Bone Matrix Research Articles

Micellar solution of [223Ra]RaCl2: Reaching renal excretion, potent efficacy in osteoblastic osteosarcoma in PDX model, biochemistry alterations and pharmacokinetics

Despite the successful use of the radiopharmaceutical radium-223 dichloride ([223Ra]RaCl2) for targeted alpha therapy of castration-resistant prostate cancer patients with bone metastases, some short-term side effects, such as diarrhea and vomiting, have been documented, causing patient discomfort. Hence, we prepared a nanosized micellar solution of [223Ra]RaCl2 and evaluated its biodistribution, pharmacokinetics, and induced biochemical changes in healthy mice up to 96 h after intraperitoneal administration as an alternative to overcome the previous limitations. In addition, we evaluated the bone specificity of micellar [223Ra]RaCl2 in patient-derived xenografts in the osteosarcoma model. The biodistribution studies revealed the high bone-targeting properties of the micellar [223Ra]RaCl2. Interestingly, the liver uptake remained significantly low (%ID/g = 0.1–0.02) from 24 to 96 h after administration. In addition, the micellar [223Ra]RaCl2 exhibited a significantly higher uptake in left (%ID/g = 0.85–0.23) and right (%ID/g = 0.76–0.24) kidneys than in small (%ID/g = 0.43–0.06) and large intestines (%ID/g = 0.24–0.09) over time, suggesting its excretion pathway is primarily through the kidneys into the urine, in contrast to the non-micellar [223Ra]RaCl2. The micellar [223Ra]RaCl2 also had low distribution volume (0.055 ± 0.003 L) and longer elimination half-life (28 ± 12 days). This nanosystem was unable to change the enzymatic activities of alanine aminotransferase, aspartate aminotransferase, gamma GT, glucose, and liquiform lipase in the treated mice. Finally, microscopic examination of the animals' osteosarcoma tumors treated with micellar [223Ra]RaCl2 indicated regression of the tumor, with large areas of necrosis. In contrast, in the control group, we observed tumor cellularity and cell anaplasia, mitotic figures and formation of neoplastic extracellular bone matrix, which are typical features of osteosarcoma. Therefore, our findings demonstrated the efficiency and safety of nanosized micellar formulations to minimize the gastrointestinal excretion pathway of the clinical radiopharmaceutical [223Ra]RaCl2, in addition to promoting regression of the osteosarcoma. Further studies must be performed to assess dose–response outcomes and organ/tissue dosimetry for clinical translation.

Direct Repair of Symptomatic Lumbar Spondylolysis Using Rod-Screw-Cable System

To assess the efficacy of a new direct lysis repair technique using internal fixation with rod, screws, and Songer cable in symptomatic lumbar spondylolysis. Between December 2015 and January 2020, patients who were diagnosed with symptomatic lumbar spondylolysis and surgically treated with a rod-screw-cable system were recruited. Pedicle screwing by the Magerl technique was performed in all included patients, followed by direct lysis repair with bone allograft and demineralized bone matrix by stabilizing the posterior lamina and spinous process using a rod-screw-cable system. Clinical outcome was measured using the visual analog scale and Oswestry disability index preoperatively and 6weeks, 3months, 6months, 1year, and 2years postoperatively. Sixteen patients were included in this study-11 men and 5 women (mean age: 47years; range, 26-67years). The lytic defects were at L4 and L5 in 6 and 10 patients, respectively. The mean follow-up period was 41months (24-62months). The visual analog scale values were 7.3, 6.1, 4.3, 3.3, 2.1, and 1.9 preoperatively and 6weeks, 3months, 6months, 1year, and 2years postoperatively, respectively. The Oswestry disability index values were 59.8%, 55.4%, 41.7%, 32.4%, 21.1%, and 16.9% for the same periods, respectively. No patient had an increase in the slip after surgery. There were no significant complications such as implant failure. Our technique provides rigid intra-segmental repair of spondylolysis without intersegmental motion interference, even if the patient is older or has disc degeneration.

The Effects of Preoperative Epidural Steroid Injection on Pseudarthrosis Following Lumbar Fusion: A Retrospective Cohort Study.

