Innovative applications of acellular adipose matrix derived film in skin soft tissue expansion

Background Skin dilation generates "extra" skin tissue through mechanical traction, but its effectiveness is limited by the proliferation capacity of keratinocytes, fibroblasts and the level of angiogenesis. Cutaneous application of drug and subcutaneous injection are common interventions to promote skin dilation, but they have defects such as uneven drug distribution, high risk of infection and single targeting. Although Acellular adipose matrix (AAM) has the potential to promote cell proliferation and angiogenesis, its hydrogel/powder dosage forms still need frequent injection, which limits clinical application. Results In this study, Acellular adipose matrix derived film (AAF) was successfully developed, and a flexible film was formed by acellular - lyophilized - enzymolysis - self-assembly process. In vitro experiments confirmed that AAF significantly promoted the activity of Human Immortalized Epidermal Cells (HaCaTs), Normal Skin Fibroblasts (NFbs) and Human Umbilical Endothelial Cells (HUVECs); It was also found that AAF can induce adipose mesenchymal stem cells (ASCs) to differentiate into adipocytes and promote subcutaneous fat regeneration. In vivo, the rat model showed that AAF wrapping expander could effectively improve the skin expansion efficiency, promote the skin thickness increase in the expanded area, and the density of new blood vessels was significantly increased compared with the comparative group, and there was no complication such as infection or skin collapse. It was found for the first time that AAF successfully formed new adipose tissue in the subcutaneous area. Conclusion AAF innovatively integrates the bionic structure of extracellular matrix and slow-release function, and solves the uneven drug distribution and associated infection risk of traditional intervention methods by regulating the synergistic regeneration of epidermodermis and vascular units. Its mechanical adaptability (dry toughness/wet plasticity) and the ability of inducing adipose regeneration provide a new strategy of both structural strengthening and metabolic support for skin dilation, also laying a mechanism and empirical foundation for clinical transformation of tissue engineering materials.