Culture in an oscillating bioreactor enhances tissue mechanical properties and collagen content. (A) Aggregate modulus and (B) total collagen content in human mesenchymal stem cell–poly(ϵ-caprolactone) (hMSC-PCL) constructs. *Significant difference due to scaffold structure (P < 0.05); **Significant difference due to culture vessel (P < 0.05). (C), (D) Histological (top) and immunohistological (bottom) appearance of day 21 hMSC-PCL constructs cultured (C) statically or (D) in a bioreactor. Tissue sections were stained for safranin-O (top, scale bar: 20 μm) and double immunostained (bottom, cellular DNA counter-stained, scale bar: 100 μm) for collagen I (red, not seen) and collagen II (green). GAG, glycosaminoglycan. Adapted from .