Bone Research Articles

INTELLIGENT INFORMATION TECHNOLOGIES TO SUPPORT DECISION-MAKING WHEN APPLYING THE CAD/CAM/CAE SYSTEM OF DESIGN AND USING ADDITIVE TECHNOLOGIES

The direction of research is the development of principles and methods for making scientifically based decisions in the design and additive manufacturing of bone substitutes based on apatite-biopolymer composites with functional properties depending on the nature of the localization of the cavity bone defect and its size. The relevance is due to the fact that the development of an intelligent decision-making support system based on neural network modeling, the development of methods for their training, tabagato-criterion optimization of design processes, will allow the creation of three-dimensional solid models of defects taking into account their spatial structure and bone substitutes for the synthesis of biomaterials with controlled composition, porosity and mechanical strength, which are optimal for a specific area of bone replacement, which will increase the effectiveness of treatment and prosthetics in orthopedics and traumatology. A set of methods for analyzing images of bone tissue, taking into account its spatial structure, which are obtained by sensors of different physical nature, with the use of neural network models, development of methods of their design, optimization, and training is proposed. A modification of the method of learning neural networks based on gradient descent, based on the application of the theory of nonlinear dynamics, is proposed. Corresponding theoretical provisions have been developed.

Exploring the multicomponent synergy mechanism of Zuogui Wan on postmenopausal osteoporosis by a systems pharmacology strategy.

To explore the multi-component synergistic mechanism of Zuogui Wan (, ZGW) in treating postmenopausal osteoporosis (PMOP). The main components and target genes of ZGW were screened via the Traditional Chinese Medicine Systems Pharmacology (TCMSP). In addition, the target gene sets of PMOP were derived from the GeneCards and Online Mendelian Inheritance in Man databases. The search tool for recurring instances of neighbouring genes (STRING) 11.0 software was used to analyze the interaction among intersecting genes. Cytoscape 3.6.1 software and the Matthews correlation coefficient (MCC) algorithm were used to screen the core genes. Fifty Sprague-Dawley female rats were randomly divided into the sham-operated (Sham) group and the four ovariectomized (OVX) subgroups. Rats subjected to Sham or OVX were administered with the vehicle (OVX, 1 mL water/100 g weight), 17β-estradiol (E2, 50 μg·kg-1·d-1), and lyophilized powder of ZGW at a low dose of 2.3 (ZGW-L) and high dose of 4.6 (ZGW-H) g·kg-1·d-1 for three months. The bone density and bone strength were assessed using dual-energy X-ray and three-point bending tests, respectively. Furthermore, enzyme-linked immun-osorbent assay, Hematoxylin-eosin staining, and western blot analysis were used to determine the potential pharmacological mechanisms of action of ZGW in PMOP. A total of 117 active compounds of ZGW were screened from the TCMSP. Furthermore, 108 intersecting genes of drugs and diseases were identified. Using STRING software and the MCC algorithm, ten core genes, including C-X-C chemokine living 8 (CXCL8), C-C chemokine receptor type 2 (CCR2), alpha-2a active receptor (ADRA2A), melatonin receptor type 1B (MTNR1B), and amyloid-beta A4 protein (APP), were identified. The anti-osteoporosis regulation network of ZGW was constructed using the Cytoscape software. The animal experiments demonstrated that ZGW groups significantly reduced the serum levels of β-C-terminal telopeptide of type I collagen (β-CTX) and increased serum levels of bone-specific alkaline phosphatase (BALP) (P < 0.05, P < 0.01). The OVX group exhibited a significant decrease in bone mineral density and bone strength compared with the Sham group (P < 0.01). Moreover, treatment with ZGW resulted in increased trabecular thickness, improved arrangement of trabecular structure, and reduced empty bone lacunae. Furthermore, treatment with ZGW significantly increased the protein expression of CXCL8, ADRA2A, and CCR2 (P < 0.05, P < 0.01), and significantly decreased the protein expression of Runx2 (P < 0.01). Furthermore, the ZGW and E2 groups demonstrated significantly increased BMD (P < 0.05, P < 0.01), improved bone strength (P < 0.05, P < 0.01), reduced expression of CXCL8, ADRA2A, and CCR2, and increased runt-related transcription factor 2 levels in bone tissue (P < 0.05, P < 0.01) compared with the OVX group. However, there were no significant differences in MTNR1B and APP expression among the groups. ZGW shows synergistic mechanisms in PMOP through multiple components, targets, and pathways.

