Increased expression of heat shock protein 70 and heat shock factor 1 in chronic dermal ulcer tissues treated with laser-aided therapy

Background Chronic dermal ulcers are also referred to as refractory ulcers. This study was conducted to elucidate the therapeutic effect of laser on chronic dermal ulcers and the induced expression of heat shock factor 1 （HSF1） and heat shock protein 70 （HSP70） in wound tissues. Methods Sixty patients with 84 chronic dermal ulcers were randomly divided into traditional therapy and laser therapy groups. Laser treatment was performed in addition to traditional therapy in the laser therapy group. The treatment efficacy was evaluated after three weeks. Five tissue sections of healing wounds were randomly collected along with five normal skin sections as controls. HSP70-positive cells from HSP70 immunohistochemical staining were counted and the gray scale of positive cells was measured for statistical analysis. Reverse transcription-polymerase chain reaction （RT-PCR） and Western blotting were performed to determine the mRNA and protein expressions of HSF1 and HSP70. Results The cure rate of the wounds and the total efficacy in the laser therapy group were significantly higher than those in the traditional therapy group （P 〈0.05, P 〈0.01, respectively）. Immunohistochemical staining revealed that the HSP70-positive cell count was significantly higher in laser therapy group than those in the traditional therapy group and controls （P 〈0.01）, and the gray scale of the cell signal was obviously lower than traditional therapy group and controls （P 〈0.05）. By contrast, the traditional therapy group and the control group were not significantly different. The RNA levels of HSF1 and HSP70 were higher in the laser therapy group by RT-PCR, but very low in normal skin and the traditional therapy group. The analysis on the gray scale of the Western blot bands indicated that the expression of HSF1 and HSP70 in the laser therapy group was significantly higher than in the traditional therapy group and the control group （P 〈0.01）, and the expression in the traditional therapy group was also higher than in the control group （P 〈0.05）. Conclusion Laser-aided therapy of chronic dermal ulcers plays a facilitating role in healing due to the mechanism of laser-activated endogenous heat shock protection in cells in wound surfaces.