Welcome to the CrouchLab@UCSF.  The Dutch anatomist Frederik Ruysch (1638-1731) said, “Blood vessels are ubiquitous, and tissues are only blood vessels variously arranged.” We study brain neurovascular development, particularly in the human brain. Blood vessel cells serve as master architects in the brain, both delivering blood and interacting with brain cells to influence their function. The two main cell types which form blood vessels are endothelial and mural cells. Endothelial cells form tubes, the basic structure of blood vessels, and also secrete factors that tell brain stem cells to make new neurons. Mural cells lie on top of endothelial cells and help to form the blood brain barrier, which blocks unwanted substances and cells from getting into the brain. In a striking example of communication between blood vessel cells and other brain cells, babies born very premature are vulnerable to bleeding specifically in an area called the germinal matrix. This condition, called germinal matrix hemorrhage (GMH), occurs to 20% of these babies and can cause stroke and death in severe cases. Unfortunately, we have no treatments for this disease and it remains unclear why vasculature in this developmental window is particularly sensitive. One critical barrier is the lack of a comprehensive understanding of the spatiotemporal dynamics of vascular cell development. Our research resolves around defining the stages of vascular stem cells in the developing brain and understanding the mechanisms that regulate their functions. We then apply this knowledge to produce novel technologies and therapeutic strategies for different brain hemorrhages in neonatal and pediatric patients. Towards these goals, we utilize neuropathological specimens, flow cytometry (FACS), bioinformatics, and cell culture, including organoid models. We partner with the UCSF PSSP, NIH (NINDS)UCSF Preterm Birth Initiative, UCSF ImmunoX, California Institute for Regenerative Medicine, Burroughs Wellcome Fund, and the American Heart Association to fund our research. For fun, we run the BreakingDownBiology blog (also funded by UCSF ImmunoX) to explain exciting scientific journal articles with every day language.