Integrated additive design and manufacturing approach for the bioengineering of bone scaffolds for favorable mechanical and biological properties.

Abstract

Additive manufacturing (AM) presents the possibility of personalized bone scaffolds with unprecedented structural and functional designs. In contrast to earlier conventional design concepts, e.g. raster-angle, a workflow was established to produce scaffolds with triply periodic minimal surface (TPMS) architecture. A core challenge is the realization of such structures using melt-extrusion based 3D printing. This study presents methods for generation of scaffold design files, finite element (FE) analysis of scaffold Young's moduli, AM of scaffolds with polycaprolactone (PCL), and a customized in vitro assay to evaluate cell migration. The reliability of FE analysis when using computer-aided designed models as input may be impeded by anomalies introduced during 3D printing. Using micro-computed tomography reconstructions of printed scaffolds as an input for numerical simulation in comparison to experimentally obtained scaffold Young's moduli showed a moderate trend (R  = 0.62). Interestingly, in a preliminary cell migration assay, adipose-derived mesenchymal stromal cells (AdMSC) migrated furthest on PCL scaffolds with Diamond, followed by Gyroid and Schwarz P architectures. A similar trend, but with an accelerated AdMSC migration rate, was observed for PCL scaffolds surface coated with calcium-phosphate-based apatite. We elaborate on the importance of start-to-finish integration of all steps of AM, i.e. design, engineering and manufacturing. Using such a workflow, specific biological and mechanical functionality, e.g. improved regeneration via enhanced cell migration and higher structural integrity, may be realized for scaffolds intended as temporary guiding structures for endogenous tissue regeneration.