Adjacent Bone Tissue Research Articles

Hip Implant Design With Three-Dimensional Porous Architecture of Optimized Graded Density

Even in a well-functioning total hip replacement, significant peri-implant bone resorption can occur secondary to stress shielding. Stress shielding is caused by an undesired mismatch of elastic modulus between the stiffer implant and the adjacent bone tissue. To address this problem, we present here a microarchitected hip implant that consists of a three-dimensional (3D) graded lattice material with properties that are mechanically biocompatible with those of the femoral bone. Asymptotic homogenization (AH) is used to numerically determine the mechanical and fatigue properties of the implant, and a gradient-free scheme of topology optimization is used to find the optimized relative density distribution of the porous implant under multiple constraints dictated by implant micromotion, pore size, porosity, and minimum manufacturable thickness of the cell elements. Obtained for a 38-year-old patient femur, bone resorption is assessed by the difference in strain energy between the implanted bone and the intact bone in the postoperative conditions. The numerical results suggest that bone loss for the optimized porous implant is only 42% of that of a fully solid implant, here taken as benchmark, and 79% of that of a porous implant with uniform density. The architected hip implant presented in this work shows clinical promise in reducing bone loss while preventing implant micromotion, thereby contributing to reduce the risk of periprosthetic fracture and the probability of revision surgery.

Expression of circ_001569 is upregulated in osteosarcoma and promotes cell proliferation and cisplatin resistance by activating the Wnt/β-catenin signaling pathway.

Circular RNAs (circRNAs), a type of non-coding RNAs derived from back-splicing, have been reported to function as gene expression regulators involved in tumor development of multiple human tumors. However, the clinical significance and underlying molecular mechanisms of circ_001569 in osteosarcoma still be unknown. In the study, we found that circ_001569 expression was significantly overexpressed in osteosarcoma tissues compared with adjacent noncancerous bone tissues. Higher circ_001569 expression significantly correlated with distant metastasis and advanced tumor stage of osteosarcoma patients. Gain-function and loss-function assays showed that circ_001569 knockdown significantly inhibited osteosarcoma cell proliferation and cell colon formation capacities. Moreover, upregulation of circ_001569 significantly promoted osteosarcoma cell resistance to cisplatin by activating Wnt/β-catenin signaling pathway. Thus, these results indicated that circ_001569 represented a novel potentially therapeutic target of osteosarcoma.

Hesperidin methyl chalcone alleviates spinal tuberculosis in New Zealand white rabbits by suppressing immune responses

Objective: Spinal tuberculosis (ST) refers to tuberculosis resulted from infections of Mycobacterium tuberculosis (Mtb) in the spinal cord. Hesperidin methyl chalcone (HMC) is a flavonoid derivative from citrus fruits with anti-inflammatory properties. We aimed to investigate the efficacy of HMC in treating ST in New Zealand white rabbit model. Design and Setting: Rabbits were infected in the sixth lumbar vertebral bodies with or without Mtb strain H37Rv followed by treatments with HMC. Outcome Measures: 10 weeks post treatments, the adjacent vertebral tissues were examined by hematoxylin–eosin staining. The expression levels of transcription factor κB (NF-κB) p65 and monocyte chemoattractant protein-1 (MCP-1/CCL2) in lymphocytes were determined using reverse transcription quantitative real-time PCR (RT-qPCR), Western blot and enzyme-linked immunosorbent assays (ELISA). The serum levels of interleukin (IL)-2, IL-4, IL-10 as well as interferon (IFN)-γ were also assessed using ELISA. Western blot was used to determine the effects of HMC on the phosphorylation of IKKα/β, p65, and IκBα in the signal transduction of NF-κB pathways. Results: HMC significantly attenuated the granulation in adjacent vertebral bone tissues. The expression of p65, IL-4, IL-10, and MCP-1 was reduced. The NF-κB pathway was suppressed, in which the phosphorylation of IκBα, IKKα/β, and p65 was inhibited whereas the relative level of IκBα was increased. Conclusion: HMC could serve as a therapeutic option to effectively inhibit granulomas formation through downregulation of MCP-1, IL-4, IL-10, and NF-κB in the treatment of ST.

