CA-Markov prediction modeling for the assessment of land use/land cover change in two sub-basins of the Tocantins-Araguaia River Basin.

Due to the anthropogenic pressures of expansion areas for livestock and agricultural production in the Brazilian Cerrado, it is of paramount importance to understand the dynamics of land use/land cover (LULC) changes in this region. Thus, we investigated LULC changes in two sub-basins of the Tocantins-Araguaia River basin from 1997 to 2015 and consequently projected future changes for the timespan between 2030 and 2050. The Formoso sub-basin experienced significant expansion of agricultural and pasture areas, whereas the Sono sub-basin limited farmland expansion (more stable native vegetation) due to substantial protected areas, trends that were also observed for future projections (2030 and 2050). Pastureland in the Formoso sub-basin increased by 5.8%, while the Sono sub-basin saw significant gains in cultivated land, according to change detection analyses during the 1997-2015 period. High stability probabilities of no change (> 70%) for grassland areas in the Sono River sub-basin and pasturelands in the Formoso River sub-basin were computed. The CA-Markov model demonstrated a high consistency level with actual LULC classes for both sub-basins, as indicated by an overall Kappa coefficient above 0.8. Future projections for 2030 and 2050 show a substantial expansion of agriculture and pasture in both sub-basins, driven by specific factors such as soil organic carbon stocks, distance from rural settlements, and proximity to rivers. Short- and mid-term simulations indicate substantial expansion of agriculture and pasture in both basins, with potential adverse impacts on water erosion. Consequently, developing policies for soil management and sustainable land use planning is essential for agroecosystem sustainability, promoting a balanced approach to economic development while addressing climate change and anthropogenic challenges.

Participation of extracellular signal-regulated kinases 1/2 in osteoblast and adipocyte differentiation of mesenchymal stem cells grown on titanium surfaces.

Osteoblasts and adipocytes coexist in the implantation site and affect the process of titanium (Ti) osseointegration. As extracellular signal-regulated kinases 1/2 (ERK1/2) are involved in osteogenesis and adipogenesis, the aim of our study was to investigate if the effects of Ti surface topography on osteoblast and adipocyte differentiation are modulated by ERK1/2. The experiments were conducted based on the effect of the ERK1/2 inhibitor, PD98059, on mesenchymal stem cells (MSCs) grown under osteogenic and adipogenic conditions on Ti with nanotopography (Ti-Nano) or on machined Ti (Ti-Machined). The results showed that, in general, ERK1/2 inhibition favored osteoblast and adipocyte differentiation of MSCs grown on Ti-Machined. In MSCs grown on Ti-Nano, ERK1/2 inhibition upregulated the expression of alkaline phosphatase and osteocalcin and reduced extracellular matrix mineralization. In terms of adipocyte differentiation, ERK1/2 inhibition elicited similar MSC responses to Ti-Nano and Ti-Machined, upregulating gene expression of adipocyte markers without affecting lipid accumulation. Our results indicate that, under osteogenic and adipogenic conditions, the responses of MSCs to Ti surface topography in terms of osteogenesis and adipogenesis are dependent on ERK1/2. Thus, a precise modulation of ERK1/2 expression and activity induced by surface topography could be a good strategy to drive the process of implant osseointegration.

Mesenchymal Stem Cells Repress Osteoblast Differentiation Under Osteogenic-Inducing Conditions.

This study was designed to investigate the influence of mesenchymal stem cells (MSCs) on osteoblast (OB) differentiation. Rat bone marrow MSCs were cultured either in growth medium that maintained a MSC phenotype or in osteogenic medium that induced differentiation into OBs. Then, cells were grown in two different culture conditions: indirect co-culture of MSCs and OBs and OBs cultured in MSC-conditioned medium. As a control culture condition, OBs were grown in osteogenic medium without the influence of MSCs. We evaluated cell proliferation, the gene expression of key bone markers, alkaline phosphatase (ALP) activity, bone sialoprotein (BSP) expression, and extracellular matrix mineralization. The results showed that, regardless of whether OBs were indirectly co-cultured with MSCs or cultured in MSC-conditioned medium, MSCs repressed OB differentiation, as evidenced by the downregulation of all evaluated bone marker genes, decreased ALP activity, inhibition of BSP protein expression, and reduced extracellular matrix mineralization. Taken together, these results indicate that despite the key role of both MSCs and OBs in the osteogenic process, the repressive effect of MSCs on OB differentiation in an osteogenic environment may represent a barrier to the strategy of using them together in cell-based therapies to induce bone repair.

