Crafting Collagen Matrix Models

Three types of extracellular matrix models were crafted for this study. Collagens solely comprised of rat tail monomers (4 g/l rat collagen type I, SERVA, Heidelberg, Germany), collagens containing only bovine skin monomers (4 g/l bovine collagen type I, Biochrom, Berlin, Germany) and collagens composed of a mixture of both collagen monomer types (rat tail and bovine skin) in a mass fraction of 1:2 were used for all collagen related experiments (Fischer et al., 2017 (link), 2019 (link), 2020 (link); Kunschmann et al., 2019 (link)). For the polymerization of the monomer solution, a 1 M phosphate buffered solution containing disodium hydrogen phosphate (Sigma Aldrich, Cat. No. 71636), sodium dihydrogen phosphate (Sigma Aldrich, Cat. No. 71507) and ultrapure water were mixed keeping stable conditions (pH value 7.4, ionic strength 0.7, final phosphate concentration 200 mM). The components were kept at 0°C for mixing and finally added to 6-well plates for invasion assays, Petri dishes for elasticity measurements, 96-well plates for investigating the polymerization dynamics, or ibidi 24-well μ-plates for studying the pore size characteristics. Due to differences in the polymerization times (Supplementary Figure S5) R and RB collagen matrices were incubated for 2 h whereas B collagens were incubated for 5 h under normal conditions.