Visualization of rat tendon in three dimensions using micro-Computed Tomography

Micro-computed tomography (CT) is an X-ray-based imaging modality that produces three-dimensional (3D), high-resolution images of whole-mount tissues, but is typically limited to dense tissues, such as bone. The X-rays readily pass-through tendons, rendering them transparent. Contrast-enhancing chemical stains have been explored, but their use to improve contrast in different tendon types and across developmental stages for micro-CT imaging has not been systematically evaluated. Therefore, we investigated how phosphotungstic acid (PTA) staining and tissue hydration impacts tendon contrast for micro-CT imaging. We showed that PTA staining increased X-ray absorption of tendon to enhance tissue contrast and obtain 3D micro-CT images of immature (postnatal day 21) and sexually mature (postnatal day 50) rat tendons within the tail and hindlimb. Further, we demonstrated that tissue hydration state following PTA staining significantly impacts soft tissue contrast. Using this method, we also found that tail tendon fascicles appear to cross between fascicle bundles. Ultimately, contrast-enhanced 3D micro-CT imaging will lead to better understanding of tendon structure, and relationships between the bone and soft tissues.• Simple tissue fixation and staining technique enhances soft tissue contrast for tendon visualization using micro-CT.• 3D tendon visualization in situ advances understanding of musculoskeletal tissue structure and organization.

Effect of M2-macrophage treated lymphatic endothelial cells on angiogenesis that promoted osteointegration

Early vascularization plays an essential role during the whole process in bone regeneration because of the function of secreting cytokines, transporting nutrients and metabolic wastes. As the preliminary basis of bone repair, angiogenesis is regulated by immune cells represented by macrophages to a great extent. However, with the discovery of the endolymphatic circulation system inside bone tissue, the role of vascularization became complicated and confusing. Herein, we developed a macrophage/ lymphatic endothelial cells (LECs)/ human umbilical vein endothelial cells (HUVECs) co-culture system to evaluate the effect of macrophage treated lymphatic endothelial cells on angiogenesis in vitro and in vivo. In this study, we collected the medium from macrophage (CM) for LECs culture. We found that CM2 could promote the expression of LECs markers and migration ability, which indicated the enhanced lymphogenesis. In addition, the medium from LECs was collected for culturing HUVECs. The CM2-treated LECs showed superior angiogenesis property including the migration capacity and expression of angiogenetic markers, which suggested the superior vascularization. Rat femoral condyle defect model was applied to confirm the hypothesis in vivo. Generally, M2-macrophage treated LECs showed prominent angiogenetic potential coupling with osteogenesis.

Mg alloys with antitumor and anticorrosion properties for orthopedic oncology: A review from mechanisms to application strategies.

As a primary malignant bone cancer, osteosarcoma (OS) poses a great threat to human health and is still a huge challenge for clinicians. At present, surgical resection is the main treatment strategy for OS. However, surgical intervention will result in a large bone defect, and some tumor cells remaining around the excised bone tissue often lead to the recurrence and metastasis of OS. Biomedical Mg-based materials have been widely employed as orthopedic implants in bone defect reconstruction, and, especially, they can eradicate the residual OS cells due to the antitumor activities of their degradation products. Nevertheless, the fast corrosion rate of Mg alloys has greatly limited their application scope in the biomedical field, and the improvement of the corrosion resistance will impair the antitumor effects, which mainly arise from their rapid corrosion. Hence, it is vital to balance the corrosion resistance and the antitumor activities of Mg alloys. The presented review systematically discussed the potential antitumor mechanisms of three corrosion products of Mg alloys. Moreover, several strategies to simultaneously enhance the anticorrosion properties and antitumor effects of Mg alloys were also proposed.

