Bone Tissue Composition Research Articles

Osteoporosis: the potential of modern bone densitometric studies

Osteoporosis is a disease that is widespread among the population and leads to early disability and a decrease in the quality of life. The review provides information on modern diagnostic imaging methods that allow to identify violations of the mineral composition of bone tissue with a high degree of reliability and at an early stage and predict the risks of fractures.The author of the article concludes that the expression «It is easier to prevent than to treat» applies to osteoporosis. And in this regard, one of the cornerstones of the tasks of doctors of related specialties is the need for early identification of persons at risk, comprehensive examination, and methods of radiation diagnostics play a significant role in this.

8353 Impact of a plant-based protein diet on bone health and body composition in Sprague Dawley rats

Abstract Disclosure: M.M. Gomes: None. I.M. de Araújo: None. S.V. Rodriguez: None. F.R. Jorge: None. F.J. de Paula: None. Introduction:Vegetarian and vegan diets are associated with some health benefits; this has contributed to their growing popularity. Although studies remain limited, there is evidence that these patients may be at greater risk of reduced bone mineral density (BMD) and increased fracture risk. The general objective of this study was to analyze the impact of a high-protein, plant-based diet on bone tissue and body composition in male Sprague Dawley rats. Methodology: The study was approved by the Animal Ethics Committee. This study was done with 10 rats in the control group (CG), which received a standard AIN-93M diet; 11 in the normoprotein vegetarian group (NVG), with a normoprotein AIN-93 diet modified with pea protein and methionine; and 11 in the high-protein vegetarian group (HVG), with a modified AIN-93 diet with 40% pea protein and methionine. The dietary intervention lasted 8 weeks. The weight of the animals was measured weekly. Basal blood glucose levels were measured at baseline. At the end of the study, 6 rats from the CG, 6 rats from the NVG, and 5 rats from the HVG were subjected to a glucose tolerance test (GTT). The dual-energy X-ray absorptiometry (DXA) technique was applied in the baseline and final periods of the experiment to evaluate body composition, bone mineral content (BMC) and BMD. After sacrifice, bone strength was measured via a three-point flexion mechanical test on the tibia; brown adipose, epididymal, and retroperitoneal tissues, as well as the liver, were weighed on an analytical balance. Blood was used to measure circulatory levels of insulin, CTX, and P1NP (n=6/group). Results: Basal weight was similar between the groups, but the final weight was lower in the HVG as compared to the CG. In the DXA evaluation, the final lean mass was not different between the groups. On the other hand, total fat mass was lower in the HVG than in the CG and the NVG and the fat percentage was lower in the HVG than in the CG. The weight of epididymal adipose tissue was lower in the HVG than in the NVG, but retroperitoneal and brown adipose tissues were lower in HVG than CG. Liver weight was similar between groups. BMD was similar between groups; however, BMC was lower in the HVG than in the CG and the NVG. Bone strength was similar between groups. There was no difference in glycemia at baseline or during GTT at the eighth week. Serum levels of insulin, CTX, and P1NP were similar between groups. Discussion and Conclusion: A normoprotein vegetarian diet that includes all essential amino acids appears to have no negative impact on body composition or BMD in rats. On the other hand, a high-protein diet with plant protein appears to have a negative impact on bone mineral content, in addition to reducing the amount of body fat and weight. This finding expands on previous results by showing that high-protein diets have a negative impact on bone even when the protein is of plant origin. Presentation: 6/1/2024

Assessment of submicron bone tissue composition in plastic-embedded samples using optical photothermal infrared (O-PTIR) spectral imaging and machine learning

