Date Time Weill Cornell researchers detect key flaw in brain modeling A type of cell derived from human stem cells that has been widely used for brain research and drug development may have been leading researchers astray for years, according to a study from scientists at Weill Cornell Medicine and Columbia University Irving Medical Center. Lis Lab/Provided Induced brain microvascular endothelial cells (IBMECs), top, cultured in 3D assume an epithelial organoid structure and express the epithelial cell marker EPCAM (purple). When they are reprogrammed by overexpression of ETV2, ERG and FLI1, they lose EPCAM expression, acquire vascular markers VE-Cad (red) and PECAM1 (green) and are able to fulfill the function of endothelial cells – forming blood vessels, shown in bottom image.