Brain microvascular endothelial cells (BMEC), the major component of the blood-brain barrier, limit the passage of substances, both soluble and cellular, from the blood into the brain. BMEC utilize unique features to distinguish themselves from peripheral endothelial cells, such as 1) intercellular tight junctions that display high electrical resistance and slow paracellular transport, 2) the absence of fenestrae and a reduced level of pinocytic activity, and 3) the expression of specialized pumps that can transport compounds out of the brain via the blood-brain barrier. Similar to peripheral endothelial cells, BMEC express, or can be induced to express, cell adhesion molecules on their surface that regulate the extravasation of leukocytes into the brain. Cultured rat BMEC have been widely used for studying the molecular and cellular properties of blood-brain barrier because of their unique functions. Understanding the molecular mechanisms of blood-brain barrier regulation may help to optimize drug delivery to the CNS and elucidate new therapies for CNS diseases. RBMEC from ScienCell Research Laboratories are isolated from adult CD® IGS rat brain. RBMEC are cryopreserved at passage one and delivered frozen. Each vial contains >5 x 105 cells in 1 ml volume. RBMEC are characterized by immunofluorescence with antibodies specific to vWF and/or CD31 (PECAM). RBMEC are negative for mycoplasma, bacteria, yeast, and fungi. RBMEC are guaranteed to further expand for 5 population doublings under the conditions provided by ScienCell Research Laboratories. Recommended medium: It is recommended to use Endothelial Cell Medium-rat (ECM-r, Cat. #1021) for culturing RBMEC in vitro.