Retrospective cohort study. The goal of this study is to evaluate the effects of preoperative lumbar epidural steroid injection on the rate of pseudarthrosis following lumbar spine fusion surgery. Epidural corticosteroids help to reduce nerve root edema and suppress proinflammatory cytokines in patients with radiculopathy. Corticosteroids may inhibit bone formation and reduce bone matrix synthesis rates. Thus, there is concern that corticosteroids may reduce lumbar fusion capability, potentially resulting in increased rates of symptomatic pseudarthrosis. We identified all patients who underwent 1-level or 2-level lumbar fusion surgery between 2018 and 2022. Patients were categorized into one of 3 groups: no preoperative epidural steroid injection (ESI) history (group 0), preoperative ESI within 90 days of surgery (group 1), or most recent ESI >90 days before surgery (group 2). The primary outcome of this study was pseudarthrosis. Binominal regression analyses were performed to determine the relationships between potential risk factors (sex, age, body mass index, smoking history, diabetes status, history of systemic steroid use, preoperative ESI, perioperative intravenous steroid administration, type of surgery, and postoperative ESI within 6mo) and the development of postoperative pseudarthrosis. A total of 446 patients were included in this study. Of those, 106 patients (23.7%) did not have a preoperative ESI (group 0), 132 patients (29.5%) had an ESI within 90 days of surgery (group 1), and 208 patients (46.6%) had their most recent ESI >90 days before surgery (group 2). The overall incidence of pseudarthrosis following lumbar fusion was 8.7% (39 of 446). Although the incidence of pseudarthrosis following ESI at any time point was higher than in our control cohort (group 0), this difference was not statistically significant. This study found no increased risk of postoperative pseudarthrosis in patients who underwent 1-level or 2-level lumbar fusions after preoperative ESI. Level III.

Chromatin accessibility and epigenetic deoxyribose nucleic acid (DNA) modifications in chronic kidney disease (CKD) osteoblasts: a study of bone and osteoblasts from pediatric patients with CKD.

Maturation defects are intrinsic features of osteoblast lineage cells in CKD patients. These defects persist ex vivo, suggesting that CKD induces epigenetic changes in bone cells. To gain insights into which signaling pathways contribute to CKD-mediated, epigenetically driven, impairments in osteoblast maturation, we characterized RNA expression and DNA methylation patterns by RNA-Seq and MethylationEpic in primary osteoblasts from nine adolescent and young adult dialysis patients with end-stage kidney disease and three healthy references. ATAC-Seq was also performed on a subset of osteoblasts. Bone matrix protein expression was extracted from the iliac crest and evaluated by proteomics. Gene set enrichment analysis was used to establish signaling pathways consistently altered in chromatin accessibility, DNA methylation, and RNA expression patterns. Single genes were suppressed in primary osteoblasts using shRNA and mineralization characterized in vitro. The effect of nuclear factor of activated T cells (NFAT) signaling suppression was also assessed using 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) incorporation. We found that signaling pathways critical for osteoblast differentiation were strongly downregulated in CKD osteoblasts. Gene set enrichment analysis identified highly significant methylation changes, differential chromatin accessibility, and altered RNA expression in NFAT signaling targets. NFAT inhibition reduced osteoblast proliferation. Combined analysis of osteoblast RNA expression and whole bone matrix composition identified 13 potential ligand-receptor pairs. In summary, epigenetic changes in CKD osteoblasts associate with altered expression of multiple osteoblast genes and signaling pathways. An increase in NFAT signaling may play a role in impaired CKD osteoblast maturation. Epigenetic changes also associate with an altered bone matrix, which may contribute to bone fragility. Further studies are necessary to elucidate the pathways affected by these genetic alterations since elucidating these pathways will be vital to correcting the underlying biology of bone disease in the CKD population.

