Hypoxia-Driven Metabolic and Apoptotic Reprogramming Amplifies Immunomodulation in Wharton’s Jelly-Derived Mesenchymal Stem Cells Beyond Bone Marrow Counterparts

Mesenchymal stem cells (MSCs) possess immunomodulatory properties that can be harnessed for treating acute graft-versus-host disease (aGVHD). In this study, we compared bone marrow- (BM) and Wharton’s Jelly-derived (WJ) MSCs and investigated how hypoxia preconditioning (1% O₂, 24 h) influences their immunoregulatory function. Using direct co-cultures with activated peripheral blood mononuclear cells from aGVHD patients, we evaluated T-cell proliferation, Treg induction, macrophage polarization, mitochondrial transfer, and MSC apoptosis. Hypoxia-preconditioned WJ-MSCs (WJ-MSCsHYP) more effectively suppressed T-cell proliferation, enhanced Treg differentiation, promoted M2 macrophage polarization, and improved T-cell metabolic balance via mitochondrial transfer. These effects were primarily driven by apoptosis and occurred independently of efferocytosis. Our findings highlight tissue-specific mechanisms underlying MSCs' immunoregulation and reveal that hypoxia enhances the therapeutic potential of WJ-MSCs. This work provides mechanistic insight into MSCs-based interventions and supports WJ-MSCsHYP as a promising cell source for immunomodulatory therapy in inflammatory disorders such as aGVHD.