Publications by authors named "Adalberto Luiz Rosa"

64 Publications

Miniplates coated by plasma electrolytic oxidation improve bone healing of simulated femoral fractures on low bone mineral density rats.

Mater Sci Eng C Mater Biol Appl 2021 Jan 4;120:111775. Epub 2020 Dec 4.

Division of Oral and Maxillofacial Surgery, Department of Diagnosis and Surgery, Aracatuba School of Dentistry, São Paulo State University (UNESP), Araçatuba, São Paulo 16015-050, Brazil. Electronic address:

The treatment of polytrauma patients represents a great challenge in the maxillofacial and orthopedic surgery fields. Therefore, this study tested the hypothesis that the use of a bioactive coating (by plasma electrolytic oxidation, PEO) on titanium microplates could improve the fracture healing of low bone mineral density (BMD) rats. Thirty female rats underwent bilateral ovariectomy surgery (OVX), and 35 rats underwent fake surgery (SHAM). Three months later, animals were subjected to femoral fracture simulation and were fixed with either non-coated (CONV) or coated (PEO) titanium miniplates. Eight weeks postoperatively, microplate/bone complexes were analyzed through computed microtomography, histometric, confocal microscopy, molecular, and biomechanical analysis. Bioactive elements (Ca and P) were incorporated on the PEO microplate and the surface was modified in a volcano-like structure. In the microCT analysis the OVX/PEO group had greater values for Tb.Th (bone trabecular thickness), Tb.Sp (separation of bone trabeculae) and Tb.N (number of trabeculae) parameters compared to the OVX/CONV group. According to histometric analysis, the OVX/PEO group showed significantly higher new bone formation than the OVX/CONV group (P < 0.05). For the fluorochrome area, the OVX groups (PEO and CONV) showed greater values for calcein precipitation (old bone) than alizarin red (new bone). Molecular results showed greater values for proteins related to the final phase of bone formation (P < 0.05) in the OVX/PEO group. The OVX/PEO group showed higher bone/miniplate system resilience compared to the others (P < 0.05). It was concluded that PEO coating optimizes bone healing on simulated femoral fractures in low bone mineral density rats. This sheds new light in the treatment of osteoporotic patients with bone fractures.
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http://dx.doi.org/10.1016/j.msec.2020.111775DOI Listing
January 2021

Green tea extract rich in epigallocatechin gallate impairs alveolar bone loss in ovariectomized rats with experimental periodontal disease.

Int J Exp Pathol 2020 12 11;101(6):277-288. Epub 2020 Nov 11.

Bone Research Lab, Department of Basic and Oral Biology, School of Dentistry of Ribeirão Preto, University of São Paulo, Ribeirão Preto, Brazil.

Periodontal disease and osteoporosis are characterized by bone resorption, and researchers have shown an association between these two diseases through increasing loss of systemic bone mass and triggering alveolar bone loss. Green tea is a common and easily accessible beverage, and evidences show that flavonoid epigallocatechin gallate (EGCG) could decrease bone loss in pathologies such as osteoporosis and periodontal disease. In order to verify its possible effects and apply them in the treatment and prevention of these diseases, this investigation aimed to evaluate the influence of green tea extract (GTE) on bone metabolism of ovariectomized rats after experimental periodontal disease (EPD) by histological, morphological and microtomographic parameters. Wistar female rats were divided into Sham, Sham + EPD, Sham + EPD + GTE, OVX, OVX + EPD and OVX + EPD + GTE groups. Immediately after surgery, gavage administration of 50 mg/kg of green tea extract (GTE) was performed for 60 days, with subsequent induction of periodontal disease by ligature 15 days before euthanasia. Mandible and femur samples were collected for histological, morphometric and microtomographic analysis. The results were analysed by means of statistical software with significance set at 5%. Histological and morphometric analysis showed a significant decrease in alveolar and femoral trabecular bone loss in groups that received GTE. Microtomographic results showed that trabecular thickness and bone surface density values in alveolar bone interradicular septum of the OVX + EPD + GTE groups were similar to the Sham group. The results obtained suggest that green tea extract may improve bone metabolism in osteoporotic rats with periodontal disease.
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http://dx.doi.org/10.1111/iep.12379DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7691221PMC
December 2020

Jabuticaba peel extract modulates adipocyte and osteoblast differentiation of MSCs from healthy and osteoporotic rats.

J Bone Miner Metab 2021 Mar 5;39(2):163-173. Epub 2020 Sep 5.

Bone Research Lab, School of Dentistry of Ribeirão Preto, University of São Paulo, Av Do Café S/N, Ribeirão Preto, SP, 14040-904, Brazil.

Introduction: The jabuticaba peel extract (JPE) contains bioactive compounds that regulate fat metabolism. Because the negative correlation between fat accumulation and bone formation in bone marrow, we hypothesized that JPE inhibits adipocyte as well as favors osteoblast differentiation of mesenchymal stromal cells (MSCs) under healthy and osteoporotic conditions, a disease that display an imbalance between adipocyte and osteoblast differentiation resulting in reduced bone mass.

Material And Methods: To test these hypotheses, bone marrow MSCs were harvested from healthy and osteoporotic rats and cultured in adipogenic and osteogenic media with three concentrations of JPE, 0.25, 5 and 10 µg/ml, and vehicle (control). After selecting the most efficient concentrations of JPE, we used them to evaluate adipocyte and osteoblast differentiation of MSCs from both sources.

Results: We observed that, in general, JPE inhibited adipocyte differentiation of MSCs with more pronounced effects in cells from healthy than osteoporotic rats. In addition, JPE increased osteoblast differentiation, exhibiting a slightly higher osteogenic potential on MSCs from osteoporotic compared to healthy condition.

Conclusion: Our results demonstrated that JPE drives MSCs to inhibit adipocyte differentiation and toward osteoblast differentiation under healthy and osteoporotic conditions. These findings pave the way for further translational studies to investigate the therapeutic possibilities of JPE in both prevention and treatment of osteoporosis.
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http://dx.doi.org/10.1007/s00774-020-01152-8DOI Listing
March 2021

Frizzled 6 disruption suppresses osteoblast differentiation induced by nanotopography through the canonical Wnt signaling pathway.

J Cell Physiol 2020 11 2;235(11):8293-8303. Epub 2020 Apr 2.

Bone Research Lab, School of Dentistry of Ribeirão Preto, University of São Paulo, Ribeirão Preto, São Paulo, Brazil.

