Optimization of 3D Extrusion-Printed Particle-Containing Hydrogels for Osteogenic Differentiation

There is a continued increase in demand for novel bone grafting substitutes to reduce reliance on and address challenges associated with allograft and autograft bone grafts. Current synthetic bone grafting substitutes exhibit low mechanical strength and bioactivity, which has inspired the development of novel grafting materials. Accelerating the translation of new bone graft substitutes requires workflows for high-throughput fabrication and analysis of particle-containing models. This study utilized 3D sacrificial printing for the fabrication of reproducible, cellular scaffolds containing tricalcium phosphate (TCP), hydroxyapatite (HA), or natural coral particles. High-throughput analysis of the cellular scaffolds included quantifying cell metabolism, viability, and calcium consumption, as well as nondestructive analysis of collagen accumulation and destructive methods for assessing cell number and morphological changes. Both particle- and non-particle-containing inks sustained cell metabolism with low and decreasing cell death for 7 days post-printing. Collagen staining, scanning electron microscopy imaging, and calcium and collagen quantification suggested that, under osteogenic induction conditions, cells migrated to the surface of the scaffolds and formed a sheet of cells and a collagen-containing extracellular matrix, thereby indicating osteogenic differentiation. The workflow described herein enables the creation of in vitro models to study the osteogenic nature of new bone grafting substitute materials. High-throughput printing combined with non-destructive screening techniques resulted in reduced time, resources, and associated costs and could be applicable to a broader range of cell types.