Assembly of hydrogel structure in a PDMS channel for intestinal microenvironment

Abstract

In vitro construction of biomimetic intestinal microenvironment has received much attention due to their special structures and related functions of epithelium. For example, closely packed array of villus and crypt structure increase the total surface area of intestinal epithelium for effective contact with nutrients. The projected structure is crucial for regulating intestinal stem cell proliferation, migration, and intestinal renewal. This structure also provides more effective cell-to-cell interaction within epithelium. In the aspect of drug permeability, gastrointestinal (GI) tract is a primary barrier of first-pass metabolism of oral administered drug. However, microfabrication of long villus structure with high aspect ratio needs complicated fabrication processes using special equipment. In addition, precise control of microenvironment has been limited in conventional methods. In this thesis, we report a novel method of hybrid biomicrofabrication using hydrogel villi structures integrated with microfluidic device to develop a biomimetic intestinal microenvironment system for more physiologically relevant study. A microfluidic device, which was fabricated with poly(dimethylsiloxane) (PDMS), was used in order to develop three-dimensional (3D) cell culture environment under fluidic condition with precise control of reagents and chemicals. We fabricated various sizes of hydrogel villi structures using mixture of alginate and collagen by replica molding from the PDMS mold without any complicated fabrication process. We proposed a latch and hook structure to stably lock-up hydrogel villi structure inside the chamber of a microfluidic device. Assembled hydrogel villi structures were maintained stably under flow condition and showed flexible responses to flow. Human epithelial colorectal adenocarcinoma cell (Caco-2) was cultured on hydrogel villi structures for 7 days and observed that Caco-2 cell adhered to hydrogel surface and proliferated. This hybrid fabrica...