Research Advances on Mesenchymal Stem Cell-Derived Exosomes in Anti-Graft-Versus-Host Disease Therapy: Mechanisms,...

Graft-versus-host disease (GVHD) remains the most severe complications following allogeneic hematopoietic cell transplantation (allo-HCT). Mesenchymal stromal cells (MSCs) have shown therapeutic potential in GVHD due to their immunomodulatory properties. However, their clinical application is constrained by safety concerns, including ectopic engraftment, microvascular obstruction, rejected by host, and potential tumor-supportive effects. Increasing evidence suggests that MSC-derived exosomes (MSC-Exos), as cell-free mediators, retain many of the beneficial effects of MSCs while exhibiting improved safety and stability profiles. MSC-Exos carry diverse bioactive cargo, including nucleic acids, lipids, and proteins, and can modulate immune responses, promote tissue repair, and restore barrier integrity. In this review, we place particular emphasis on both immunoregulation and tissue barrier protection as dual mechanisms underlying MSC-Exos efficacy in GVHD. We further discuss emerging preclinical and clinical evidence, as well as key challenges in translation.