Micropatterned polymer surfaces improve retention of endothelial cells exposed to flow-induced shear stress

Article type: Research Article

Authors: Daxini, Sachin C.^; | Nichol, Jason W.^; | Sieminski, Alisha L.^; | Smith, Geoffrey | Gooch, Keith J.^; | Shastri, V. Prasad^{; ; ; ;}

Affiliations: Masters in Biotechnology Program, School of Engineering and Applied Science, University of Pennsylvania, Philadelphia, PA, USA | Department of Bioengineering, University of Pennsylvania, Philadelphia, PA, USA | Institute for Medicine and Engineering, University of Pennsylvania, Philadelphia, PA, USA | Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, PA, USA | Department of Biomedical Engineering, Ohio State University, Columbus, OH, USA | Joseph Stokes Jr. Research Center, Children's Hospital of Philadelphia, USA | Department of Biomedical Engineering, Vanderbild University, Nashville, TN, USA

Note: [] Equally contributing authors.

Note: [] Address for correspondence: Dr. V. Prasad Shastri, 5824 Stevenson Center, Department of Biomedical Engineering, Vanderbilt University, Nashville, TN 37232, USA. Tel.: + 615 322 8005; Fax: +1 615 343 7919; E-mail: Prasad.Shastri@vanderbilt.edu.

Abstract: The use of synthetic polymeric vascular grafts is limited by the thrombogenecity of most biomaterials. Efforts to reduce thrombogenicity by seeding grafts with endothelial cells, the natural non-thrombogenic lining of blood vessels, have been thwarted by flow-induced cell detachment. We hypothesized that by creating well-defined micro-textured patterns on a surface, fluid flow at the surface can be altered to create discrete regions of low shear stress. We further hypothesized that, due to reduced shear stress, these regions will serve as sanctuaries for endothelial cells and promote their retention. To test these hypotheses, well-defined micro-textured polyurethane (PU) surfaces consisting of arrays of parallel 95-micron wide and 32-micron deep channels were created using an etched silicon template and solvent casting techniques. Based on computational fluid dynamics, under identical bulk flow conditions, the average local shear stress in the channels (46 dyn/cm2) was 28% lower than unpatterned surfaces (60 dyn/cm2). When PU surfaces pre-seeded with endothelial cells (EC) were exposed to the same bulk flow rate, EC retention was significantly improved on the micropatterned surfaces relative to un-patterned surfaces (92% vs. 58% retention).

Keywords: Endothelial cells, microfabrication, retention, computational fluid dynamics, vascular grafts, tissue engineering

Journal: Biorheology, vol. 43, no. 1, pp. 45-55, 2006