Rat Primary Lung Microvascular Endothelial Cells are isolated from tissue of 1-day-old neonatal Sprague-Dawley Rats. Rat Primary Lung Microvascular Endothelial Cells are grown in T75 tissue culture flasks pre-coated with gelatin-based coating solution for 0.5 hour and incubated in Creative Bioarray Culture Complete Growth Medium generally for 3-7 days. Cultures are then expanded. Prior to shipping, cells are detached from flasks and immediately cryo-preserved in vials. Each vial contains at least 1x10^6 cells per ml and is delivered frozen. The method we use to isolate primary endothelial cells was developed based on a combination of established and our proprietary methods. These cells are pre-coated with PECAM-1 (CD31) antibody, following the application of Dynabeads pre-coated with secondary antibody.