Fabrication and Characterization of Ceramic-Polymer composite 3D scaffolds and Demonstration of Osteoinductive propensity with gingival Mesenchymal Stem Cells

Bone tissue engineering involves the usage of metals, polymers, and ceramics as the base constituents in the fabrication of various biomaterial 3D scaffolds. Of late, the composite materials facilitating enhanced osteogenic differentiation/regeneration have been endorsed as the ideally suited bone grafts for addressing critical-sized bone defects. Here, we report the successful fabrication of 3D composite scaffolds with collagen type I (Col-I) in conjunction with three different crystalline phases of calcium-phosphate (CP) nanomaterials [hydroxyapatite (HAp), beta-tricalcium phosphate ({beta}TCP), biphasic hydroxyapatite ({beta}TCP-HAp or BCP)], obtained by altering the pH as the major variable. The fabricated 3D scaffolds consisting of [~]70 wt % CP nanomaterials and [~] 30 Wt % of Col-I did mimic the ECM of bone tissue. The different Ca/P ratio and the orientation of CP nanomaterials in CP/Col-I composite scaffolds altered the microstructure, surface area, porosity, and mechanical strength of the scaffolds and also influenced the bioactivity, biocompatibility, and osteogenic differentiation of gingival-derived mesenchymal stem cells (gMSCs). The microstructure of CP/Col-I 3D scaffolds assessed by Micro-CT analysis revealed randomly oriented interconnected pores with pore sizes ranging from 80-250, 125-380, and 100-450{micro}m respectively for {beta}TCP/Col-I, BCP/Col-I, and HAp/Col-I scaffolds. Among these, the BCP/Col-I achieved the highest surface area ([~] 42.6 m2/g) and porosity ([~]85%), demonstrated improved bioactivity and biocompatibility, and promoted osteogenic differentiation of gMSCs. Interestingly, the Ca2+ ions (3 mM) released from scaffolds could also facilitate the osteocyte differentiation of gMSCs sans osteoinduction. Collectively, our study has demonstrated the ECM mimicking biphasic CP/Col-I 3D scaffold as an ideally suited tissue-engineered bone graft.