The effects of microwave irradiation on the proliferation of cultured human keloid-derived fibroblasts and the mechanism involved

Abstract

Objective To explore the effects of microwave irradiation on the proliferation of keloid-derived fibroblasts so as to analyze the expression of collagen-1 and the activation of the signaling pathway involved. Methods Cells from a human keloid scar were cultured in vitro and randomly divided into a control group without any intervention, a 10 mW/cm2 microwave irradiation (10-MI) group and a 20 mW/cm2 microwave irradiation (20-MI) group. Aliquots of the latter 2 groups were irradiated at their corresponding intensities for 5 min, 15 min and 30 min. The growth of fibroblasts was evaluated using MTT assay. The expression of collagen-1 and changes in the phosphorylation of protein JNK were detected using western blotting. Results Compared with the control group, no significant differences in the average growth of the keloid-derived fibroblasts were observed in the 10-MI group, but significant differences were observed in the 20-MI group and among the three sub-groups irradiated for different durations. The expression of type 1 collagen was significantly down-regulated after irradiation in a time-dependent manner. After microwave radiation at 20 mW/cm2, JNK was significantly activated compared to the control group at the different time points. Conclusions Microwave irradiation at 20 mW/cm2 can significantly inhibit the proliferation of keloid-derived fibroblasts and the down-regulation is correlated with the irradiation′s duration. It can also significantly inhibit collagen-1 expression and relieve scar formation through activating the JNK signal pathway. Key words: Keloids; Fibroblasts; Microwaves; Collagen-1; JNK protein