Optimization of Monoenergetic Extrapolations in Dual-Energy CT for Metal Artifact Reduction in Different Body Regions and Orthopedic Implants

To define an optimal monoenergetic extrapolation (ME) in dual-energy computed tomography (DECT) for metal artifact reduction (MAR) including different body regions and orthopedic implants. DECT scans were acquired with dual-source CT (SOMATOM Force, Siemens, Germany) at tube voltage A 80-100 kV/B Sn150 kV from 39 patients (mean 54.1 ± 20.7 years, 23 male vs. 16 female) with orthopedic implants ranging from wires to joint implants. Scans were assembled in four groups based on scan regions and volume. Single- and weighted-energy images at a ratio of 0.3 and MEs at 100, 130, 160, and 190 keV were produced using vendor-specific postprocessing software (Syngo.Via, Siemens, Germany). Artifact degree was assessed quantitatively by metal-induced Hounsfield unit changes in relation to reference tissues. Visibility of screw-bone interface, hardware integrity, adjacent bone, and soft tissues were visually rated on a four-point Likert scale (0, none; 3, strong artifacts with nondiagnostic quality). Optimal energy was visually determined by side-by-side comparisons. Artifact degree was statistically compared between regions and energies. Metal-induced attenuation changes were most severe in large scan volume groups for all energies. Reference tissue attenuation outside metal artifacts was not affected by ME (p = 0.57). Independent of region, ME at 130-190 keV quantitatively performed significantly better for MAR than the remainder. ME 130 keV showed the highest frequency (54%) in optimal energy ratings based on qualitative image criteria. DECT significantly reduces image artifacts in patients with orthopedic hardware and prospective choice of ME at 130 keV may suit best for optimal MAR, independent of region or implant.

Role of taurine upregulated gene 1 as a predictor of poor outcome in osteosarcoma.

Previous studies have found that long noncoding RNA taurine upregulated gene 1 (TUG1) can regulate osteosarcoma cells apoptosis and proliferation; the aim of this study was to investigate the clinical significance of TUG1 in osteosarcoma. The expression of TUG1 was detected by real-time and quantitative polymerase chain reaction assay in 94 pairs of tumor tissues and corresponding noncancerous bone tissues of osteosarcoma patients. Its correlations with clinicopathologic features were analyzed, and the significance of TUG1 as a prognostic factor was determined. This study shows that the expression of TUG1 in osteosarcoma tissues was significantly higher than that in adjacent normal bone tissues. Upregulation of TUG1 was significantly correlated with the larger tumor size and advanced tumor-node-metastases stage of osteosarcoma patients. Kaplan-Meier curve showed a decreased overall survival time of osteosarcoma patients with high TUG1 expression. Moreover, univariate and multivariate analyses suggested that low-expression level of TUG1 was an independent poor prognostic indicator for osteosarcoma patients. In conclusion, our data support TUG1 as a potential prognostic predictor and gene therapy target with its high expression in tumor tissues and its association with carcinogenesis and progression in osteosarcoma.

LncRNA CCAT2 enhances cell proliferation via GSK3β/β-catenin signaling pathway in human osteosarcoma.

Osteosarcoma(OS) is a kind of malignant bone tumor. The aim of the manuscript is to investigate the clinical significance and the functional effects of long non-coding (lncRNA) coloncancer-associated transcript 2 (CCAT2) in osteosarcoma. Expression of CCAT2 was detected by quantitative Real-time PCR (qRT-PCR) in 50 cases of osteosarcoma tissue samples and adjacent normal bone tissues. Kaplan-Meier survival analysis and log-rank test were used to assess the association between CCAT2 expression and prognosis of OS patients. Cell Counting Kit 8 and cell colony formation assays were performed to evaluate cell proliferation. The protein expression of PCNA, p-GSK3β, GSK3β, and β-catenin were analyzed using Western blot analysis. We demonstrated that lncRNA CCAT2 expression was significantly upregulated in OS tissues compared to adjacent normal bone tissues. Higher lncRNA CCAT2 expression positively associated with larger tumor size, advanced tumor stage and poor overall survival (OS) rate of patients. In vitro, knockdown of lncRNA CCAT2 suppressed cell proliferation and colony formation ability. In contrast, overexpression of lncRNA CCAT2 showed promoting cell proliferation effects in OS. Also, we found that knockdown of lncRNA CCAT2 inhibited GSK3β/β-catenin signaling by reducing p-GSK3β and β-catenin expression, but increasing GSK3β expression. Our results showed that CCAT2 is a crucial oncogene in OS and may be a potential therapeutic target of OS.

