Retinoic Acid and VEGF Delay Smooth Muscle Relative to Endothelial Differentiation to Coordinate Inner and Outer Coronary Vessel Wall Morphogenesis

Rationale: Major coronary vessels derive from the proepicardium, the cellular progenitor of the epicardium, coronary endothelium, and coronary smooth muscle cells (CoSMCs). CoSMCs are delayed in their differentiation relative to coronary endothelial cells (CoEs), such that CoSMCs mature only after CoEs have assembled into tubes. The mechanisms underlying this sequential CoE/CoSMC differentiation are unknown. Retinoic acid (RA) is crucial for vascular development and the main RA-synthesizing enzyme is progressively lost from epicardially derived cells as they differentiate into blood vessel types. In parallel, myocardial vascular endothelial growth factor (VEGF) expression also decreases along coronary vessel muscularization. Objective: We hypothesized that RA and VEGF act coordinately as physiological brakes to CoSMC differentiation. Methods and Results: In vitro assays (proepicardial cultures, cocultures, and RALDH2 [retinaldehyde dehydrogenase-2]/VEGF adenoviral overexpression) and in vivo inhibition of RA synthesis show that RA and VEGF act as repressors of CoSMC differentiation, whereas VEGF biases epicardially derived cell differentiation toward the endothelial phenotype. Conclusion: Experiments support a model in which early high levels of RA and VEGF prevent CoSMC differentiation from epicardially derived cells before RA and VEGF levels decline as an extensive endothelial network is established. We suggest this physiological delay guarantees the formation of a complex, hierarchical, tree of coronary vessels. (Circ Res. 2010;107:204-216.)

Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP)[05/60637-6]

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP)[06/50843-0]

DGU

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES/DGU)[4096/09-6]

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Conselho Nacional de Desenvolvimento Tecnologico (CNPq)[477418/2004-0]

Conselho Nacional de Desenvolvimento Tecnologico (CNPq)[305260/2007-3]

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Spanish Ministry of Science and Innovation

Spanish Ministry of Innovation and Science[BFU2009-07929]

Junta de Andalucia (Spain)

Junta de Andalucia[P06-CTS-01614]

Spanish cooperative networks on research TERCEL and RECAVA (ISCIII)

Spanish cooperative networks on research TERCEL and RECAVA (ISCIII)

European Union

European Union[LSHM-CT-2005-018630]