Influence of periodontal tissue thickness on buccal plate remodelling on immediate implants with xenograft.

AIM: To evaluate the influence of gingival thickness and bone grafting on buccal bone plate remodelling after immediate implant placement in sockets with thin buccal bone, using a flapless approach. MATERIALS AND METHODS: The gingiva of eight dogs was thinned at one side of the mandible, mandibular premolars were extracted without flaps, and four implants were installed on each side at 1.5 mm from the buccal bone. The sites were randomly assigned into: TG (test group) = thin gingiva; TG + GM (TG with grafting material); CG (control group) = normal gingiva; and CG + GM (CG with grafting material). After 12 weeks the dogs were sacrificed and the samples were processed for histological analysis. RESULTS: All animals exhibited a thin buccal bone initially. In all the experimental groups the buccal gap was filled with newly formed bone and the buccal bone level was slightly apical to the implant shoulder. There were no statistically significant differences among the groups for the histomorphometric parameters. CONCLUSIONS: The thickness of the buccal bone was a fundamental factor in buccal bone plate resorption, even with flapless implantation. The gingival thickness or the addition of a biomaterial in the gap did not influence the results.

Clinical, radiographic, and histological analyses of calcium phosphate cement as filling material in maxillary sinus lift surgery.

BACKGROUND: The installation of dental implants in the posterior maxilla is often faced with resorbed alveolar processes, resulting from a combination of pneumatization of the maxillary sinus, the effects of periodontal disease, and physiological bone resorption. The sinus lift surgery has been practiced since 1980 with the aim to increase bone height in this region for an implant supported prosthetic rehabilitation, and various filling materials have been used for such. OBJECTIVES: This study aimed to clinically, radiographically, and histologically evaluate a preparation of calcium phosphate cement (Bone Source(®), BS) used as filling material in maxillary sinus elevation surgery. METHODS: Ten patients were operated requiring maxillary sinus graft for future placement of osseointegrated implants. After a period ranging from 9 to 16 months, a clinical evaluation and biopsy of the grafted area in the region adjacent to the axis of the implant to be inserted were performed. RESULTS: Clinically and radiographically, no evidence of resorption/substitution of BS was noticed. Although no patients have had postoperative complications and the material presented fully biocompatible characteristics with woven bone in intimate contact with BS, it was not possible to place any implants due to minimal bone formation and friability of the material. CONCLUSION: It was concluded that despite the osteoconductive capacity of BS, this conventional calcium phosphate preparation does not support sufficient amount of new bone formation that could allow its use as filling material for maxillary sinus floor lift and subsequent dental implant placement.

Nanotopography directs mesenchymal stem cells to osteoblast lineage through regulation of microRNA-SMAD-BMP-2 circuit.

The aim of this study was to investigate if chemically produced nanotopography on titanium (Ti) surface induces osteoblast differentiation of cultured human bone marrow mesenchymal stem cells (hMSCs) by regulating the expression of microRNAs (miRs). It was demonstrated that Ti with nanotopography induces osteoblast differentiation of hMSCs as evidenced by upregulation of osteoblast specific markers compared with untreated (control) Ti at day 4. At this time-point, miR-sequencing analysis revealed that 20 miRs were upregulated (>twofold) while 20 miRs were downregulated (>threefold) in hMSCs grown on Ti with nanotopography compared with control Ti. Three miRs, namely miR-4448, -4708, and -4773, which were significantly downregulated (>fivefold) by Ti with nanotopography affect osteoblast differentiation of hMSCs. These miRs directly target SMAD1 and SMAD4, both key transducers of the bone morphogenetic protein 2 (BMP-2) osteogenic signal, which were upregulated by Ti with nanotopography. Overexpression of miR-4448, -4708, and 4773 in MC3T3-E1 pre-osteoblasts noticeably inhibited gene and protein expression of SMAD1 and SMAD4 and therefore repressed the gene expression of key bone markers. Additionally, it was observed that the treatment with BMP-2 displayed a higher osteogenic effect on MC3T3-E1 cells grown on Ti with nanotopography compared with control Ti, suggesting that the BMP-2 signaling pathway was more effective on this surface. Taken together, these results indicate that a complex regulatory network involving a miR-SMAD-BMP-2 circuit governs the osteoblast differentiation induced by Ti with nanotopography. J. Cell. Physiol. 229: 1690-1696, 2014. © 2014 Wiley Periodicals, Inc.

