Enhancing the potency of Mesenchymal Stem Cells to boost Neural Stem Cell differentiation

Hypoxic-ischemic encephalopathy (HIE) is one of the leading causes of neonatal mortality and severe long-term neurological morbidity in infants born at term. Current treatment options for HIE are limited, but mesenchymal stem cell (MSC) therapy is an emerging and promising strategy. Our group has shown previously that intranasal administration of bone marrow-derived MSCs (bmMSCs) in a mouse model of neonatal HIE reduces infarct size by 40-50% and improves sensorimotor and cognitive outcome. The proposed mechanism of action of bmMSCs is that transplanted bmMSCs secrete different factors and therefore boost the endogenous regeneration of the injured brain by driving the differentiation of neural stem cells (NSCs) towards the neural cell fate. The current study aimed to enhance the efficacy of therapy for HIE by hypoxic preconditioning (HP) bmMSCs at 1% O2. In vivo, HIE was induced in 9-day-old C57Bl/6j mouse pups and HP-bmMSCs, normoxic bmMSCs (N-bmMSCs) or vehicle solution were given intranasally 10 days later. Both HP-bmMSCs and N-bmMSCs significantly reduced infarct size and sensorimotor impairment after HIE compared to vehicle treatment. Importantly, HP-bmMSCs were superior to N-bmMSCs in reducing infarct size (P=0.04) and improved sensorimotor outcome (P=0.01). In addition, ex vivo gene expression profiling identified several promising upregulated factors to explain the enhanced potency of HP-bmMSCs. Moreover, by using an in vitro bmMSC/NSC non-contact co-culture differentiation assay, we demonstrated that HP-bmMSCs enhanced the differentiation of NSCs towards neuronal cell fate compared to N-bmMSCs. Moreover, HP-bmMSCs changed the neuronal morphology of differentiated NSCs. The study also aimed to investigate the effect hucMSCs from different donors on the differentiation of NSCs. Our in vitro non-contact co-culture differentiation assay indicated that hucMSCs-31813 enhanced the expression of the neuronal marker bIII-tubulin with a greater potency compared to hucMSCs-27781. Concluding, HP enhances the therapeutic efficacy of bmMSCs by reducing brain damage and improving functional outcome. HP induces changes in the gene expression profile and secretome, which enhances the neuroregenerative potential of bmMSCs. HP is a promising optimizing strategy for bmMSC therapy and might lead to improvement in the neurodevelopmental outcome of infants born with HIE.