This study aimed to investigate if wingless-related integration site (Wnt) signaling participates in the high osteogenic potential of titanium with nanotopography (Ti-Nano). We showed that among the several components of the Wnt signaling pathway, Frizzled 6 (Fzd6) was the transcript most intensely modulated by nanotopography compared with the untreated Ti surface (Ti-Machined). Then, we investigated whether and how Fzd6 participates in the regulation of osteoblast differentiation caused by nanotopography. The Fzd6 silencing with CRISPR-Cas9 transfection in MC3T3-E1 cells induced a more pronounced inhibition of osteoblast differentiation of cells cultured on nanotopography than those cultured on Ti-Machined. The analysis of the expression of calcium-calmodulin-dependent protein kinase II and β-catenin demonstrated that Fzd6 disruption inhibited the osteoblast differentiation induced by Ti-Nano by preventing the activation of Wnt/β-catenin but not that of Wnt/Ca signaling, which is usually triggered by the receptor Fzd6. These findings elucidate the biological function of Fzd6 as a receptor that triggers Wnt/β-catenin signaling and the cellular mechanisms modulated by nanotopography during osteoblast differentiation.
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http://dx.doi.org/10.1002/jcp.29674DOI Listing
November 2020

Role of embryonic origin on osteogenic potential and bone repair capacity of rat calvarial osteoblasts.

J Bone Miner Metab 2020 Jul 20;38(4):481-490. Epub 2020 Feb 20.

Bone Research Lab, School of Dentistry of Ribeirão Preto, University of São Paulo, Av do Café s/n, Ribeirão Preto, SP, 14040-904, Brazil.

Introduction: The aim of this study was to evaluate the in vitro osteogenic potential of osteoblasts from neural crest-derived frontal bone (OB-NC) and mesoderm-derived parietal bone (OB-MS) and the bone formation induced by them when injected into calvarial defects.

Materials And Methods: Calvarial bones were collected from newborn Wistar rats (3-day old) and characterized as frontal and parietal prior to OB-NC and OB-MS harvesting. The cells were cultured, and several parameters of osteoblast differentiation were evaluated. These cells, or PBS without cells (control), were locally injected into 5-mm rat calvarial defects (5 × 10 cells/defect) and after 4 weeks bone formation was evaluated by morphometric and histological analyses.

Results: The characterization of frontal and parietal bones assured the different embryonic origin of both cell populations, OB-NC and OB-MS. The OB-NC presented higher proliferation while the OB-MS presented higher alkaline phosphatase (ALP) activity, extracellular matrix mineralization and gene expression of runt-related transcription factor 2, Alp, bone sialoprotein and osteocalcin revealing their high osteogenic potential. µCT analysis indicated that there was higher amount of bone formation in defects injected with both OB-NC and OB-MS compared to the control. Moreover, the bone tissue formed by both cells displayed the same histological characteristics.

Conclusions: Despite the distinct in vitro osteogenic potential, OB-NC and OB-MS induced similar bone repair in a rat calvarial defect model. Thus, osteoblasts, irrespective of their in vitro osteogenic potential linked to embryonic origins, seem to be suitable for cell-based therapies aiming to repair bone defects.
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http://dx.doi.org/10.1007/s00774-020-01090-5DOI Listing
July 2020

Effect of focal adhesion kinase inhibition on osteoblastic cells grown on titanium with different topographies.

J Appl Oral Sci 2020 7;28:e20190156. Epub 2020 Feb 7.

Universidade de São Paulo, Faculdade de Odontologia de Ribeirão Preto, Bone Research Laboratory, Ribeirão Preto, São Paulo, Brasil.

Objective: The present study aimed to investigate the participation of focal adhesion kinases (FAK) in interactions between osteoblastic cells and titanium (Ti) surfaces with three different topographies, namely, untreated (US), microstructured (MS), and nanostructured (NS).

Methodology: Osteoblasts harvested from the calvarial bones of 3-day-old rats were cultured on US, MS and NS discs in the presence of PF-573228 (FAK inhibitor) to evaluate osteoblastic differentiation. After 24 h, we evaluated osteoblast morphology and vinculin expression, and on day 10, the following parameters: gene expression of osteoblastic markers and integrin signaling components, FAK protein expression and alkaline phosphatase (ALP) activity. A smooth surface, porosities at the microscale level, and nanocavities were observed in US, MS, and NS, respectively.

Results: FAK inhibition decreased the number of filopodia in cells grown on US and MS compared with that in NS. FAK inhibition decreased the gene expression of Alp, bone sialoprotein, osteocalcin, and ALP activity in cells grown on all evaluated surfaces. FAK inhibition did not affect the gene expression of Fak, integrin alpha 1 ( Itga1 ) and integrin beta 1 ( Itgb1 ) in cells grown on MS, increased the gene expression of Fak in cells grown on NS, and increased the gene expression of Itga1 and Itgb1 in cells grown on US and NS. Moreover, FAK protein expression decreased in cells cultured on US but increased in cells cultured on MS and NS after FAK inhibition; no difference in the expression of vinculin was observed among cells grown on all surfaces.

Conclusions: Our data demonstrate the relevance of FAK in the interactions between osteoblastic cells and Ti surfaces regardless of surface topography. Nanotopography positively regulated FAK expression and integrin signaling pathway components during osteoblast differentiation. In this context, the development of Ti surfaces with the ability to upregulate FAK activity could positively impact the process of implant osseointegration.
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http://dx.doi.org/10.1590/1678-7757-2019-0156DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6999121PMC
February 2020

Inhibitory effects of dabigatran etexilate, a direct thrombin inhibitor, on osteoclasts and osteoblasts.

Thromb Res 2020 02 23;186:45-53. Epub 2019 Dec 23.

Department of Oral Surgery and Pathology, Faculty of Dentistry, Federal University of Minas Gerais, Belo Horizonte, MG, Brazil. Electronic address:

Introduction: Anticoagulants are widely used in orthopedic surgery to decrease the risk of deep vein thrombosis. While significant bone impairment is induced by long-term heparin therapy, little is known about the effects of direct oral anticoagulants (DOACs). Herein, we investigated the effects of dabigatran etexilate (Pradaxa®), a DOAC inhibitor of thrombin, on bone cells using in vitro and ex vivo cell culture models.

Materials And Methods: Osteoblasts and osteoclasts exposed to different concentrations of dabigatran etexilate and untreated cells were assayed for cell differentiation and activity. Favorable osteogenic conditions for osteoblasts were tested using titanium with nanotopography (Ti-Nano). In addition, mice treated with a dabigatran etexilate solution had bone marrow cells analyzed for the ability to generate osteoclasts.

