Characterization of Additive Manufactured Scaffolds

At the increasing pace with which additive manufacturing technologies are advancing, it is possible nowadays to fabricate a variety of three-dimensional (3D) scaffolds with controlled structural and architectural properties. Examples span from metal cellular solids, which find application as prosthetic devices, to bioprinted constructs holding the promise to regenerate tissues and organs. These 3D porous constructs can display a variety of physicochemical and mechanical properties depending on the used material and on the design of the pore network to be created. To determine how these properties change with changing the scaffold’s design criteria, a plethora of characterization methods are applied in the biofabrication field. In this chapter, we review the most common techniques used to characterize such fabricated scaffolds by additive manufacturing technologies

Scaffold-free human mesenchymal stem cell construct geometry regulates long bone regeneration

Biomimetic bone tissue engineering strategies partially recapitulate development. We recently showed functional restoration of femoral defects using scaffold-free human mesenchymal stem cell (hMSC) condensates featuring localized morphogen presentation with delayed in vivo mechanical loading. Possible effects of construct geometry on healing outcome remain unclear. Here, we hypothesized that localized presentation of transforming growth factor (TGF)-β1 and bone morphogenetic protein (BMP)-2 to engineered hMSC tubes mimicking femoral diaphyses induces endochondral ossification, and that TGF-β1 + BMP-2-presenting hMSC tubes enhance defect healing with delayed in vivo loading vs. loosely packed hMSC sheets. Localized morphogen presentation stimulated chondrogenic priming/endochondral differentiation in vitro. Subcutaneously, hMSC tubes formed cartilage templates that underwent bony remodeling. Orthotopically, hMSC tubes stimulated more robust endochondral defect healing vs. hMSC sheets. Tissue resembling normal growth plate was observed with negligible ectopic bone. This study demonstrates interactions between hMSC condensation geometry, morphogen bioavailability, and mechanical cues to recapitulate development for biomimetic bone tissue engineering