A novel hybrid 3D-printed titanium scaffold for osteogenesis in a rabbit calvarial defect model.

The aim of this study was to explore an innovative method to improve the osteogenic ability of porous titanium. We used gelatin (Gel) and nano-hydroxyapatite (nHA) to construct micro-scaffolds within the pores of porous titanium alloy. We compared three groups: control, Gel:nHA = 1:0, and Gel:nHA = 1:1. We assessed cell attachment, cell proliferation, and osteogenic (alkaline phosphatase [ALP] and collagen type 1 [Col-1]) and cytoskeletal (Talin) gene and protein expression in MC3T3-E1 cells. We also evaluated osteogenic abilities in a rabbit calvarial defect model. Our results showed that micro-scaffolds can improve new bone formation both in vitro and in vivo. Between the two micro-scaffold groups, the Gel:nHA = 1:1 group exhibited the most satisfactory results. It had a multi-hierarchical pore structure with a mean pore size of 156±86 μm. The Gel:nHA = 1:1 group exhibited significantly higher gene and protein expression of ALP, Col-1, and Talin. This group also exhibited the most new bone volume during in vivo experiments. The 3D micro-scaffold structure was an effective method of porous titanium modification that not only provided appropriate cell growth conditions but may also be used as a carrier of bioactive factors in the future.