Recent Advances in Biomaterial Design for Bone Regenerative Therapy: A Mini Review

Abstract: Longevity has been associated with morbidity and an increase in age-related illnesses, linked to tissue degeneration and gradual loss of biological functions. Bone is an important organ that gradually degenerates with increasing lifespan. The remodeling phase plays a huge role in maintaining the ability of bone to regenerate and maintain its stability and function throughout life. Hence, bone health represents one of the major challenges to elderly citizens due to the increase of injury associated with bone degeneration, such as fragility and risks of fractures. In the virtue of improving the regenerative function of bone tissues, a specialized field of bone tissue engineering (BTE) has been introduced to improve the current strategies in treating bone degenerative disorders. Most of the research performed in BTE focuses on the optimization of key components to generate new bone formation, including the scaffold. A scaffold plays a significant role in establishing the structural form that interconnects major elements of the tissue engineering triad. To date, many types of biomaterials have been explored in BTE, ranging from natural and synthetic materials to nanocomposites. However, ideal scaffolds that display excellent biocompatibility and mechanical properties, approved for clinical practices are yet available. This paper aims to describe the up-to-date advancements in scaffold for new bone generation, highlighting the essential elements and strategies in selecting suitable biomaterials for bone repair.

Bone mineral density and osteoporosis related risk factors in type 2 diabetes mellitus

Diabetes mellitus negatively affects bone tissue and unfavourably impacts bone mineral density (BMD), therfore increasing the probability of fractures through pathological mechanisms. This study aimed to explore the factors associated with BMD and osteoporosis risk in individuals with a diagnosis of type 2 diabetes mellitus (T2DM). An investigation was undertaken involving 49 patients diagnosed with T2DM who fulfilled the specified criteria. These individuals underwent BMD assessment as part of a cross-sectional study. The analysis encompassed both univariate and bivariate approaches, utilizing the Chi-square test (X2) and binary logistic regression methods. A total of 30 participants (61%) have decreased BMD. Among the participants aged 60 years and above, 83.4% exhibited a decreased BMD status (osteopenia and osteoporosis), in contrast to the under 60 years age group, in which 40% displayed decreased BMD status. Older age (&amp;gt;60 years) is a risk factor for decreasing bone density onset of diabetes mellitus (DM) diagnosis, duration of DM, glycemic control, body mass index (BMI), use of thiazolidinediones (TZD) drugs, kidney function, were not associated with lower BMD in T2DM patients.

Smart responsive in situ hydrogel systems applied in bone tissue engineering

The repair of irregular bone tissue suffers severe clinical problems due to the scarcity of an appropriate therapeutic carrier that can match dynamic and complex bone damage. Fortunately, stimuli-responsive in situ hydrogel systems that are triggered by a special microenvironment could be an ideal method of regenerating bone tissue because of the injectability, in situ gelatin, and spatiotemporally tunable drug release. Herein, we introduce the two main stimulus-response approaches, exogenous and endogenous, to forming in situ hydrogels in bone tissue engineering. First, we summarize specific and distinct responses to an extensive range of external stimuli (e.g., ultraviolet, near-infrared, ultrasound, etc.) to form in situ hydrogels created from biocompatible materials modified by various functional groups or hybrid functional nanoparticles. Furthermore, “smart” hydrogels, which respond to endogenous physiological or environmental stimuli (e.g., temperature, pH, enzyme, etc.), can achieve in situ gelation by one injection in vivo without additional intervention. Moreover, the mild chemistry response-mediated in situ hydrogel systems also offer fascinating prospects in bone tissue engineering, such as a Diels–Alder, Michael addition, thiol-Michael addition, and Schiff reactions, etc. The recent developments and challenges of various smart in situ hydrogels and their application to drug administration and bone tissue engineering are discussed in this review. It is anticipated that advanced strategies and innovative ideas of in situ hydrogels will be exploited in the clinical field and increase the quality of life for patients with bone damage.

