Immunomodulatory amnion-derived mesenchymal stromal cells preserve muscle function in a mouse model of Duchenne muscular dystrophy.

BACKGROUND: Duchenne muscular dystrophy (DMD) is an incurable genetic disease characterized by degeneration and necrosis of myofibers, chronic inflammation, and progressive muscle weakness resulting in premature mortality. Immunosuppressive multipotent mesenchymal stromal cell (MSC) therapy could be an option for DMD patients. We focused on amnion-derived mesenchymal stromal cells (AMSCs), a clinically viable cell source owing to their unique characteristics, such as non-invasive isolation, mitotic stability, ethical acceptability, and minimal risk of immune reaction and cancer. We aimed to identify novel immunomodulatory effects of AMSCs on macrophage polarization and their transplantation strategies for the functional recovery of skeletal and cardiac muscles. METHODS: We used flow cytometry to analyze the expression of anti-inflammatory M2 macrophage markers on peripheral blood mononuclear cells (PBMCs) co-cultured with human AMSCs (hAMSCs). hAMSCs were intravenously injected into DMD model mice (mdx mice) to assess the safety and efficacy of therapeutic interventions. hAMSC-treated and untreated mdx mice were monitored using blood tests, histological examinations, spontaneous wheel-running activities, grip strength, and echocardiography. RESULTS: hAMSCs induced M2 macrophage polarization in PBMCs via prostaglandin E2 production. After repeated systemic hAMSC injections, mdx mice exhibited a transient downregulation of serum creatin kinase. Limited mononuclear cell infiltration and a decreased number of centrally nucleated fibers were indicative of regenerated myofibers following degeneration, suggesting an improved histological appearance of the skeletal muscle of hAMSC-treated mdx mice. Upregulated M2 macrophages and altered cytokine/chemokine expressions were observed in the muscles of hAMSC-treated mdx mice. During long-term experiments, a significant decrease in the grip strength in control mdx mice significantly improved in the hAMSC-treated mdx mice. hAMSC-treated mdx mice maintained running activity and enhanced daily running distance. Notably, the treated mice could run longer distances per minute, indicating high running endurance. Left ventricular function in DMD mice improved in hAMSC-treated mdx mice. CONCLUSIONS: Early systemic hAMSC administration in mdx mice ameliorated progressive phenotypes, including pathological inflammation and motor dysfunction, resulting in the long-term improvement of skeletal and cardiac muscle function. The therapeutic effects might be associated with the immunosuppressive properties of hAMSCs via M2 macrophage polarization. This treatment strategy could provide therapeutic benefits to DMD patients.

Human amnion-derived mesenchymal stem cells attenuate xenogeneic graft-versus-host disease by preventing T cell activation and proliferation.

Acute graft-versus-host disease (GVHD) is characterized by severe tissue damage that is a life-threatening complication of allogeneic hematopoietic stem cell transplantation. Due to their immunosuppressive properties, mesenchymal stem cells (MSC) have been increasingly examined for the treatment of immune-related diseases. We aimed to assess the immunosuppressive effects of human amnion-derived MSC (AMSC) in a xenogeneic GVHD NOD/Shi-scid IL2rγnull mouse model using human peripheral blood mononuclear cells (PBMC). Additionally, we used human bone marrow-derived MSC (BMSC) as comparative controls to determine differences in immunomodulatory functions depending on the MSC origin. Administration of AMSC significantly prolonged survival, and reduced human tumor necrosis factor-α (TNF-α) concentration and percentage of programmed cell death protein-1 receptor (PD-1)+CD8+ T cell populations compared with in GVHD control mice. Furthermore, colonic inflammation score and percentage of human CD8+ T cell populations in AMSC-treated mice were significantly lower than in GVHD control and BMSC-treated mice. Interestingly, gene expression and protein secretion of the PD-1 ligands were higher in AMSC than in BMSC. These findings are the first to demonstrate that AMSC exhibit marked immunosuppression and delay acute GVHD progression by preventing T cell activation and proliferation via the PD-1 pathway.