Understanding the composition of bone tissue at the submicron level is crucial to elucidate factors contributing to bone disease and fragility. Here, we introduce a novel approach utilizing optical photothermal infrared (O-PTIR) spectroscopy and imaging coupled with machine learning analysis to assess bone tissue composition at 500 nm spatial resolution. This approach was used to evaluate thick bone samples embedded in typical poly(methyl methacrylate) (PMMA) blocks, eliminating the need for cumbersome thin sectioning. We demonstrate the utility of O-PTIR imaging to assess the distribution of bone tissue mineral and protein, as well as to explore the structure-composition relationship surrounding microporosity at a spatial resolution unattainable by conventional infrared imaging modalities. Using bone samples from wildtype (WT) mice and from a mouse model of osteogenesis imperfecta (OIM), we further showcase the application of O-PTIR spectroscopy to quantify mineral content, crystallinity, and carbonate content in spatially defined regions across the cortical bone. Notably, we show that machine learning analysis using support vector machine (SVM) was successful in identifying bone phenotypes (typical in WT, fragile in OIM) based on input of spectral data, with over 86% of samples correctly identified when using the collagen spectral range. Our findings highlight the potential of O-PTIR spectroscopy and imaging as valuable tools for exploring bone submicron composition.

Features of densitometric assessment of bone tissue parameters in the verification of osteoporotic changes in young men with Hodgkin's lymphoma

BACKGROUND: The development of osteoporosis in males is associated with a complex interaction of various factors, including: deficiency of sex hormones, heredity, physical activity, nicotine use, etc. In young men with Hodgkin's lymphoma, the development of the osteoporotic process is very multifactorial due to the influence of tumor cells, pathogenetic therapy, as well as a secondary decrease in androgens on the composition of bone tissue and a decrease in BMD. AIMS: To determine the parameters of bone mineral density in young men with Hodgkin's lymphoma and to assess the risks of osteoporosis associated with pathogenetic therapy of the disease. MATERIALS AND METHODS: The study included 26 men, of whom 14 were diagnosed with Hodgkin's lymphoma, and the control group included 12 healthy males. All patients underwent a two-adsorption X-ray scan of bone tissue in the lumbar spine, as well as the femur. The following parameters were identified and studied: MPC, Z-criterion, T-criterion for all participants in both study groups. RESULTS: The analysis of bone mineral density in patients with Hodgkin's lymphoma showed a significant decrease in the parameter in two measurement areas: the lumbar spine and the proximal femur. Significantly more often in men with Hodgkin's lymphoma, a decrease in the Z-criterion to osteopenia/osteoporosis was noted in the lumbar spine. A decrease in the T-criterion in patients with Hodgkin's lymphoma to osteopenia/osteoporosis was noted in the proximal and femoral neck. CONCLUSIONS: Young men with Hodgkin's lymphoma who have received pathogenetic therapy, including cytostatic drugs and glucocorticosteroids, are at high risk of developing the osteoporotic process and its complications. The decrease in densitometric parameters (MPC, Z-criterion, T-criterion) in patients with Hodgkin's lymphoma to osteopenia/osteoporosis, noted in the proximal part and femoral neck, indicates a high risk of fractures of this localization and requires the development of a strategy for their prevention.

A 3D micro-CT assessment of composition and structure of bone tissue after vertical and horizontal alveolar ridge augmentation using CAD/CAM-customized titanium mesh.

To date, no studies have exploited micro-CT in humans to evaluate bone morphology and structure after bone augmentation with CAD/CAM-customized titanium mesh, in mandible and maxilla. The aim of this study was to assess the composition and microstructure of bone biopsy through micro-CT analysis. Bone augmentation at both maxillary and mandible sites was performed on 30 patients randomly treated with customized mesh, either alone (M-) or covered with resorbable membrane (M+), in both cases filled 50:50 with autogenous bone and xenograft. After 6 months, biopsies were taken and micro-CT was performed on consecutive 1-mm-thick VOIs from coronal to apical side, measuring tissue volumes, trabecular thickness, spacing, and number. In both groups, irrespective of membrane use, bone tissue (M-: 29.76% vs. M+: 30.84%) and residual graft material (M-: 14.87% vs. M+: 13.11%) values were similar. Differences were site-related (maxillary vs. mandibular) with higher percentage of bone tissue and trabecular density of low-mineralized bone and overall bone in the mandible. The composition and structure of bone tissue, as assessed by micro-CT after alveolar ridge augmentation using CAD/CAM-customized titanium meshes, showed similar features regardless of whether a collagen membrane was applied.