Results: Dabigatran etexilate at concentrations of 1 μg/mL and 2 μg/mL did not impact osteoclast or osteoblast viability. The drug inhibited osteoclast differentiation and activity as observed by the reduction of TRAP+ cells, resorption pits and gene and protein expression of cathepsin K. Consistently, osteoclasts from mice treated with dabigatran showed decreased area, resorptive activity, as well as gene and protein expression of cathepsin K. In osteoblast cultures, grown both on polystyrene and Ti-Nano, dabigatran etexilate reduced alkaline phosphatase (ALP) activity, matrix mineralization, gene expression of ALP and osteocalcin.

Conclusions: Dabigatran etexilate inhibited osteoclast differentiation in ex vivo and in vitro models in a dose-dependent manner. Moreover, the drug reduced osteoblast activity even under optimal osteogenic conditions. This study provides new evidence regarding the negative overall impact of DOACs on bone cells.
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http://dx.doi.org/10.1016/j.thromres.2019.12.014DOI Listing
February 2020

Effect of stem cells combined with a polymer/ceramic membrane on osteoporotic bone repair.

Braz Oral Res 2019 Sep 9;33:e079. Epub 2019 Sep 9.

Universidade de São Paulo - USP, School of Dentistry of Ribeirão Preto , Bone Research Lab , Ribeirão Preto , SP , Brazil .

Cell therapy associated with guided bone regeneration (GBR) can be used to treat bone defects under challenging conditions such as osteoporosis. This study aimed to evaluate the effect of mesenchymal stem cells (MSCs) in combination with a poly(vinylidene-trifluoroethylene)/barium titanate (PVDF-TrFE/BT) membrane on bone repair in osteoporotic rats. Osteoporosis was induced in female rats by bilateral removal of the ovaries (OVX) or sham surgery (SHAM), and the osteoporotic condition was characterized after 5 months by microtomographic and morphometric analyses. Calvarial defects were created in osteoporotic rats that immediately received the PVDF-TrFE/BT membrane. After 2 weeks, bone marrow-derived MSCs from healthy rats, characterized by the expression of surface markers using flow cytometry, or phosphate-buffered saline (PBS) (Control) were injected into the defects and bone formation was evaluated 4 weeks post-injection by microtomographic, morphometric, and histological analyses. A reduction in the amount of bone tissue in the femurs of OVX compared with SHAM rats confirmed the osteoporotic condition of the experimental model. More bone formation was observed when the defects were injected with MSCs compared to that with PBS. The modification that we are proposing in this study for the classical GBR approach where cells are locally injected after a membrane implantation may be a promising therapeutic strategy to increase bone formation under osteoporotic condition.
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http://dx.doi.org/10.1590/1807-3107BOR-2019.vol33.0079DOI Listing
September 2019

Titanium with nanotopography induces osteoblast differentiation through regulation of integrin αV.

J Cell Biochem 2019 10 15;120(10):16723-16732. Epub 2019 May 15.

Bone Res Lab, School of Dentistry of Ribeirao Preto, University of São Paulo, Ribeirao Preto, Brazil.

Topographical modifications of titanium (Ti) at the nanoscale level generate surfaces that regulate several signaling pathways and cellular functions, which may affect the process of osseointegration. Here, we investigated the participation of integrin αV in the osteogenic capacity of Ti with nanotopography. Machined titanium discs (untreated) were submitted to treatment with H SO /H O to produce the nanotopography (nanostructured). First, the greater osteogenic capacity of the nanotopography that increased osteoblast differentiation of mesenchymal stem cells compared with untreated topography was shown. Also, the nanostructured surface increased (regulation ≥ 1.9-fold) the gene expression of 6 integrins from a custom array plate utilized to evaluate the gene expression of 84 genes correlated with cell adhesion signaling pathway, including integrin αV, which is involved in osteoblast differentiation. By silencing integrin αV in MC3T3-E1 cells cultured on nanotopography, the impairment of osteoblast differentiation induced by this surface was observed. In conclusion, it was shown that nanotopography regulates the expression of several components of the cell adhesion signaling pathway and its higher osteogenic potential is, at least in part, due to its ability to upregulate the expression of integrin αV. Together with previous data that showed the participation of integrins α1, β1, and β3 in the nanotopography osseoinduction activity, we have uncovered the pivotal role of this family of membrane receptors in the osteogenic potential of this surface.
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http://dx.doi.org/10.1002/jcb.28930DOI Listing
October 2019

Effect of cell source and osteoblast differentiation on gene expression profiles of mesenchymal stem cells derived from bone marrow or adipose tissue.

J Cell Biochem 2019 Feb 11. Epub 2019 Feb 11.

Bone Research Lab, School of Dentistry of Ribeirão Preto, University of São Paulo, Ribeirão Preto, São Paulo, Brazil.

Mesenchymal stem cells (MSCs) have been used in therapies for bone tissue healing. The aim of this study was to investigate the effect of cell source and osteoblast differentiation on gene expression profiles of MSCs from bone marrow (BM-MSCs) or adipose tissue (AT-MSCs) to contribute for selecting a suitable cell population to be used in cell-based strategies for bone regeneration. BM-MSCs and AT-MSCs were cultured in growth medium to keep MSCs characteristics or in osteogenic medium to induce osteoblast differentiation (BM-OBs and AT-OBs). The transcriptomic analysis was performed by microarray covering the entire rat functional genome. It was observed that cells from bone marrow presented higher expression of genes related to osteogenesis, whereas cells from adipose tissue showed a higher expression of genes related to angiogenesis and adipocyte differentiation, irrespective of cell differentiation. By comparing cells from the same source, MSCs from both sources exhibited higher expression of genes involved in angiogenesis, osteoblast differentiation, and bone morphogenesis than osteoblasts. The clustering analysis showed that AT-OBs exhibited a gene expression profile closer to MSCs from both sources than BM-OBs, suggesting that BM-OBs were in a more advanced stage of differentiation. In conclusion, our results suggest that in cell-based therapies for bone regeneration AT-MSCs could be considered for angiogenic purposes, whereas BM-MSCs and osteoblasts differentiated from either source could be better for osteogenic approaches.
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http://dx.doi.org/10.1002/jcb.28463DOI Listing
February 2019

Effect of cell therapy with allogeneic osteoblasts on bone repair of rat calvaria defects.

Cytotherapy 2018 10 5;20(10):1267-1277. Epub 2018 Sep 5.

Cell Culture Laboratory, School of Dentistry of Ribeirão Preto, University of São Paulo, Ribeirão Preto, SP, Brazil. Electronic address:

Background Aims: Regenerative medicine strategies based on cell therapy are considered a promising approach to repair bone defects. The aims of this study were to evaluate the effect of subculturing on the osteogenic potential of osteoblasts derived from newborn rat calvaria and the effect of these osteoblasts on bone repair of rat calvaria defects.

