Topical hADSCs-HA Gel Promotes Skin Regeneration and Angiogenesis in Pressure Ulcers by Paracrine Activating PPARβ/δ Pathway

Chaoying Jin,1,2,* Ruolin Zhao,3,4,* Weihang Hu,5 Xiaolong Wu,4 Li Zhou,6 Letian Shan,4,6 Huiling Wu1,2 1Department of Plastic and Aesthetic Center, The First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, Zhejiang, 310003, People’s Republic of China; 2School of Medicine, Zhejiang University, Hangzhou, Zhejiang, 310020, People’s Republic of China; 3Yichen Biotechnology Co., Ltd, Hangzhou, Zhejiang, 311200, People’s Republic of China; 4Fuyang Academy, Zhejiang Chinese Medical University, Hangzhou, Zhejiang, 311403, People’s Republic of China; 5Department of Critical Care Medicine, Zhejiang Hospital, Hangzhou, Zhejiang, 310013, People’s Republic of China; 6The First Affiliated Hospital, Zhejiang Chinese Medical University, Hangzhou, Zhejiang, 310060, People’s Republic of China*These authors contributed equally to this workCorrespondence: Letian Shan; Huiling Wu, Email [email protected]; [email protected]: Pressure ulcer is common in the bedridden elderly with high mortality and lack of effective treatment. In this study, human-adipose-derived-stem-cells-hyaluronic acid gel (hADSCs-HA gel) was developed and applied topically to treat pressure ulcers, of which efficacy and paracrine mechanisms were investigated through in vivo and in vitro experiments.Methods: Pressure ulcers were established on the backs of C57BL/6 mice and treated topically with hADSCs-HA gel, hADSCs, hyaluronic acid, and normal saline respectively. The rate of wound closure was observed continuously during the following 14 days and the wound samples were obtained for Western blot, histopathology, immunohistochemistry, and proteomic analysis. Human dermal fibroblasts (HDFs) and human venous endothelial cells (HUVECs) under normal or hypoxic conditions were treated with conditioned medium of human ADSCs (ADSC-CM), then CCK-8, scratch test, tube formation, and Western blot were conducted to evaluate the paracrine effects of hADSCs and to explore the underlying mechanism.Results: The in vivo data demonstrated that hADSCs-HA gel significantly accelerated the healing of pressure ulcers by enhancing collagen expression, angiogenesis, and skin proliferation. The in vitro data revealed that hADSCs strengthened the proliferation and wound healing capabilities of HDFs and HUVECs, meanwhile promoted collagen secretion and tube formation through paracrine mode. ADSC-CM was also proved to exert protective effects on hypoxic HDFs and HUVECs. Besides, the results of proteomic analysis and Western blot elucidated that lipid metabolism and PPARβ/δ pathway mediated the healing effect of hADSCs-HA gel on pressure ulcers.Conclusion: Our research showed that topical application of hADSCs-HA gel played an important role in dermal regeneration and angiogenesis. Therefore, hADSCs-HA gel exhibited the potential as a novel stem-cell-based therapeutic strategy of treating pressure ulcers in clinical practices. Keywords: pressure ulcer, wound healing, human adipose derived stem cell, hydrogel, PPARβ/δ, lipid metabolism, skin regeneration