Altered extracellular matrix and mechanotransduction gene expression in rat bone tissue following long-term estrogen deficiency.

Osteoporosis is primarily associated with bone loss, but changes in bone tissue matrix composition and osteocyte mechanotransduction have also been identified. However, the molecular mechanisms underlying these changes and their relation to bone loss are not fully understood. The objectives of this study were to (1) conduct comprehensive temporal gene expression analyses on cortical bone tissue from ovariectomized rats, with a specific focus on genes known to govern matrix degradation, matrix production, and mechanotransduction, and (2) correlate these findings with bone mass, trabecular and cortical microarchitecture, and mineral and matrix composition. Microarray data revealed 35 differentially expressed genes in the cortical bone tissue of the ovariectomized cohort. We report that catabolic gene expression abates after the initial accelerated bone loss period, which occurs within the first 4wk of estrogen deficiency. However, in long-term estrogen deficiency, we report increased expression of genes associated with extracellular matrix deposition (Spp1, COL1A1, COL1A2, OCN) and mechanotransduction (Cx43) compared with age-matched controls and short-term estrogen deficiency. These changes coincided with increased heterogeneity of mineral-to-matrix ratio and collagen maturity, to which extracellular matrix markers COL1A1 and COL1A2 were positively correlated. Interestingly, mineral heterogeneity and collagen maturity, exhibited a negative correlation with PHEX and IFT88, associated with mechanosensory cilia formation and Hedgehog (Hh) signaling. This study provides the first insight into the underlying mechanisms governing secondary mineralization and heterogeneity of matrix composition of bone tissue in long-term estrogen deficiency. We propose that altered mechanobiological responses in long-term estrogen deficiency may play a role in these changes.

Evaluation of the elemental composition and radiological density of bone tissue when replacing a metaphyseal defect with bioceramic phosphate-silicate granules (experimental study)

Background: It is known that bioceramic implants containing various calcium or silicon compounds in isolation demonstrate osteoconductive effect in the replacement of post-traumatic bone defects. The combined use of these elements in single material should potentiate the organotypic filling of the bone cavity by creating favorable ion microenvironment and staged biodegradation. AIM: To identify the correlation of radiological indicators of the density of newly formed bone tissue and content of micro- and macronutrients in a bone defect when it is replaced by bioceramics with various mass ratio of calcium phosphate and silicate. MATERIALS AND METHODS: The study was performed on male rabbits of the “white giant” breed, which, after receiving a standardized delimited metaphysical bone defect, implants with variable ratio of calcium phosphate and calcium silicate (in proportions of 40/60, 50/50 and 60/40 wt. %) were used to replace it. The results were evaluated using multispiral computed tomography and scanning electron microscopy energy dispersive analysis with detection by the method of correlation analysis of possible connections between the obtained data. RESULTS: Quantitative indicators of calcium and phosphorus content in bone regenerate in all groups increased mainly in the period from 30 to 60 days, and silicon content, reaching maximum amounts by the 30th day of the experiment, subsequently decreased monotonously, which showed participation of this element in the starting regenerative processes, and its decrease served as a marker of organotypic restructuring. In the elemental analysis of newly formed bone tissue during implantation of bioceramics containing phosphate and calcium silicate in the proportion of 60/40 wt. %. The highest amounts of calcium, phosphorus and silicon and the highest density of newly formed bone tissue were noted, which had direct correlation, and this pattern was observed both in the early stages (30 days) and throughout the experimental study. CONCLUSION: Analyzing the data obtained, it can be concluded that it is advisable to study the features of the course of reparative osteogenesis depending on the ionic environment, as well as the high potential of using synthetic bioceramics in general and the prospects of using implants on the basis of phosphate-silicate composites for bone defects replacement.