Osteocalcin: Beyond Bones.

Apart from basic roles such as supporting the body, protecting internal organs, and storing calcium, the skeletal system also performs hormonal functions. In recent years, several reports have been published on proteins secreted by bones and their impact on the homeostasis of the entire body. These proteins include fibroblast growth factor 23, sclerostin, lipocalin 2, and osteocalcin. Osteocalcin, the most abundant non-collagenous protein in bone tissue, is routinely measured as a clinical marker for diagnosing bone metabolism disorders. Its molecule undergoes numerous transformations, with decarboxylation being the critical process. Decarboxylation occurs in the acidic environment typical of bone resorption, facilitating the release of the molecule into the bloodstream and enabling its hormonal action. Decarboxylated osteocalcin promotes insulin secretion and stimulates the proliferation of pancreatic islet β-cells. It also plays a role in reducing the accumulation of visceral fat and decreasing fat storage in the liver. Furthermore, decarboxylated osteocalcin levels are inversely correlated with fasting serum glucose levels, total body fat, visceral fat area, and body mass index. Apart from its role in energy metabolism, osteocalcin affects testosterone production and the synthesis of glucagon-like peptide-1. It is also actively involved in muscle-bone crosstalk and influences cognitive function.

A Pilot Study on Circulating, Cellular, and Tissue Biomarkers in Osteosarcopenic Patients

Aging comes with the loss of muscle and bone mass, leading to a condition known as osteosarcopenia. Circulating, cellular, and tissue biomarkers research for osteosarcopenia is relatively scarce and, currently, no established biomarkers exist. Here we find that osteosarcopenic patients exhibited elevated basophils and TNFα levels, along with decreased aPPT, PT/INR, IL15, alpha-Klotho, DHEA-S, and FGF-2 expression and distinctive bone and muscle tissue micro-architecture and biomarker expressions. They also displayed an increase in osteoclast precursors with a concomitant imbalance towards spontaneous osteoclastogenesis. Similarities were noted with osteopenic and sarcopenic patients, including a lower neutrophil percentage and altered cytokine expression. A linear discriminant analysis (LDA) on models based on selected biomarkers showed a classification accuracy in the range of 61–78%. Collectively, our data provide compelling evidence for novel biomarkers for osteosarcopenia that may hold potential as diagnostic tools to promote healthy aging.

Brillouin scattering from biomedical samples: the challenge of heterogeneity.

Abstract Brillouin light scattering (BLS), a non-destructive and non-contact technique, offers a powerful tool for probing the micromechanical properties of biological tissues. However, the inherent heterogeneity of biological tissues can pose significant challenges in interpreting BLS spectra. In this study, we introduce a novel method that harnesses the intensity information within a single BLS spectrum to directly estimate the Voigt average of the longitudinal modulus. Additionally, we use a method to determine the ratio of the squared Pockels coefficients for photoelastically heterogeneous samples, based on global analysis of a 2D BLS map. This method is shown to effectively determine the photoelastic ratio of soft and hard components of human bone tissues, enabling the calculation of the average elastic moduli. Furthermore, it has the remarkable ability to generate maps of the filling factor of the scattering volume, shedding valuable light on the intricate structure and topography of rough surfaces under BLS mapping.

Metformin treatment prevents experimental metabolic syndrome-induced femoral bone marrow adiposity in rats.

