Mechanisms and analysis of intraneural blood vessel patterning in the quail neural tube.

摘要

Neurovascular development requires communication between two embryonic organ systems, the neuroepithelium and blood vessels. During neural tube development, blood vessels enter at stereotypical locations from the surrounding peri-neural vascular plexus, forming an intraneural vascular pattern. We first investigated the role of VEGF-signaling from the neural tube in blood vessel ingression and pattern formation. Localized, ectopic expression of heparin-binding VEGF165 or VEGF189 from the avian neural tube resulted in supernumerary vessel sprouts and disrupted vessel patterning. Conversely, localized loss of endogenous VEGF-A signaling in the neural tube, via ectopic expression of the VEGF inhibitor sFlt-1, locally blocked blood vessel ingression. Thus, we demonstrated that neural-derived VEGF-A has a direct role in the spatially localized molecular crosstalk required for neurovascular development and vessel patterning in the neural tube.;Though necessary and sufficient for blood vessel sprout formation, neural tube-derived VEGF was not sufficient to explain why blood vessel sprouts form at specific times and highly stereotypical locations within the neural tube. The neural tube is also a patterned structure, and we hypothesized that normal processes of neural tube development, such as programmed neurogenesis and dorsoventral patterning of neurons, influence the blood vessel pattern. To test this, we manipulated both the timing of neurogenesis and dorsoventral neuronal patterning via electroporation of genes known to regulate these processes. We demonstrated that the specific time of neuronal differentiation within the neural tube is important for regulating the timing of angiogenic sprout ingression. Furthermore, perturbations in neuronal cell fate specification along the dorsoventral axis of the neural tube predictably altered the locations where angiogenic sprouts ingressed. This allowed us to identify pro- and anti-angiogenic regions along the dorsoventral axis of the neural tube. This work demonstrates that neural tube development and blood vessel patterning are linked and that the neural tube directs both the timing and spatial distribution of ingressing blood vessels in quail.