3D modular bioceramic scaffolds for the investigation of the interaction between osteosarcoma cells and MSCs

Recent advances in bone tissue engineering have shown promise for bone repair post osteosarcoma excision. However, conflicting research on mesenchymal stem cells (MSCs) has raised concerns about their potential to either promote or inhibit tumor cell proliferation. It is necessary to thoroughly understand the interactions between MSCs and tumor cells. Most previous studies only focused on the interactions between cells within the tumor tissues. It has been challenging to develop an in vitro model of osteosarcoma excision sites replicating the complexity of the bone microenvironment and cell distribution. In this work, we designed and fabricated modular bioceramic scaffolds to assemble into a co-culture model. Because of the bone-like composition and mechanical property, tricalcium phosphate bioceramic could mimic the bone microenvironment and recapitulate the cell-extracellular matrix interaction. Moreover, the properties for easy assembly enabled the modular units to mimic the spatial distribution of cells in the osteosarcoma excision site. Under this co-culture model, MSCs showed a noticeable tumor-stimulating effect with a potential risk of tumor recurrence. In addition, tumor cells also could inhibit the osteogenic ability of MSCs. To undermine the stimulating effects of MSCs on tumor cells, we present the methods of pre-differentiated MSCs, which had lower expression of IL-8 and higher expression of osteogenic proteins. Both in vitro and in vivo studies confirm that pre-differentiated MSCs could maintain high osteogenic capacity without promoting tumor growth, offering a promising approach for MSCs’ application in bone regeneration. Overall, 3D modular scaffolds provide a valuable tool for constructing hard tissue in vitro models. Statement of significanceBone tissue engineering using mesenchymal stem cells (MSCs) and biomaterials has shown promise for bone repair post osteosarcoma excision. However, conflicting researches on MSCs have raised concerns about their potential to either promote or inhibit tumor cell proliferation. It remains challenges to develop in vitro models to investigate cell interactions, especially of osteosarcoma with high hardness and special composition of bone tissue. In this work, modular bioceramic scaffolds were fabricated and assembled to co-culture models. The interactions between MSCs and MG-63 were manifested as tumor-stimulating and osteogenesis-inhibiting, which means potential risk of tumor recurrence. To undermine the stimulating effect, pre-differentiation method was proposed to maintain high osteogenic capacity without tumor-stimulating, offering a promising approach for MSCs’ application in bone regeneration.

Real-Time Monitoring of Thermal Phenomena during Femtosecond Ablation of Bone Tissue for Process Control.

Femtosecond (fs) laser technology is currently being considered in innovative fields such as osteotomy and treatment of hard tissue thanks to the achievable high resolution and ability to prevent tissue damage. In a previous study, suitable process parameters were obtained to achieve competitive ablation rates on pork femur processing. Nevertheless, a better control of thermal accumulation in the tissue during laser ablation could further improve the postoperative regeneration of the treated bone compared with conventional procedures and push forward the exploitation of such technology. This study presents methods for real time analyses of bone tissue temperature and composition during fs laser ablation and highlights the importance of implementing an efficient cooling method of bone tissue in order to achieve optimized results. Results show that it is possible to achieve a larger process window for bone tissue ablation where bone tissue temperature remains within the protein denaturation temperature in water-based processing environment. This is a key outcome towards a clinical exploitation of the presented technology, where higher process throughputs are necessary. The effects of process parameters and environments on bone tissue were confirmed by LIBS technique, which proved to be an efficient method by which to record real-time variation of bone tissue composition during laser irradiation.

Design, analysis and optimization of porous titanium alloys scaffolds by using additive manufacture

