The effects of mesenchymal stem cells in a murine sclerodermatous model of graft-versus-host disease

Abstract

Human chronic graft-versus-host disease (CGVHD) shares clinical characteristics with a murine sclerodermatous GVHD (scl GVHD) model that is characterized by skin and lung fibrosis. We used B10.D2 → BALB/c model of scl GVHD, which differ at minor histocompatibility loci, to address the therapeutic effect of mesenchymal stem cells (MSCs) on the development of CGVHD. MSCs were intravenously treated on days 3, 5 and 7 post-transplantation. The clinical severity of cutaneous scl GVHD was significantly attenuated after the treatment of MSCs. Pathologically, animals treated with MSCs showed less fibrosis and inflammatory cell infiltrations in skin and ear but not in visceral organs including lung and liver. Accordingly, the mRNA expression of collagen type 1 α1, 1 α2 and 3 α1 as well as collagen production were significantly reduced after the MSC treatment only in skin compared to the allogeneic scl GVHD controls. MSCs down-regulated mRNA of proinflammatory cytokines mainly in skin tissues and among them TGF-β expression was consistently reduced 28 days after HSCT. The effects of MSCs on molecular markers implicated in persistent TGF-β signaling and fibrosis, such as phosphatase and tensin homolog (PTEN), p-Smad2/3 and matrix metaloprotease-1 (MMP-1) were observed at the skin tissues. MSCs inhibited infiltration of immune cells into skin through down-regulating CCR4, CCR8 and CCR10 on donor CD4 T cells and CCR1 on CD11b monocytes. Moreover, MSCs diminished the expression of mRNA for chemokines such as CCL1, CCL8, CCL17, CCL22 and CCL3, in skin. In conclusion, treatment of MSCs early after transplant attenuated cutaneous scl GVHD by selectively blocking of immune cell migration and down-regulating the chemokines and chemokine receptors.