EPO and ischemia: The study found that the expression of HIF-1α and its target genes VEGF, EPO, and GTP in the ischemic penumbra increased significantly after ischemia and hypoxia (Stowe et al., 2008; Zhang et al., 2010), which was conducive to promoting collateral angiogenesis and glucose metabolism, improving the blood flow supply and energy supply in the penumbra, and enabling the survival of this part of neurons.