In order to have a stronger bond with the surrounding bone, the bone prosthesis needs to have interconnecting pores for bone cells to grow and more importantly to avoid stress shielding. At the same time, human bones have different composition and structure of bone tissue in different parts of the body due to different physical factors of the person, so the elastic modulus of the bones that need to be supported and replaced are not the same. And additive manufacturing has the advantages of rapid, efficient and precise manufacturing of complex shapes and high-quality three-dimensional structures, which can manufacture porous scaffold bone prosthesis, and achieve more accurate mechanical property requirements by controlling the design parameters. To study the effect of design strut length and design strut cross-section diameter size on the elastic modulus of tetrahedral titanium alloy scaffold unit, and with the help of UG NX, several digital models of porous titanium alloy scaffolds were constructed with the strut length and the strut cross-section diameter size as the parameters of variation, and then the elastic modulus of each porous titanium alloy scaffold was measured by ANSYS Workbench 2022, and the elasticity modulus of each porous titanium alloy scaffold was further derived from the relationship between the strut length and strut cross-section diameter size and the porous titanium alloy scaffold. Then the elastic modulus of each porous titanium alloy bracket was measured by ANSYS Workbench 2022, and the mathematical model between the strut length, strut cross-section size and elastic modulus of the porous titanium alloy bracket was further derived. Then, ANSYS Workbench 2022 was used to measure the elastic modulus of each porous titanium alloy bracket and further derive the mathematical model between strut length, strut cross-section diameter size and elastic modulus of the porous titanium alloy bracket, with the help of which the elastic modulus of the porous titanium alloy bracket with specific diameters and strut lengths was finally deduced to validate the correctness of the above predicted mathematical model, and to make reasonable explanations and corrections for the deviations. explanation and correction of deviations. As a result, the rapid prototyping technology can be used to design the required porous titanium alloy bracket in a more detailed way.

Self-adaptable calcium-based bioactive phosphosilicate-infused gelatin-hyaluronic hydrogel for orthopedic regeneration

Bone regeneration is a critical and intricate process vital for healing fractures, defects, and injuries. Although conventional bone grafts are commonly used, they may fall short of optimal outcomes, thereby driving the need for alternative therapies. This research endeavors to explore synergistically designed Hyalo Glass Gel (HGG), and its explicitly for bone tissue engineering and regenerative medicine. The HGG composite comprises a modifiable calcium-based bioactive phosphosilicates-incorporated/crosslinked gelatin-hyaluronic scaffold showcasing promising functional characteristics. The study underscores the distinct attributes of each constituent (gelatin (Gel), hyaluronic acid (HA), and 45S5 calcium sodium phosphosilicates (BG)), and their cooperative influences on the scaffold's performance. Careful manipulation of crosslinking methods facilitates customization of HGG's mechanical attributes, degradation kinetics, and structural features, aligning them with the requisites of bone tissue engineering applications. Moreover, the integration of BG augments the scaffold's bioactivity, thereby expediting tissue regenerative processes. This comprehensive evaluation encompasses HGG's physicochemical aspects, mechanical traits rooted in viscoelasticity, as well as its biodegradability, in-vitro bioactivity, and interactions with stem cells. The result obtained underscores the viscoelastic nature of HGG, substantiating its capacity to foster mesenchymal stem cell viability, proliferation, and differentiation. Significantly, HGG manifests biocompatibility and adjustable attributes, exhibits pronounced drug (vancomycin) retention abilities, rendering it apt for wound healing, drug delivery, and bone regeneration. Its distinctive composition, tailored attributes, and mimicry of bone tissue's extracellular matrix (ECM) due to its bioactive nature, collectively situate its potential as a versatile biomaterial for subsequent research and development endeavors with compelling prospects in bone tissue engineering and regenerative medicine.

Three-Dimensional Printing of Graphene Oxide/Poly-L-Lactic Acid Scaffolds Using Fischer-Koch Modeling.

Accurately printing customizable scaffolds is a challenging task because of the complexity of bone tissue composition, organization, and mechanical behavior. Graphene oxide (GO) and poly-L-lactic acid (PLLA) have drawn attention in the field of bone regeneration. However, as far as we know, the Fischer-Koch model of the GO/PLLA association for three-dimensional (3D) printing was not previously reported. This study characterizes the properties of GO/PLLA-printed scaffolds in order to achieve reproducibility of the trabecula, from virtual planning to the printed piece, as well as its response to a cell viability assay. Fourier-transform infrared and Raman spectroscopy were performed to evaluate the physicochemical properties of the nanocomposites. Cellular adhesion, proliferation, and growth on the nanocomposites were evaluated using scanning electron microscopy. Cell viability tests revealed no significant differences among different trabeculae and cell types, indicating that these nanocomposites were not cytotoxic. The Fischer Koch modeling yielded satisfactory results and can thus be used in studies directed at diverse medical applications, including bone tissue engineering and implants.

