en Clinical Biochemistry Clinical Biochemistry Study Protocol Study Protocol <strong>Background: </strong>Vessel endothelial cells are extensively applied to study the mechanism of atherosclerosis. Some cellular sources including human umbilical artery endothelial cells (HUAECs) and human umbilical vein endothelial cells (HUVECs) are mostly applied in the experimental studies. We described a method for isolating the human endothelial cells from the human thoracic aorta.<br> &nbsp;&nbsp; <strong>Methods:</strong> Normal aortic samples were prepared from subjects with brain death in Masih Daneshvari Hospital. The endothelial cells were isolated using collagenase and were evaluated by the measurement of CD31 marker. Furthermore, the digestion efficacy was studied by vessel histological analysis, and the adhesion mechanism was investigated by leukocyte endothelial adhesion assay kit.<br> &nbsp;&nbsp; <strong>Results and Conclusion:</strong> The isolation protocol is found as a fast and simple technique with a proper cellular load to separate the endothelial cells from the human aorta.<br> &nbsp; Human aortic endothelial cell, Cell isolation, Protocol 312 316 http://mjiri.iums.ac.ir/browse.php?a_code=A-10-4480-1&slc_lang=en&sid=1 Adeleh Poursaleh adelepoursaleh@yahoo.com 200319475328460062654 200319475328460062654 No Biochemistry Department, Iran University of Medical Sciences, Tehran, Iran Golnaz Esfandiari golnaz65@yahoo.com 200319475328460062655 200319475328460062655 No Biochemistry Department, Iran University of Medical Sciences, Tehran, Iran Farahnaz Sadegh Beigee fbeigi@gmail.com 200319475328460062656 200319475328460062656 No Shahid Beheshti University of Medical Sciences, Masih Daneshvari Hospital, Tehran, Iran Nahal Eshghifar N.eshghifar@gmail.com 200319475328460062657 200319475328460062657 No Department of Cellular and Molecular biology, Faculty of Advanced Science and Tech-nology, Tehran Medical Sciences, Islamic Azad University, Tehran, Iran Mohammad Najafi nbsmmsbn@iums.ac.ir 200319475328460062658 200319475328460062658 Yes Cellular and Molecular Research Center; Biochemistry Department, Firoozabadi Hospital, & Biochemistry Department, Iran University of Medical Sciences, Tehran, Iran