Tighe A. Spurlin, John Elliott, and Anne L. Plant 


 The majority of cell-based assays performed to elucidate cellular pathways and responses to drugs and toxins have been performed in cells on plasma treated polystyrene dishes or ill-defined extracellular matrix (ECM) protein coatings. In many studies, cell responses have been shown to be sensitive to surface topography, protein coverage, surface chemistry, and extracellular matrix composition, supramolecular structure, and mechanical features. Type I collagen gels have been widely used as model ECM systems for cell studies, since collagen is a highly prevalent ECM in vivo. However, gels are fragile structures that are difficult to characterize and use with quantitative optical microscopy. We have previously shown that thin films of Type I collagen fibrils can be used to alleviate the difficulties associated with collagen gels. Thin films of collagen fibrils have been shown to provide cells with an ECM environment that induces cell responses that are indistinguishable from those seen in cells on the thicker gels in terms of spreading, proliferation, integrin ligation, and tenascin-C expression. Thin films of collagen are highly reproducible, but we have up to now only used one source of Type I collagen to prepare them. To determine if different sources of Type I collagen can be used to create a robust, reproducible, and standardized biomimetic surface for cell assay applications, we prepared films using type I collagen from different manufactures and characterized them with atomic force microscopy and optical microscopy. Results from this series of studies illustrate that collagen films created using the same protocol but different comparable sources of collagen show fibril content that ranges from 43.4 % 1.32 % to 6.6 % 0.6 %. In initial studies we have observed that vascular smooth muscle cell spread area can differ dramatically from 2043 m2 121 m2 to 6616 m2 237 m2 depending on the source of the Type I collagen used. The findings suggest that different Type 1 collagen preparations are not identical, and highlight the importance of carefully characterizing and reporting the characteristics of the surfaces that cells are grown on during biological assays.