Priming with interleukin‐1α and chemical hypoxia modulates the mesenchymal stem cell secretome to dampen microglial inflammation and promote neuroprotection

Abstract Background and Purpose We hypothesised that dual priming of human bone marrow‐derived human mesenchymal stem cells (hBMSCs) with interleukin‐1alpha (IL‐1α) and CoCl 2 (a hypoxia mimetic) would modulate their therapeutic efficacy for hypoxic‐ischaemic conditions. Experimental Approach hBMSCs were primed individually or in combination. To test the anti‐inflammatory and cytoprotective properties, primed‐hBMSCs‐derived conditioned media (CM) was applied to lipopolysaccharide (LPS)‐treated BV2 microglial cells (inflammation model) and BV2 cells exposed to oxygen glucose deprivation (OGD) (hypoxic injury model). The neuroprotective effect was evaluated by assessing neuronal death (using neuron‐like cells NLCs) following exposure to OGD/reoxygenation (OGD/R) in the presence of various CMs. Key Results Priming significantly altered hBMSCs' secretion profiles. IL‐1α triggered significant ( P < 0.05 ) release of inflammatory mediators/cytokines, notably TNF‐α, ICAM‐1 and G‐CSF. Except for G‐SCF, dual‐priming did not potentiate their release. While single priming with either IL‐1α or hypoxia‐mimetic did not induce remarkable secretion of the neurotrophins β‐NGF and BDNF, the dual‐priming caused a potentiated increase ( P < 0.05 ) in the secretion of these neurotrophins. In the LPS model, CM from dual‐primed hBMSCs significantly reduced the secretion of pro‐inflammatory cytokines, TNF‐α and IL‐6. In the OGD/R model, priming did not significantly influence the marked reduction ( P < 0.05 ) of pro‐inflammatory cytokines IL‐1β, IL‐6 and TNF‐α. Lastly, CMs from primed hBMSCs reduced neuronal cytotoxicity, yet only CM from dual‐primed hBMSCs significantly ( P < 0.05 ) restored metabolic activity in NLCs following OGD/R. Conclusions and Implications These findings highlight dual priming as a promising strategy for optimising MSC‐based approaches for hypoxic–ischaemic conditions.