Effects of rmBMP-7 on Osteoblastic Cells Grown on a Nanostructured Titanium Surface

Abstract

This study evaluates the effects of the availability of exogenous BMP-7 on osteoblastic cells’ differentiation on a nanotextured Ti surface obtained by chemical etching (Nano-Ti). The MC3T3-E1 and UMR-106 osteoblastic cell lines were cultured for 5 and 7 days, respectively, on a Nano-Ti surface and on a control surface (Control-Ti) in an osteogenic medium supplemented with either 40 or 200 ng/mL recombinant mouse (rm) BMP-7. The results showed that MC3T3-E1 cells exhibited distinct responsiveness when exposed to each of the two rmBMP-7 concentrations, irrespective of the surface. Even with 40 ng/mL rmBMP-7, important osteogenic effects were noticed for Control-Ti in terms of cell proliferation potential; Runx2, Osx, Alp, Bsp, Opn, and Smad1 mRNA expression; and in situ ALP activity. For Nano-Ti, the effects were limited to higher Alp, Bsp, and Opn mRNA expression and in situ ALP activity. On both surfaces, the osteogenic potential of UMR-106 cultures remained unaltered with 40 ng/mL rmBMP-7, but it was significantly reduced when the cultures were exposed to the 200 ng/mL concentration. The availability of rmBMP-7 to pre-osteoblastic cells at the concentrations used alters the expression profile of osteoblast markers, indicative of the acquisition of a more advanced stage of osteoblastic differentiation. This occurs less pronouncedly on the nanotextured Ti and without reflecting in higher mineralized matrix production by differentiated osteoblasts on both surfaces.

Influence of a Physiologically Formed Blood Clot on Pre-Osteoblastic Cells Grown on a BMP-7-Coated Nanoporous Titanium Surface

“…To obtain Nano-Ti, commercially pure grade 2 Ti discs (Realum, São Paulo, Brazil), modified to exhibit a hollowed surface ( Figure S1 ), were cleaned by sonication and etched in a solution consisting of equal volumes of concentrated 30% H 2 O 2 and H 2 SO 4 (95–97%) for 4 h (10 mL/disc) at room temperature (RT) [ 12 , 20 ]. Then, they were rinsed in distilled water, air dried, and autoclaved.…”

“…The strategies used to functionalize with BMP-7 involve modifications of the biomaterial surface chemistry and topography at a nanoscale, including those of metals [ 8 , 9 , 10 , 11 ]. In a previous initial study, we observed that the effects of providing 40 and 200 ng/mL of a recombinant mouse (rm) BMP-7 to osteoblastic cells grown on titanium (Ti) were modulated by the nanotopographic features of its surface, with an increased expression of the osteoblast markers osteopontin (OPN) and alkaline phosphatase (ALP), but without enhancement in the mineralized matrix formation [ 12 ]. Interestingly, the Ti nanotopography (Nano-Ti) per se (without rmBMP-7 in the culture medium) promoted osteogenic differentiation compared with an almost flat surface at a nanoscale [ 12 ].…”

“…In a previous initial study, we observed that the effects of providing 40 and 200 ng/mL of a recombinant mouse (rm) BMP-7 to osteoblastic cells grown on titanium (Ti) were modulated by the nanotopographic features of its surface, with an increased expression of the osteoblast markers osteopontin (OPN) and alkaline phosphatase (ALP), but without enhancement in the mineralized matrix formation [ 12 ]. Interestingly, the Ti nanotopography (Nano-Ti) per se (without rmBMP-7 in the culture medium) promoted osteogenic differentiation compared with an almost flat surface at a nanoscale [ 12 ]. Based on these results, we designed the present study aiming to evaluate the effects of rmBMP-7-functionalized Nano-Ti on in vitro osteoblastic differentiation when a physiological blood clot is formed prior to the cell culture analyses.…”

“…The present study goes further by including the formation of a physiological blood clot using the surgical approach proposed elsewhere [ 18 ] and adapted to our conditions to ensure the implant placement in a mouse dorsal dermal tissue model. The implant Ti discs were chemically treated with a mixture of sulfuric acid (H 2 SO 4 ) and hydrogen peroxide (H 2 O 2 ) to create a highly hydrophilic, biomimetic TiO 2 nanotopography [ 19 ] supportive of (i) functionalization with organic molecules by physisorption [ 20 ] and (ii) osteogenic differentiation [ 12 , 21 ]. The average roughness of Nano-Ti has been reported to be on the order of 9 nm, with nanopore depths ranging from 5 to 25 nm [ 22 , 23 ].…”

Role of BMP-7 on biological parameters osseointegration of dental implants: Preliminary results of a preclinical study

“…However, there are no uniform results regarding the osteogenic power of BMP-7-functionalized Ti; an in vitro study by Togashi et al (2009) found no effect of the addition of rhBMP-7 to the culture medium on the viability, proliferation, or differentiation of osteoblastlike cells, whereas others have found superior osteogenic power of samples with BMP-7 (Cirano et al, 2014). Zuardi et al (2022) in a recent study, demonstrated that the effects of BMP-7 on osteogenic differentiation in vitro, would be conditioned by the topography of the surface on which the cell cultures are grown, the concentration of the growth factor in the culture medium and the stage of differentiation of the osteoblastic cells. Chen et al (2013) developed a BMP-7-activated Ti gene delivery system for in vitro osteoblast culture and found enhanced differentiation capacity.…”