Tracing the Change and Contribution of Subcutaneous Adipose to Skin Expansion Using a Luciferase-Transgenic Fat Transplantation Model.

Abstract

During skin expansion, subcutaneous adipose tissue undergoes the greatest change. The adipose layer appears to gradually thin or even disappear in long-term expansion. The response and contribution of adipose tissue to skin expansion remain to be elucidated. The authors established a novel expansion model by transplanting luciferase-transgenic adipose tissue into the rat dorsum, followed by integrated expansion, to trace the dynamic changes in subcutaneous adipose tissue during expansion and the migration of adipose tissue-derived cells. In vivo luminescent imaging was performed to continuously track the adipose tissue changes. Histologic analysis and immunohistochemical staining evaluated the regeneration and vascularization of the expanded skin. Growth factor expression in expanded skin with or without adipose tissue was determined to evaluate the paracrine effect of adipose tissue. Adipose tissue-derived cells were traced in vitro by anti-luciferase staining, and their fate was determined by costaining for PDGFRα, DLK1, and CD31. In vivo bioimaging showed that cells in adipose tissue were alive during expansion. After expansion, the adipose tissue exhibited fibrotic-like structures, with more DLK1 + preadipocytes. Skin expanded with adipose tissue was significantly thicker than that without adipose tissue, with more blood vessels and cell proliferation. Vascular endothelial growth factor, epidermal growth factor, and basic fibroblast growth factor expression was higher in adipose tissue than in skin, indicating paracrine support from adipose tissue. Luciferase-positive adipose tissue-derived cells were observed in expanded skin, indicating direct participation in skin regeneration. Adipose tissue transplantation can effectively promote long-term skin expansion by contributing to vascularization and cell proliferation by means of various mechanisms. The authors' findings suggest that it would be better if the expander pocket is dissected over the superficial fascia to preserve a layer of adipose tissue with skin. In addition, their findings support the treatment of fat grafting when expanded skin presents with thinning.