Electrical field effects on endothelial cell adhesion and growth on conducting biomaterials surfaces.

摘要

A major problem for vascular graft implants is poor long-term patency for small-diameter (<6 mm) prostheses. Small-diameter woven Dacron RTM or expanded polytetrafluoroethylene (e-PTFE) grafts often occlude in a short time due to thrombus or polytetrafluoroethylene intimal hyperplasia. It has generally been considered that an endothelial cell lining of such grafts might reduce thrombogenicity and thereby produce a more biomimetic prosthesis.;Electrical stimulation has been studied for effects on in vitro cell growth, motility, and adhesion characteristics, as well as for in vivo wound healing. A comprehensive literature review was conducted which suggested the need for further research concerning the effects of electrical fields on endothelial cell adhesion and growth properties.;The focus of these studies was therefore to determine the effect of electrical fields on the proliferation and adhesion characteristics of endothelial cells cultured on various substrates using low-voltage direct current. Voltages of 0, 0.5, and 1 volt were used for in vitro endothelial cell cultures plated at 50,000 and 100,000 cells/mL. Growth experiments were performed on glass, MylarRTM, Indium Tin Oxide (ITO)-glass, on ITO-, carbon-, and gold-palladium-coated MylarRTM, and on polypyrrole-coated DacronRTM. Proliferation of endothelial cells was determined at 12, 24, and 36 hours. Adhesion characteristics were measured using a novel flow adhesion system. Characterization was via cell staining in conjunction with optical microscopy and a 6-keto-prostaglandin-F 1alpha assay to measure cell viability.;Results of these cell growth studies in electric fields indicate that low voltage stimulation moderately increased endothelial cell growth on most substrates. The release of 6-keto-prostaglandin-F1alpha decreased over time at most cell concentrations and voltage levels. Cell adhesion experiments provided contrary results to the growth studies and suggested Rested that low-voltage electric fields may be detrimental to cell adhesion. These findings imply that current density may be more important than voltage drop across a surface.;Based on this research, further studies of low-voltage electric field effects on endothelial cell growth characteristics appear warranted, with emphasis on cell adhesion; with the ultimate goal of increasing endothelialization and patency for small-diameter vascular grafts and other vascular prostheses.