Adding beta-tricalcium phosphate ceramic to additive manufactured 3D porous Ti6Al4V scaffolds enhances osteogenic activity of human mesenchymal stromal cells in vitro

Titanium is widely used in orthopedic and cranio-maxillofacial surgery because of its excellent mechanical properties and biocompatibility, but it lacks bioactivity in bone. Incorporating calcium phosphate ceramics such as beta-tricalcium phosphate (TCP) can enhance osteoconductivity. Additive manufacturing methods based on powder bed fusion typically cannot produce metal-ceramic composites. This study evaluated human mesenchymal stromal cell (hMSC) responses to novel 3D porous titanium-alloy (Ti6Al4V) scaffolds fabricated by 3D fiber deposition containing up to 10 wt% TCP. Scaffolds were manufactured as Ti6Al4V alone (Ti0) or composites with 5 wt% (Ti5) or 10 wt% (Ti10) TCP, with similar to 500 mu m fully interconnected pores. hMSCs were cultured for up to 28 days in basic, osteogenic, or mineralization medium. Cell behavior was assessed by DNA and metabolic assays, osteogenic differentiation by ALP activity, ELISA (OCN, OPN) and RT-qPCR (RUNX-2, ALP, OCN, OPN), ECM formation by SEM, and mineralization by Alizarin Red S staining. All scaffolds supported cell attachment and metabolic activity. Early osteogenic markers were reduced in TCP-containing scaffolds, whereas late-stage markers (OCN, OPN) were upregulated in Ti10. ECM coverage was complete after 14 days. Mineralization showed an increasing trend with increasing TCP content. These 3D porous Ti6Al4V-TCP scaffolds support hMSC attachment, osteogenic differentiation, ECM formation, and mineralization in vitro, suggesting potential for regeneration of large load-bearing bone defects.