Pearl Powder Hybrid Bioactive Scaffolds from Microfluidic 3D Printing for Bone Regeneration.

The development of bioactive scaffolds by mimicking bone tissue extracellular matrix is promising for bone regeneration. Herein, inspired by the bone tissue composition, a novel pearl powder (PP) hybrid fish gelatin methacrylate (GelMa) hydrogel scaffold loaded with vascular endothelial growth factor (VEGF) for bone regeneration is presented. With the help of microfluidic-assisted 3D printing technology, the composition and structure of the hybrid scaffold can be accurately controlled to meet clinical requirements. The combination of fish skin GelMa and PP also endowed the hybrid scaffold with good biocompatibility, cell adhesion, and osteogenic differentiation ability. Moreover, the controlled release of VEGF enables the scaffold to promote angiogenesis. Thus, the bone regeneration in the proposed scaffolds could be accelerated under the synergic effect of osteogenesis and angiogenesis, which has been proved in the rat skull defect model. These features indicate that the PP hybrid scaffolds will be an ideal candidate for bone regeneration in clinical applications.

Microscopic and elemental analysis of jaw bone tissue in injury

Since the jawbone tissue is injured at the stage of metal dental implant introduction, the problem of inflammatory complication development leading to a breakdown in osseointegration remains relevant. Of interest are the immunological mechanisms of inflammatory process development during the emission of metal nanoparticles, as well as the mechanisms of its subsidence after the removal of a metal object. Microscopic and elemental analysis of the bone tissue of the Wistar rat lower jaw after artificial traumatization was carried out. During the experiment, the situation of presence of a metal foreign body in the bone bed was simulated. An insulin needle was injected into the connective tissue of the lower jaw, followed by its removal after seven days. Microscopic analysis of bone tissue was performed using a Tesscan Vega 4 scanning electron microscope. The teeth alveoli cortical layer surface, connection of the jaws with a gap, stratification of the cartilaginous layer were determined at low magnification in direct projection. Using higher magnification in the direct projection there are visible dense-structural crystalline inclusions, foci of necrosis in the area of junctions of the jaws alveolar processes. The elemental composition of bone tissue was obtained by atomic emission spectroscopy by iCAP 6300 Duo. In the test sample, the quantitative ratio of calcium and phosphorus was 1.68, which slightly exceeds the optimal value of 1.67. An upward change in this ratio indicates a decrease in phosphorus level, which can be interpreted as local osteoporosis. In addition, the following elements were found: Bi, Ga, Pb, Ti, Zn in the amount of 0.03-0.06 mass percent. The list of these elements corresponds to the chemical composition of an insulin needle, indicating the penetration of metal particles into bone bed tissues. The emission of nanoparticles and their subsequent association to micro- and submicron sizes, their persistence, as well as biocorrosion in areas of active bone formation can be a trigger for the development of an aseptic inflammatory process. This effect is due to both a direct damaging factor and an indirect effect through specific signal molecules produced in response to tissue damage.

Research and Application of Medical Polyetheretherketone as Bone Repair Material.

Polyetheretherketone (PEEK) can potentially be used for bone repair because its elastic modulus is similar to that of human natural bone and good biocompatibility and chemical stability. However, its hydrophobicity and biological inertness limit its application in the biomedical field. Inspired by the composition, structure, and function of bone tissue, many strategies are proposed to change the structure and functionality of the PEEK surface. In this review, the applications of PEEK in bone repair and the optimization strategy for PEEK's biological activity are reviewed, which provides a direction for the development of multifunctional bone repair materials in the future.

