granulocyte-macrophage colony-stimulating factor released into the medium, was significantly reduced by adding SD-282. The apoptotic beta-cell percentage was significantly lower in islets cultured with 0.1 microM SD-282, but not 0.3 microM, as compared with the control. Stimulation indices measured in vitro were higher but without significance (P = 0.06); the function of transplanted islets in diabetic NOD-scid mice was also better in 0.1-microM SD-282 group as compared with control.

Conclusions: Better islet function was obtained by adding 0.1 microM SD-282 to the serum-free culture medium. This improvement was associated with suppression of cytokine production and prevention of beta-cell apoptosis. However, this beneficial effect was diminished at a higher concentration.