Improving osteoinduction and osteogenesis of Ti6Al4V alloy porous scaffold by regulating the pore structure

Abstract

Titanium alloy scaffolds with a porous structure have attracted much attention in bone defect repair. However, which pore structure is more beneficial to bone defect repair is controversial. In the present research, the Ti6Al4V alloy porous scaffolds with gradient pore sizes were designed and fabricated. The microstructure characterization, tests of mechanical properties, and in vitro and in vivo experiments have been performed to systematically evaluate the effect of pore size on osteoinduction and osteogenesis. The results revealed that the contact angle with water, compressive strength, and elastic modulus of the Ti6Al4V alloy porous scaffolds decreased gradually with the increase of pore size. However, there were obvious drops when the pore size of the porous scaffold was around 600 μm. As the pore size increased, the proliferation and integrin β1 of RAW 264.7 macrophages seeded on Ti6Al4V alloy porous scaffolds increased at first, reaching a maximum value at a pore size of around 600 μm, and then decreased subsequently. The proliferation, integrin β1, and osteogenic gene-related expressions of Bone marrow mesenchymal stem cells (BMSCs) seeded on Ti6Al4V alloy porous scaffolds with different pore sizes all exhibited similar variations which rose with increased pore size firstly, obtaining the maximum value at pore size about 600 μm, and then declined. The in vivo experiments confirmed the in vitro results, and the Ti6Al4V alloy porous scaffold with a pore size of 600 μm possessed the better capability to induce new bone formation. Therefore, for the design of Ti6Al4V alloy with a regular porous scaffold, the surface morphology, porosity, strength, and elastic modulus should be considered systematically, which would determine the capability of osteoinduction and osteogenesis.

Effects of Aging on Osteosynthesis at Bone–Implant Interfaces

“…This contributes to a phenomena known as "stress shielding" whereby there is a reduction in bone density as a result of removal of the typical stress from the bone by an implant. The stress-shielding effect can create poor bone integration with scaffolds and eventually can lead to aseptic loosening [112]. The ideal implant has the lightweight properties of titanium alloy and a similar elastic modulus as bone without sacrificing mechanical strength.…”

Effect of 3D-Printed Porous Titanium Alloy Pore Structure on Bone Regeneration: A Review

“…Finally, by implanting the implant into rabbits, it was concluded that the biological performance of the P700 group with an actual pore diameter of approximately 600 µm was better than that of the other two groups. Wang et al [77] created consistently sized cubic pores measuring 300 µm, 400 µm, 500 µm, 600 µm, 700 µm, 800 µm, 900 µm, and 1000 µm through a combination of in vivo and in vitro experiments. The structural modifications and experimental outcomes are depicted in Figure 4d-f.…”

“…Cells are stained with actin filaments (red) and nuclei (blue) [76]. (D): Pore size analysis of Ti6Al4V and cell-staining results(live: green; dead: red), the green circle represents the pore size measured by Image-J software (Version 1.54) [77]. (E): Optical pictures of porous titanium alloys with different pore sizes [77].…”

“…(D): Pore size analysis of Ti6Al4V and cell-staining results(live: green; dead: red), the green circle represents the pore size measured by Image-J software (Version 1.54) [77]. (E): Optical pictures of porous titanium alloys with different pore sizes [77]. (F): Quantitative analysis of BV/TV [77] (* p < 0.05, ** p < 0.01, and *** p < 0.001, when compared with P500).…”

“…(E): Optical pictures of porous titanium alloys with different pore sizes [77]. (F): Quantitative analysis of BV/TV [77] (* p < 0.05, ** p < 0.01, and *** p < 0.001, when compared with P500). (Reprinted with permission from Ref.…”