Bone Research Articles

Polyurethane nanofiber scaffolds for future bone tissue applications: Using β‐cyclodextrin and zinc oxide nanoparticles to improve the properties

AbstractNumerous strategies exist to design a suitable bone graft made from polyurethane (PU) nanofibers. However, using PU nanofibers is impractical owing to their hydrophobicity. This work transforms the hydrophobicity of PU nanofibers using β‐cyclodextrin (β‐CD) and zinc oxide (ZnO) nanoparticles (NPs). Transmission and scanning electron microscopy (SEM) indicated the size of ~100 to 200 nm for ZnO NPs, and these NPs could finely harmonize inside nanofibers. The phenolphthalein absorbance test confirmed the inclusion of ZnO and β‐CD. Fourier transform infrared, X‐ray diffraction, and photoelectron spectroscopy showed that synthesized composites have intermolecular hydrogen interactions between the PU, β‐CD, and ZnO NPs. These embellishments improved the hydrophilicity from a contact angle of 60.2 ± 0.2° to 0°. The tensile strength of modified fibers increased from 2.16 ± 0.14 to 6.65 ± 6.0 MPa. The incorporation of ZnO NPs caused the mineralization of the nanofibers and the maximum number of hydroxyapatite NPs in the composite, which had the highest concentration of ZnO NPs. These nanofiber mats boosted the proliferation of Human Embryonic Kidney 293 T cells till 6 days of culture for the nanofiber with 5% β‐CD and 75 mg ZnO NPs combination. Cell fixation studies indicated the successful attachment of cells onto nanofibers. Consequently, our multifunctional scaffolds could be osteoproductive and osteoinductive biomaterials for future bone tissue engineering.

Targeting nerve growth factor-mediated osteosarcoma metastasis: mechanistic insights and therapeutic opportunities using larotrectinib

Osteosarcoma (OS) therapy presents numerous challenges, due largely to a low survival rate following metastasis onset. Nerve growth factor (NGF) has been implicated in the metastasis and progression of various cancers; however, the mechanism by which NGF promotes metastasis in osteosarcoma has yet to be elucidated. This study investigated the influence of NGF on the migration and metastasis of osteosarcoma patients (88 cases) as well as the underlying molecular mechanisms, based on RNA-sequencing and gene expression data from a public database (TARGET-OS). In osteosarcoma patients, the expression of NGF was significantly higher than that of other growth factors. This observation was confirmed in bone tissue arrays from 91 osteosarcoma patients, in which the expression levels of NGF and matrix metallopeptidase-2 (MMP-2) protein were significantly higher than in normal bone, and strongly correlated with tumor stage. In summary, NGF is positively correlated with MMP-2 in human osteosarcoma tissue and NGF promotes osteosarcoma cell metastasis by upregulating MMP-2 expression. In cellular experiments using human osteosarcoma cells (143B and MG63), NGF upregulated MMP-2 expression and promoted wound healing, cell migration, and cell invasion. Pre-treatment with MEK and ERK inhibitors or siRNA attenuated the effects of NGF on cell migration and invasion. Stimulation with NGF was shown to promote phosphorylation along the MEK/ERK signaling pathway and decrease the expression of microRNA-92a-1-5p (miR-92a-1-5p). In in vivo experiments involving an orthotopic mouse model, the overexpression of NGF enhanced the effects of NGF on lung metastasis. Note that larotrectinib (a tropomyosin kinase receptor) strongly inhibited the effect of NGF on lung metastasis. In conclusion, it appears that NGF promotes MMP-2-dependent cell migration by inhibiting the effects of miR-92a-1-5p via the MEK/ERK signaling cascade. Larotrectinib emerged as a potential drug for the treatment of NGF-mediated metastasis in osteosarcoma.

Comparison of the biomechanical properties of grafts in three anterior cruciate ligament reconstruction techniques based on three-dimensional finite element analysis

ObjectiveTo evaluate the biomechanical characteristics of grafts from three different anterior cruciate ligament (ACL) reconstructive surgeries and to determine which method is better at restoring knee joint stability.MethodsA 31-year-old female volunteer was enrolled in the study. According to the magnetic resonance imaging of her left knee, a three-dimensional model consisting of the distal femur, proximal tibia and fibula, ACL, posterior cruciate ligament, medial collateral ligament and lateral collateral ligament was established. Then, the ACL was removed from the original model to simulate the knee joint after ACL rupture. Based on the knee joint model without the ACL, single-bundle ACL reconstruction, double-bundle ACL reconstruction, and flat-tunnel ACL reconstruction were performed. The cross-sectional diameters of the grafts were equally set as 6 mm in the three groups. The bone tissues had a Young’s modulus of 17 GPa and a Poisson’s ratio of 0.36. The ligaments and grafts had a Young’s modulus of 390 MPa and a Poisson’s ratio of 0.4. Six probes were placed in an ACL or a graft to obtain the values of the equivalent stress, maximum principal stress, and maximum shear stress. After pulling the proximal tibia with a forward force of 134 N, the distance that the tibia moved and the stress distribution in the ACL or the graft, reflected by 30 mechanical values, were measured.ResultsThe anterior tibial translation values were similar among the three groups, with the double-bundle ACL reconstruction group performing the best, followed closely by the patellar tendon ACL reconstruction group. In terms of stress distribution, 13 out of 30 mechanical values indicated that the grafts reconstructed by flat bone tunnels had better performance than the grafts in the other groups, while 12 out of 30 showed comparable outcomes, and 5 out of 30 had worse outcomes.ConclusionCompared with traditional single-bundle and double-bundle ACL reconstructions, flat-tunnel ACL reconstruction has advantages in terms of stress dispersion. Additionally, flat-tunnel ACL reconstruction falls between traditional double-bundle and single-bundle ACL reconstructions in terms of restoring knee joint stability and is superior to single-bundle ACL reconstruction.