Effect of titanium ions on the Hippo/YAP signaling pathway in regulating biological behaviors of MC3T3-E1 osteoblasts.

Titanium (Ti) and its corresponding alloys have been widely applied in dental and orthopedic implants. Owing to abrasion and corrosion of implants in the unfavorable electrolytic aqueous environment of the host body, Ti ions could be released from implants and accumulated in local tissues. Recent studies have found that excessive Ti ions were toxic to osteoblasts in adjacent bone tissues and subsequently influenced long-term effects on implant prostheses. However, the potential molecular mechanisms underlying the damage to osteoblasts induced by Ti ions remained unclear. Hippo signaling has been confirmed to be involved in organ size and tissue regeneration in many organs, while its roles in osteoblasts differentiation and bone repair remained elusive. Therefore, we hypothesize that YAP, a regulator of Hippo pathway, inhibited osteoblast growth, skeletal development and bone repair, as well as excessive Ti ions promoted the progression of YAP activation. This study aimed to explore the role of Hippo/YAP signaling pathway in the biotoxicity effect of Ti ions on osteoblast behaviors. Here, we confirmed that 10ppm Ti ions, a minimum concentration gradient previously reported that was capable of suppressing osteoblasts growth, induced nuclear expression of YAP in osteoblasts in our study. Furthermore, 10ppm Ti ion-induced YAP activation was found to downregulate osteogenic differentiation of MC3T3-E1 cells. Most importantly, the hypothesis we proposed that knockdown of YAP did reverse the inhibitory effect of 10ppm Ti ions on osteogenesis has been verified. Taken together, our work provides insights into the mechanism of which YAP is involved in regulating osteoblast behaviors under the effect of Ti ions, which may help to develop therapeutic applications for Ti implant failures and peri-implantitis.

English

These Tap casting and powder metallurgy methods used to produce the 45S5 Bioglass. This study revealed that the bioglass modified with 0.2% Y2O3 has about 700% increases in hardness. The modification of bioglass with 0.2% Y2O3 leads to a 44% increase in fracture toughness values. This study revealed that the 0.2% Y2O3 bioglass composition-modification improves the fracture strength by almost 150%. The laboratory histological sections showed that 45S5 bioglass (original composition materials showed nether systemic nor local inflammation with new bone formation at site of implantation. The Y2O3 modified the 45S5 bioglass showed no inflammation reactions as well, but no new bone formation and regeneration was noticed in the adjacent bone tissue.

The miR-17-92 cluster/QKI2/β-catenin axis promotes osteosarcoma progression

Quaking(QKI) is an RNA binding protein, and it has been shown to serve as a tumor suppressor. However, the expression and functions of QKI in osteosarcoma progression remain poorly understood. In this study, we aimed to explore the expression of QKI2 in osteosarcoma tissues and to determine the mechanisms underlying aberrant QKI2 expression and the effect of QKI2 on osteosarcoma progression. We found that QKI2 was significantly down-regulated in osteosarcoma tissues compared with adjacent normal bone tissues. Using a series of molecular biological techniques, we demonstrated that all members of the miR-17-92 cluster were up-regulated and contributed to the down-regulation of QKI2 expression in osteosarcoma. Functional examination showed that QKI2 inhibited the proliferation, migration and invasion of osteosarcoma cells via decreasing the expression of β-catenin. Conclusively, we revealed that the regulatory axis consisting of the miR-17-92 cluster/QKI2/β-catenin plays a crucial role in the development and progression of osteosarcoma.

Isoliquiritigenin attenuates spinal tuberculosis through inhibiting immune response in a New Zealand white rabbit model.