How osteons form: A quantitative hypothesis-testing analysis of cortical pore filling and wall asymmetry

Osteon morphology provides valuable information about the interplay between different processes involved in bone remodelling. The correct quantitative interpretation of these morphological features is challenging due to the complexity of interactions between osteoblast behaviour, and the evolving geometry of cortical pores during pore closing. We present a combined experimental and mathematical modelling study to provide insights into bone formation mechanisms during cortical bone remodelling based on histological cross-sections of quiescent human osteons and hypothesis-testing analyses. We introduce wall thickness asymmetry as a measure of the local asymmetry of bone formation within an osteon and examine the frequency distribution of wall thickness asymmetry in cortical osteons from human iliac crest bone samples from women 16–78 years old. Our measurements show that most osteons possess some degree of asymmetry, and that the average degree of osteon asymmetry in cortical bone evolves with age. We then propose a comprehensive mathematical model of cortical pore filling that includes osteoblast secretory activity, osteoblast elimination, osteoblast embedment as osteocytes, and osteoblast crowding and redistribution along the bone surface. The mathematical model is first calibrated to symmetric osteon data, and then used to test three mechanisms of asymmetric wall formation against osteon data: (i) delays in the onset of infilling around the cement line; (ii) heterogeneous osteoblastogenesis around the bone perimeter; and (iii) heterogeneous osteoblast secretory rate around the bone perimeter. Our results suggest that wall thickness asymmetry due to off-centred Haversian pores within osteons, and that nonuniform lamellar thicknesses within osteons are important morphological features that can indicate the prevalence of specific asymmetry-generating mechanisms. This has significant implications for the study of disruptions of bone formation as it could indicate what biological bone formation processes may become disrupted with age or disease.

In vitro evaluation of BMSCs early proliferation on minocycline-loaded electrospun nanofibers membrane.

Electrospun nanofibers could simulate the natural extracellular matrix (ECM) of the host bone, while minocycline (MINO) is a broad-spectrum tetracycline antibiotic which has been found to have multiple non-antibiotics biological effects that promotes osteogenesis in vitro and in vivo. The present study aims at constructing a polylactic acid (PLA) electrospun nanofiber membrane loaded with MINO to enhance Bone marrow mesenchymal stem cells (BMSCs) adhesion and proliferation for early clinical treatment. The MINO-PLA membrane were characterized by scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR) and in vitro drug release study. The antibacterial ability was also investigated. In addition, in vitro cellular proliferation experiment was performed to verify whether the PLA electrospun nanofibers membrane loaded with MINO enhance BMSCs adhesion and proliferation. Analyzing the drug release and cell growth results, it was found that only the effective concentration of MINO-PLA could help the growth of BMSCs in the short term. This is related to the drug release rate of MINO-PLA and the initial concentration of MINO. This study shows that by controlling the concentration and release rate of MINO with electrospinning PLA, BMSCs could proliferate on it, and a new bone repair material had been made in this study.

A Modified Protocol for Staining of Undecalcified Bone Samples Using Toluidine Blue—A Histological Study in Rabbit Models

Undecalcified bone histology is a valuable diagnostic method for studying bone microarchitecture and provides information on bone formation, resorption, and turnover. It has various clinical and research applications. Toluidine blue has been widely adopted as a staining technique for hard-tissue specimens. It provides a clear identification of bone structural and cellular features and the distinctions between them. Furthermore, the method allows for an excellent definition of the cement lines that mark the fields of bone remodeling. Some of the suggested and currently used processing and staining protocols are too complex and time-consuming, which necessitates their modification and/or optimization. This research aims to develop a simplified protocol for staining plastic-embedded undecalcified bone specimens with toluidine blue. The samples were obtained from the tibial bones of rabbits, and experiments with and without pre-etching were conducted. Our results demonstrated that the optimal visualization of the bone microstructure and its cellular components was achieved in the samples without acid pre-etching and dehydration after staining.

Effectiveness of a collagen matrix seal and xenograft in alveolar ridge preservation: an experimental study in dogs

Majority of previous studies on alveolar ridge preservation (ARP) used collagen membranes as barrier membranes, and further evidence for ARP in dehiscent extraction sockets with a deproteinized bovine bone mineral (DBBM) and matrix is needed. The aim of this study is to assess the impact of non-cross linked collagen membranes (membrane) and crosslinked collagen matrices (matrix) on ARP using DBBM in extraction sockets with buccal dehiscence. In six mongrel dogs, the mesial roots of three mandibular premolars (P2, P3, and P4) were extracted 1 month after dehiscence defect induction. Two experimental groups were randomly assigned: (1) DBBM with a membrane (DBBM/membrane group) and (2) DBBM with a matrix (DBBM/matrix group). Three-dimensional (3D) volumetric, microcomputed tomography (μCT), and histologic analyses were performed to assess the ridge preservation. Both groups were effective to maintain the ridge width (p > 0.05), and the DBBM/matrix group showed more favorable soft tissue regeneration and bone quality in the histological analysis (p = 0.05). Based on these results, DBBM/matrix could be better choice for ARP in cases of buccal dehiscence defects.