Autogenous bone combined with anorganic bovine bone for maxillary sinus augmentation: analysis of the osteogenic potential of cells derived from the donor and the grafted sites.

OBJECTIVES: This study aimed to comparatively evaluate the in vitro osteogenic potential of cells obtained from the mandibular ramus (MR, autogenous bone donor site) and from the maxillary sinus (MS) bone grafted with a mixture of anorganic bovine bone (ABB) and MR prior to titanium implant placement (MS, grafted implant site). MATERIAL AND METHODS: Cells were obtained from three patients subjected to MS floor augmentation with a 1 : 1 mixture of ABB (GenOx Inorg(®) ) and MR. At the time of the sinus lift procedure and after 8 months, prior to implant placement, bone fragments were taken from MR and MS, respectively, and subjected to trypsin-collagenase digestion for primary cell culturing. Subcultured cells were grown under osteogenic condition for up to 21 days and assayed for proliferation/viability, osteoblast marker mRNA levels, alkaline phosphatase (ALP) activity and calcium content/Alizarin red staining. ALP activity was also determined in primary explant cultures exposed to GenOx Inorg(®) (1 : 1 with MR) for 7 days. Data were compared using either the Mann-Whitney U-test or the Kruskal-Wallis test. RESULTS: MS cultures exhibited a significantly lower osteogenic potential compared with MR cultures, with a progressive increase in cell proliferation together with a decrease in osteoblast markers, reduced ALP activity and calcium content. Exposure of MR-derived primary cultures to GenOx Inorg(®) inhibited ALP activity. CONCLUSION: These results suggest that the use of GenOx Inorg(®) in combination with MR fragments for MS floor augmentation inhibits the osteoblast cell differentiation at the implant site in the long term.

Functionalization with Polyphenols of a Nano-Textured Ti Surface through a High-Amino Acid Medium: A Chemical-Physical and Biological Characterization.

The study aimed to identify an effective mechanism of adsorption of polyphenols on a nano-textured Ti surface and to evaluate the osteogenic differentiation on it. The source of polyphenols was a natural extract from red grape pomace. A chemical etching was used to form an oxide layer with a nanoscale texture on Ti; this layer is hydrophilic, but without hydroxyl groups with high acidic-basic chemical reactivity. The samples were characterized by electron and fluorescence microscopies, UV-Vis spectroscopy, contact angle measurements, zeta potential titration curves, and Folin-Ciocâlteu test. The presence of an adsorbed layer of polyphenols on the functionalized surface, maintaining redox ability, was confirmed by several tests. Consistent with the surface features, the adsorption was maximized by dissolving the extract in a high-amino acid medium, with respect to an inorganic solution, exploiting the high affinity of amino acids for polyphenols and for porous titanium surfaces. The osteogenic differentiation was assessed on an osteoblastic cell line by immunofluorescence, cell viability, expression of key osteoblast markers, and extracellular matrix mineralization. The surfaces functionalized with the extract diluted in the range 1 × 10-5-1 mg/mL resulted in having a greater osteogenic activity for the highest concentration, with lower values of cell viability; higher expression of alkaline phosphatase, bone sialoprotein, and collagen; and lower levels of osteopontin. In conclusion, the functionalization of a nano-textured Ti surface with polyphenols can potentially favor the osteogenic activity of osseointegrated implants.

Efficacy of a bioactive glass-ceramic (Biosilicate) in the maintenance of alveolar ridges and in osseointegration of titanium implants.

OBJECTIVES: The aims of this research were to evaluate the efficacy of a bioactive glass-ceramic (Biosilicate) and a bioactive glass (Biogran) placed in dental sockets in the maintenance of alveolar ridge and in the osseointegration of Ti implants. MATERIAL AND METHODS: Six dogs had their low premolars extracted and the sockets were implanted with Biosilicate, Biogran particles, or left untreated. After the extractions, measurements of width and height on the alveolar ridge were taken. After 12 weeks a new surgery was performed to take the final ridge measurements and to insert bilaterally three Ti implants in biomaterial-implanted and control sites. Eight weeks post-Ti implant placement block biopsies were processed for histological and histomorphometric analysis. The percentages of bone-implant contact (BIC), of mineralized bone area between threads (BABT), and of mineralized bone area within the mirror area (BAMA) were determined. RESULTS: The presence of Biosilicate or Biogran particles preserved alveolar ridge height without affecting its width. No significant differences in terms of BIC, BAMA, and BABT values were detected among Biosilicate, Biogran, and the non-implanted group. CONCLUSIONS: The results of the present study indicate that filling of sockets with either Biosilicate or Biogran particles preserves alveolar bone ridge height and allows osseointegration of Ti implants.