Dataset of Finite Element Models of Normal and Deformed Thoracolumbar Spine

Adult spine deformity (ASD) is prevalent and leads to a sagittal misalignment in the vertebral column. Computational methods, including Finite Element (FE) Models, have emerged as valuable tools for investigating the causes and treatment of ASD through biomechanical simulations. However, the process of generating personalised FE models is often complex and time-consuming. To address this challenge, we present a dataset of FE models with diverse spine morphologies that statistically represent real geometries from a cohort of patients. These models are generated using EOS images, which are utilized to reconstruct 3D surface spine models. Subsequently, a Statistical Shape Model (SSM) is constructed, enabling the adaptation of a FE hexahedral mesh template for both the bone and soft tissues of the spine through mesh morphing. The SSM deformation fields facilitate the personalization of the mean hexahedral FE model based on sagittal balance measurements. Ultimately, this new hexahedral SSM tool offers a means to generate a virtual cohort of 16807 thoracolumbar FE spine models, which are openly shared in a public repository.

Global quality of life and mortality risk in patients with cancer: a systematic review and meta-analysis.

This systematic review and meta-analysis aimed to examine the impact of global quality of life (QOL) on mortality risk in patients with cancer, considering cancer type and timepoint of QOL assessment. A systematic search was conducted using Cumulated Index to Nursing and Allied Health Literature, PubMed/MEDLINE, and Scopus databases from inception to December 2022. Observational studies that assessed QOL and examined mortality risk in patients with cancer were extracted. Subgroup analyses were performed for cancer types and timepoints of QOL assessment. Overall, global QOL was significantly associated with mortality risk (hazard ratio: 1.06, 95% confidence interval: 1.05-1.07; p < 0.00001). A subgroup analysis based on cancer type demonstrated that lung, head and neck, breast, esophagus, colon, prostate, hematologic, liver, gynecologic, stomach, brain, bladder, bone and soft tissue, and mixed type cancers were significantly associated with mortality risk; however, melanoma and pancreatic cancer were not significantly associated with mortality risk. Additionally, global QOL was associated with mortality risk at all timepoints (pretreatment, posttreatment, and palliative phase); pretreatment QOL had the largest impact, followed by posttreatment QOL. These findings provide evidence that QOL is associated with mortality risk in patients with cancer at any timepoint. These results indicate the importance of evaluating the QOL and supportive interventions to improve QOL in any phase.

Intraoperative near-infrared fluorescence guided surgery using indocyanine green (ICG) may aid the surgical removal of benign bone and soft tissue tumours

BackgroundBenign bone and soft tissue tumours encompass a broad, heterogenous range of tumours with varying clinical characteristics. These are often managed surgically with either curettage or marginal excision, but unfortunately have high rates of local recurrence. Indocyanine green (ICG) is a fluorescent dye which can be used to identify solid malignancies intraoperatively but its use is not yet established in benign bone and soft tissue tumours. This study aims to assess whether these tumours fluoresce when administered with ICG pre-operatively and whether this helps surgeons to identify tumour intra-operatively. Patients and methodsPatients with locally aggressive benign bone and soft tissue tumours were administered with 25–75 mg of ICG preoperatively at the induction of anaesthesia. Fluorescence was imaged intraoperatively using the Stryker SPY-PHI camera. ResultsOf the 12 patients included, 11 tumours fluoresced. The surgeons felt the fluorescence guided the procedure in 7 out of the 11 cases which fluoresced. It was felt to be particularly useful in the curettage of bone tumours, in which curettage could be repeated until the absence of fluorescence on imaging. After 12 months, no patients had local recurrence of the tumour. There were no adverse events recorded in this study and surgeons found the technology acceptable. ConclusionsThe use of ICG for fluorescence guided surgery is a promising technology to improve outcomes of surgery for benign bone and soft tissue tumours. Further, longer term, study with a control arm is needed to identify whether it results in a reduction in the local recurrence rate.

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.

