Human embryonic stem cell attachment and growth on different extracellular matrices. (A): Representative images from phase-contrast microscopy at days 1 and 4 of hESC-C cells expanded on different extracellular matrices. Scale bars = 100 μm. Fold increase in cell concentration (B) and metabolic activity (C) measured by alamarBlue assay for hESC-C cells. Error bars denote the mean ± SD of four measurements. ∗∗, p < .01; ∗∗∗, p < .001 determined by one-way analysis of variance. Abbreviations: CS, CELLstart; MEF-CM, mouse embryonic fibroblast-conditioned medium; MG, Matrigel; Synth, Synthemax; SA, StemAdhere.