Additional file 1 of Type I collagen facilitates safe and reliable expansion of human dental pulp stem cells in xenogeneic serum-free culture

Additional file 1: Figure S1. Phase-contrast images of DPSCs cultured in xenogeneic serum-free culture conditions on the coated substrates as follows: type I collagen supplied by (a) Nitta Gelatin and (b) Corning; fibronectin supplied by (a) Irvine Scientific and (b) Corning; laminin supplied by (a) Corning and (b) BD Biosciences and poly-D-lysine supplied by Corning. In the initial cell growth test, cells were seeded at 5 × 103 cells/cm2 (conventional cell density when passaging) and the images were taken on day 4 post-seeding. Scale bars, 200 μm.