Hyperglycaemic conditions decrease cultured keratinocyte mobility: implications for impaired wound healing in patients with diabetes

BACKGROUND: Elevated blood glucose in patients with diabetes mellitus (DM) leads to complications including poor wound healing. Proper keratinocyte migration and proliferation are the crucial steps during re-epithelialization. We hypothesize that the impaired wound healing in patients with DM is due to the disruption of proper re-epithelialization. OBJECTIVES: We aimed to explore the effects of high glucose on keratinocytes in terms of cell migration and proliferation. METHODS: Keratinocytes were cultivated in normal and high glucose conditions. Their viability was evaluated by MTS assay. Transwell migration and in vitro scratch assays were used to evaluate their mobility. The mRNA expressions and activities of matrix metalloproteinase (MMP)-2 and MMP-9 were determined. The mRNA of their respective physiological inhibitors, tissue inhibitor of MMP (TIMP)-1 and TIMP-2, was also evaluated. Immunofluorescent staining and Western blotting were used to examine the expression of phosphorylated focal adhesion kinase (pp125(FAK)). The impacts of high glucose on keratinocyte proliferation were assessed by 5-bromo-2'-deoxyuridine incorporation assay. RESULTS: High glucose treatment did not affect keratinocyte viability up to 3 days. In contrast, the mobility of keratinocytes, the activities and gene expressions of MMP-2 and MMP-9, the expression of pp125(FAK), and the cell proliferation after 5 days were significantly downregulated after hyperglycaemic treatments while the mRNA expression of TIMP-1 increased. CONCLUSIONS: Under hyperglycaemic conditions, keratinocytes demonstrate reduced migration and decreased proliferation capacities. These impairments of keratinocyte functions are likely to result in inadequate re-epithelialization. These defective physiological events provide a reasonable explanation for the poor wound healing commonly observed in patients with DM.