Abstract
Human endothelial cells derived from the capillary bed of endometrial decidua were studied in vitro using medium 199 supplemented with 20% fetal calf serum. Cells in primary and subcultures were identified in parallel by electron microscopy and indirect immunofluorescence microscopy. The abundance of microfilaments appearing in small bundles, the micropinocytotic vesicles in the cell periphery, the occurrence of characteristic Weibel-Palade bodies and the intense and specific fluorescence after decoration with antibodies to Factor VIII protein all were criteria for a positive demonstration of the endothelial character in the cell cultures derived from the capillary bed of the human decidua. The proliferative activity of the in vitro system was studied by autoradiography of the endothelial cells after exposure to [3H]-thymidine at various periods of incubation. A statistically highly significant difference (p>0.001) was found between periods of 4-6 and 6-8 days of incubation and between 6-8 and 8-10 days of incubation (p>0.01). No such difference was found between 8-10 and 10-14 days of incubation. When the medium was switched to complete M 199+ 10% fetal calf serum and 10% human plasma containing 76 pg/ml of estradiol the thymidine index was 5 to 4 times as high as in the control medium after 5 to 6 days of incubation.
The results indicate that the in vitro system developed on endometrial capillaries derived from human decidua provides a stable low background of DNA synthesis against which small amounts of possible mediators of endothelial mitoses, e.g. estradiol, progesterone and various synthetic progestogens, can be tested.