A simple method for isolating and culturing the rat brain microvascular endothelial cells

Brain microvascular endothelial cells (BMECs), a main component of the blood–brain barrier, play a critical role in the pathogenesis of many brain diseases. The primary culture of BMECs has been used in various models for studying cerebrovascular diseases in vitro. However, there are still several problems existing in the isolation and cultivation of primary rat BMECs, such as low yield, contamination with other cell types, and requirement of a large number of animals and expensive growth factor. In this study, we describe a simple, economical (without any growth factor) and repeatable method to obtain endothelial cells with high purity (> 99%) and yield (about 2.2 × 107 per rat) from cerebral cortexes of neonatal rat, mainly from gray matter. In vitro examinations determined that the isolated cells expressed typical phenotypic markers of differentiated brain endothelium such as multiple drug resistant protein, von Willebrand factor, platelet endothelial cell adhesion molecule 1 (PECAM-1/CD31), and intercellular adhesion molecule (ICAM). These cells also possessed morphological and ultra-structural characteristics that were observed by phase contrast microscope and electric microscope. Then GFAP and α-SMA were used, respectively, to identify astrocyte and pericyte which were potential to contaminate primary culturing of BMECs. And specific reaction of endothelial cells to external stimulation was tested by culture with TNF-α for 24 h. All these results of our experiments supply that our protocol provides an effective and reliable method to obtain high purity and yield of rat BMECs and offers a useful tool for studying cellular physiology, cerebrovascular diseases, brain tumors, blood–brain barrier and neurovascular units, etc.