Biomaterials 24 (2003) 5139–5144 Adhesion and proliferation of human endothelial cells on photochemically modified polytetrafluoroethylene T. Gumpenberger a , J. Heitz a, *, D. B . auerle a , H. Kahr b , I. Graz b , C. Romanin b , V. Svorcik c , F. Leisch d a Department of Applied Physics, Johannes Kepler University, Linz A-4040, Austria b Institute of Biophysics, Johannes Kepler University, Linz A-4040, Austria c Department of Solid State Engineering, Institute of Chemical Technology, Prague 166 28, Czech Republic d Cardiovascular Division, City Hospital Linz (AKH), Linz A-4021, Austria Received 15 January 2003; accepted 15 June 2003 Abstract We studied the adhesion and proliferation of human endothelial cells on photochemically modified polytetrafluoroethylene samples.ThepolymersurfacesweremodifiedbyexposuretotheultravioletlightofaXe 2 Ã -excimerlampatawavelengthof172nmin an ammonia atmosphere. Treatment times were between 10 and 20min. The endothelial cell density was determined 1, 3 and 8 days after seeding by image analysis. Surface modification of the samples resulted in a significant increase in the number of adhering cells and in the formation of a confluent cell layer after 3–8 days. The results were comparable than those obtained on polystyrene Petri dishes, which are used as standard substrates in cell cultivation. Thus modified PTFE appears to be a promising material for the fabrication of artificial vascular prostheses coated with endothelial cells. r 2003 Elsevier Ltd. All rights reserved. Keywords: Polytetrafluoroethylene; Surface treatment; Endothelial cells; Cell adhesion; Cell proliferation 1. Introduction Polytetrafluoroethylene (PTFE) is one of the most commonly used polymers in medicine, e.g., for con- struction of vascular prostheses [1], tubes for nerve regeneration [2] and subcutaneous augmentation mate- rials [3] or in maxillofacial surgery [4]. For many applications improved biocompatibility of PTFE would be advantageous. There are especially several attempts to make the inner surface of PTFE-based vascular prostheses attractive for endothelial cells, because these cells are regarded as optimal contact layer to the blood stream. One method is to coat the surface with a thin protein layer (e.g., fibronectin) [5,6]. However, the adsorption of the protein layer on unmodified PTFE is limited and the use of biological materials, especially those of xeno- and allogenic origin, is associated with the risk of pathogen transfer, formation of thrombi in blood-contacting devices and immune reactions [7]. We have demonstrated that the attractiveness of uncoated PTFE for colonization with living cells in vitro can be markedly improved by exposure of the polymer to ultraviolet (UV)-light with wavelengths lo200nm in a reactive NH 3 atmosphere [8,9]. This photochemical treatment is quite promising because of its high efficiency and the possibility of single-parameter control as compared to other types of surface modification techniques such as, e.g., plasma treatment [10–12]. In the present paper we extent our recent investiga- tions on fibroblasts and smooth muscle cells to the adhesionandproliferationpropertiesofhumanendothe- lial cells (HEC) on photochemically modified PTFE. 2. Material and methods 2.1. Modification of PTFE The experiments were performed on PTFE foils with a thickness of 25 mm (Goodfellow Ltd., Cambridge, UK). The foils were cleaned with alcohol and acetone in an ultrasonic bath. The NH 3 gas employed during ARTICLE IN PRESS *Corresponding author. Tel.: +43-732-2468-9248; fax: +43-732- 2468-9242. E-mail address: johannes.heitz@jku.at (J. Heitz). 0142-9612/$-see front matter r 2003 Elsevier Ltd. All rights reserved. doi:10.1016/S0142-9612(03)00460-5