Do Cardiotonic Steroids Evoke a Proliferative Response in Human VSMCs?
In light of our previous findings that ouabain stimulates proliferation of canine VSMCs, 6 we wished to determine whether this response was unique to the dog or whether VSMCs from other species, especially humans, responded similarly. Because of their ready availability, we selected human umbilical blood vessels as a good source of VSMCs. Isolation of VSMCs from human umbilical blood vessels has been described previously. 14,15 However, in the present studies, we have extended the characterization of cultured smooth muscle cells from human umbilical veins. Cells isolated and cultured as described in Methods were characterized in passage 2. Confluent cultures demonstrated a “hill and valley” growth pattern and morphology typical of VSMCs. As illustrated in Figure 1, these cells were positive for the vascular smooth muscle markers α-smooth muscle actin, calponin, SM22α, and smooth muscle myosin. In contrast, endothelial cells isolated from the same vessels were negative for all 4 protein