Spinal tuberculosis (ST) is the tuberculosis caused by Mycobacterium tuberculosis (Mtb) infections in spinal curds. Isoliquiritigenin 4,2′,4′-trihydroxychalcone, ISL) is an anti-inflammatory flavonoid derived from licorice (Glycyrrhiza uralensis), a Chinese traditional medicine. In this study, we evaluated the potential of ISL in treating ST in New Zealand white rabbit models. In the model, rabbits (n=40) were infected with Mtb strain H37Rv or not in their 6th lumbar vertebral bodies. Since the day of infection, rabbits were treated with 20 mg/kg and 100 mg/kg of ISL respectively. After 10 weeks of treatments, the adjacent vertebral bone tissues of rabbits were analyzed through Hematoxylin-Eosin staining. The relative expression of Monocyte chemoattractant protein-1 (MCP-1/CCL2), transcription factor κB (NF-κB) p65 in lymphocytes were verified through reverse transcription quantitative real-time PCR (RT-qPCR), western blotting and enzyme-linked immunosorbent assays (ELISA). The serum level of interleukin (IL)-2, IL-4, IL-10 and interferon γ (IFN-γ) were evaluated through ELISA. The effects of ISL on the phosphorylation of IκBα, IKKα/β and p65 in NF-κB signaling pathways were assessed through western blotting. In the results, ISL has been shown to effectively attenuate the granulation inside adjacent vertebral tissues. The relative level of MCP-1, p65 and IL-4 and IL-10 were retrieved. NF-κB signaling was inhibited, in which the phosphorylation of p65, IκBα and IKKα/β were suppressed whereas the level of IκBα were elevated. In conclusion, ISL might be an effective drug that inhibited the formation of granulomas through downregulating MCP-1, NF-κB, IL-4 and IL-10 in treating ST.

Characterization of different osteoclast phenotypes in the progression of bone invasion by oral squamous cell carcinoma.

The present study aimed to characterize different phenotypes of osteoclasts in the progression of bone invasion by oral squamous cell carcinoma (OSCC). A local bone invasion model of OSCC was established by injecting SCC25 human OSCC cells into the center of calvariae in nude mice, and all mice were found to have a typical bone resorption area. Staining for tartrate-resistant acid phosphatase (TRAP) revealed various types of giant osteoclasts in the tumour-bone interface. Bone marrow cells (BMCs) were isolated from the nude mice for primary osteoclast culture, but only a few giant osteoclasts were generated. Additionally, special blood centrifuge tubes were utilized to obtain large numbers of peripheral blood mononuclear cells (PBMCs). Using magnetic activated cell sorting (MACS) and the cytokines colony-stimulating factor (CSF) and receptor activator of nuclear factor-κB ligand (RANKL), we differentiated human osteoclasts from CD14+ monocytes of PBMCs. Bone resorption was further confirmed by a bone resorption assay. Finally, Transwell inserts were used for indirect cell co-culture of SCC25 cells and CD14+ monocytes. Expression of specific osteoclast markers was detected by real-time PCR and western blotting. After co-culture for 3 and 6 days, conditioned medium (CM) of SCC25 cells stimulated the expression of osteoclast markers, and additional osteoclasts were detected through staining of TRAP and F-actin. In the present study distinct osteoclast phenotypes were observed in the established bone invasion animal model, and were confirmed using various primary osteoclast cultures. CM of OSCC cells may promote the expression of osteoclast markers and induce the differentiation of monocytes to mature osteoclasts, which can resorb adjacent bone tissue.

Type 2 diabetes mellitus BALB/c mice are more susceptible to granulomatous amoebic encephalitis: Immunohistochemical study

