ARTICLE Enhancement of Permeability in Endothelial Cells for the Development of an Antithrombogenic Bioartificial Hemofilter Duc M. Vu, 1 Tun A. Yokoyama, 1 Kaichiro Sawada, 1 Miho Inagaki, 1 Genta Kanai, 1 Jianxin Lu, 1 Takatoshi Kakuta, 1 Stephen Adler, 2 Masaomi Nangaku, 3 Akira Saito 1 1 Division of Nephrology and Metabolism, Department of Medicine, Tokai University School of Medicine, Bohseidai, Isehara, Kanagawa 259-1193, Japan; telephone: þ81-463-93-1121 ext. 2350; fax: þ81-463-92-4374; e-mail: asait@is.icc.u-tokai.ac.jp 2 Division of Nephrology, New York Medical College, Valhalla, New York 3 Division of Nephrology and Endocrinology, University of Tokyo School of Medicine, Tokyo, Japan Received 11 December 2007; revision received 18 March 2008; accepted 20 March 2008 Published online 3 April 2008 in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/bit.21918 ABSTRACT: For the development of an antithrombogenic bioartificial hemofilter, in which the inner surface of hollow fibers is lined by endothelial cells, it is essential to increase the permeability of the cells in order to achieve a sufficient ultrafiltrate. We tried to increase it by using an actin microfilament polymerization inhibitor, cytochalasin B (CyB). Fifty mg/mL CyB was added for 2 h to the culture medium of confluent rat glomerular endothelial cells (RGEC) and human umbilical vein endothelial cells (HUVEC). Under the 130 mmHg hydrostatic pressure, the CyB-treated group produced significantly more ultra- filtration than the non-treated control group and this increase was maintained for at least 7 days. Horseradish peroxidase (HRP) permeability acutely and reversibly increased in the CyB-treated group compared with the non-treated control group. Scanning electron microscopy revealed a larger average diameter and increased number of fenestrae on the CyB-treated endothelial cells, compared with the non-treated cells. This phenomenon also lasted for at least 7 days. The platelet adherence test showed that CyB did not deteriorate the antithrombogenic property of endothelial cells. These results indicate that CyB is potentially applicable for the enhancement of endothelial cell permeability in an antithrombogenic bioartificial hemofilter. Biotechnol. Bioeng. 2008;101: 634–641. ß 2008 Wiley Periodicals, Inc. KEYWORDS: rat glomerular endothelial cell; human umbi- lical vein endothelial cell; cytochalasin B; bioartificial hemofilter; fenestrae; ultrafiltration Introduction Chronic renal failure continues to cause a major burden, regardless of advances in renal replacement therapies. Current standard hemodialysis therapy has only replaced the filtration function of glomerulus intermittently and imperfectly. Therefore, long-term hemodialysis patients usually suffer from complications due to inadequate therapy resulting in high mortality, high morbidity, and low quality of life. We have previously clarified that continuous hemofiltra- tion of 10 L per day significantly reduced the serum levels of urea, creatinine, uric acid, and b 2 -microglobulin, compared with the current hemodialysis therapy (Saito et al., 1995). The advantage of the continuous hemofiltration is that it is more physiological, and therefore, it can prevent side effects and also reduce the patient’s burden. However, to achieve such a continuous hemofiltration, one hemofilter must work for a long duration without using systemic anti- coagulation. The present hemofilter, even with the use of a systemic anticoagulation, merely works for up to 24 h. In an attempt to overcome this obstacle, a number of studies have been carried out and yielded hopeful results. Iwasaki et al. (2003) reported that coating of 2-methacry- loyloxyethyl phosphorylcholine (MPC) copolymer on the Correspondence to: A. Saito Contract grant sponsor: Ministry of Education, Culture, Sports, Science and Technol- ogy of Japan Contract grant number: 2-12470213 634 Biotechnology and Bioengineering, Vol. 101, No. 3, October 15, 2008 ß 2008 Wiley Periodicals, Inc.