Methods: Cells were obtained from 50 newborn rat calvaria, and primary osteoblasts (OB) were compared with first passage (OB-P1) in terms of osteogenic potential by assaying cell proliferation, alkaline phosphatase (ALP) activity, extracellular matrix mineralization and gene expression of the osteoblastic markers RUNX2, ALP, osteocalcin and bone sialoprotein. Then, 5-mm calvaria defects were created in 24 Wistar rats, and after 2 weeks, they were locally injected with 50 µL of phosphate-buffered saline containing either 5 × 10 osteoblasts (OB-P1, n = 12) or no cells (control, n = 12). Four weeks post-injection, the bone formation was evaluated by micro-computed tomography and histological analyses. Data were compared by analysis of variance, followed by the Student-Newman-Keuls's test or Student's t-test (P ≤ 0.05).

Results: OB-P1 showed high proliferation and ALP activity, and despite the reduced gene expression of osteoblastic markers and extracellular matrix mineralization compared with OB, they displayed osteogenic potential, being a good choice for injection into calvaria defects. The micro-tomographic and histological data showed that defects treated with OB-P1 presented higher bone formation compared with control defects.

Discussion: Our results indicate that cells derived from newborn rat calvaria retain osteoblastic characteristics after subculturing and that these osteoblasts stimulate bone repair in a rat calvaria defect model.
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http://dx.doi.org/10.1016/j.jcyt.2018.06.010DOI Listing
October 2018

Menopause transition promotes distinct modulation of mRNAs and miRNAs expression in calvaria and bone marrow osteoblastic cells.

Cell Biol Int 2018 Jan 17;42(1):12-24. Epub 2017 Jul 17.

Department of Morphology, Physiology and Basic Pathology, School of Dentistry of Ribeirão Preto, University of São Paulo, Ribeirão Preto, São Paulo, Brazil.

Investigation on functional genome research may contribute to the knowledge of functional roles of different mRNAs and miRNAs in bone cells of osteoporotic animals. Currently, few studies indicate the changes in gene modulation that osteoporosis causes in osteoblastic cells from different sites. Thus, the purpose of this investigation was to evaluate cell viability, alkaline phosphatase activity and modulation of mRNAs/miRNAs in osteoblastic cells from calvaria and bone marrow by means of microarray technology. Wistar female rats were divided in sham operated and ovariectomized groups. After 150 days of ovariectomy, cells were isolated from both sites to perform cell culture. Results showed that calvaria cells from ovariectomized rats had a decrease in viability when compared to control groups and to bone marrow cells from osteoporotic rats after 3 days. Alkaline phosphatase activity decreased in calvaria cells from ovariectomized rats whereas it was increased in bone marrow osteoblastic cells in the same group. Microarray data analysis showed 5447 differentially expressed mRNAs and 82 differentially expressed miRNAs in calvaria cells. The same way, 4399 mRNAs and 54 miRNAs were expressed in bone marrow cells. mRNAs associated with bone metabolism such as Anxa5, Sp7, Spp1, Notch1 were distinctively modulated in both sites, as well as miRNAs such as miR-350, miR-542-3p, miR-204-5p, and miR-30e-3p. The RNA species identified in this study could be further used as targets for treatment or prevention of osteoporosis.
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http://dx.doi.org/10.1002/cbin.10802DOI Listing
January 2018

Bioactive-glass ceramic with two crystalline phases (BioS-2P) for bone tissue engineering.

Biomed Mater 2017 Aug 9;12(4):045018. Epub 2017 Aug 9.

Cell Culture Laboratory, School of Dentistry of Ribeirão Preto, University of São Paulo, Ribeirão Preto, SP, Brazil.

We aimed to evaluate the in vitro osteogenic and osteoinductive potentials of BioS-2P and its ability to promote in vivo bone repair. To investigate osteogenic potential, UMR-106 osteoblastic cells were cultured on BioS-2P and Bioglass 45S5 discs in osteogenic medium. The osteoinductive potential was evaluated using mesenchymal stem cells (MSCs) cultured on BioS-2P, Bioglass 45S5 and polystyrene in non-osteogenic medium. Rat bone calvarial defects were implanted with BioS-2P scaffolds alone or seeded with MSCs. UMR-106 proliferation was similar for both materials, while alkaline phosphatase (ALP) activity and mineralization were higher for BioS-2P. Bone sialoprotein (BSP), RUNX2 and osteopontin (OPN) gene expression and BSP, OPN, ALP and RUNX2 protein expression were higher on BioS-2P. For MSCs, ALP activity was higher on Bioglass 45S5 than on BioS-2P and was lower on polystyrene. All genes were highly expressed on bioactive glasses compared to polystyrene. BioS-2P scaffolds promoted in vivo bone formation without differences in the morphometric parameters at 4, 8 and 12 weeks. After 8 weeks, the combination of BioS-2P with MSCs did not increase the quantity of new bone compared to the BioS-2P alone. To stimulate osteoblast activity, drive MSC differentiation and promote bone formation, BioS-2P is a good choice as a scaffold for bone tissue engineering.
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http://dx.doi.org/10.1088/1748-605X/aa768eDOI Listing
August 2017

Osteopontin expression in co-cultures of human squamous cell carcinoma-derived cells and osteoblastic cells and its effects on the neoplastic cell phenotype and osteoclastic activation.

Tumour Biol 2016 Sep 16;37(9):12371-12385. Epub 2016 Jun 16.

Cell Culture Laboratory, Department of Morphology, Physiology and Basic Pathology, School of Dentistry of Ribeirão Preto, University of São Paulo, Av. do Café, s/n, Monte Alegre, Ribeirão Preto, São Paulo, 14040-904, Brazil.

This study evaluated the temporal expression of osteopontin (OPN) in co-cultures of human osteoblastic cells (SAOS-2) and oral squamous cell carcinoma (OSCC)-derived cells (SCC9) and examined the effects of osteoblast-derived OPN on the neoplastic cell phenotype. Additionally, the effects of these co-cultures on subsequent osteoclastic activity were explored. SCC9 cells were plated on Transwell® membranes that were either coated or not coated with Matrigel and were then co-cultured with SAOS-2 cells during the peak of OPN expression. SCC9 cells exposed to OPN-silenced SAOS-2 cultures and SCC9 cells cultured alone served as controls. SCC9 cells were quantitatively evaluated for cell adhesion, proliferation, migration, and invasion into Matrigel. The impact of co-culturing SAOS-2 and SCC9 cells on the resorptive capacity of U-937-derived osteoclastic cells was also investigated. Furthermore, a reciprocal induction of SAOS-2 and SCC9 cells in terms of OPN expression over the co-culture interval was identified. SAOS-2-secreted OPN altered the SCC9 cell phenotype, leading to enhanced cell adhesion and proliferation and higher Matrigel invasion. This invasion was also enhanced, albeit to a lesser degree, by co-culture with OPN-silenced SAOS-2 cells. Cell migration was not affected. Co-culture with SAOS-2 cells-mainly during the period of peak OPN expression-promoted over-expression of IL-6 and IL-8 by SCC9 cells and enhanced the resorptive capacity of osteoclastic cells. Taken together, these results suggest that osteoblast-derived OPN affects the interactions among OSCC-derived epithelial cells, osteoblasts, and osteoclasts, which could contribute to the process of bone destruction during bone invasion by OSCC.
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http://dx.doi.org/10.1007/s13277-016-5104-0DOI Listing
September 2016

Poly(Vinylidene Fluoride-Trifluorethylene)/barium titanate membrane promotes de novo bone formation and may modulate gene expression in osteoporotic rat model.