Motivation for the study. Most research supports a negative association between metabolic syndrome and bone health, although there is an overall lack of consensus. Therefore, there is a need for research in this area to develop a better understanding. Main findings. Metabolic syndrome induced by a fructose-rich diet increases the adipogenic predisposition of bone marrow progenitor cells and femoral medullary adiposity in rats. Furthermore, this can be partially prevented by co-treatment with metformin. Implications. Experimental metabolic syndrome has negative effects on bone tissue and can be prevented by oral treatment with metformin as a normoglycemic drug. To determine the effect of metformin (MET) treatment on adipogenic predisposition of bone marrow progenitor cells (BMPC), bone marrow adiposity and bone biomechanical properties. 20 young adult male Wistar rats were sorted into four groups. Each of the groups received the following in drinking water: 100% water (C); 20% fructose (F); metformin 100 mg/kg wt/day (M); or fructose plus metformin (FM). After five weeks the animals were sacrificed. Both humeri were dissected to obtain BMPC, and both femurs were dissected to evaluate medullary adiposity (histomorphometry) and biomechanical properties (3-point bending). BMPC were cultured in vitro in adipogenic medium to evaluate RUNX2, PPAR-γ and RAGE expression by RT-PCR, lipase activity and triglyceride accumulation. The fructose-rich diet (group F) caused an increase in both triglycerides in vitro, and medullary adiposity in vivo; being partially or totally prevented by co-treatment with metformin (group FM). No differences were found in femoral biomechanical tests in vivo, nor in lipase activity and RUNX2/PPAR-γ ratio in vitro. DRF increased RAGE expression in BMPC, being prevented by co-treatment with MET. Metabolic syndrome induced by a fructose-rich diet increases femoral medullary adiposity and, in part, the adipogenic predisposition of BMPC. In turn, this can be totally or partially prevented by oral co-treatment with MET.

Duration of cefazolin prophylaxis did not impact infection risk in a murine model of joint arthroplasty.

To minimize periprosthetic joint infection (PJI) risk, some clinicians prescribe extended antibiotic prophylaxis (EAP) following total joint arthroplasty (TJA). Given the limited evidence supporting EAP, we sought to evaluate impact of prophylactic antibiotic duration on PJI risk in a murine TJA model. A titanium prosthesis was implanted into the proximal tibia of 89 mice and inoculated with 102 colony forming units (cfu) of Staphylococcus aureus Xen36. Control mice (n = 20) did not receive antibiotics. Treated mice received either 24 h (n = 35) or 4 days (n = 34) of cefazolin prophylaxis. Cultures were obtained from the prostheses, tibia, femur, and knee tissues 3 weeks after surgery. All mice in the control group developed PJI. Both prophylaxis regimens reduced the rate of PJI relative to the control, with only 2/35 mice in the 24-h cohort (p < 0.0001) and 1/34 in 4-day cohort developing PJI (p < 0.0001). CFU counts from the prostheses, bone and knee tissues were reduced for the 24-h and 4-day prophylaxis cohorts relative to the control (p < 0.0001 for both). There was no difference in rates of PJI or CFU counts between the two prophylaxis cohorts (p = 0.58). Prophylactic cefazolin profoundly reduced rates of PJI in a murine model of TJA in which all control animals developed PJI. Extending cefazolin prophylaxis duration from 24 h to 4 days did not result in improved PJI rates or decreased bacterial loads in infected cases. While these results strongly support use of antibiotic prophylaxis for TJA, EAP did not appear to add benefit in the described mouse model.

The Prevalence and Risk Factors of Low Bone Mineral Density in the Population of the Abay Region of Kazakhstan

