By starting endothelial cells induction using BMP-4 , bFGF plus Matrigel treatment, we provided a relatively closed environment for the organoid development, where the outlayer of cells are induced to form PECAM-1 positive endothelial cells, which then proliferate preferably on the Matrigel coating layer to make a cyst that prevent the inner cells for fully interact with the outside factors, allowing them to differentiate to other cell types such as neural cells. This evidence concerns the gene PECAM1 and cyst.