In vivo study of a novel 3D-printed motion-preservation artificial cervical corpectomy construct: short-term imaging and biocompatibility evaluations in a goat model

BackgroundNonfusion technologies, such as motion-preservation devices, have begun a new era of treatment options in spine surgery. Motion-preservation approaches mainly include total disc replacement for anterior cervical discectomy and fusion. However, for multisegment fusion, such as anterior cervical corpectomy and fusion, the options are more limited. Therefore, we designed a novel 3D-printed motion-preservation artificial cervical corpectomy construct (ACCC) for multisegment fusion. The aim of this study was to explore the feasibility of ACCC in a goat model.MethodsGoats were treated with anterior C3 corpectomy and ACCC implantation and randomly divided into two groups evaluated at 3 or 6 months. Radiography, 3D CT reconstruction and MRI evaluations were performed. Biocompatibility was evaluated using micro-CT and histology.ResultsPostoperatively, all goats were in good condition, with free neck movement. Implant positioning was optimal. The relationship between facet joints was stable. The range of motion of the C2-C4 segments during flexion–extension at 3 and 6 months postoperatively was 7.8° and 7.3°, respectively. The implants were wrapped by new bone tissue, which had grown into the porous structure. Cartilage tissue, ossification centres, new blood vessels, and bone mineralization were observed at the porous metal vertebrae-bone interface and in the metal pores.ConclusionsThe ACCC provided stabilization while preserving the motion of the functional spinal unit and promoting bone regeneration and vascularization. In this study, the ACCC was used for anterior cervical corpectomy and fusion (ACCF) in a goat model. We hope that this study will propel further research of motion-preservation devices.

Barbed Pharyngoplasty simulation using a 3D-printed model: design and validation study.

Learning how to use barbed sutures and perform Barbed Pharyngoplasty (BP) is challenging due to limited surgical training opportunities. This work aims to design, develop, and validate a new 3D surgical simulator to train ENT residents and specialists in performing BP. The Barbed Pharyngoplasty Simulator (BPS) was designed using diagnostic images of the facial mass and testing different materials to replicate the mucosal and bony tissues. ENT specialists with experience in BP and ENT residents were included in the validation study and were asked to perform the Alianza BP. After the simulation, they compiled the Face and Content Validity Questionnaires. The BPS consists of a reusable cranial structure that contains the disposable palatopharyngeal structure, replicating the palatal structures and the tongue. Fifteen experienced ENT specialists and nine residents were included in the study. Findings demonstrated that the BPS faithfully replicated the muscular and fibrous-bony palatopharyngeal structures, with only 11% of residents having a negative opinion of the mucosal tissue. All the participants positively rated the sensation of using surgical instruments on the simulator. Also, ENT residents rated all aspects of the content validity test from normal to excellent, while specialists rated the BPS as a general training tool from normal to excellent; for lateral pharyngoplasty, BP, and Alianza, only 6.7% of participants disagreed with its usefulness, and 13.3% disagreed with it for anterior pharyngoplasty. The BPS proposed in this preliminary study can potentially be a valuable tool in BP surgical training for residents and young otolaryngologists.

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.

Causal effects of gut microbiota on the risk of osteomyelitis: a Mendelian randomization study.

Osteomyelitis is characterized by an inflammatory process initiated by microorganisms, leading to infection and subsequent degradation of bone tissue. Several studies have indicated a potential link between gut microbiota and the occurrence of osteomyelitis. Utilizing the benefits of Mendelian randomization, which mitigates issues of confounding and reverse causation, we employed this approach to ascertain the presence of a causal connection between gut microbiota and osteomyelitis. Additionally, we aimed to pinpoint gut microbiota that could potentially exert substantial influence. We performed a rigorous screening of single nucleotide polymorphisms in GWAS summary statistics for gut microbiota and osteomyelitis. The 2,542 instrumental variables obtained after screening were subjected to MR analyses, including inverse variance weighting, weighted median, weighted mode, MR-Egger, and Mendelian randomization pleiotropy residual sum and outlier test. We then validated the reliability of the results by performing sensitivity analyses on the MR of 196 well-defined gut microbiota. We established a causal relationship between gut microbiota and osteomyelitis through MR analysis. Additionally, we identified a taxon of significant importance and six taxons with nominal significance. Specifically, the family Bacteroidales S24.7 group exhibited an association with a diminished risk of osteomyelitis development. Conversely, the class Bacilli, class Bacteroidia, order Bacteroidales, order Lactobacillales, family Streptococcaceae, and genus Coprococcus3 displayed an increased risk of developing osteomyelitis. The MR outcomes for these seven taxa remained stable throughout a series of sensitivity analyses. This study demonstrated a causal relationship between gut microbiota and osteomyelitis by Mendelian randomization. We hope that this study will provide a new direction for the treatment of osteomyelitis, which has a paucity of therapeutic options.

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.

Biomechanical Finite Element Analysis of Bone Tissues with Different Scales in the Bone Regeneration Area after Scoliosis Surgery

Biomechanical Finite Element Analysis of Bone Tissues with Different Scales in the Bone Regeneration Area after Scoliosis Surgery

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.