Figure 4.

Mechanical properties of hybrid scaffolds with MSCs were compared in both static and bioreactor conditions. A,B) Schematic representation and actual images of the stretch-flex bioreactor used. Image of the scaffold in flexed C) and stretch D) states within the bioreactor. E-G) Comparison of collagen, DNA, and collagen/DNA values determined from both static and bioreactor cultures. Though DNA values were higher in the static samples, the collagen produced per DNA was higher in the bioreactor, suggesting that physical stimulation increased cellular enzymatic activity. H) F-actin confirms the presence and progression of MSCs across the scaffold following bioreactor cultivation. Comparison of hybrid scaffold mechanical properties in both I) static and J-L) bioreactor conditions, with and without cells over the two-week culture time. The presence of cells increased the some mechanical values in hybrid scaffolds placed in both static and bioreactor conditions. Higher stiffness for scaffolds without cells in the bioreactor suggests increased alignment but lower UTS, and higher deformation for these scaffolds is due to the higher rate of degradation under mechanical stimulation. The increased values of stiffness and UTS for the scaffolds with the cells confirmed that scaffolds hold their integrity and ECM generation, which correlated with collagen/DNA data results in improved mechanical properties.