High mobility group box 1 promotes the differentiation of spinal ependymal cells into astrocytes rather than neurons

Spinal ependymal cells are involved in proliferation, differentiation and migration after spinal cord injury (SCI) and represent an endogenous source of repair cells for treating SCI. However, 95% of activated ependymal cells eventually differentiate into astrocytes after SCI and ultimately contribute more than half of the new astrocytes that form glial scars in vivo. The factors that regulate the fate of ependymal cells after SCI remain unclear. High mobility group box 1 (HMGB1) is regarded as an important proinflammatory factor in nerve injury, and recent studies have shown that HMGB1 can regulate the fate of stem cells after injury. In this study, we investigated whether HMGB1 released from reactive astrocytes after SCI regulates the proliferation and differentiation of ependymal cells in vitro. Ependymal cells extracted and cultured from the spinal cord of mice were separately treated with astrocyte culture medium (ACM), IL-1β, ACM (IL-1β) and the HMGB1 protein, and the proliferation and differentiation of ependymal cells were detected. Additionally, an HMGB1-neutralizing antibody (anti-HMGB1) was added to further verify the regulatory effect of HMGB1 on ependymal cells. The results showed that HMGB1 released from reactive astrocytes promoted ependymal cell differentiation into astrocytes and inhibited ependymal cell differentiation into neurons in vitro; however, the effect disappeared after the addition of anti-HMGB1. HMGB1 had no significant effect on ependymal cell proliferation. Our findings demonstrate that HMGB1 can regulate the differentiation of ependymal cells after SCI. These results provide a new strategy for the treatment of SCI.