Production of ordered collagen matrices for three-dimensional cell culture

The aim of this study was to produce collagen gels with controlled fibrillar order as matrices for cell culture. Their structural characterization and colonization by human dermal fibroblasts arc presently reported. Ordered matrices are obtained by using the property of type I collagen monomers to self-assemble in liquid crystalline arrays by slow evaporation of acidic solutions at high concentrations. Induction of fibrillogenesis concomittent with the stabilization of the supramolecular order is then obtained, within petri dishes, by gelation of the viscous preparations under ammoniac vapours. For comparison, dermal equivalents, in which collagen compaction depends on fibroblasts contraction, are made according to the method of Bell et al. (Proc. Natl. Acad. Sci. 76(3) (1979) 1274). The fibrillar arrangement of the collagen network in the samples is determined by polarizing optical microscopy and by transmission electron microscopy. Whereas dermal equivalents exhibit heterogeneous distributions of fibrils, two differents types of order are obtained in the stabilized liquid crystalline collagen samples, namely aligned, i.e. nematic, at 20 mg/ml, or crimped, i.e. precholesteric, at 40 mg/ml. The morphology and behaviour of fibroblasts seeded on the surface of the matrices are analysed from day 1 to day 21. The cells are viable, proliferate at the surface of ordered matrices and migrate up to 400 microm in depth. Production of concentrated and ordered collagen matrices provides new perspectives to study the behaviour of cells in a valorized three-dimensional context where the fibrillar organization becomes close to in vivo situations.