Abstract:

Objective To investigate the role of caspase 3 in HMME-induced apoptosis in hypertrophic scar fibroblasts（HSFs）. Methods Fibroblasts were obtained from 10 patients with untreated hypertrophic scar, and subjected to a primary culture. After 4 to 6 passages of culture, the HSFs were divided into 3 groups to remain untreated （control group）, be treated with HMME followed by photodynamic therapy （HMME-PDT group）, or the combination of HMME and Z-DEVD-FMK followed by photodynamic therapy （caspase 3 inhibitor group）. At 12 hours after the therapy, HSFs were collected and immunofluorescence microscopy was used to observe the fluorescence intensity of caspase 3 after staining with fluorescein isocyanate （FITC） and popodium iodide （PI）, flow cytometry was performed to determine the percentage of caspase 3-positive HSFs and apoptosis rate in HSFs after single staining with FITC and PI respectively. Results The fluorescence intensity of caspase 3 was weak in the control group and caspase 3 inhibitor group, but was strong in the HMME-PDT group. An increased percentage of caspase 3-positive HSFs was noted in the HMME-PDT group compared with the control group and caspase 3 inhibitor group （30.86% ± 1.21% vs. 3.12% ± 0.28% and 2.46% ± 0.18%, t = 19.92, 21.76, both P < 0.05）. The apoptosis rate in HSFs was significantly higher in the HMME-PDT group and caspase 3 inhibitor group than in the control group（30.54% ± 3.78% and 10.46% ± 2.15% vs. 2.45% ± 0.22%, t = 35.90, 27.97, both P < 0.05）, and higher in the HMME-PDT group than in the caspase 3 inhibitor group. Conclusions The apoptosis in HSFs induced by HMME-PDT is closely related to the activation of caspase 3, while caspase 3 seems to be dispensable for the apoptosis.

Key words: Caspase3