Subrata Chakrabarti

The University of Western Ontario, Chief of Pathology and Laboratory Medicine, LHSC/SJHC, 339 Winderemere Rd., London, ON, Canada N6A 5A5

Abstract:

Aims: miRNA play an important role in post-transcriptional regulation of gene expression in all physiological and pathological processes. Our previous studies showed that miR-200b regulates VEGF mediated angiogenesis and miR-146a regulates extracellular matrix protein, fibronectin (FN) production. In this study, we examined the effects of these two miRNAs in wound healing in diabetic and control animals.

Methods: Microvascular endothelial cells (ECs) were exposed to low and high glucose levels and were tested for VEGF and FN production and examined for angiogenesis. They were also transfected with miRNA mimics and inhibitors of these miRNAs (antagomirs). Furthermore, wounds in the back of mice with or without STZ induced diabetes were treated with single application of these antagomirs, alone or in combinations. The wounds were measured and tissues from the wounds were examined for mRNA and miRNA expression.

Results: In the ECs, glucose induced increased VEGF and FN production and angiogenesis. Production of VEGF or FN was also augmented in the low glucose exposed cells by miR-200b or miR-146a inhibitor transfection. In the animals, compared to transfection reagent only, wound healing processes were accelerated by miR-200b or miR-146a inhibitor. However, such acceleration was most pronounced (50% reduction) when these two inhibitors were combined. Histological examination demonstrated generation of mature fibrous tissue following such application. In the diabetic animals, although such process was delayed, similar patterns were seen.