Reduced reproductive capacity of freshly harvested endothelial cells in smokers: A possible shortcoming in the success of seeding?

Abstract

In an attempt to explain the failure of first clinical trials of autologous endothelial seeding in smokers, the initial reproductive capacity of saphenous vein endothelial cells from smokers and nonsmokers was studied by a replicate microwell technique. Endothelial cells were enzymatically harvested from saphenous vein segments of patients with coronary bypasses (21 smokers and 18 nonsmokers). After 15 minutes (group A) and 7 minutes (group B) of collagenase exposure, the endothelial cell harvest from donors who smoked was 41% (p < 0.02) lower for group A and 30% (p < 0.2) lower for group B than that from nonsmokers. In analogy, the viable cell yield was 32% (p < 0.04) and 29% (p < 0.05) lower for groups A and B, respectively, in cultures from donors who smoked. Daily cell counts over an ensuing 10-day period also revealed a significant difference in the proliferative behavior of endothelial cells from smokers and nonsmokers. Whereas endothelial cells from nonsmokers regularly entered the exponential phase of proliferation on day 4.4 ± 1.8 (group A) and day 4.6 ± 1.3 (group B), endothelial cells from smokers reached the logarithmic growth phase either with delay (day 6.8 ± 2.1, group A) or remained completely quiescent (group B). Lower harvest efficiency and suppressed reproductive capacity of endothelial cells in smokers—on top of an already critically low inoculum in single-staged endothelial cell seeding—might explain the failure of initial clinical trials.