Interfacing Three-Dimensional Curved Structures and Cellular Adhesion

Abstract

Curvature is a fundamental geometric design principle found in an array of biological systems, such as vasculature. Therefore, in studying cellular processes such as adhesion, proliferation and migration, it is important to consider the effects of curved 3D micro-topography as compared to flat 2D substrates, which are far more common. Creating these 3D curved systems requires novel approaches as well. Microfluidic devices would seem to be a good approach for this as they have often been utilized as a platform for studying cell adhesion and migration in vitro. However, the fabrication of curved, non-rectangular channels has been a major challenge to the field of microfluidics due to conventional fabrication methods. To overcome these limitations, we have developed a novel and robust approach using mechanical micromachining in combination with a two-step reverse polymer molding process to fabricate microfluidic channels with circular cross-sectional geometries. Here, we utilize these 3D microfluidic networks to study the effects of curvature on cell adhesion mechanics. Both fibroblast (NIH-3T3) and endothelial (HUVEC) cell lines were cultured within circular cross-section microfluidic channels and on reserve molded cylindrical curved polymers. Cell morphology on these curved versus flat substrates was then characterized via confocal and scanning electron microscopy. Furthermore, the formation of stable focal adhesions and cytoskeletal organization was analyzed by immunofluorescent confocal microscopy. We believe that this approach for fabricating bioinspired microfluidic systems provides a powerful platform for interfacing cellular interactions with curved 3D structures, which could be useful in a variety of fields from vascular biology and immune cell transmigration to cell mechanotransduction and tissue engineering.