Ischemia is not required for arteriogenesis in zebrafish embryos.
OBJECTIVE
The role of ischemia in collateral vessel development (arteriogenesis) is a contentious issue that cannot be addressed using mammalian models. To investigate this, we developed models of arteriogenesis using the zebrafish embryo, which gains sufficient oxygenation via diffusion to prevent ischemia in response to arterial occlusion.


RESULTS
We studied gridlock mutant embryos that suffer a permanently occluded aorta and show that these restore aortic blood flow by collateral vessels. We phenocopied gridlock mutants by laser-induced proximal aortic occlusion in transgenic Fli1:eGFP/GATA1:dsRED embryos. Serial imaging showed these restore aortic blood flow via collateral vessels by recruitment of preexisting endothelium in a manner similar to gridlocks. Collateral aortic blood flow in gridlock mutants was dependent on both nitric oxide and myeloid cells. Confocal microscopy of transgenic gridlock/Fli1:eGFP mutants demonstrated no aberrant angiogenic response to the aortic occlusion. qPCR of HIF1alpha expression confirmed the absence of hypoxia in this model system.


CONCLUSIONS
We conclude that NO and myeloid cell-dependent collateral vessel development is an evolutionarily ancient response to arterial occlusion and is able to proceed in the absence of ischemia.
MRC Centre for Developmental and Biomedical Genetics, University of Sheffield, UK.
Caroline
C
Gray
Ian M
IM
Packham
François
F
Wurmser
Nicholas C
NC
Eastley
Paul G
PG
Hellewell
Philip W
PW
Ingham
David C
DC
Crossman
Timothy J A
TJ
Chico
D000818:Animals; D030801:Animals, Genetically Modified; D001018:Aortic Diseases / Q000196:embryology / Q000235:genetics / Q000378:metabolism / Q000503:physiopathology*; D001157:Arterial Occlusive Diseases / Q000196:embryology / Q000235:genetics / Q000378:metabolism / Q000503:physiopathology*; D001158:Arteries / Q000196:embryology / Q000254:growth & development* / Q000378:metabolism; D051792:Basic Helix-Loop-Helix Proteins / Q000235:genetics / Q000378:metabolism; D015687:Cell Hypoxia; D003097:Collateral Circulation; D004195:Disease Models, Animal; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000235:genetics / Q000378:metabolism; D007511:Ischemia / Q000196:embryology / Q000235:genetics / Q000378:metabolism / Q000503:physiopathology*; D018613:Microscopy, Confocal; D009154:Mutation; D022423:Myeloid Cells / Q000378:metabolism; D018919:Neovascularization, Physiologic; D009569:Nitric Oxide / Q000378:metabolism; D019001:Nitric Oxide Synthase / Q000378:metabolism; D051789:Proto-Oncogene Protein c-fli-1 / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D013997:Time Factors; D015027:Zebrafish / Q000196:embryology* / Q000235:genetics / Q000378:metabolism; D029961:Zebrafish Proteins / Q000235:genetics / Q000378:metabolism
D051792:Basic Helix-Loop-Helix Proteins; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D009569:Nitric Oxide; D019001:Nitric Oxide Synthase; D051789:Proto-Oncogene Protein c-fli-1; D012333:RNA, Messenger; D029961:Zebrafish Proteins; C405954:hey2 protein, zebrafish; C000621936:hif1aa protein, zebrafish