A biphasic calcium phosphate/acylated methacrylate gelatin composite hydrogel promotes osteogenesis and bone repair

ABSTRACT Purpose/Aim Bone defects caused by trauma, tumors, congenital malformation, or inflammation are very common in orthopedics. In recent years, mimicking the composition and structure of natural bone tissue has become a hot topic in biomaterial research, with the aim of developing an ideal biomaterial for bone defect transplantation. Here, the feasibility of a biphasic calcium phosphate (BCP)/acylated methacrylate gelatin (GelMA) composite hydrogel to repair bone defects was evaluated in vitro and in rats. Materials and Methods The biocompatibility of a biphasic calcium phosphate (BCP)/acylated methacrylate gelatin (GelMA) composite hydrogel was evaluated by cytoskeleton staining, live/dead cell staining and cell proliferation assays. The in vitro osteogenic activities of the composite hydrogel were evaluated by alkaline phosphatase and alizarin red staining, as well as osteogenic gene expression analysis at both transcript and protein levels. The in vivo bone repair activities were evaluated using the rat skull defect model. Results The BCP/GelMA composite hydrogel displayed excellent biocompatibility and promoted osteogenesis of bone marrow mesenchymal stem cells in vitro. In addition, the BCP/GelMA composite hydrogel markedly promoted new bone formation in the rat skull-defect model. Conclusions BCP/GelMA composite hydrogel may be an effective artificial material for bone tissue engineering.

Hydroxyapatite/poly(vinyl alcohol)/chitosan coating with gentamicin for orthopedic implants

Electrophoretic deposition (EPD) was employed to fabricate composite coatings aimed for orthopedic implants. Hydroxyapatite (HAP), poly(vinyl alcohol) (PVA) and chitosan (CS) coatings, with or without antibiotic gentamicin (Gent) were deposited in a single-step process from aqueous suspension, using EPD. Polymer/mineral composite coatings were formed with the aim to mimic the natural composition of bone tissue, along with improved coatings antibacterial properties, at the same time serving as a drug carrier, allowing local administration of antibiotic. Structural and morphological characterization of HAP/PVA/CS and HAP/PVA/CS/Gent coatings was investigated by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TG/DTG), and scanning electron microscopy (SEM) proving carbonate-substituted HAP. The presence of gentamicin contributed to the bactericidal activity of composite HAP/PVA/CS/Gent coating against Staphylococcus aureus and Escherichia coli. Cytotoxicity studies were performed towards human MRC-5 and mice L929 fibroblast cell lines, and both investigated samples (HAP/PVA/CS and HAP/PVA/CS/Gent) expressed good biocompatibility, without causing toxic effect on tested cells. Biomineralization potential was investigated by measuring the alkaline phosphatase activity, demonstrating high potential of HAP/PVA/CS/Gent to induce the growth of new HAP layer. Therefore, the present investigation proposes the production of composite coatings from non-toxic (aqueous) suspensions, consisting of biocompatible and bioactive components, along with antibiotic gentamicin, improving the antibacterial coatings' properties.

Variation in Juvenile Long Bone Properties as a Function of Age: Mechanical and Compositional Characterization.

Bone is a heterogeneous, hierarchical biocomposite material made of an organic matrix filled with a mineral component, which plays an important role in bone strength. Although the effect of the mineral/matrix ratio on the mechanical properties of bone during aging has been intensively investigated, the relationship between the mechanical properties and the chemical composition of bone with age requires additional research in juvenile individuals. In this study, bone coupons from bovine and ovine animal species were machined from cortical areas of long bones to quantify whether the variation in mechanical properties at different stages of development is related to the change in the composition of bone tissue. An energy-dispersive X-ray detector (EDX) attached to a scanning electron microscope (SEM) was used to perform a compositional analysis of the tissue. In addition, nanoindentation analyses were carried out to address how the elastic modulus changed with age. Nonparametric statistical analyses found significant differences (p < 0.05) in Ca content and elastic modulus between species, but no differences were found within each species with development. A multiple linear regression model found that the elastic modulus was significantly related to the decrease in P and C in the samples, to the animal species (larger in bovine), and development, although not linearly. This model also found an interaction between Ca and development that could explain the lack of significance of the relationship between the elastic modulus and development in the univariate models.

