Comparative gene expression of equine iMSCs and BM-MSCs: profiling their immune properties in vitro

Mesenchymal stem cells (MSCs) hold great therapeutic promise in the horse. However, in vitro senescence of primary MSCs results in repeated invasive tissue harvesting and cellular heterogeneity. Therefore, deriving MSCs from induced pluripotent stem cells (iPSCs), referred to as iMSCs, has emerged as a promising alternative. Nevertheless, because iMSCs are obtained in the lab from epigenetically reprogrammed iPSCs, they could present altered gene expression related to their function and recognition by the immune system. The interaction between the patient’s immune system and MSCs plays a key role in their efficacy and safety, based on their ability to both regulate (immunomodulation) and to provoke (immunogenicity) an immune response. These properties have not yet been explored in equine iMSCs. This study aims to compare the immunomodulatory and immunogenic gene expression profiles of equine iMSCs and primary equine bone marrow-derived MSCs (BM-MSCs) before and after exposure to allogeneic MHC-mismatched lymphocytes. Three lines of equine iMSCs, derived from 3 iPSC lines from the same donor, and 3 lines of equine BM-MSCs, derived from 3 different donors, were cocultured with allogeneic MHC-mismatched equine lymphocytes to assess their interaction. Prior and after their coculture, the expression of genes related to immunomodulation (VCAM1, IL6, COX2, iNOS, IDO) and immunogenicity (CD40, CD80, MHC-I, MHC-II) of iMSCs/BM-MSCs was assessed by RT-qPCR. Exposure to lymphocytes changed the gene expression immune profile of both equine iMSCs and BM-MSCs, and differences were observed between the 2 types of cells. Overall, and in terms of gene expression, BM-MSCs showed a higher immunomodulatory profile, while both iMSCs and BM-MSCs displayed a comparable immunogenic profile. Although equine iMSCs may exhibit lower immunomodulatory capacity than primary BM-MSCs, their relatively low immunogenic profile suggests they could be safely administered. Further functional analysis and in vivo studies are required to determine whether iMSCs offer therapeutic advantages over primary MSCs in horses.