The Yaniv Lab
The main interest of our lab is to elucidate the cellular and molecular mechanisms underlying the formation of blood and lymphatic vessels during vertebrate embryogenesis.
Why study vascular development?
The development of the vascular system is one of the earliest events in organogenesis. All other organs depend on a vascular supply for delivery of nutrients, oxygen, and for clearance of wastes. Serious disruptions in the formation of the vascular network are lethal early in post-implantation, while the maintenance of vessel integrity and the control of vessel physiology have important consequences throughout embryonic and adult life.
In recent years, it has become clear that many of the signals implicated in embryonic vascular development are reactivated during disease states of angiogenesis such as tissue ischemia, coronary heart disease and cancer-promoted angiogenesis. This has further reinforced the potential medical relevance of vascular development studies such as those carried out in our laboratory.
Fig. 1. Development of the vascular system: During vasculogenesis, endothelial progenitors give rise to a primitive vascular labyrinth of arteries and veins; during subsequent angiogenesis, the network expands, pericytes (PCs) and smooth muscle cells (SMCs) cover nascent endothelial channels, and a stereotypically organized vascular network emerges. Lymph vessels develop via transdifferentiation from veins. Modified from Carmeliet, P. (2005)
Our lab takes advantage of the optical clarity and genetic accessibility of the zebrafish embryo to study vessel formation in vivo. Zebrafish embryos develop externally and are optically clear, providing noninvasive and high-resolution observation of the entire vascular system at every stage of embryonic development. In addition, the formation and anatomical layout of the fish vasculature are similar to that of other vertebrates, and most of the genes currently known to act as key players in embryonic vascular development are highly conserved in zebrafish.
This movie shows timelapse multiphoton confocal images of vessel dynamics in fli-EGFP transgenic zebrafish. Elongating angiogenic sprouts migrate between the somites to give rise to a dorsal branch. Highly dynamic behavior involving extension and retraction of numerous filopodia can be seen as the sprouts extend dorsally.