In addition, other studies have shown that transfer of VEGFR-2+/Sca-1+/CXCR4+ cultured early-outgrowth EPCs failed to reverse CH-induced PH [27] and that BM-derived late-outgrowth endothelial cell can contribute to vascular repair of an injured systemic artery, but they cannot rescue injured pulmonary vasculature under MCT-induced PH [176]. This evidence concerns the gene CXCR4 and cyclic hematopoiesis.