Browning of human subcutaneous adipose tissue after its transplantation in nude mice

Background: The clinical unpredictability of autologous fat grafting originates partially from the unique characteristics of adipose tissue. Evidences of adipose remodeling toward browning (developing of brown-like adipocytes in white adipose tissue) in response to trauma are emerging. With regard to fat grafting surgery procedure by which adipose tissue depots are directly and ubiquitously traumatized, whether it affect adipose phenotype change toward browning has not been previously reported. Methods: Human subcutaneous adipose tissues were harvested from the abdominal region of female patients via liposuction and were then injected into the dorsal flank of athymic nude mice. After 12 weeks, fat grafts were harvested and subjected to histological analysis. Results: Hematoxylin and eosin staining showed appearance of small multilocular adipocytes in the peripheral region of the grafts. These adipocytes exhibited higher staining for uncoupling protein 1 (fat-browning-specific marker), mitochondrial protein and CD31 compared with the central ones, indicating the presence of brown-like adipocytes, namely beige adipocytes, in this area. Furthermore, immunofluorescence staining demonstrated that these beige adipocytes might be derived from de novo adipogenesis from progenitors of graft origin. Conclusions: Results of this study suggest that browning of subcutaneous white adipose tissue participates in adaptive tissue remodeling following grafting and contributes to adipose tissue repair. # Lihong Qiu, and Zhaoxiang Zhang contributed equally to this research and should be viewed as co-first authors. Financial Disclosure Statement: None of the authors has a financial interest in any of the products or devices mentioned in this article. Acknowledgments: This study was supported by the National Natural Science Foundation of China (81671932, 81701919 and 81401598). The authors thank all of their colleagues at the Institute of Plastic Surgery, Xijing Hospital, Fourth Military Medical University, for their full cooperation and support. *Corresponding author: Chenggang Yi, M.D., Ph.D., Department of Plastic Surgery, Xijing Hospital, Fourth Military Medical University, No. 15, Changle West Road, Xi'an, Shaanxi 710032, China. Tel: +86-029-775306; Fax: +86-029-84775301; Email: yichg@163.com ©2018American Society of Plastic Surgeons

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