Mechanical micronization of lipoaspirates for the treatment of hypertrophic scars

Hypertrophic scars cause cosmetic and functional problems for patients, and their treatment remains challenging. Mechanical micronization of adipose tissue can remove adipocytes and concentrate functional cells. Stromal vascular fraction (SVF)-gel is obtained by a series of simple mechanical processes, including shifting between syringes and centrifugation. This study aimed to assess the therapeutic effect of SVF-gel on hypertrophic scars.A model of hypertrophic scars was established in rabbit ears. SVF-gel and SVF cells were obtained from rabbit inguinal fat pads and injected into scars. Phosphate-buffered saline (PBS) was used as a control. Scars were structurally characterized by histologic and immunohistochemical analyses. Expression of inflammatory and fibrogenic genes was evaluated.Hypertrophic scars became less visible and softer following injection of SVF-gel or SVF cells. Dermal thickness was significantly lower in the groups treated with SVF-gel and SVF cells than in the PBS-treated group. Treatment with SVF-gel restored subcutaneous fat tissue in scars, while treatment with SVF cells and PBS did not. Injection of SVF-gel and SVF cells reduced macrophage infiltration in the dermal layer and decreased mRNA expression of interleukin-6 and monocyte chemoattractant protein-1. In addition, the level of myofibroblasts and collagen deposition were reduced in the groups treated with SVF-gel and SVF cells.SVF-gel has therapeutic effects on hypertrophic scars. Injection of SVF-gel into hypertrophic scars restores subcutaneous fat tissue and reduces the levels of macrophages and myofibroblasts; thus, it decreased the dermal thickness of the scar.