(276f) Effect of Biomimetic Substrate Microtopography on Intestinal Epithelial Cell Behavior

The inner surface of the small intestine contains a monolayer of epithelial cells resting on a basement membrane, a specialized form of the extracellular matrix (ECM)), which supports and facilitates the growth and differentiation of epithelial cells. The basement membrane has a convoluted topography consisting of finger-like projections (villi) with deep invaginations (crypts) between the villi. The migration, proliferation, differentiation, and function of small intestinal epithelial cells vary with position relative to these structures. Thus, crypt-villus micro-architecture may induce changes in cell phenotype. Understanding the role of micron-scale topographic factors will provide a foundation for intestinal tissue engineering research using biomimetic scaffolds. In present study, crypt and villus structures were simplified as a micro-well array and a micro-pillar array, respectively. Both poly-dimethylsiloxane (PDMS) and type I collagen cell culture substrates with designed topography were fabricated using soft lithography technique. Caco-2 cells were cultivated on both substrates. Cell morphology, viability, proliferation, and differentiation were evaluated.

It was found that the microtopography affects Caco-2 morphology and migration. Cells cultured in PDMS substrates with 50 um and 100 um diameter wells had much more distinct protrusions than the cells cultured on flat substrates, and generally extended their protrusions towards vertical sidewalls. Cells tended to avoid attachment to the sharp bottom corner of well structures, often bridging this corner in attaching both to the bottom and side walls of the micro-wells. It was also observed that on the collagen substrates, cells tended to elongate along the top boundaries of wells. Substrate topography also influenced cell differentiation; the expression of cell differentiation markers (i.e. alkaline phosphatase, aminopeptidase N, and pipetidyl peptidase IV) varied with substrate topography. Especially in the case of alkaline phosphatase, cells grown on collagen substrates with 100 um-well array had the highest alkaline phosphatase activity, comparing with flat, 50 um-well, and 500 um-well collagen substrates.