One of the tissue engineering strategies to promote bone regeneration is the association of cells and biomaterials. In this context, the aim of this study was to evaluate if cell source, either from bone marrow or adipose tissue, affects bone repair induced by osteoblastic cells associated with a membrane of poly(vinylidene-trifluoroethylene)/barium titanate (PVDF-TrFE/BT). Mesenchymal stem cells (MSC) were isolated from rat bone marrow and adipose tissue and characterized by detection of several surface markers. Also, both cell populations were cultured under osteogenic conditions and it was observed that MSC from bone marrow were more osteogenic than MSC from adipose tissue. The bone repair was evaluated in rat calvarial defects implanted with PVDF-TrFE/BT membrane and locally injected with (1) osteoblastic cells differentiated from MSC from bone marrow, (2) osteoblastic cells differentiated from MSC from adipose tissue or (3) phosphate-buffered saline. Luciferase-expressing osteoblastic cells derived from bone marrow and adipose tissue were detected in bone defects after cell injection during 25 days without difference in luciferin signal between cells from both sources. Corroborating the in vitro findings, osteoblastic cells from bone marrow combined with the PVDF-TrFE/BT membrane increased the bone formation, whereas osteoblastic cells from adipose tissue did not enhance the bone repair induced by the membrane itself. Based on these findings, it is possible to conclude that, by combining a membrane with cells in this rat model, cell source matters and that bone marrow could be a more suitable source of cells for therapies to engineer bone.

In this study, we evaluated the effect of poly(vinylidene fluoride-trifluoroethylene)/barium titanate (P(VDF-TrFE)/BT) membrane on in vivo bone formation. Rat calvarial bone defects were implanted with P(VDF-TrFE)/BT and polytetrafluoroethylene (PTFE) membranes, and at 4 and 8 weeks, histomorphometric and gene expression analyses were performed. A higher amount of bone formation was noticed on P(VDF-TrFE)/BT compared with PTFE. The gene expression of RUNX2, bone sialoprotein, osteocalcin, receptor activator of nuclear factor-kappa B ligand, and osteoprotegerin indicates that P(VDF-TrFE)/BT favored the osteoblast differentiation compared with PTFE. These results evidenced the benefits of using P(VDF-TrFE)/BT to promote new bone formation, which may represent a promising alternative to be employed in guided bone regeneration.

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The major role of integrins is to mediate cell adhesion but some of them are involved in the osteoblasts–titanium (Ti) interactions. In this study, we investigated the participation of integrins in osteoblast differentiation induced by Ti with nanotopography (Ti‐Nano) and with microtopography (Ti‐Micro). By using a PCR array, we observed that, compared with Ti‐Micro, Ti‐Nano upregulated the expression of five integrins in mesenchymal stem cells, including integrin β3, which increases osteoblast differentiation. Silencing integrin β3, using CRISPR‐Cas9, in MC3T3‐E1 cells significantly reduced the osteoblast differentiation induced by Ti‐Nano in contrast to the effect on T‐Micro. Concomitantly, integrin β3 silencing downregulated the expression of integrin αv, the parent chain that combines with other integrins and several components of the Wnt/β‐catenin and BMP/Smad signaling pathways, all involved in osteoblast differentiation, only in cells cultured on Ti‐Nano. Taken together, our results showed the key role of integrin β3 in the osteogenic potential of Ti‐Nano but not of Ti‐Micro. Additionally, we propose a novel mechanism to explain the higher osteoblast differentiation induced by Ti‐Nano that involves an intricate regulatory network triggered by integrin β3 upregulation, which activates the Wnt and BMP signal transductions. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 107A: 1303–1313, 2019.

Among bone morphogenetic proteins (BMPs), BMP-9 has been described as one with higher osteogenic potential. Here, we aimed at evaluating the effect of BMP-9 on the osteoblast differentiation of cells grown on titanium (Ti) with nanotopography, a well-known osseoinductive surface. MC3T3-E1 cells were grown either in absence or presence of BMP-9 (20 nM) on Ti with nanotopography (Ti-Nano) or machined Ti (Ti-Machined) for up to 21 days to evaluate the gene expression of RUNX2, osterix, osteocalcin, bone sialoprotein, SMAD6 and SMAD4, protein expression of SMAD4, ALP activity and extracellular matrix mineralization. As expected BMP-9 increased osteoblast differentiation irrespective of Ti surface topography; however, the cells grown on Ti-Nano were more responsible to BMP-9 compared with cells grown on Ti-machined. This could be, at least in part, due to the fact that Ti-Nano may act on both ways, by increasing the activation (SMAD4) and decreasing the inhibition (SMAD6) of the signaling pathway triggered by BMP-9, while Ti-Machined only decrease the inhibition (SMAD6) of this pathway. In conclusion, the combination of the osteogenic potential of BMP-9 with the osseoinductive capacity of Ti-Nano could be a promising strategy to favor the osseointegration of Ti implants.

No abstract

The investigated narrow implants presented mechanical performance under fatigue that suggests their safe use as single crowns in the anterior region.

Clinical success of implant therapy is directly related to titanium (Ti) surface properties and the quality of bone tissue. The treatment of Ti implants with H2SO4/H2O2 is a feasible, reproducible, and low-cost technique to create surface nanotopography (Ti-Nano). As this nanotopography induces osteoblast differentiation, we hypothesized that it may affect bone response to Ti. Thus, this study was designed to evaluate the bone response to a machined Ti implant treated with H2SO4/H2O2 to generate Ti-Nano and to compare it with a commercially available microtopographic Ti implant (Ti-Porous). Implants were placed in rabbit tibias and evaluated after 2 and 6 weeks, and the bone tissue formed around them was assessed by microtomography to record bone volume, bone surface, specific bone surface, trabecular number, trabecular thickness, and trabecular separation. Undecalcified histological sections were used to determine the percentages of bone-to-implant contact, bone area formed between threads, and bone area formed in the mirror area. At the end of 6 weeks, the removal torque was evaluated using a digital torque gauge. The results showed bone formation in close contact with both Ti-Nano and Ti-Porous implants without relevant morphological and morphometric differences, in addition to a similar removal torque irrespective of surface topography. In conclusion, our results have shown that a simple and low-cost method using H2SO4/H2O2 is highly efficient for creating nanotopography on Ti surfaces, which elicits a similar bone response compared with microtopography presented in a commercially available Ti implant.