Granulomatous amoebic encephalitis (GAE) is a chronic, difficult to resolve infection caused by amphizoic amoebae of the genus Acanthamoeba, which in most cases occurs in immunosuppressed persons or with chronic diseases such as diabetes. In this study, we describe the early events of A. culbertsoni infection of GAE in diabetic mice model. Diabetes was induced in male BALB/c mice, with a dose of streptozotocin (130 mg/kg). Healthy and diabetic mice were inoculated via intranasal with 1 × 106 trophozoites of A. culbertsoni. Then were sacrificed and fixed by perfusion at 24, 48, 72 and 96 h post-inoculation, the brains and nasopharyngeal meatus were processed to immunohistochemical analysis. Invasion of trophozoites in diabetic mice was significantly greater with respect to inoculated healthy mice. Trophozoites and scarce cysts were immunolocalized in respiratory epithelial adjacent bone tissue, olfactory nerve packets, Schwann cells and the epineurium base since early 24 h post-inoculation. After 48 h, trophozoites were observed in the respiratory epithelium, white matter of the brain, subcortical central cortex and nasopharyngeal associated lymphoid tissue (NALT). At 72 h, cysts and trophozoites were immunolocalized in the olfactory bulb with the presence of a low inflammatory infiltrate characterized by polymorphonuclear cells. Scarce amoebae were observed in the granular layer of the cerebellum without evidence of inflammation or tissue damage. No amoebas were observed at 96 h after inoculation, suggesting penetration to other tissues at this time. In line with this, no inflammatory infiltrate was observed in the surrounding tissues where the amoebae were immunolocalized, which could contribute to the rapid spread of infection, particularly in diabetic mice.All data suggest that trophozoites invade the tissues by separating the superficial cells, penetrating between the junctions without causing cytolytic effect in the adjacent cells and subsequently reaching the CNS, importantly, diabetes increases the susceptibility to amoebae infection, which could favor the GAE development.

MiR-451 inhibits cell growth, migration and angiogenesis in human osteosarcoma via down-regulating IL 6R

Osteosarcoma (OS) has become one of the most common primary malignant tumors in the children and adolescents with a poor prognosis owing to its high malignant and metastatic potential. Although increasing evidence indicates that miR-451 could inhibit the growth and metastasis of OS, its effect on angiogenesis in OS is still very poor. What is more, the mechanism by which miR-451 affects the OS has not been fully elucidated. In the present study, miR-451 was reduced in human osteosarcoma tissues compared with the adjacent bone tissues, and the introduction of miR-451 dramatically inhibited the growth, migration and angiogenesis in OS. Additionally, it was suggested that IL 6R is a direct target gene of miR-451. Silencing of IL 6R suppressed the growth, migration and angiogenesis of OS, which was consistent with the effect of overexpression of miR-451. In conclusion, our data demonstrate that miR-451 may function as a potential suppressor of tumor growth, migration and angiogenesis in OS via down-regulating IL 6R, suggesting a promising therapeutic avenue for managing OS.

Highly expressed ribosomal protein L34 indicates poor prognosis in osteosarcoma and its knockdown suppresses osteosarcoma proliferation probably through translational control.

Osteosarcoma has devastating health implications on children and adolescents. However, due to its low incidence and high tumor heterogeneity, it is hard to achieve any further improvements in therapy and overall survival. Ribosomal protein L34 (RPL34) has been increasingly recognized to promote the proliferation of malignant cells, but its role in osteosarcoma has not been investigated. In this study, real-time quantitative PCR (RT-qPCR) and immunohistochemistry revealed that RPL34 was highly expressed in osteosarcoma tissues when compared to adjacent tissues and normal bone tissues. Survival analysis showed that high expression of RPL34 predicted a poor prognosis for osteosarcoma patients. Knockdown of RPL34 in Saos-2 cells via lentivirus-mediated small interfering RNA (siRNA) significantly inhibited cell proliferation, induced cell apoptosis and G2/M phase arrest. Moreover, screening of transcription factors using University of California Santa Cruz (UCSC) Genome Browser, protein-protein interaction (PPI) network analysis, Gene Ontology (GO) and pathway enrichment analysis revealed that MYC participates in the transcriptional regulation of RPL34, which interacts with the subunits of eukaryotic translation initiation factor 3 (eIF3) and probably involves the translational control of growth-promoting proteins. Our findings suggest that RPL34 plays an important role in the proliferation of osteosarcoma cells.

