Internal Tissue Expansion Induces Outward Migration of ADSCs From the Subcutaneous Fat Flap to Promote Skin...

Repair of large soft tissue defects by tissue expansion often faces difficulties in skin expansion. Particularly in those who have lost a significant amount of skin and subcutaneous tissue due to total mastectomy, tissue expansion may result in skin breakdown and exposure of the expander. Subcutaneous fat construction by autologous fat grafting before expansion seems to assist skin expansion. We hypothesize that it may be related to the adipose-derived stem cells (ADSCs) in subcutaneous fat. In this study, we confirmed this phenomenon through animal experiments and provided a preliminary investigation of the possible mechanisms involved. Four groups were designed for the experiment, experimental group (EG) for autologous fat flap transfer and tissue expansion. Fat grafting control group (FGCG), where only autologous fat flap transfer was performed without tissue expansion. Tissue expansion control group (TECG) did not perform autologous fat flap transfer but only skin tissue expansion on the back. Blank control group (BCG) has not received any surgery. In each group of 20 rats, skin, and fat flaps of the dilated area were sampled at four time points (7, 14, 21, and 28 days, n = 5), and the immediate skin retraction rate of the expanded area in the EG and TECG groups was measured to evaluate the expansion effect. GFP⁺ADSCs were observed to demonstrate whether they were facilitated by tissue expansion and migrated from autologous fat flaps to skin. Our study supported that fat layer construction prior to skin expansion helps to promote skin growth. The promotion may be related to the migration of ADSCs from adipose to dermis by compression, and ADSCs migrating to dermis further promote skin stretching through direct differentiation or paracrine cytokines to promote cell proliferation and collagen synthesis.