Osteoporosis is considered a serious public health problem that particularly affects the postmenopausal period. In 2018, in the Republic of Kazakhstan, the prevalence of osteoporosis was 10.0, and the incidence was 3.7 new cases, per 100,000 adults, respectively. The objective of this study was to assess the prevalence of osteoporosis and indicate the main factors affecting low bone mineral density by screening the adult population of the Abay region, Kazakhstan. The target group comprised 641 respondents aged between 18 and 65 years old, from a Kazakh population, who had been living in the Abay region since birth. All participants filled out a questionnaire and were subjected to a bone mineral density measurement by means of dual-energy X-ray absorptiometry (DXA) between 15 July 2023 and 29 February 2024. Logistic regression analysis was conducted to assess the association between low bone mineral density and key demographic characteristics, such as lifestyle factors and nutritional habits. We identified the prevalence of low bone mass (osteopenia) and osteoporosis to be 34.1%, with the highest prevalence of 48.3% being found in the older population group (50+ years). The regression analysis revealed a number of indicators associated with the likelihood of bone sparing. However, only four of these showed significance in the final multivariate model (R2 = 22.4%). These were age (adjusted odds ratio (AOR) 1.05) and fracture history (AOR 1.64) directly associated with the likelihood of low bone density. Meanwhile, the body mass index (AOR 0.92) and the consumption of nuts and dried fruits (AOR 0.48) reduced the chance of bone tissue demineralization. Additional studies examining the prevalence and any emerging risk factors for osteoporosis are needed to advance clinical epidemiological knowledge and implement public health programs.

Recent Advances in Bone Grafts in Oral and Maxillofacial Surgery

Bone resorption, which is the loss of bone tissue, cannot be reversed after tooth loss. As a result, the affected area lacks sufficient bone volume for successful implant treatment. To address this issue, bone grafting is the only viable solution and is required in one out of every four dental implants. The ideal biomaterial substitute for bone repair should have osteogenic, osteoinductive, and osteoconductive properties, as well as the ability to stimulate the neo-angiogenesis process. It should also avoid any antigenic, teratogenic, or carcinogenic reactions, and prevent systemic toxicity complications. The purpose of this article is to provide an overview of the various materials used for bone grafts and biomaterial substitutes for bone repair, as well as to discuss current and future perspectives in this field.

Transcriptomic characteristics analysis of bone from chronic osteomyelitis

To explore the molecular mechanism of chronic osteomyelitis and to clarify the role of MAPK signal pathway in the pathogenesis of chronic osteomyelitis, by collecting and analyzing the transcriptional information of bone tissue in patients with chronic osteomyelitis. Four cases of traumatic osteomyelitis in limbs from June 2019 to June 2020 were selected, and the samples of necrotic osteonecrosis from chronic osteomyelitis (necrotic group), and normal bone tissue (control group) were collected. Transcriptome information was collected by Illumina Hiseq Xten high throughput sequencing platform, and the gene expression in bone tissue was calculated by FPKM. The differentially expressed genes were screened by comparing the transcripts of the Necrotic group and control group. Genes were enriched by GO and KEGG. MAP3K7 and NFATC1 were selected as differential targets in the verification experiments, by using rat osteomyelitis animal model and immunohistochemical analysis. A total of 5548 differentially expressed genes were obtained by high throughput sequencing by comparing the necrotic group and control group, including 2701 up-regulated and 2847 down-regulated genes. The genes enriched in MAPK pathway and osteoclast differentiation pathway were screened, the common genes expressed in both MAPK and osteoclast differentiation pathway were (inhibitor of nuclear factor κ subunit Beta, IκBKβ), (mitogen-activated protein kinase 7, MAP3K7), (nuclear factor of activated t cells 1, NFATC1) and (nuclear factor Kappa B subunit 2, NFκB2). In rat osteomyelitis model, MAP3K7 and NFATC1 were highly expressed in bone marrow and injured bone tissue. Based on the transcriptome analysis, the MAPK signaling and osteoclast differentiation pathways were closely related to chronic osteomyelitis, and the key genes IκBKβ, MAP3K7, NFATC1, NFκB2 might be new targets for clinical diagnosis and therapy of chronic osteomyelitis.

