The neuroprotective effect of mesenchymal stem cells is mediated through inhibition of apoptosis in hypoxic ischemic injury

Background: Neonatal hypoxia ischemia causes severe brain damage. Stem cell therapy is a promising method for treating neuronal diseases. Clinical translation of human umbilical cord-derived mesenchymal stem cells (UC-MSCs) for the recovery of neurons after hypoxic ischemic encephalopathy (HIE) may represent an effective therapy.

Methods: Primary neurons were exposed to oxygen-glucose deprivation (OGD) and subsequently cocultured with UC-MSCs. Apoptosis was examined by Annexin V-FITC-PI. Genes related to apoptosis were detected using RT-PCR and western-blot analyses. Using an in vivo model, HIE was induced in postnatal day 7 mice, and UC-MSCs were transplanted via the intraventricular route. UC-MSC migration was investigated by immunofluorescence, and lesion volumes were measured by TTC staining. Apoptosis in injured brain cells was detected by the TUNEL assay. RT-PCR and ELISA were used to detect the expression of inflammatory factors in cells and animal tissues.

Results: Flow cytometry analysis revealed that apoptosis in injured neurons was inhibited by UC-MSCs. The RT-PCR and western blot results indicated that coculture inhibited the expression of proapoptotic genes and upregulated expression of antiapoptotic genes. In the animal model, transplanted UC-MSCs migrated toward the cerebral lesion site and decreased the lesion extent in HIE. TUNEL staining showed that the MSC group exhibited significantly reduced numbers of TUNEL-positive cells. RT-PCR and ELISA showed that UC-MSCs inhibited the upregulation of TNF-α and IL-1β in response to hypoxic ischemic injury.

Conclusion: These results indicate that UC-MSCs exert neuroprotective effects against hypoxic ischemic injury by inhibiting apoptosis, and the mechanism appears to be through alleviating the inflammatory response.