J Mater Sci Mater Med 2016 Dec 21;27(12):180. Epub 2016 Oct 21.

Faculty of Dentistry of Ribeirão Preto, University of São Paulo-USP, Ribeirão Preto, São Paulo, Brazil.

Osteoporosis is a chronic disease that impairs proper bone remodeling. Guided bone regeneration is a surgical technique that improves bone defect in a particular region through new bone formation, using barrier materials (e.g. membranes) to protect the space adjacent to the bone defect. The polytetrafluorethylene membrane is widely used in guided bone regeneration, however, new membranes are being investigated. The purpose of this study was to evaluate the effect of P(VDFTrFE)/BT [poly(vinylidene fluoride-trifluoroethylene)/barium titanate] membrane on in vivo bone formation. Twenty-three Wistar rats were submitted to bilateral ovariectomy. Five animals were subjected to sham surgery. After 150 days, bone defects were created and filled with P(VDF-TrFE)/BT membrane or PTFE membrane (except for the sham and OVX groups). After 4 weeks, the animals were euthanized and calvaria samples were subjected to histomorphometric and computed microtomography analysis (microCT), besides real time polymerase chain reaction (real time PCR) to evaluate gene expression. The histomorphometric analysis showed that the animals that received the P(VDF-TrFE)/BT membrane presented morphometric parameters similar or even better compared to the animals that received the PTFE membrane. The comparison between groups showed that gene expression of RUNX2, BSP, OPN, OSX and RANKL were lower on P(VDF-TrFE)/BT membrane; the gene expression of ALP, OC, RANK and CTSK were similar and the gene expression of OPG, CALCR and MMP9 were higher when compared to PTFE. The results showed that the P(VDF-TrFE)/BT membrane favors bone formation, and therefore, may be considered a promising biomaterial to support bone repair in a situation of osteoporosis.
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http://dx.doi.org/10.1007/s10856-016-5799-xDOI Listing
December 2016

Aging impairs osteoblast differentiation of mesenchymal stem cells grown on titanium by favoring adipogenesis.

J Appl Oral Sci 2016 Jul-Aug;24(4):376-82

- Universidade de São Paulo, Faculdade de Odontologia de Ribeirão Preto, Laboratório de Cultura de Células, Ribeirão Preto, SP, Brasil.

Objective: We investigated the osteoblast and adipocyte differentiation of mesenchymal stem cells (MSCs) from young and aged rats cultured on Ti.

Material And Methods: Bone marrow MSCs derived from 1-month and 21-month rats were cultured on Ti discs under osteogenic conditions for periods of up to 21 days and osteoblast and adipocyte markers were evaluated.

Results: Cell proliferation, alkaline phosphatase (ALP) activity, extracellular matrix mineralization and gene expression of RUNX2, osterix, ALP, bone sialoprotein, osteopontin, and osteocalcin were reduced in cultures of 21-month rats compared with 1-month rats grown on Ti. Gene expression of PPAR-γ , adipocyte protein 2, and resistin and lipid accumulation were increased in cultures of 21-month rats compared with 1-month rats grown on the same conditions.

Conclusions: These results indicate that the lower osteogenic potential of MSCs derived from aged rats compared with young rats goes along with the higher adipogenic potential in cultures grown on Ti surface. This unbalance between osteoblast and adipocyte differentiation should be considered in dental implant therapy to the elderly population.
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http://dx.doi.org/10.1590/1678-775720160037DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4990367PMC
December 2016

Effect of collagen sponge and fibrin glue on bone repair.

J Appl Oral Sci 2015 Nov-Dec;23(6):623-8

Laboratório de Cultura de Células, Faculdade de Odontologia de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP, Brazil.

Unlabelled: The ability of hemostatic agents to promote bone repair has been investigated using in vitro and in vivo models but, up to now, the results are inconclusive. Objective In this context, the aim of this study was to compare the potential of bone repair of collagen sponge with fibrin glue in a rat calvarial defect model.

Material And Methods: Defects of 5 mm in diameter were created in rat calvariae and treated with either collagen sponge or fibrin glue; untreated defects were used as control. At 4 and 8 weeks, histological analysis and micro-CT-based histomorphometry were carried out and data were compared by two-way ANOVA followed by Student-Newman-Keuls test when appropriated (p≤0.05).

Results: Three-dimensional reconstructions showed increased bone formation in defects treated with either collagen sponge or fibrin glue compared with untreated defects, which was confirmed by the histological analysis. Morphometric parameters indicated the progression of bone formation from 4 to 8 weeks. Additionally, fibrin glue displayed slightly higher bone formation rate when compared with collagen sponge.

Conclusion: Our results have shown the benefits of using collagen sponge and fibrin glue to promote new bone formation in rat calvarial bone defects, the latter being discreetly more advantageous.
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http://dx.doi.org/10.1590/1678-775720150374DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4716700PMC
July 2016

Changes in actin and tubulin expression in osteogenic cells cultured on bioactive glass-based surfaces.

Microsc Res Tech 2015 Nov 5;78(11):1046-53. Epub 2015 Oct 5.

Cell Culture Laboratory, Faculty of Dentistry of Ribeirão Preto, University of São Paulo, Ribeirão Preto, SP, Brazil.

