(534e) Chemical and Topographical Modification to Polydimethylsiloxane Surfaces Affect Growth and Adhesion of Caco-2 Cells

Oral drug dosing is most desirable due to patient convenience. The Caco-2 model is widely used in predicting oral absorption during the early stages of the drug discovery process, called early ADME. However, Caco-2 does not always accurately predict oral absorption, partially due to low protein expression levels in culture. Development of a Caco-2 model that more accurately predicts drug absorption than the existing model would be beneficial to oral drug discovery and development.

Both chemical and physical cues are known to affect cell phenotype. Manipulation of the culture environment can induce Caco-2 cells to express a phenotype resembling more closely small intestinal epithelial cells in absorption properties. Soft lithography techniques were used to create physically biomimetic cell culture substrates with topological features of crypt regions in small intestinal basal lamina. As polydimethylsiloxane (PDMS) silicone elastomer is a commonly used material in the soft lithography process, it was selected to fabricate the basal lamina analogs.

Though PDMS is biocompatible, it is not an ideal material for cell culture due to its poor cell adhesion properties. In the present study, PDMS surfaces were modified to promote cell adhesion. Caco-2 cell attachment and viability on modified PDMS were examined. The influence of chemical composition of PDMS, surface treatment of PDMS by coating with negatively charged molecules (e.g. poly-D-lysine, lecithin), and deposition of extra-cellular matrix (ECM) proteins (e.g. laminin, fibronectin, collagen) on the attachment and growth of Caco-2 cells were observed. Generally, Caco-2 cells preferred to attach on collagen-coated PDMS and fibronectin-coated PDMS.

Cell attachment and growth were also investigated on topographically modified PDMS. The basic microstructures created were wells. The structures were 120 um in height and had varied diameters (from 50 to 500 um) and wall to wall spacing (from 50 to 500 um), which approximately mimic dimensions of small intestinal crypts. Fibronectin was passively absorbed onto patterned surfaces. Caco-2 cells were seeded onto the micropatterned PDMS substrates. Caco-2 cells had a greater tendency to attach on smooth surfaces compared to areas containing microstructures. Caco-2 cells demonstrated the ability to attach on the steep sidewalls of well structures.