Cox-2 inhibition potentiates mouse bone marrow stem cell engraftment and differentiation-mediated wound repair.

Abstract

Engraftment of transplanted stem cells is often limited by cytokine and noncytokine proinflammatory mediators at the injury site. We examined the role of Cyclooxygenase-2 (Cox-2)-induced cytokine-mediated inflammation on engraftment of transplanted bone marrow stem cells (BMSCs) at the wound site. BMSCs isolated from male C57/BL6J mice were transplanted onto excisional splinting wounds in syngenic females in presence or absence of celecoxib, Cox-2 specific inhibitor (50 mg/kg, body weight [b wt]), to evaluate engraftment and wound closure. Inflammatory cell infiltration and temporal expression of inflammatory cytokines at the wound bed were determined using immunohistochemical and quantitative-real time polymerase chain reaction (qPCR) analysis, respectively. Mechanistic studies were performed on a murine macrophage cell line (J774.2) to evaluate the effect of interleukin (IL)-17A. Celecoxib administration led to a significantly high percent of wound closure, cellular proliferation, collagen deposition, BMSCs engraftment and re-epithelialization at the wound site. Interestingly, recruitment of CD4⁺T cells and F4/80⁺ macrophages as well as BMSC transplantation induced up-regulation of Cox-2 and IL-17A gene expression levels were reverted by celecoxib administration. Exogenous supplementation of recombinant interleukin (rIL)-17 to J774.2 cells significantly increased proliferation and gene expression of cytokines -IL-1β, IL-6, IL-8, IL-18 and tumor necrosis factor (TNF)-α via nuclear translocation of nuclear factor kappa B (NFκB)p65/50 subunit. Conditioned media of rIL-17 treated J774.2 cells when supplemented to BMSCs depicted a dose-dependent increase in the number of apoptotic cells and proapoptotic protein expression that was perturbed by celecoxib or IL-17 neutralizing antibody. Finally, celecoxib led to a dose-dependent increase in BMSC differentiation into keratinocyte-like cells in vitro. Celecoxib protects transplanted BMSCs from Cox-2/IL-17-induced inflammation and increases their engraftment, differentiation into keratinocytes and re-epithelialization thereby potentiating wound tissue repair.