The present study evaluated whether the changes in the labeling pattern of cytoskeletal proteins in osteogenic cells cultured on bioactive glass-based materials are due to altered mRNA and protein levels. Primary rat-derived osteogenic cells were plated on Bioglass® 45S5, Biosilicate®, and borosilicate (bioinert control). The following parameters were assayed: (i) qualitative epifluorescence analysis of actin and tubulin; (ii) quantitative mRNA and protein expression for actin and tubulin by real-time PCR and ELISA, respectively, and (iii) qualitative analysis of cell morphology by scanning electron microscopy (SEM). At days 3 and 7, the cells grown on borosilicate showed typical actin and tubulin labeling patterns, whereas those on the bioactive materials showed roundish areas devoid of fluorescence signals. The cultures grown on bioactive materials showed significant changes in actin and tubulin mRNA expression that were not reflected in the corresponding protein levels. A positive correlation between the mRNA and protein as well as an association between epifluorescence imaging and quantitative data were only detected for the borosilicate. SEM imaging of the cultures on the bioactive surfaces revealed cells partly or totally coated with material aggregates, whose characteristics resembled the substrate topography. The culturing of osteogenic cells on Bioglass® 45S5 and Biosilicate® affect actin and tubulin mRNA expression but not the corresponding protein levels. Changes in the labeling pattern of these proteins should then be attributed, at least in part, to the presence of a physical barrier on the cell surface as a result of the material surface reactions, thus limiting fluorescence signals.
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http://dx.doi.org/10.1002/jemt.22583DOI Listing
November 2015

Association of mesenchymal stem cells and osteoblasts for bone repair.

Regen Med 2015 ;10(2):127-33

Cell Culture Laboratory, School of Dentistry of Ribeirão Preto, University of São Paulo; Av. do Café, s/n - 14040-904 - Ribeirão Preto, SP, Brazil.

Aim: We tested the hypothesis that the association of bone marrow mesenchymal stem cells (MSCs) and osteoblasts (OBs) optimize bone repair.

Materials & Methods: MSCs were cultured in growth or osteogenic medium and seeded into gelatin sponge prior to implantation. Defects were created into rat calvariae and implanted with gelatin sponge without cells, with MSCs, with OBs and with association of MSCs and OBs. Histological analysis and micro-CT-based histomorphometry were carried out after 4 weeks.

Results: Increased bone formation was observed in defects treated with cells and bone volume was greater in defects treated with either OBs or MSCs/OBs.

Conclusion: Association of MSCs and OBs did not increase the process of bone repair compared with cell-based therapy using either MSCs or OBs alone.
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http://dx.doi.org/10.2217/rme.14.75DOI Listing
January 2016

Bone tissue response to plasma-nitrided titanium implant surfaces.

J Appl Oral Sci 2015 Jan-Feb;23(1):9-13

Cell Culture Laboratory, School of Dentistry of Ribeirão Preto, University of São Paulo, Ribeirão Preto, SP, Brazil.

A current goal of dental implant research is the development of titanium (Ti) surfaces to improve osseointegration. Plasma nitriding treatments generate surfaces that favor osteoblast differentiation, a key event to the process of osteogenesis. Based on this, it is possible to hypothesize that plasma-nitrided Ti implants may positively impact osseointegration. Objective The aim of this study was to evaluate the in vivo bone response to Ti surfaces modified by plasma-nitriding treatments. Material and Methods Surface treatments consisted of 20% N2 and 80% H2, 450°C and 1.5 mbar during 1 h for planar and 3 h for hollow cathode. Untreated surface was used as control. Ten implants of each surface were placed into rabbit tibiae and 6 weeks post-implantation they were harvested for histological and histomorphometric analyses. Results Bone formation was observed in contact with all implants without statistically significant differences among the evaluated surfaces in terms of bone-to-implant contact, bone area between threads, and bone area within the mirror area. Conclusion Our results indicate that plasma nitriding treatments generate Ti implants that induce similar bone response to the untreated ones. Thus, as these treatments improve the physico-chemical properties of Ti without affecting its biocompatibility, they could be combined with modifications that favor bone formation in order to develop new implant surfaces.
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http://dx.doi.org/10.1590/1678-775720140376DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4349113PMC
July 2015

Clinical, Histological and Cellular Evaluation of Vertico-Lateral Maxillary Reconstruction Associating Alveolar Osteogenic Distraction and Fresh-Frozen Bone Allograft.

J Oral Implantol 2015 Jun 31;41(3):326-31. Epub 2013 Oct 31.

1  Department of Oral and Maxillofacial Surgery and Periodontology, School of Dentistry of Ribeirao Preto, University of Sao Paulo, Ribeirao Preto, SP, Brazil.

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http://dx.doi.org/10.1563/AAID-JOI-D-13-00102DOI Listing
June 2015

Cytotoxicity testing of methyl and ethyl 2-cyanoacrylate using direct contact assay on osteoblast cell cultures.

J Oral Maxillofac Surg 2013 Jan 26;71(1):35-41. Epub 2012 Oct 26.

Department of Morphology, Ribeirão Preto Dental School, São Paulo University, Ribeirão Preto, São Paulo, Brazil.

Purpose: Cyanoacrylate has been used as a commercial tissue adhesive. Recently, ethyl 2-cyanoacrylate has been suggested for the fixation of onlay autogenous bone graft. However, ethyl 2-cyanoacrylate must be biocompatible with bone tissue. This study evaluated the cytotoxicity of cyanoacrylate adhesives using a direct contact assay on human oral osteoblast cells.

Materials And Methods: Osteoblastic cells derived from human alveolar bone of the mandible were cultured with or without cyanoacrylate. The CA1 group contained methyl 2-cyanoacrylate, the CA2 group contained ethyl 2-cyanoacrylate, and the CA3 group did not contain cyanoacrylate (control). This study investigated cell morphology, which included the inhibition zone, and cytotoxicity was evaluated using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, which was measured as optical density. Data from the MTT assay were tested statistically using SigmaStat 3.5.

Results: Dead cells found around the CA1- and CA2-treated cells constituted inhibitory zones that varied from 200 to 500 μm. There was no inhibitory zone in the CA3 group. Cell viability evaluated by the MTT assay showed that the CA2 and CA3 optical densities were not significantly different. The CA1 optical densities differed significantly from the CA3 optical densities.

Conclusions: Within the limits of this study, the MTT method supported the conclusion that ethyl 2-cyanoacrylate is biocompatible according to a direct contact assay on human osteoblast cell cultures and suggests its usefulness in bone graft fixation.
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http://dx.doi.org/10.1016/j.joms.2012.09.002DOI Listing
January 2013

Characterization and in vitro evaluation of bacterial cellulose membranes functionalized with osteogenic growth peptide for bone tissue engineering.

J Mater Sci Mater Med 2012 Sep 24;23(9):2253-66. Epub 2012 May 24.

Institute of Chemistry, Universidade Estadual Paulista, (UNESP), Rua Francisco Degni 55, Araraquara, SP, 14800-900, Brazil.