Biopolymer-based membranes associated with osteogenic growth peptide for guided bone regeneration.

Barrier membranes for guided bone regeneration (GBR) mainly promote mechanical maintenance of bone defect space and induce osteopromotion. Additionally, biopolymer-based membranes may provide greater bioactivity and biocompatibility due to their similarity to extracellular matrix (ECM). In this study, biopolymers-based membranes from bacterial cellulose (BC) and collagen (COL) associated with osteogenic growth peptide (OGP(10-14)) were evaluated to determine in vitro osteoinductive potential in early osteogenesis; moreover, histological study was performed to evaluate the BC-COL OGP(10-14) membranes on bone healing after GBR in noncritical defects in rat femur. The results showed that the BC-COL and BC-COL OGP(10-14) membranes promoted cell proliferation and alkaline phosphatase activity in osteoblastic cell cultures. However, ECM mineralization was similar between cultures grown on BC OGP(10-14) and BC-COL OGP(10-14) membranes. In vivo results showed that all the membranes tested, including the peptide-free BC membrane, promoted better bone regeneration than control group. Furthermore, the BC-COL OGP(10-14) membranes induced higher radiographic density in the repaired bone than the other groups at 1, 4 and 16 weeks. Histomorphometric analyses revealed that the BC-COL OGP(10-14) induced higher percentage of bone tissue in the repaired area at 2 and 4 weeks than others membranes. In general, these biopolymer-based membranes might be potential candidates for bone regeneration applications.

The effect of collagen coating on titanium with nanotopography on in vitro osteogenesis.

Several studies have shown the positive effects of Ti either with nanotopography or coated with collagen on osteoblast differentiation. Thus, we hypothesized that the association of nanotopography with collagen may increase the in vitro osteogenesis on Ti surface. Ti discs with nanotopography with or without collagen coating were characterized by scanning electron microscopy and atomic force microscopy. Rat calvaria-derived osteoblastic cells were cultured on both Ti surfaces for up to 14 days and the following parameters were evaluated: cell proliferation, alkaline phosphatase (ALP) activity, extracellular matrix mineralization, protein expression of bone sialoprotein (BSP) and osteopontin (OPN), and gene expression of collagen type 1a (Coll1a), runt-related transcription factor 2 (Runx2), osterix (OSX), osteocalcin (OC), Ki67, Survivin, and Bcl2-associated X protein (BAX). Surface characterization evidenced that collagen coating did not alter the nanotopography. Collagen coating increased cell proliferation, ALP activity, extracellular matrix mineralization, and Coll1a, OSX, OC, and BAX gene expression. Also, OPN and BSP proteins were strongly detected in cultures grown on both Ti surfaces. In conclusion, our results showed that the combination of nanotopography with collagen coating stimulates the early, intermediate, and final events of the in vitro osteogenesis and may be considered a potential approach to promote osseointegration of Ti implants. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 2783-2788, 2017.

Bioactive glass-based surfaces induce differential gene expression profiling of osteoblasts.

The ability of Biosilicate® with two crystalline phases (BioS-2P) to drive osteoblast differentiation encourages the investigation of the cellular mechanisms involved in this process. Then, the aim of our study was to analyze the large-scale gene expression of osteoblasts grown on BioS-2P compared with Bioglass® 45S5 (45S5). Osteoblasts differentiated from rat bone marrow mesenchymal stem cells were cultured under osteogenic conditions on BioS-2P, 45S5 and polystyrene (control). After 10 days, the expression of 23,794 genes was analyzed using mRNA Sequencing and the data were validated by real-time PCR. The BioS-2P exhibited 5 genes upregulated and 3 downregulated compared with 45S5. Compared with control, BioS-2P upregulated 15 and downregulated 11 genes, while 45S5 upregulated 25 and downregulated 21 genes. Eight genes were commonly upregulated and 4 downregulated by both bioactive glasses. In conclusion, our results demonstrated that bioactive glasses affect the gene expression profiling of osteoblasts. Most of the regulated genes by both BioS-2P and 45S5 are associated with the process of mineralization highlighting their osteostimulation property that is, at least in part, derived from the ability to modulate the intracellular machinery to promote osteoblast genotype expression. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 419-423, 2017.

