Various vascular pathologies are due to abnormal regulation of endothelial cell (EC) function. In this thesis, human EC and zebrafish models have been developed to investigate the underlying mechanisms for rescuing insufficient vascular and preserving vascular integrity. The properties of phytoestrogen compounds that are found in vascular protective Chinese medicine have also been evaluated with these models. The first section investigated the actions of formononetin in human umbilical vein endothelial cell (HUVEC) and in zebrafish vasculature. It was observed that formononetin, a phytoestrogen isoflavonoid, induced cell migration and stress fiber formation in HUVEC with modest cell proliferation. The response was mediated through estrogen receptor α (ERα)-enhanced Rho-associated protein kinase (ROCK) pathway with the formation of ERα/ROCK-II complex. EC migration and proliferation are involved in re-vascularization and angiogenesis. In line with this, formononetin induced angiogenesis in zebrafish embryo through ROCK and the vascular endothelial growth factor (VEGF) signaling pathway. The second session established a chemical-induced vascular damage model in zebrafish in vivo. Treatment of zebrafish embryos with VEGFR tyrosine kinase inhibitor (VRI) significantly inhibited blood vessel formation and caused the disappearance of pre-existing blood vessels in the regions of ISV (intersegmental vessels) and DLAV (dorsal longitudinal anastomotic vessels). The loss of blood vessel was due to inhibition of angiogenesis and increased EC apoptosis. Furthermore, post-treatment of calycosin, another phytoestrogen isoflavonoid, restored VRI-induced blood vessel loss through ERα-mediated PI3K/Akt/Bad cell survival pathway. The last session established a hemorrhagic stroke model by using atorvastatin to induce intracerebral hemorrhage in zebrafish in vivo. Defects in endothelial permeability can cause hemorrhagic stroke. It was observed that atorvastatin disrupted endothelial cell-cell junction and vascular integrity. Atorvastatin inhibited the post-translation isoprenylation of small GTPases and disrupted the regulation on Src/ROCK-II/VE-cadherin/catenins associated with adherens junction and actin cytoskeleton. The results suggest that inhibiting Src and/or ROCK signaling might be beneficial for the management of cerebral hemorrhage. In summary, the survival and migration of EC and its cellular structural integrity are essential to vascular maintenance and regeneration. The cellular and zebrafish models established in this study will be useful tools for further investigating vascular pathologies. Vascular protective compounds can be effectively evaluated with these models for the treatment of pathologies such as ischemic chronic wounds and myocardial ischemia, and the improvement of vascular integrity in hemorrhagic stroke.