During cerebral ischemia, NHE1 is activated, resulting in Na+ overload and cell swelling in astrocytes; this eliminates the corresponding BBB maintenance function of astrocytes, leading to BBB damage.252 Song et al. demonstrated that Wnt7a/7b expression was upregulated and the BBB was repaired, after knocking out the Nhe1 gene in the astrocytes of cerebral ischemic mice. The gene discussed is WNT7A; the disease is brain ischemia.