In vitro biocompatibility of a novel membrane of the composite poly(vinylidene-trifluoroethylene)/barium titanate.

This study was aimed at investigating the in vitro biocompatibility of a novel membrane of the composite poly(vinylidene-trifluoroethylene)/barium titanate (P(VDF-TrFE)/BT). Osteoblastic cells were obtained from human alveolar bone fragments and cultured under standard osteogenic condition until subconfluence. First passaged cells were cultured on P(VDF-TrFE)/BT and expanded polytetrafluoroethylene (e-PTFE--control) membranes in 24-well plates. Cell adhesion and spreading were evaluated at 30 min, and 4 and 24 h. For proliferation assay, cells were cultured for 1, 7, and 10 days. Cell viability was detected by trypan blue at 7 and 10 days. Total protein content and alkaline phosphatase (ALP) activity were measured at 7, 14, and 21 days. Cultures were stained with Alizarin red at 21 days, for detection of mineralized matrix. Data were compared by ANOVA and Student t test. Cell attachment (p = 0.001), cell number (p = 0.001), and ALP activity (p = 0.0001) were greater on P(VDF-TrFE)/BT. Additionally, doubling time was greater on P(VDF-TrFE)/BT (p = 0.03), indicating a decreased proliferation rate. Bone-like nodule formation took place only on P(VDF-TrFE)/BT. The present results showed that both membranes are biocompatible. However, P(VDF-TrFE)/BT presented a better in vitro biocompatibility and allowed bone-like nodule formation. Therefore, P(VDF-TrFE)/BT could be an alternative membrane to be used in guided tissue regeneration.

Effect of Surface Nanotopography on Bone Response to Titanium Implant.

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.

Histomorphometric analysis of the bone-implant contact obtained with 4 different implant surface treatments placed side by side in the dog mandible.

PURPOSE: The different implant systems available today present several types of surface treatment, with the aim of optimization of bone-implant contact. This study compared 4 different types of implant surfaces. MATERIALS AND METHODS: The first, second, third, and fourth mandibular premolars were extracted from 5 young adult mongrel male dogs. Ninety days after removal, four 3.75-mm-diameter, 10-mm-long screw-type implants (Paragon) were placed with different surface treatments in mandibular hemiarches. The dogs received 2 implants of each of the following surface treatments: smooth (machined), titanium plasma spray (TPS), hydroxyapatite coating (HA), and sandblasting with soluble particles (SBM). The implants were maintained unloaded for 90 days. After this period, the animals were sacrificed, and the hemimandibles were extracted and histologically processed to obtain non-decalcified sections. Two longitudinal ground sections were made for each implant and analyzed under light microscopy coupled to a computerized system for histomorphometry. RESULTS: The following means were obtained for bone-implant contact percentage: machined = 41.7%, TPS = 48.9%, HA = 57.9%, and SBM = 68.5%. DISCUSSION: The means for all treatments that added roughness to the implant surface were numerically superior to the mean found for the machined surface. However, this difference was statistically significant only between groups SBM and machined (Tukey test, P < .05). CONCLUSIONS: The SBM-treated surface provided a greater bone-implant contact than a machined surface after 90 days without loading in this model.

Comparative study of enamel matrix derivative with or without GTR in the treatment of class II furcation lesions in dogs.

Chronic Class II furcation lesions were created in four dogs. After 21 days, group I remained as a control, group 2 was treated with membranes and enamel matrix derivative (EMD), and group 3 received EMD alone. Healing in group 1 was characterized by a long junctional epithelium and discrete bone formation; group 2 showed reduced bone formation; and group 3 showed significant bone regeneration (area of new bone = 67.36%+/-3.93%; distance from furcation roof to bone crest = 0.57+/-0.15 mm). The EMD led to significant regeneration of the furcation lesions, and the association with membranes was detrimental.

The effect of plasma-nitrided titanium surfaces on osteoblastic cell adhesion, proliferation, and differentiation.

