Oxidative Stress and Pulmonary Endothelial Cell Death Associated With Varicose Vein Sclerotherapy : Potential Mechanism of Complications

CTD Lee1, MS Whiteley1,2, JM Li1. 1University of Surrey, Guildford, UK, 2The Whiteley Clinic, Guildford, UK

Varicose veins affect up to 30-40% of the population and are associated with significant discomfort, skin damage, and complications including ulceration and perforation. Chemical sclerotherapy has been widely used to treat varicose vein disease but has been associated with complications such as deep vein thrombosis and neurological problems. However, no study has investigated the potential pathological side-effects and mechanisms of damage to endothelial cells in downstream vessels and organs such as the lung, where the residual chemical passes through. In this study, we investigated the effects of two of the most commonly used detergent sclerosants, sodium tetradecyl sulphate (STS) and polidocanol (POL), on human pulmonary microvascular endothelial cells (HPMEC) in vitro, and on oxidative damage to mouse lungs ex vivo. STS and POL significantly increased endothelial reactive oxygen species (ROS) production compared to controls (p<0.05) at concentrations as low as 50nM and 30nM respectively (~1500-fold dilutions of clinically used concentrations), and caused dose-dependent (0.025-2µM) HPMEC cell death as examined by trypan blue exclusion (n≥3) and MTT cytotoxicity assay (n≥12). STS and POL-induced cell death was time- and dose-dependent and at a concentration of 1µM, 100- and 50-fold dilutions respectively of clinical preparations, 80% of cells were dead in 90 minutes compared to controls. Furthermore, STS and POL at 200nM appeared to cause breakdown of capillary structures grown on Matrigel which did not occur with vehicle-treated capillaries.

The potential clinical relevance of our discovery was validated by ex vivo lung perfusion (3 minutes) of mice (C57BL/6J background, n=6). All studies were performed in accordance with protocols approved by the Home Office under the Animals (Scientific Procedures) Act 1986, UK. POL at 30nM, a concentration adjusted to account for dilution in the blood, caused a significant increase (p<0.05) in ROS production compared to vehicle-treated controls as detected by lucigenin (5 µM)-chemiluminescence, indicative of inflammation and cell damage. In summary, sclerotherapy can cause endothelial cell death and capillary damage, and lung oxidative stress and inflammation, at concentrations much lower than those used clinically. This has significant clinical relevance in patient therapy selection and in preventing sclerotherapy-associated complications.