The aim of this study was to characterize the physicochemical properties of bacterial cellulose (BC) membranes functionalized with osteogenic growth peptide (OGP) and its C-terminal pentapeptide OGP[10-14], and to evaluate in vitro osteoinductive potential in early osteogenesis, besides, to evaluate cytotoxic, genotoxic and/or mutagenic effects. Peptide incorporation into the BC membranes did not change the morphology of BC nanofibers and BC crystallinity pattern. The characterization was complemented by Raman scattering, swelling ratio and mechanical tests. In vitro assays demonstrated no cytotoxic, genotoxic or mutagenic effects for any of the studied BC membranes. Culture with osteogenic cells revealed no difference in cell morphology among all the membranes tested. Cell viability/proliferation, total protein content, alkaline phosphatase activity and mineralization assays indicated that BC-OGP membranes enabled the highest development of the osteoblastic phenotype in vitro. In conclusion, the negative results of cytotoxicity, genotoxicity and mutagenicity indicated that all the membranes can be employed for medical supplies, mainly in bone tissue engineering/regeneration, due to their osteoinductive properties.
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http://dx.doi.org/10.1007/s10856-012-4676-5DOI Listing
September 2012

Effects of type I collagen coating on titanium osseointegration: histomorphometric, cellular and molecular analyses.

Biomed Mater 2012 Jun 9;7(3):035007. Epub 2012 Mar 9.

Cell Culture Laboratory, School of Dentistry of Ribeirao Preto, University of Sao Paulo, Ribeirao Preto, SP, Brazil.

The investigation of titanium (Ti) surface modifications aiming to increase implant osseointegration is one of the most active research areas in dental implantology. This study was carried out to evaluate the benefits of coating Ti with type I collagen on the osseointegration of dental implants. Acid etched Ti implants (AETi), either untreated or coated with type I collagen (ColTi), were placed in dog mandibles for three and eight weeks for histomorphometric, cellular and molecular evaluations of bone tissue response. While the histological aspects were essentially the same with both implants being surrounded by lamellar bone trabeculae, histomorphometric analysis showed more abundant bone formation in ColTi, mainly at three weeks. Cellular evaluation showed that cells harvested from bone fragments in close contact with ColTi display lower proliferative capacity and higher alkaline phosphatase activity, phenotypic features associated with more differentiated osteoblasts. Confirming these findings, molecular analyses showed that ColTi implants up-regulates the expression of a panel of genes well known as osteoblast markers. Our results present a set of evidences that coating AETi with collagen fastens the osseointegration by stimulating bone formation at the cellular and molecular levels, making this combination of morphological and biochemical modification a promising approach to treat Ti surfaces.
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http://dx.doi.org/10.1088/1748-6041/7/3/035007DOI Listing
June 2012

Low-level laser therapy influences mouse odontoblast-like cell response in vitro.

Photomed Laser Surg 2012 Apr 29;30(4):206-13. Epub 2012 Feb 29.

School of Dentistry of Ribeirão Preto, Cell Culture Laboratory-Department of Morphology, Stomatology and Physiology, University of São Paulo, Ribeirão Preto, SP, Brazil.

Objective: The purpose of this study was to analyze the influence of two different irradiation times with 85 mW/cm(2) 830 nm laser on the behavior of mouse odontoblast-like cells.

Background Data: The use of low-level laser therapy (LLLT) to stimulate pulp tissue is a reality, but few reports relate odontoblastic responses to irradiation in in vitro models.

Methods: Odontoblast-like cells (MDPC-23) were cultivated and divided into three groups: control/nonirradiated (group 1); or irradiated with 85 mW/cm(2), 830 nm laser for 10 sec (0.8 J/cm(2)) (group 2); or for 50 sec (4.2 J/cm(2)) (group 3) with a wavelength of 830 nm. After 3, 7, and 10 days, it was analyzed: growth curve and cell viability, total protein content, alkaline phosphatase (ALP) activity, calcified nodules detection and quantification, collagen immunolocalization, vascular endothelial growth factor (VEGF) expression, and real-time polymerase chain reaction (PCR) for DMP1 gene. Data were analyzed by Kruskall-Wallis test (α=0.05).

Results: Cell growth was smaller in group 2 (p<0.01), whereas viability was similar in all groups and at all periods. Total protein content and ALP activity increased on the 10th day with 0.8 J/cm(2) (p<0.01), as well as the detection and quantification of mineralization nodules (p<0.05), collagen, and VEGF expression (p<0.01). The expression of DMP1 increased in all groups (p<0.05) compared with control at 3 days, except for 0.8 J/cm(2) at 3 days and control at 10 days.

Conclusions: LLLT influenced the behavior of odontoblast-like cells; the shorter time/smallest energy density promoted the expression of odontoblastic phenotype in a more significant way.
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http://dx.doi.org/10.1089/pho.2011.3087DOI Listing
April 2012

The influence of osteoblast differentiation stage on bone formation in autogenously implanted cell-based poly(lactide-co-glycolide) and calcium phosphate constructs.

Tissue Eng Part A 2012 May 10;18(9-10):999-1005. Epub 2012 Feb 10.

Cell Culture Laboratory, School of Dentistry of Ribeirão Preto, University of São Paulo, São Paulo, Brazil.

We tested the hypothesis that the osteoblast differentiation status of bone marrow stem cells (BMSCs) combined with a three-dimensional (3D) structure modulates bone formation when autogenously implanted. Rat BMSCs were aspirated, expanded, and seeded into a 3D composite of poly(lactide-co-glycolide) and calcium phosphate (PLGA/CaP) to produce a hybrid biomaterial. Calvarial defects were implanted with (1) scaffold without cells (SC/NC), (2) scaffold and BMSCs (SC+BMSC), (3) scaffold and osteoblasts differentiated for 7 days (SC+OB7), and (4) for 14 days (SC+OB14). After 4 weeks, there was more bone formation in groups combining scaffold and cells, SC+BMSC and SC+OB7. A nonsignificant higher amount of bone formation was observed on SC+OB14 compared with SC/NC. Additionally, more blood vessels were counted within all hybrid biomaterials, without differences among them, than into SC/NC. These findings provide evidences that the cell differentiation status affects in vivo bone formation in autogenously implanted cell-based constructs. Undifferentiated BMSCs or osteoblasts in early stage of differentiation combined with PLGA/CaP scaffold favored bone formation compared with plain scaffold and that one associated with more mature osteoblasts.
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http://dx.doi.org/10.1089/ten.TEA.2011.0405DOI Listing
May 2012

Oxidative nanopatterning of titanium surfaces promotes production and extracellular accumulation of osteopontin.

Braz Dent J 2011 ;22(3):179-84

Ribeirão Preto Dental School, USP - University of São Paulo, Ribeirão Preto, SP, Brazil.

