Total collagen production and type-II collagen protein in the differentiated human umbilical cord mesenchymal stromal cells cultured in Matrigel™. Human umbilical cord mesenchymal stromal cells were cultured for 1 to 21 days in a three-dimensional Matrigel™ system. (A) Immunostaining for type II collagen (Col II) (n = 4, only the represented image shown; scale bar = 50 μm). (B) Total collagen content normalized to DNA (collagen/DNA, n = 4, mean ± standard error) in cells (a, significant difference was detected between IGF-1 treatment group and control at day 13 only, one-factor analysis of variance, followed by Tukey’s post-hoc analysis, P <0.05). IGF-1, insulin-like growth factor-1; TGF, transforming growth factor.