A multi-level comparative analysis of human femoral cortical bone quality in healthy cadavers and surgical safe margin of osteosarcoma patients

Osteosarcoma is the most common primary malignancy of bone. However, the potential variation it brings to the adjacent undamaged bone tissue is seldom investigated. In this study, we conducted a multi-level comparison of human femoral cortical bone quality in healthy cadavers (aged 42±11 years) and in resected safe margin of osteosarcoma patients (aged 49±15 years). The objective of this study was to document the changes with exposure to osteosarcoma condition in bone mechanical strength, structural morphology and elementary composition, evaluated by static and dynamic mechanical analysis (DMA), scanning electron microscopy (SEM) imaging, X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR). The resected clinical samples from healthy and osteosarcoma conditioned bones were grouped into the Tumor and Healthy groups, and shaped into regular beam specimens or pulverized according to testing protocols. The results of mechanical tests confirmed osteolytic deteriorations in mineral phase of the Tumor group, in terms of significant reductions in storage modulus (−53.6%, at 1Hz), bending strength (−53.0%) and stiffness (−64.8%) as compared to the Healthy group. However, the energy dissipation/absorption ability of the collagen phase in the Tumor group did not differ from the Healthy group statistically. Although specimens showed no visible morphological difference, a decline in osteocyte lacunar density in bone specimens from the Tumor group was discovered (−54.4%, p<0.001). Higher magnification observation showed that the cell-free lacunae in the Tumor group were occluded by randomized overgrown collagen fibers. XRD and FTIR analysis further demonstrated a lower hydroxyapatite crystallinity and decreased mineral:matrix ratio in pulverized samples from the Tumor group, mainly due to the prominent Amide peaks. Taken together, these data revealed a previously unrecognized effect of osteosarcoma on the adjacent “normal” bone quality. The current study may provide insights on bone tumor pathology and an advanced understanding of surgical safe margin.

Retraction Note: Down-regulation of miR-133a and miR-539 are associated with unfavorable prognosis in patients suffering from osteosarcoma.

[This retracts the article DOI: 10.1186/s12935-015-0237-6.].

Retraction note: Down-regulation of microRNA-26a and up-regulation of microRNA-27a contributes to aggressive progression of human osteosarcoma.

Osteosarcoma is the most common primary bone malignancy with high local aggressiveness and rapid metastasizing potential, resulting in poor survival. Increasing reports suggest that deregulated microRNAs (miRNAs) might provide novel therapeutic targets for cancers. However, the expression of miR-26a and miR-27a in osteosarcoma need further investigation in clinical samples. In our study, we evaluate the expression of these miRNAs in osteosarcoma tissues and compared with paired adjacent non-tumor bone tissues using RT-qPCR. Total RNA was purified from patients with osteosarcoma and noncancerous bone tissues. Real-time PCR was applied to quantify the expression level of miR-26a and miR-27a. Moreover, the correlation of these markers with clinicopathological characteristics was also evaluated in osteosarcoma patients. A cox proportional hazards model was performed to assess multivariate analyses of prognostic values. Our result suggested that miR-26aexpression level in osteosarcoma bone tissue was significantly lower than that in the paired noncancerous bone tissues. MiR-27a expression was higher in osteosarcoma bone tissue in comparison with paired noncancerous bone tissues. The results indicated that low expression level of miR-26a and high expression of miR-27a were associated with high TNM stage (P = 0.001; P = 0.012), tumor grade (P = 0.007; P = 0.016), and distant metastasis (P = 0.004; P = 0.001). Kaplan-Meier analysis and log-rank test indicated that patients with low expression of miR-26a and high expression of miR-27a had shorter overall survival (log-rank test: P < 0.001). Multivariate Cox proportional hazards model analysis showed that low expression of miR-26a and high expression of miR-27a (P = 0.021; P = 0.011), high TNM stage (P = 0.001; P = 0.003), tumor grade (P = 0.005; P = 0.01), and distant metastasis.(P = 0.002; P = 0.005) were independent prognostic factors for overall survival patients with osteosarcoma cancer. In conclusion, our findings suggested that expression level of miR-26a and miR-27a contributes to aggressive progression of this malignancy. Therefore, may have clinical potentials as a non-invasive diagnostic/prognostic biomarker for osteosarcoma patients.

µXRF Elemental Mapping of Bioresorbable Magnesium-Based Implants in Bone.

