Effect of human stromal vascular fraction gel on the treatment of patients with skin depressed scar and its mechanism

Objective To observe content of cytokine in human stromal vascular fraction gel (SVF-GEL) and effect of SVF-GEL on biological behaviors of epidermal and dermal cells in vitro and clinical efficacy of SVF-GEL. Methods (1) SVF-GEL was prepared using liposuction aspirates harvested from females who received abdomen liposuction in author′s unit. SVF-GEL (1 mL) and high-glucose Dulbecco′s modified eagle medium (DMEM, 1 mL) were respectively cultured for 24 h with high-glucose DMEM containing 10% fetal calf serum, 10 g/L penicillin, and 10 g/L streptomycin, denoted as SVF-GEL group and negative control group, with 6 samples in each group. Content of epidermal growth factor (EGF) and vascular endothelial growth factor (VEGF) in the supernatant was determined by enzyme-linked immunosorbent assay. (2) A number of 5×10⁵ human skin fibroblasts (HSF) and HaCaT cells in logarithmic phase were inoculated and cultured in Transwell chambers for 12 h. All Transwell chambers containing cells were divided into SVF-GEL group (0.5 mL SVF-GEL was added for co-culture) and control group (0.5 mL high-glucose DMEM was added for co-culture), with 9 samples in each group for HSF and HaCaT cells. Scratch assay was performed after culture for 24 h, and residual scratch width was observed at post scratch hour (PSH) 0 (immediately), 24, and 48. Cell migration distance was measured at PSH 24 and 48. After culture for 24, 48, and 72 h, the number of living cell was counted using cell counter. (3) From June 2018 to June 2019, SVF-GEL was applied clinically to treat 15 patients with depressed scars on face, including 2 males and 13 females, aged 19 to 42 years. Survival condition of SVF-GEL and whether complications or not were observed 6 months after surgery. Before surgery and 6 months after surgery, depressed degree, color, and pliability of scar were compared. Vancouver Scar Scale (VSS) was employed to access color, vascularity, and pliability before surgery and 6 months after surgery, and total score was calculated. The number of patients with complete satisfaction or satisfaction was counted six months after surgery. Data were processed with analysis of variance of factorial design, paired samples

test, and Wilcoxon rank sum test. Results (1) The content of EGF in SVF-GEL group and negative control group was (316.6±12.8) and (3.4±0.6) pg/mL, and the content of VEGF in SVF-GEL group and negative control group was (568.67±12.19) and (4.93±0.16) pg/mL, with statistically significant differences between the two groups (

=48.777, 92.485,

<0.01). (2) Residual scratch widths of HSF and HaCaT in SVF-GEL group and control group were decreased gradually along with time elapse, in which those in SVF-GEL group at PSH 24 and 48 were less than those in control group. At PSH 24 and 48, cell migration distances of HSF and HaCaT in SVF-GEL group were more than those in control group (

_HSF=-20.304, -43.516,

_HaCaT=-15.060, -8.684,

<0.01). After culture for 24, 48, and 72 h, the number of living cell of HSF and HaCaT in SVF-GEL group was significantly more than that in control group (

_HSF=-3.374, -6.809, -18.036,

_HaCaT=-4.793, -6.028, -8.141,

<0.05 or

<0.01). (3) Six months after surgery, SVF-GEL grafted into patients survived well without complications, and depressed degree of scar ameliorated obviously with lightened pigmentation and softer texture as compared with before surgery. Compared with those before surgery, VSS scores of color, vascularity, and pliability, and total score of 15 patients with depressed scars on face were obviously decreased 6 months after surgery (

=-2.06, -2.07, -2.07,

=-15.811,

<0.05 or

<0.01). One patient was satisfied with the clinical outcome, and the rest 14 patients were completely satisfied with the clinical outcomes. Conclusions SVF-GEL contains cytokines EGF and VEGF, which can enhance cell migration ability and proliferation ability of HSF and HaCaT cells and have obvious effects on depressed scars for clinical application.