Mineral density and chemical composition of the rats’ mandibles in experimental models of generalized periodontitis

The most severe and difficult to treat symptoms of generalized periodontitis associated with diabetes mellitus are changes in bone tissue. The aim of the research was to conduct a comparative study of the mineral density and chemical composition of the mandibular bone tissue in rats in the modeling of generalized periodontitis, which develops against the background of metabolic disorders in type 2 diabetes mellitus, and after additional use of strontium ranelate. The study was carried out on 24 white male Wistar rats weighing 230-250 g, divided into three groups, 8 animals in each (in I group streptozocin and nicotinamide were administered, in II group - additionally penicylamine, in III group – additionally strontium ranelate) and 6 intact rats were used as a control. According to data of computer tomography, it was found that in the control group the average values of the mineral density are 1450.0±125.0 HU, in I group – 1320.0±120.0 HU (p&gt;0.05), in II group –1100.0±110.0 HU (p˂0.05), in III group –1400.0±137.0 HU (p&gt;0.05). Thus, the most pronounced decrease in mineral density is observed in the case of the combined use of nicotinamide, streptozotocin and penicylamine, while strontium ranelate helps to normalize this indicator. According to atomic emission spectrometry, the mineralization index – the ratio of calcium / phosphorus – was 1.14 in the control group, 1.05 – in I, 1.0 – in II and 1.26 – in III. The strontium content in the samples of the III group exceeded the control values by almost two times (p˂0.001) in comparison with its significant decrease in the samples of the I and II groups (p˂0.05). An increase in the strontium content led to a decrease in the content of other elements, which is explained by the competitive substitution in apatite crystals. So, strontium ranelate activates remineralization of the bone component of the periodontium.

Temporal and spatial changes in bone mineral content and mechanical properties during breast-cancer bone metastases

Cancer cells favour migration and metastasis to bone tissue for 70–80 % of advanced breast cancer patients and it has been proposed that bone tissue provides attractive physical properties that facilitate tumour invasion, resulting in osteolytic and or osteoblastic metastasis. However, it is not yet known how specific bone tissue composition is associated with tumour invasion. In particular, how compositional and nano-mechanical properties of bone tissue evolve during metastasis, and where in the bone they arise, may affect the overall aggressiveness of tumour invasion, but this is not well understood. The objective of this study is to develop an advanced understanding of temporal and spatial changes in nano-mechanical properties and composition of bone tissue during metastasis. Primary mammary tumours were induced by inoculation of immune-competent BALB/c mice with 4T1 breast cancer cells in the mammary fat pad local to the right femur. Microcomputed tomography and nanoindentation were conducted to quantify cortical and trabecular bone matrix mineralisation and nano-mechanical properties. Analysis was performed in proximal and distal femur regions (spatial analysis) of tumour-adjacent (ipsilateral) and contralateral femurs after 3 weeks and 6 weeks of tumour and metastasis development (temporal analysis). By 3 weeks post-inoculation there was no significant difference in bone volume fraction or nano-mechanical properties of bone tissue between the metastatic femora and healthy controls. However, early osteolysis was indicated by trabecular thinning in the distal and proximal trabecular compartment of tumour-bearing femora. Moreover, cortical thickness was significantly increased in the distal region, and the mean mineral density was significantly higher in cortical and trabecular bone tissue in both proximal and distal regions, of ipsilateral (tumour-bearing) femurs compared to healthy controls. By 6 weeks post-inoculation, overt osteolytic lesions were identified in all ipsilateral metastatic femora, but also in two of four contralateral femora of tumour-bearing mice. Bone volume fraction, cortical area, cortical and trabecular thickness were all significantly decreased in metastatic femora (both ipsilateral and contralateral). Trabecular bone tissue stiffness in the proximal femur decreased in the ipsilateral femurs compared to contralateral and control sites. Temporal and spatial analysis of bone nano-mechanical properties and mineralisation during breast cancer invasion reveals changes in bone tissue composition prior to and following overt metastatic osteolysis, local and distant from the primary tumour site. These changes may alter the mechanical environment of both the bone and tumour cells, and thereby play a role in perpetuating the cancer vicious cycle during breast cancer metastasis to bone tissue.