CD73(+) adipose-derived stem cells reduce scar formation through PLOD1

BACKGROUND: Reducing cutaneous scar formation is important for assessing the success of skin wound healing. Although it is generally accepted that adipose-derived mesenchymal stem cells (AMSCs) have substantial therapeutic potential, efforts are continuously made to improve the outcome of AMSC therapy. Post-transcriptional suppression of procollagen-lysine 1, 2-oxoglutarate 5-dioxygenase 1 (PLOD1) in AMSCs has been shown to greatly reduce scar formation during skin wound healing, likely through modulating macrophage polarization. In the present study, we tested whether a CD73(+) subpopulation of AMSCs could reduce scar formation compared with CD73(–) AMSCs. METHODS: The gene profile of CD73(+) versus CD73(–) AMSCs was obtained from a validated public database, GSE167219. AMSCs were isolated from adipose tissue surrounding the groin of mice, after which CD73(+) versus CD73(–) AMSCs were sorted using flow cytometry. PLOD1 levels were determined in CD73(+) versus CD73(–) AMSCs. Then, PLOD1 in CD73(–) AMSCs was depleted by a short-hair interfering RNA against PLOD1 (sh-PLOD1), while PLOD1 in CD73(+) AMSCs was increased by expression of a PLOD1 transgene. A blade was used to induce a skin injury on the middle back of the mice. Either CD73(+) AMSCs or CD73(+) PLOD1 AMSCs or CD73(–) AMSCs or CD73(–) sh-PLOD1 AMSCs were intravenously transplanted into the injured region of the mice. Fibrosis and the underlying mechanisms were investigated. Co-immunoprecipitation was performed to evaluate interaction between CD73 and PLOD1. RESULTS: CD73(+) AMSCs expressed significantly lower levels of PLOD1, a potent stimulator of fibrosis, compared with CD73(–) AMSCs. Transplantation of CD73(+) AMSCs generated significantly reduced fibrosis at the skin injury site compared with CD73(–) AMSCs. However, expression of PLOD1 in CD73(+) AMSCs abolished its advantageous effects on fibrosis reduction, while depletion of PLOD1 in CD73(–) AMSCs improved the outcome of fibrosis to the levels of transplantation of CD73(+) AMSCs. Co-immunoprecipitation showed no direct protein interaction between CD73 and PLOD1. CONCLUSIONS: CD73(+) AMSCs are a subgroup of AMSCs with better therapeutic effects on wound healing, and can inhibit scar formation through reduced PLOD1 in an indirect manner.