Hyperglycaemic conditions hamper keratinocyte locomotion via sequential inhibition of distinct pathways: new insights on poor wound closure in patients with diabetes

Background Diabetes mellitus (DM) is characterized by impaired insulin signalling, elevated plasma glucose, and predisposition towards complications involving several organs. A major complication of DM is impairment of wound healing. In the re-epithelialization process during wound healing, migration of keratinocytes is a crucial step. Our previous report demonstrated that keratinocytes cultured in hyperglycaemic media showed decreased cell mobility. Objectives The current study aimed to explore the effects of high glucose on keratinocyte migration after different treatment durations. Methods Keratinocytes were cultivated for indicated time periods under various concentrations of glucose. Relevant assays including Transwell migration and in vitro wound scratch assays, flow cytometric analysis, matrix metalloproteinase-1 (MMP-1) activity assay, determination of mRNA expression and Western blotting were performed. Results We demonstrated that (i) keratinocyte motility progressively and significantly decreased; (ii) the keratinocyte activation marker K16 was significantly suppressed; (iii) expression of alpha 2 beta 1 integrin and MMP-1, both crucial for keratinocyte locomotion on collagen type I, was significantly downregulated; and (iv) expression of the phosphorylated signal transducer and activator of transcription-1 significantly decreased after hyperglycaemic treatment. More specifically, different pathways become involved after prolonged duration of high glucose cultivation to reduce keratinocyte locomotion further. Conclusions We have demonstrated that high glucose treatment results in progressive suppression of keratinocyte locomotion and elucidated the molecular mechanisms involved. These results provide a reasonable explanation for the poor wound healing seen in patients with DM.