Evidence for injurious effect of cocaethylene in human microvascular endothelial cells

Background: Cocaethylene (CE) is a conjugate of cocaine and ethanol that may contribute to the pathogenesis of systemic vascular diseases. This study was conducted to investigate the effect of CE on human microvascular endothelial cells (HMEC-1) in culture. Methods: Proliferating and confluent monolayers of HMEC-1 were used for assessing growth kinetics, viability, cytotoxicity, and morphologic/barrier alterations after CE treatment (0-1 mmol/l) for up to 7 days. The Trypan blue exclusion, lactate dehydrogenase (LDH) release assay, manual cell counts, and silver nitrate staining technique were used. Results: The doubling times of 30.0 and 31.4 h for the 0.5 and 1.0 mmol/l CE-treated HMEC-1, respectively, were significantly longer than the 28.6 h for the control group (p<0.05). The viabilities of 90.4±3.8% (control) and 93.1±1.9% (CE-treated) from the Trypan blue exclusion-staining experiments indicated non-lethality of CE. LDH activities of 173±33 U/l (control) and 157±43 U/l (CE-treated) confirmed the absence of CE cytotoxicity. Silver staining results indicated increased monolayer permeability as demonstrated by the formation of intercellular gaps after 1 h of exposure. Conclusions: HMEC-1 exposure to CE induced cellular injury that could affect the permeability of small blood vessels. These cellular changes could in part be the pivotal point for studies to explain the edema and inflammation in surrounding tissues of individuals exposed to CE.