Optimal HO preconditioning to improve bone marrow mesenchymal stem cells' engraftment in wound healing.

Background: The transplantation of bone marrow mesenchymal stem cells (BMSCs) is a promising therapeutic strategy for wound healing. However, the poor migration capacity and low survival rate of transplanted BMSCs in wounds weaken their potential application.

Objective: To identify the optimal protocol for BMSCs preconditioned with HO and improve the therapeutic efficacy using HO-preconditioned BMSCs in wound healing.

Methods: Mouse BMSCs were exposed to various concentrations of HO, and the key cellular functional properties were assessed to determine the optimal precondition with HO. The HO-preconditioned BMSCs were transplanted into mice with full-thickness excisional wounds to evaluate their healing capacity and tissue engraftment.

Results: Treatment BMSCs with 50 μM HO for 12 h could significantly enhance their proliferation, migration, and survival by maximizing the upregulation of cyclin D1, SDF-1, and its receptors CXCR4/7 expressions, and activating the PI3K/Akt/mTOR pathway, but inhibiting the expression of p16 and GSK-3β. Meanwhile, oxidative stress-induced BMSC apoptosis was also significantly attenuated by the same protocol pretreatment with a decreased ratio of Bax/Bcl-2 and cleaved caspase-9/3 expression. Moreover, after the identification of the optimal protocol of HO precondition in vitro, the migration and tissue engraftment of transfused BMSCs with HO preconditioning were dramatically increased into the wound site as compared to the un-preconditioned BMSCs. The increased microvessel density and the speedy closure of the wounds were observed after the transfusion of HO-preconditioned BMSCs.

Conclusions: The findings suggested that 50 μM HO pretreated for 12 h is the optimal precondition for the transplantation of BMSCs, which gives a considerable insight that this protocol may be served as a promising candidate for improving the therapeutic potential of BMSCs for wound healing.