Human Mesenchymal Stromal Cells Attenuate Hyperoxia-Induced Cellular Impairment of Immature Oligodendrocyte and Neurons.

Preterm infants are at high risk of developing long-term brain injury such as encephalopathy of prematurity (EoP). Hyperoxia is a major contributor to EoP, affecting white and grey matter, with immature oligodendrocytes and hippocampal neurons being particularly vulnerable. While no causal therapy is available, mesenchymal stromal cells (MSCs) show therapeutic potential and are considered a promising candidate, although their effector mechanisms remain incompletely understood. Primary oligodendrocytes were isolated from mixed glial cultures of P0-P2 rats and hippocampal neurons from E16 rat embryos. On day 3 (oligodendrocytes) and day 5 (neurons) after isolation, cells were exposed to hyperoxia for 8 h and subsequently co-cultured indirectly with naive or hypoxic-preconditioned human MSCs (hMSCs) for 48 h under standard culture conditions. Degeneration, proliferation, differentiation and mitochondrial respiration were assessed in both cell types. Both naive and hypoxic-preconditioned hMSCs attenuated hyperoxia-induced degeneration, reduced proliferation and mitochondrial respiration failure. Although oligodendrocyte differentiation, assessed by myelin basic protein (MBP) expression, was modulated neither by hyperoxia nor by hMSC treatment, the dendritic structure in hippocampal neurons was impaired by hyperoxia and improved by hMSC treatment. Notably, hypoxic-preconditioned hMSCs showed a stronger therapeutic effect than naive hMSCs on hyperoxia-damaged hippocampal neurons. These findings indicate that indirect hMSC co-culture mitigates hyperoxia-induced impairment of immature oligodendrocytes and hippocampal neurons and that hypoxic preconditioning may modulate this effect in a cell type-specific manner.