Production of Agarose-Hydroxyapatite Composites via Supercritical Gel Drying, for Bone Tissue Engineering

Bone tissue engineering (BTE) is the most promising strategy to repair bones injuries and defects. It relies on the utilization of a temporary support to host the cells and promote nutrient exchange (i.e., the scaffold). Supercritical CO2 assisted drying can preserve scaffold nanostructure, crucial for cell attachment and proliferation. In this work, agarose aerogels, loaded with hydroxyapatite were produced in view of BTE applications. Different combinations of agarose concentration and hydroxyapatite loadings were tested. FESEM and EDX analyses showed that scaffold structure suffered from partial closure when increasing filler concentration; hydroxyapatite distribution was homogenous, and Young’s modulus improved. Looking at BTE applications, the optimal combination of agarose and hydroxyapatite resulted to be 1% w/w and 10% w/v, respectively. Mechanical properties showed that the produced composites could be eligible as starting scaffold for BTE, with a Young’s Modulus larger than 100 kPa for every blend.

Correlation between Ca Release and Osteoconduction by 3D-Printed Hydroxyapatite-Based Templates.

The application of hydroxyapatite (HA)-based templates is quite often seen in bone tissue engineering since that HA is an osteoconductive bioceramic material, which mimics the inorganic component of mineralized tissues. However, the reported osteoconductivity varies in vitro and in vivo, and the levels of calcium (Ca) release most favorable to osteoconduction have yet to be determined. In this study, HA-based templates were fabricated by melt-extrusion 3D-printing and characterized in order to determine a possible correlation between Ca release and osteoconduction. The HA-based templates were blended with poly(lactide-co-trimethylene carbonate) (PLATMC) at three different HA ratios: 10, 30, and 50%. The printability and physical properties of the HA templates were compared with those of pristine PLATMC. In vitro, osteoconductivity was assessed using seeded human bone marrow-derived mesenchymal stem cells. A mild rate of Ca release was observed for HA10 templates, which exhibited higher mineralized extracellular matrix (ECM) secretion than PLATMC at 14 and 21 days. In contrast, the high rate of Ca release exhibited by HA30 and HA50 templates was associated with reduced osteoconduction and impeded mineralized ECM secretion in vitro. Similar results were observed in vivo. In the calvarial defect model in rabbit, PLATMC and HA10 templates exhibited the highest amount of new bone formation, with obvious contact osteogenesis on their surfaces. In contrast, HA30 and HA50 exhibited distant osteogenesis and reduced amounts of new bone ingrowth. It is concluded that HA-based templates are osteoconductive only at low rates of Ca release.

Freeze‐Casting of Arbitrary‐Shaped Porous Ceramics

Porous ceramics hold the great potential in the field such as bone tissue engineering, superinsulation material, and energy storage. However, it is quite challenging to fabricate them with arbitrary shape using conventional processes. Herein, a method to fabricate arbitrary‐shaped porous ceramic structure is presented by combining traditional freeze‐casting process and indirect three‐dimensional printing technology. Various polydimethylsiloxane (PDMS) soft molds are prepared for freeze‐casting, and diverse‐shaped porous ceramics are fabricated. It proves that PDMS molds are ideal choices for freeze‐casting of porous ceramics with complex geometries. The freeze‐casting process of a complex‐shaped model with PDMS is simulated by finite element analysis. The effect of the solid loading of the alumina suspension on the microstructure and compressive strength of the as‐fabricated porous ceramics are investigated. The present study provides a strategy to fabricate complex‐shaped porous ceramic structure that can be used in a wide variety of applications.

Hydrogel Coatings of Implants for Pathological Bone Repair.

Hydrogels are well-suited for biomedical applications due to their numerous advantages, such as excellent bioactivity, versatile physical and chemical properties, and effective drug delivery capabilities. Recently, hydrogel coatings have developed to functionalize bone implants which are biologically inert and cannot withstand the complex bone tissue repair microenvironment. These coatings have shown promise in addressing unique and pressing medical needs. This review begins with the major functionalized performance and interfacial bonding strategy of hydrogel coatings, with a focus on the novel external field response properties of the hydrogel. Recent advances in the fabrication strategies of hydrogel coatings and their use in the treatment of pathologic bone regeneration are highlighted. Finally, challenges and emerging trends in the evolution and application of physiological environment-responsive and external electric field-responsive hydrogel coatings for bone implants are discussed. This article is protected by copyright. All rights reserved.