Synergistic Effect of rhBMP-2 Protein and Nanotextured Titanium Alloy Surface to Improve Osteogenic Implant Properties

Abstract

One of the major limitations during titanium (Ti) implant osseointegration is the poor cellular interactions at the biointerface. In the present study, the combined effect of recombinant human Bone Morphogenetic Protein-2 (rhBMP-2) and nanopatterned Ti6Al4V fabricated with Directed irradiation synthesis (DIS) is investigated in vitro. This environmentally-friendly plasma uses ions to create self-organized nanostructures on the surfaces. Nanocones (≈36.7 nm in DIS 80°) and thinner nanowalls (≈16.5 nm in DIS 60°) were fabricated depending on DIS incidence angle and observed via scanning electron microscopy. All samples have a similar crystalline structure and wettability, except for sandblasted/acid-etched (SLA) and acid-etched/anodized (Anodized) samples which are more hydrophilic. Biological results revealed that the viability and adhesion properties (vinculin expression and cell spreading) of DIS 80° with BMP-2 were similar to those polished with BMP-2, yet we observed more filopodia on DIS 80° (≈39 filopodia/cell) compared to the other samples (<30 filopodia/cell). BMP-2 increased alkaline phosphatase activity in all samples, tending to be higher in DIS 80°. Moreover, in the mineralization studies, DIS 80° with BMP-2 and Anodized with BMP-2 increased the formation of calcium deposits (>3.3 fold) compared to polished with BMP-2. Hence, this study shows there is a synergistic effect of BMP-2 and DIS surface modification in improving Ti biological properties which could be applied to Ti bone implants to treat bone disease.

Latest Trends in Surface Modification for Dental Implantology: Innovative Developments and Analytical Applications

“…Other authors have used femtosecond laser [103,104] or directed irradiation synthesis (DIS) [105,106] techniques to obtain micro-and nano-textured surfaces of titanium implants to improve osseointegration by the replication of bone structures, increasing protein attachment and therefore cell adhesion.…”

Nanotextured porous titanium scaffolds by argon ion irradiation: Toward conformal nanopatterning and improved implant osseointegration

“…Nanofeatures that mimic the native ECM have promoted cell attachment, osteogenesis and vascularization. 20,30 In this context, ALP enzyme, an early bone differentiation marker expressed by osteoblastic cells 50,51 on these irradiated porous substrates was evaluated at 7 and 14 days. On day 7, ALP activity increases on porous Ar + irradiated samples and their non-irradiated counterparts compared to FD (Figure 11A).…”

“…Thus, it is present in the maturation and the beginning of the mineralization stages of osteoblast differentiation. 50,51 To evaluate the final stage of mineralization by mature osteoblasts 51 we used Alizarin red to quantify calcium nodule production on the surfaces (Figures 11C and S3), which appears to be higher in Porous Ti Ar + DIS samples compared to FD samples. The optical images in Figure 11D indicated evidence of red deposits localized on the porous surfaces, compared to FD.…”

“…Osteogenic progenitors decrease their proliferation rate in favor of differentiation, of which ALP is an early marker as it is involved in the synthesis of inorganic phosphates to form hydroxyapatite. Thus, it is present in the maturation and the beginning of the mineralization stages of osteoblast differentiation 50,51 . To evaluate the final stage of mineralization by mature osteoblasts 51 we used Alizarin red to quantify calcium nodule production on the surfaces (Figures 11C and S3), which appears to be higher in Porous Ti Ar + DIS samples compared to FD samples.…”

The Effect of the Topmost Layer and the Type of Bone Morphogenetic Protein-2 Immobilization on the Mesenchymal Stem Cell Response

“…Recent studies have shown that this improved adhesion may result from the interplay between integrins and BMP receptors [ 16 , 50 ]. Mesa-Restrepo et al [ 51 ] reported that the presence of BMP-2 on Ti discs plays an important role in cellular adhesion and spreading of C2C12 cells by increasing of filopodia number per cell and vinculin expression. It was shown that BMP-2 enhances the formation of focal adhesions and stress fibers in osteoblasts by increasing α5 and β1 integrin expression and also triggers cell migration [ 52 ].…”