iPSC-derived mesenchymal stromal cells (iMSC) provide superior support for hematopoietic reconstitution compared to BM-MSCs

Abstract Background Mesenchymal stromal cells (MSCs) have demonstrated therapeutic promise in regenerative medicine and hematopoietic support; however, the clinical utility of bone marrow-derived MSCs (BM-MSCs) is constrained by donor variability, limited expansion potential, and heterogeneity. Methods To overcome these challenges, we developed induced MSCs (iMSCs) from adult skin fibroblast-derived induced pluripotent stem cells (iPSCs) using a novel non-integrating synthetic mRNA reprogramming strategy. Results The resulting iMSCs exhibited robust contact inhibition, trilineage differentiation capacity, and superior proliferative potential (>70 doublings) under both normoxic and hypoxic conditions exceeding BM-MSC potential. Molecular profiling by transcriptomic, proteomic, and secretome analyses revealed a high degree of similarity between iMSCs and BM-MSCs, including expression of canonical MSC markers and hematopoietic niche-supportive genes such as THY1, LEPR, and CXCL12. The iMSCs secreted high levels of SDF-1, MMP1, MCP1, VEGF A, LIF and TWEAK compared to BM-MSCs. Importantly, no evidence of sarcoma formation or ectopic tissue development was observed after intraperitoneal, subcutaneous, or intravenous delivery in NSGS mice, affirming the safety profile of iMSCs. Functionally, iMSCs created a supportive microenvironment for patient-derived acute myeloid leukemia (AML) cells in vitro and promoted CD34⁺hematopoietic progenitor colony formation. In xenograft and syngeneic models, co-transplantation with iMSCs enhanced CD34⁺ cell engraftment and hematopoietic reconstitution compared to no MSC or BM-MSCs. Notably, iMSCs were resistant to conditioning agents including cyclophosphamide, fludarabine, and busulfan, as well as to high-dose irradiation—mirroring the chemoresistance of BM-MSCs and enabling their use in post-chemotherapy support. In vivo, intrafemoral injection of iMSCs resulted in bone marrow engraftment and migration to contralateral femurs and spleens in both NSGS and immunocompetent mice. iMSC-treated animals displayed significantly accelerated white blood cell, platelet count and hemoglobin recovery following sublethal irradiation compared to BM-MSC-treated or control groups. Conclusion, Data suggest the use of iMSCs as a scalable, genetically stable, and homogenous alternative to BM-MSCs, with superior expansion capacity for hematopoietic engraftment after myeloablation therapy.