This study investigated the distribution of the elemental constituents of Mg-based implants at various stages of the degradation process in surrounding bone tissue, with a focus on magnesium (Mg), as the main component of the alloy, and yttrium (Y), due to its potential adverse health effects. The measurements were performed on the implant-bearing thin sections of rat bone in a time series of implant degradation between one and 18 months. Micro X-ray fluorescence analysis (μXRF) with a special spectrometer meeting the requirements for the measurements of low-Z elements was used. It was found that the migration and accumulation behaviour of implant degradation products is element-specific. A sharp decrease in Mg was observed in the immediate vicinity of the interface and no specific accumulation or aggregation of Mg in the adjacent bone tissue was detected. By contrast, Y was found to migrate further into the bone over time and to remain in the tissue even after the complete degradation of the implant. Although the nature of Y accumulations must still be clarified, its potential health impact should be considered.

The Characterization and Osteogenic Activity of Nanostructured Strontium-Containing Oxide Layers on Titanium Surfaces.

The aim of this study was to compare strontium-containing implant (Sr-Ti) surfaces with modified pure Ti (Mod Ti) on the promotion of osteogenesis in vitro and in vivo. The Sr-Ti surfaces were fabricated by hydrothermal treatment. The Mod Ti surfaces were used as a control. These surfaces were characterized with scanning electron microscopy, x-ray diffractometer, and x-ray photoelectron spectroscopy. The biologic activity was analyzed by initial adhesion, proliferation, alkaline phosphatase (ALP), osteocalcin, and osteogenesis-related genes in vitro. Hematoxylin and eosin (H&E) staining and immunohistochemistry analysis of tissue adjacent to this implant were used to evaluate osteogenic activity in vivo. The results confirmed multiple nanogranules on the Sr-Ti surface composed of well-crystallized TiO₂ and SrTiO₃ phases. Long-term release of Sr enhanced mesenchymal stem cell (MSC) initial adhesion, the production of ALP, osteocalcin, and upregulated osteogenesis-related genes. For in vivo osteogenic evaluation, mesenchymal-like cells were adhered on these two surfaces under the electron microscope and transitory hematoma in adjacent bone tissue by H&E staining. The Stro-1-labeled MSCs were noted around the Sr-Ti surface in immunohistochemistry analysis. This study suggests that Sr-Ti surfaces with nanostructures could promote the response of MSCs in vitro, and recruit Stro-1 labeled MSCs in vivo.

MiR-106a-5p Suppresses the Proliferation, Migration, and Invasion of Osteosarcoma Cells by Targeting HMGA2.

We aim to investigate the effect of miR-106a-5p on the proliferation, migration, and invasion of osteosarcoma (OS) cells by targeting high-mobility group AT-hook 2 (HMGA2). Real-time fluorescent quantitative polymerase chain reaction (RT-qPCR) was used for detecting the expressions of miR-106-5p and HMGA2 in 137 OS and adjacent normal bone tissues. Immunohistochemistry was applied for the HMGA2 protein expression detection. Luciferase reporter gene assay was conducted for verifying whether miR-106-5p targeted HMGA2. MG63 and U2SO cells were respectively divided into five groups: Blank, miR-106a-5p, scramble, HMGA2-siRNA, and miR-106a-5p+HMGA2 groups. RT-qPCR and western blot were applied for detecting the expressions of miR-106a-5p and HMGA2 in five groups. Proliferation rate, cell cycle, invasion, and migration ability of OS cells were detected using methyl thiazolyl-tetrazolium, 5-ethynyl-2'-deoxyuridine (Edu) assay, flow cytometry, and Transwell. Compared with adjacent normal tissues, OS tissues presented with decreased miR-106a-5p expressions, elevated HMGA2 mRNA, and positive expressions (all p < 0.05). The sensitivity and specificity of miR-106a-5p were 97.8%, 93.43%, and HMGA2 mRNA were 97.8%, 99.27%, separately. miR-106a-5p and HMGA2 expressions were associated with tumor size, Enneking stage, distant metastasis, and lung metastasis. Expressions of HMGA2 in OS cells in miR-106a-5p and HMGA2 siRNA groups were both significantly decreased with the same downregulation level, and the proliferation rates in both groups were obviously slowed down after 48 h (both p < 0.001). Edu positive cells, S phase cells (majority of cells blocked at G0/G1 phase), migratory and invasive cells were obviously decreased (all p < 0.05). Downregulation of miR-106a-5p was found in OS tissues, and upregulation of miR-106a-5p can inhibit the proliferation, migration, and invasion by targeting HMGA2 in OS cells.