The integration of pore size and porosity distribution on Ti-6A1-4V scaffolds by 3D printing in the modulation of osteo-differentation

Abstract

Purpose: In this study, pore size and porosity distribution of porous Ti-6Al-4V scaffolds (pTi) were controlled by 3D printing. The effects of pore size distribution at a constant porosity, or porosity distribution at a constant pore size pertaining to functions of adhesion, proliferation, and differentiation of the mouse embryonic osteoblast precursor (MC3T3-E1) cells were researched separately. Methods: 3D printing was used to design five groups of pTi, designated as PS300/HP, PS300/LP, PS500/HP, PS500/LP, and PS800/HP based on pore size and porosity distribution. MC3T3-E1 cells were cultured on pTi, and non-porous Ti-6Al-4V samples (npTi) were prepared as control. The pTi was characterized with the scanning electron microscopy (SEM). MC3T3-E1 cells were stained via AlamarBlue assay and viability and proliferation analyzed. The mRNA levels of alkaline phosphatase (ALP), osteocalcin (OCN), collagentype-1 (Col-1), and runt-related transcription factor 2 (Runx2) in MC3T3-E1 cells were analyzed by real-time PCR analysis. Results: The average pore size and porosity of pTi were recorded as (301 ± 9 μm, 58.8 ± 1.8%), (300 ± 9 μm, 43.4 ± 1.3%), (501 ± 11 μm, 58.3 ± 1.2%), (499 ± 12 μm, 42.7 ± 1.1%), and (804 ± 10 μm, 58.9 ± 1.3%), respectively. SEM images confirmed active attachment of cells and oriented with the direction of metal rod after pTi/MC3T3-E1 co-culture for 3 and 7 days. In addition, MC3T3-E1 cells grown on the PS800/HP displayed significantly higher proliferation compared with each group after 3 days incubation ( p < 0.05). Moreover, cells showed some degree of proliferation in all groups, with the highest value recorded for PS800/HP after culture for 7 days ( p < 0.05). The gene expression pattern of ALP, OCN, Col-1, and Runx2 confirmed that these were down-regulated when pore size increased or porosity decreased of pTi ( p < 0.05). Conclusion: The pTi facilitated the adhesion and differentiation of osteoblast when pore size decreased or porosity increased. The scaffold model resembles physical modification with porous structures, which has potential application in the surface modifications of Ti implant.

Plasma Spray vs. Electrochemical Deposition: Toward a Better Osteogenic Effect of Hydroxyapatite Coatings on 3D-Printed Titanium Scaffolds

“…Furthermore, very small HA particles might induce cytotoxicity if they have been ingested by cells (Epple, 2018). Another previous study has also confirmed the beneficial effects of the pore size and porosity of 3D-printed scaffolds on cell proliferation and differentiation (Wo et al, 2020). However, it is not well understood whether EDHA and PSHA coatings on the 3D printing Ti scaffold can change the aperture and porosity of the scaffold and if there are different effects of these 2 HA coatings on cell proliferation, osteogenic differentiation, and bone integration in vivo.…”

“…However, unlike plain HA coatings, 3D-printed Ti scaffolds have inherent porous structures. Thus, the influence of pore size and porosity of HA coatings on 3D-printed Ti scaffolds should be considered, which may further influence osteointegration ( Wo et al, 2020 ). Hence, various techniques involving the fabrication of 3D-printed Ti scaffolds with HA coating have received increased biomedical research attention in recent years.…”

Enlightenment of Growth Plate Regeneration Based on Cartilage Repair Theory: A Review

“…(3) A wide range of available materials: unlike conventional fabricating techniques, 3D printing uses a variety of materials, including metals, alloys, polymers, and bioceramics ( Tardajos et al, 2018 ). (4) Precise individual customization: through a CAD software monitor, the pore size and porosity are made highly consistent with expectations, consequently, it is possible to fabricate gradient scaffolds with accurately designed pore sizes ( Wo et al, 2020 ).…”

3D‐printed hydroxyapatite scaffolds for bone tissue engineering: A systematic review in experimental animal studies

“…In addition, another crucial aspect that significantly influences the success of bone grafts in producing fracture repair is their structure, especially the adequate size and interconnectivity of the pores, which allow cell attachment, proliferation and differentiation. [14][15][16] In this context, additive manufacturing, also known as 3D printing, has emerged as a disruptive technology for rapid prototyping and for manufacturing bone grafts. 17 3D printing bone grafts have many advantages over other manufacturing techniques, such as the possibility of facilitating potential patient-specific graft fabrication and controlling porosity, introducing interconnected pore structures and managing shapes and sizes.…”

“…In addition, another crucial aspect that significantly influences the success of bone grafts in producing fracture repair is their structure, especially the adequate size and interconnectivity of the pores, which allow cell attachment, proliferation and differentiation 14–16 . In this context, additive manufacturing, also known as 3D printing, has emerged as a disruptive technology for rapid prototyping and for manufacturing bone grafts 17 .…”