Kaempferol promotes angiogenesis through HIF-1α/VEGF-A/Notch1 pathway in ischemic stroke rats

Stroke is a severe disease characterized by the obstruction of blood vessels in the central nervous system. An essential therapeutic strategy for ischemic stroke is strengthening angiogenesis, which effectively promotes the long-term recovery of neurological function. Therefore, it is critical to explore and develop new drugs that promote angiogenesis after ischemic stroke. Kaempferol has been employed to treat ischemic diseases; However, its proangiogenic effects in ischemic stroke remain unclear. In the study, we explored the long-term therapeutic effects and mechanisms of kaempferol on ischemic stroke in vivo and in vitro. A rat model of autologous thrombus stroke and oxygen-glucose deprivation (OGD)-induced human brain microvascular endothelial cells (HBMECs) model was established to assess the effects of kaempferol in vivo (50 mg/kg/d, ig, 14 d) and in vitro (0.1, 0.3, 1 μmol L^-1). The results showed that long-term administration of kaempferol ameliorated neurological deficits and infarct volume in ischemic stroke rats. In addition, kaempferol relieved vascular embolization; enhanced microvascular endothelial cell survival, proliferation, migration, and lumen formation; increased the density of microvessels in the peri-infarct cortex; and promoted neovascular structure remodeling by increasing the coverage of astrocyte end-feet and expression of tight-junction proteins (TJPs). Further analysis revealed that the HIF-1α/VEGF-A/Notch1 signaling pathway was activated by kaempferol, and that inhibition of Notch1 blocked kaempferol-induced angiogenesis. Taken together, our results indicate that kaempferol exerts neuroprotective effects by stimulating endogenous angiogenesis and neovascular structural remodeling via the HIF-1α/VEGF-A/Notch1 signaling pathway, suggesting the therapeutic potential of kaempferol in ischemic stroke.