1:Division of Hematopoietic Innovative Therapies, Biomedical Innovation Unit, Centro de Investigaciones Energéticas Medioambientales y Tecnológicas (CIEMAT), Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER) and Instituto de Investigación Sanitaria Fundación Jiménez Díaz (IIS-FJD, UAM), Madrid 28040. Spain.

Mesenchymal stromal cells (MSCs) currently constitute one of the cell type more frequently used in advanced therapies.  While previous pre-clinical data have shown the efficacy of MSCs to revert graft versus host disease (GvHD) after allogeneic transplantation, only moderate therapeutic effects have been observed in clinical trials. With the purpose of increasing the anti-GvHD effect of these cells, adipose tissue derived human MSCs (Ad-MSCs) were transduced with a lentiviral vector carrying CXCR4 and IL10, two molecules involved in cell migration to inflamed sites and with potent anti-inflammatory properties, respectively. In vitro experiments showed that the stable expression of these molecules in Ad-MSCs (CXCR4-IL10-MSCs) efficiently enhanced the migration of MSCs towards SDF1 when compared to unmodified Ad-MSCs. CXCR4-IL10-MSCs also displayed enhanced capacity to inhibit the proliferation of activated T cells. Using a humanized GvHD mouse model generated by the transplantation of human peripheral blood mononuclear cells into immunodeficient NSG mice, a single dose of CXCR4-IL10-MSCs induced a decreased in the  GvHD clinical score compared to unmodified Ad-MSCs and confirmed by histopatologic analysis in the target organs. Moreover, CXCR4-IL10-MSCs also induced a polarization from a pro-inflammatory (Th1 and Th17) to an anti-inflammatory profile (CD3⁺-IL10⁺) and a significant increase in the number of regulatory B and T cells, compared to unmodified Ad-MSCs. Taken together, our preclinical studies strongly suggest that the lentiviral-medicated expression of CXCR4 and IL10 should improve the clinical efficacy of MSC-based cell therapies to treat GvHD.