Mitomycin C Treatment Significantly Reduces Central Damage of Islets in Culture

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Abstract

Objectives

We recently reported that mitomycin C (MMC) treatment and subsequent culture of islets significantly prolongs graft survival in allotransplantation and xenotransplantation models. The present study was performed to determine the changes in morphology and signal transduction in pancreatic islets after MMC treatment.

Methods

Freshly isolated rat islets were treated with 10 μg/mL MMC for 30 minutes and then cultured for up to 3 days. The samples were processed for immunohistologic studies and electron microscopic examination at various times after treatment. A DNA fragmentation assay was performed to detect apoptotic cell death. Western blotting was performed to determine the effects of MMC on signal transduction.

Results

As early as 4 hours after culture, the islets showed central damage; most cells were necrotic and stained with anti–high mobility group box 1 antibody, and a few were apoptotic. The ratio of the damaged area to the whole area was significantly decreased after MMC treatment. Western blotting showed that MMC treatment increased the levels of activated forms of p53 and p21waf1, whereas levels of the activated forms of Akt and caspase-3 were unchanged.

Conclusions

Mitomycin C treatment protects islets from the progression of central damage during culture. The p53–p21waf1 pathway might be involved in these effects.

Abbreviations

MMC - mitomycin C, HMGB1 - high mobility group box 1

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