Biomoteriols 16 zyxwvutsrqponmlkjih (1995) 1223-1227 0 1995 zyxwvutsrqponmlkjihgfedcbaZ Elsevier Science Limited Printed in Great Britain. All rights reserved 014%9612/ 95/ $10.00 zyxwvutsrq Adhesive protein expression on endothelial cells after contact in vitro with polyethylene terephthalate coated with pyrolytic carbon E. Cenni, D. Granchi, CR. Arciola, G. Ciapetti, L. Savarino, S. Stea, D. Cavedagna, A. Di Leo* and A. Pizzoferrato Laboratory for Biocompafibilify Research on implant Materials, lsfifufi Ortopedici Rizzoli, 40736 Bologna, Italy; l /sfifufo di Fisiopafologia de//a Riproduzione, Policlinico S. Orsola, Bologna, lfaly This research aims at evaluating the expression of some adhesive proteins on endothelial cell surface after contact with polyethylene terephthalate coated with pyrolytic carbon (PET+ PC). Twenty-two different cultures of human umbilical vein endothelial cells (HUVECs) were put in contact with PET + PC. Both HUVECs grown without the biomaterial and HUVECs incubated with endotoxin were used as control. After 24h, platelet endothelial cell adhesion molecule-l (PECAM-l), endothelial leucocyte adhesion molecule-l (ELAM-l), intercellular adhesion molecule-l (ICAM-1) and vascular cell adhesion molecule-l (VCAM-1) were evaluated on the cells by monoclonal antibodies and flow cytometry. In agreement with the literature, after 24 h the culture incubated with endotoxin determined a significant increase in the percentage of positive cells for ELAM-1, a significant increase in fluores- cence intensity for ICAM-1, and a significant increase in the percentage of positive cells and fluores- cence intensity for VCAM-1. After 24 h of culture with PET + PC, no significant variations in the antigens examined were observed. This demonstrates that such material does not activate in vitro the proteins involved in the adhesion between leucocytes and endothelium or in the adhesion between endothelial cells themselves. Keywords: Endothelium, adhesins, pyrolytic carbon, f/ow cytometry Received 30 September 1994; accepted 6 January 1995 Endothelial cell cultures are used to assay the biocom- patibility of the materials used for vascular prostheses, evaluating in particular the capability of these cells to adhere and grow onto various materials. In fact prosthe- sis coating with endothelial cells is an important condition which positively affects implant patency’. In order to foresee the efficacy of the endothelial cell seeding of the prosthesis and to prepare materials more suitable for this practice, it is necessary to know the mechanisms regulating the endothelium adhesion on the substratum. Cell adhesion is a complex phenomenon, regulated by molecules occurring on the membrane, generically defined as adhesins, which determine both the adhesion among cells and the adhesion of a cell to an acellular substratum. The adhesin expression on the cell surface is not constant in time, but it can be modified by various stimuli. Correspondence to Dr I:. Cenni. These molecules are commonly divided into the superfamily of immunoglobulins and the families of integrins, selectins and caderins’. In this research, adhesive molecules which are most commonly used for endothelium integrity study were evaluated. Platelet endothelial cell adhesion molecule-l (PECAM-1; CD31) is a glycoprotein belonging to the superfamily of the immunoglobulins, named in this way because its structure is similar to that of true immunoglobulin. PECAM-1 occurs on endothelial cell membrane, close to the intercellular junctions, and regulates endothelial cell adhesion to other cells of the same type and to leucocytes3. Endothelial leucocyte adhesion molecule-l (ELAM- l), a glycoprotein of the selectin family, occurs at low concentration on endothelial cell surface in basal conditions, but it increases remarkably in the presence of endotoxin, interleukin-1 (IL-l) and tumour necrosis factor (TNF). The increase in the concentration of ELAM-1 on the cell membrane peaks 4 h after the 1223 Biomaterials 1995, Vol. 16 No. 16