Abstract 15284: Von Hippel Lindau Mutant Zebrafish Display Pathological Angiogenesis That is Blood Flow Dependent
Introduction: Hypoxia drives pathological angiogenesis but the contribution of hemodynamic force in these processes is unknown. Mutations in von hippel lindau protein (vhl) upregulate hypoxic signalling. We therefore used vhl mutant zebrafish to examine the interactions between hypoxic signalling, hemodynamic force and developmental angiogenesis.
Methods: vhl mutant zebrafish were crossed with a fli1;eGFP transgenic expressing Green Fluorescent Protein in endothelial cytoplasm. Embryonic vascular development was observed in mutants and wild type siblings by confocal microscopy. To determine the role of blood flow in vascular development, we knocked down cardiac troponin T2 by morpholino antisense (which prevents any cardiac output but does not affect early development), or used microsurgery to exsanguinate embryos (reducing hematocrit and aortic blood velocity but preserving blood flow).
Results: Serial microscopy of the developing trunk vasculature revealed vhl mutant embryos display excessive angiogenesis (Fig 1, upper panels). Since vhl mutants have hyperphysiological cardiac outputs, we used exsanguination to reduce aortic flow in vhl mutants to wildtype levels, but this did not affect the aberrant angiogenesis. However, complete absence of blood flow due to troponin T2 knockdown prevented excessive angiogenesis in vhl mutants (Figs 1 lower panels & Fig 2), implying both blood flow and hypoxic signalling are required for hypoxia driven angiogenesis.
Conclusion: Angiogenesis in response to hypoxic signalling is critically dependent upon haemodynamic force, whereas developmental vasculogenesis can proceed in the absence of any blood flow.
- © 2011 by American Heart Association, Inc.