Effect and mechanism of human umbilical cord mesenchymal stem cells on preventing murine acute graft-versus-host disease

Abstract

Objective To determine the prophylactic effect of human umbilical cord mesenchymal stem cells (HUCMSCs) on murine acute graft-versus-host disease (aGVHD) and preliminarily explore its mechanism. Methods In order to establish a mouse model of aGVHD, the male BALB/c mice were transplanted with bone marrow cells and spleen lymphocytes from male C57BL/6 mice after receiving 7.5 Gy total body irradiation (TBI) on the day of allogeneic hematopoietic stem cell transplantation (allo-HSCT). The mice were divided into BM group and aGVHD group, receiving 500 μL cell suspension containing 5×106 bone marrow cells or 5×106 bone marrow cells and 5×106 spleen cells, respectively, by tail vein. Their survival rate, clinical score and loss of body weight were assessed, chimerism was detected by flow cytometry, and pathological changes of target organs (lung, liver, colon, small intestine) were detected by HE staining. The HUCMSCs at passage 4 were collected and transplanted into aGVHD+MSCs group of BALB/c mice. The mice were then divided into aGVHD group (model group), aGVHD+MSCs group (5×106 bone marrow cells and 5×106 spleen cells and 5×105 HUCMSCs). Besides, the serum concentration of IFN-γ and TNF-α were detected by ELISA, and the infiltration and apoptosis of lymphocytes were detected by flow cytometry. Results Compared with the BM group, the aGVHD group showed a decreased survival rate, higher clinical score, and much obvious body weight loss (P < 0.05) and severer pathological injuries (P < 0.05). The mice achieved complete chimerism after transplantation. The aGVHD+MSCs group showed increased survival rate, lower clinical score and slighter pathological injuries (P < 0.05), the serum concentrations of IFN-γ and TNF-α were decreased (P < 0.05), and the apoptosis of CD4+ T cells in target organs was increased while the count was decreased (P < 0.05). Conclusion HUCMSCs infusion effectively prevent the development of murine aGVHD after allo-HSCT through mediating the apoptosis of lymphocytes to decrease their infiltration in target organs and regulating the secretion of inflammatory factors.

Keywords

• allogeneic hematopoietic stem cell transplantation
• acute graft-versus-host disease
• human umbilical cord mesenchymal stem cells
• cellular therapy
• inflammatory cytokine