The Role of Substrate Topography and Stiffness on MSC Cells Functions: Key Material Properties for Biomimetic Bone Tissue Engineering.

The hypothesis of the present research is that by altering the substrate topography and/or stiffness to make it biomimetic, we can modulate cells behavior. Substrates with similar surface chemistry and varying stiffnesses and topographies were prepared. Bulk PCL and CNTs-reinforced PCL composites were manufactured by solvent casting method and electrospinning and further processed to obtain tunable moduli of elasticity in the range of few MPa. To ensure the same chemical profile for the substrates, a protein coating was added. Substrate topography and properties were investigated. Further on, the feedback of Wharton's Jelly Umbilical Cord Mesenchymal Stem Cells to substrates characteristics was investigated. Solvent casting scaffolds displayed superior mechanical properties compared to the corresponding electrospun films. However, the biomimetic fibrous texture of the electrospun substrates induced improved feedback of the cells with respect to their viability and proliferation. Cells' adhesion and differentiation was remarkably pronounced on solvent casting substrates compared to the electrospun substrates. Soft substates improved cells multiplication and migration, while stiff substrates induced differentiation into bone cells. Aspects related to the key factors and the ideal properties of substrates and microenvironments were clarified, aiming towards the deep understanding of the required optimum biomimetic features of biomaterials.