Simultaneous isolation of endothelial and smooth muscle cells from human umbilical artery or vein and their growth response to low-density lipoproteins

In the pathogenesis of atherosclerosis the interplay of endothelial cells (ECs) and smooth muscle cells (SMCs) is disturbed. Oxidatively modified low-density lipoproteins (oxLDLs), important stimulators of atherosclerotic plaque formation in vessels, modify the growth response of both cell types. To compare growth responses of ECs and SMCs of the same vessel with oxLDLs, we developed a method to isolate both cell types from the vessel walls of umbilical cords by enzymatic digestion. The method further allowed the simultaneous isolation of venous and arterial cells from a single umbilical cord. In culture, venous ECs showed an elongated appearance compared with arterial ECs, whereas SMCs of artery and vein did not look different. Smooth muscle cells of both vessel types responded to oxLDLs (60 microg/ml) with an increase in their (3)H]-thymidine incorporation into DNA. On the contrary, ECs of artery or vein decreased (3)H]-thymidine incorporation and cell number in the presence of oxLDLs (60 microg/ml) of increasing oxidation grade. Thus, human umbilical SMCs and ECs of the same vessel show a disparate growth response toward oxLDLs. But the physiologically more relevant minimal oxLDLs did not decrease proliferation in venous ECs but only in arterial ECs. This difference in tolerance toward minimal oxLDLs should be taken into account while using venous or arterial ECs of umbilical cord for research in atherosclerosis. Further differences of venous and arterial ECs in tolerance toward minimal oxLDLs could be of clinical relevance for coronary artery bypass grafts.