Hypoxia induced angiogenesis and upregulation of VEGF: An in vivo study using Zebrafish model [ ]

Cobalt chloride, a known hypoxic agent is able to induce angiogenesis in zebrafish embryos. The concept of this study is to sense the effect of CoCl2 during development, using zebrafish as model system. Embryos exposed transdermally to varying concentrations (0.5-5μM) of CoCl2 has shown to enhance the formation of blood vessel and intersegmental vessel (ISV), as detected by RBC and alkaline phosphatase staining respectively. Length, size, sprouting junction of blood vessels were measured using the software angioquant and shown significant change with increasing concentrations. An increase in VEGF, VEGF-R2 and HIF-1α mRNA expression were observed through qPCR, while western blotting analysis revealed a considerable increase in VEGF expression and a complete inhibition of VEGF under hypoxia with SU5416, an inhibitor of VEGF signalling. The ability of CoCl2 to induce angiogenesis in zebrafish embryos might be through the enhanced expression of HIF-1α, VEGF, and VEGF-R2, the key player of angiogenesis and the results obtained with SU 5416 is suggestive the involvement of VEGF signalling during embryonic development.