The bone-biomaterial interface has been characterized by layers of afibrillar extracellular matrix (ECM) enriched in non collagenous proteins, including osteopontin (OPN), a multifunctional protein that in bone controls cell adhesion and ECM mineralization. Physical and chemical aspects of biomaterial surfaces have been demonstrated to affect cell-ECM-substrate interactions. The present paper described the ability of oxidative nanopatterning of titanium (Ti) surfaces to control extracellular OPN deposition in vitro. Ti discs were chemically treated by a mixture of H2SO4/H2O2 for either 30 min [Nano(30') Ti] or 4 h [Nano(4h) Ti]. Non-etched Ti discs were used as control. Primary osteogenic cells derived from newborn rat calvarial bone were plated on control and etched Ti and grown under osteogenic conditions up to 7 days. High resolution scanning electron microscopy revealed that treated Ti discs exhibited a nanoporous surface and that areas of larger nanopits were noticed only for Nano(4h) Ti. Large extracellular OPN accumulation were detectable only for Nano(4h) Ti, which was associated with OPN-positive cells with typical aspects of migrating cells. At day 3, quantitative results in terms of areas of OPN labeling were as follows: Nano(4h) Ti > Nano(30') Ti > Control Ti. In conclusion, chemically nanostructured Ti surfaces may support the enhancement of endogenous extracellular OPN deposition by osteogenic cells in vitro depending on the etching time, a finding that should be taken into consideration in strategies to biofunctionalize implant surfaces with molecules with cell adhesion capacity.
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http://dx.doi.org/10.1590/s0103-64402011000300001DOI Listing
January 2012

Effect of low-level laser therapy after rapid maxillary expansion on proliferation and differentiation of osteoblastic cells.

Lasers Med Sci 2012 Jul 13;27(4):777-83. Epub 2011 Aug 13.

Department of Pediatric Dentistry and Othodontic, School of Dentistry of Ribeirao Preto, University of Sao Paulo, Ribeirao Preto, SP, Brazil.

The aim of this study was to investigate the osteoblastic activity of cells derived from the midpalatal suture upon treatment with low-level laser therapy (LLLT) after rapid maxillary expansion (RME). A total of 30 rats were divided into two groups: experimental I (15 rats with RME without LLLT) and experimental II (15 rats with RME + LLLT). The rats were euthanized at 24 h, 48 h, and 7 days after RME, when the osteoblastic cells derived from the rats' midpalatal suture were explanted. These cells were cultured for periods up to 17 days, and then in vitro osteogenesis parameters and gene expression markers were evaluated. The cellular doubling time in the proliferative stage (3-7 days) was decreased in cultured cells harvested from the midpalatal suture at 24 and 48 h after RME + LLLT, as indicated by the increased growth of the cells in a culture. Alkaline phosphatase activity at days 7 and 14 of the culture was increased by LLLT in cells explanted from the midpalatal suture at 24 and 48 h and 7 days after RME. The mineralization at day 17 was increased by LLLT after RME in all periods. Results from the real-time PCR demonstrated that cells harvested from the LLLT after RME group showed higher levels of ALP, Runx2, osteocalcin, type I collagen, and bone sialoprotein mRNA than control cells. More pronounced effects on ALP activity, mineralization, and gene expression of bone markers were observed at 48 h after RME and LLLT. These results indicate that the LLLT applied after RME is able to increase the proliferation and the expression of an osteoblastic phenotype in cells derived from the midpalatal suture.
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http://dx.doi.org/10.1007/s10103-011-0968-0DOI Listing
July 2012

The effect of photosensitizer drugs and light stimulation on osteoblast growth.

Photomed Laser Surg 2011 Oct 13;29(10):699-705. Epub 2011 Jun 13.

Faculdade de Filosofia Ciências e Letras de Ribeirão Preto, Departamento de Química-Universidade de São Paulo, Ribeirão Preto, São Paulo, Brazil.

Objective: A promising new treatment in dentistry involves the photodynamic process, which utilizes a combination of two therapeutic agents, namely a photosensitizer drug and a low dose of visible light. We investigated the in vitro effect of low intensity laser irradiation (visible light irradiation at 670 nm) using doses ranging between 0.5 and 3 J/cm(2), combined with nanoemulsion (NE) of the photosensitizer drug aluminum phthalocyanine chloride (AlClPc), ranging from 0.5 to 5 μmol/L, on the growth and differentiation of osteoblastic cells isolated from rat bone marrow.

Background Data: Treatments using laser radiation of low intensity in dentistry are of great interest, especially in bucco-maxillofacial surgery and dental implantology, where this approach is currently employed to stimulate osteogenesis. In the presence of oxygen, the combination of these agents could induce cellular biostimulation, via an efficient noninvasive method.

Methods: We have done the colorimetric MTT assay, collagen content, total protein content, ALP activity and bone-like nodule formation.

Results: We observed that an increased number of viable cells was evident upon application of a laser dosage equal to 0.5 J/cm(2) when combined with 0.5 μmol/L of AlClPc/NE, suggesting cellular biostimulation.

Conclusions: It was possible to demonstrate that low intensity laser irradiation can play an important role in promoting biostimulation of osteoblast cell cultures. Therefore, whether biostimulation of osteoblastic cell cultures by photodynamic therapy or the cytotoxic effect of this therapy occurs only depends upon the light dose, and the results can be completely reversed.
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http://dx.doi.org/10.1089/pho.2010.2929DOI Listing
October 2011

Effects of a novel calcium aluminate cement on the early events of the progression of osteogenic cell cultures.

Braz Dent J 2011 ;22(2):99-104

Ribeirão Preto Dental School, University of São Paulo, SP, Brazil.

The present study evaluated the progression of osteogenic cell cultures exposed to a novel calcium aluminate cement (CAC+) in comparison with the gold standard mineral trioxide aggregate (MTA). Cells were enzimatically isolated from newborn rat calvarial bone, plated on glass coverslips containing either CAC+ or a control MTA samples in the center, and grown under standard osteogenic conditions. Over the 10-day culture period, roundening of sample edges was clearly noticed only for MTA group. Although both cements supported osteogenic cell adhesion, spreading, and proliferation, CAC+-exposed cultures showed significantly higher values in terms of total cell number at days 3 and 7, and total protein content and alkaline phosphatase activity at day 10. The present in vitro results indicate that the exposure to CAC+ supports a higher differentiation of osteogenic cells compared with the ones exposed to MTA. Further experimental studies should consider CAC+ as a potential alternative to MTA when the repair of mineralized tissues is one of the desired outcomes in endodontic therapy.
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http://dx.doi.org/10.1590/s0103-64402011000200002DOI Listing
September 2011