In this study, we evaluated the effect of new plasma-nitrided Ti surfaces on the progression of osteoblast cultures, including cell adhesion, proliferation and differentiation. Ti surfaces were treated using two plasma-nitriding protocols, hollow cathode for 3 h (HC 3 h) and 1 h (HC 1 h) and planar for 1 h. Untreated Ti surfaces were used as control. Cells derived from human alveolar and rat calvarial bones were cultured on Ti surfaces for periods of up to 14 days and the following parameters were evaluated: cell morphology, adhesion, spreading and proliferation, alkaline phosphatase (ALP) activity, extracellular matrix mineralization, and gene expression of key osteoblast markers. Plasma-nitriding treatments resulted in Ti surfaces with distinct physicochemical characteristics. The cell adhesion and ALP activity were higher on plasma-nitrided Ti surfaces compared with untreated one, whereas cell proliferation and extracellular matrix mineralization were not affected by the treatments. In addition, the plasma-nitrided Ti surfaces increased the ALP, reduced the osteocalcin and did not affect the Runx2 gene expression. We have shown that HC 3 h and planar Ti surfaces slightly favored the osteoblast differentiation process, and then these surfaces should be considered for further investigation using preclinical models.

Progression of osteogenic cell cultures grown on microtopographic titanium coated with calcium phosphate and functionalized with a type I collagen-derived peptide.

BACKGROUND: The functionalization of metallic surfaces aims at promoting the cellular response at the biomaterial-tissue interface. This study investigates the effects of the functionalization of titanium (Ti) microtopography with a calcium phosphate (CaP) coating with and without peptide 15 (P-15), a synthetic peptide analog of the cell-binding domain of collagen I, on the in vitro progression of osteogenic cells. METHODS: Sandblasting and acid etching (SBAE; control) Ti microtopography was coated with CaP, enabling the loading of two concentrations of P-15: 20 or 200 µg/mL. A machined Ti was also examined. Rat calvarial osteogenic cells were cultured on Ti disks with the surfaces mentioned above for periods up to 21 days (n = 180 per group). RESULTS: CaP coating exhibited a submicron-scale needle-shaped structure. Although all surfaces were hydrophobic at time zero, functionalization increased hydrophilicity at equilibrium. Microtopographies exhibited a lower proportion of well-spread cells at 4 hours of culture and cells with long cytoplasmic extensions at day 3; modified SBAE supported higher cell viability and larger extracellular osteopontin (OPN) accumulation. For SBAE and modified SBAE, real-time polymerase chain reaction showed the following results: 1) lower levels for runt-related transcription factor 2 at 7 days and for bone sialoprotein at days 7 and 10 as well as higher OPN levels at days 7 and 10 compared to machined Ti; and 2) higher alkaline phosphatase levels at day 10 compared to day 7. At 14 and 21 days, modified SBAE supported higher proportions of red-dye-stained areas (calcium content). CONCLUSION: Addition of a CaP coating to SBAE Ti by itself may affect key events of in vitro osteogenesis, ultimately resulting in enhanced matrix mineralization; additional P-15 functionalization has only limited synergistic effects.

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

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.

Bone tissue, cellular, and molecular responses to titanium implants treated by anodic spark deposition.

A myriad of titanium (Ti) surface modifications has been proposed to hasten the osseointegration. In this context, the aim of this study was to perform histomorphometric, cellular, and molecular analyses of the bone tissue grown in close contact with Ti implants treated by anodic spark deposition (ASD-AK). Acid-etched (AE) Ti implants either untreated or submitted to ASD-AK were placed into dog mandibles and retrieved at 3 and 8 weeks. It was noticed that both implants, AE and ASD-AK, were osseointegrated at 3 and 8 weeks. Histomorphometric analysis showed differences between treatments only for bone-to-implant contact, being higher on AE implants. Although not backed by histomorphometric results, gene expression of key bone markers was higher for bone grown in close contact with ASD-AK and for cells harvested from these fragments and cultured until subconfluence. Cell proliferation at days 7 and 10 and alkaline phosphatase activity at day 10 was higher on AE surfaces. No statistical significant difference was noticed for extracellular matrix mineralization at 17 days. Our results have shown that the Ti fixtures treated by ASD-AK allowed in vivo osseointegration and induced higher expression of key markers of osteoblast phenotype, suggesting that this surface treatment could be considered to produce implants for clinical applications.