Chitosan/Nanohydroxyapatite/Hydroxyethyl-cellulose-based printable formulations for local alendronate drug delivery in osteoporosis treatment

Osteoporosis is a silent bone disease and a growing health issue. Despite recent progress in diagnosis and treatment, effective therapeutic strategies are still needed. One of the possible solutions is the implantation of engineered drug-releasing scaffolds at the disease site. To boost this approach further, we aimed to develop printable materials (the inks) for the construction of patient-specific 3D scaffolds with drug-release capability. The inks were composed of chitosan – a natural osteoinductive polysaccharide, nanohydroxyapatite – a natural bone matrix ingredient improving mechanical properties, sodium alendronate – a bioactive drug, and hydroxyethyl-cellulose – a filler improving printability. Printed scaffolds were crosslinked with citric acid or KOH. After coating with collagen and gelatin, they demonstrated biocompatibility with the adipose-derived mesenchymal stem cells and MG-63 cell line. They also showed a sustained release of alendronate for 50 days, causing a significant reduction in the expression of the osteoclast-specific gene markers that indicated the osteoclast-inhibiting capacities of these coated scaffolds. This work demonstrates the potential of developed printable materials to find applications as cell and drug carriers for the treatment of osteoporosis.

PERITENON AND SYNOVIAL TPPP3+ PROGENITOR CELLS CONTRIBUTE TO POST-TRAUMATIC HETEROTOPIC BONE FORMATION

Heterotopic ossification (HO) is defined as aberrant bone formation in extraskeletal locations. In this process, local stromal cells of mesenchymal origin abnormally differentiate, resulting in pathologic cartilage and bone matrix deposition. However, the specific cell type and mechanisms beyond this process are not well understood, in part due to the heterogeneity of progenitor cells involved. Here, a combination of single cell RNA sequencing (scRNA-Seq) and lineage tracing, defined the extent to which synovial / tendon sheath progenitor cells contribute to HO. For this purpose, a Tppp3 (tubulin polymerization-promoting protein family member 3) inducible reporter model was used, in combination with either Scx (Scleraxis) or Pdgfra (Platelet derived growth factor receptor alpha) reporter animals. Both arthroplasty-induced and tendon injury-mouse experimental HO models were utilized. ScRNA-Seq of tendon-induced traumatic HO suggested that Tppp3 is a progenitor cell marker for either osteochondral or tendon or cells. After HO induction, Tppp3 reporter+ cell population expanded in number and contributed to cartilage and bone formation in tendon and joint-associated HO. Using double reporter animals, we found that both Pdgfra+Tppp3+ and Pdgfra+Tppp3- progenitor cells produced HO-associated cartilage. Finally, the examination of human samples showed a significant population of TPPP3+ cells overlapping with osteogenic markers in areas of HO. Overall, these results provide novel observations that peritenon and synovial progenitor cells undergo abnormal osteochondral differentiation and contribute to heterotopic bone formation after trauma.

Functions and Metabolism of Amino Acids in Bones and Joints of Cats and Dogs.

The bone is a large and complex organ (12-15% of body weight) consisting of specialized connective tissues (bone matrix and bone marrow), whereas joints are composed of cartilage, tendons, ligaments, synovial joint capsules and membranes, and a synovial joint cavity filled with synovial fluid. Maintaining healthy bones and joints is a dynamic and complex process, as bone deposition (formation of new bone materials) and resorption (breakdown of the bone matrix to release calcium and phosphorus) are the continuous processes to determine bone balance. Bones are required for locomotion, protection of internal organs, and have endocrine functions to maintain mineral homeostasis. Joints are responsible for resisting mechanical stress/trauma, aiding in locomotion, and supporting the overall musculoskeletal system. Amino acids have multiple regulatory, compositional, metabolic, and functional roles in maintaining the health of bones and joints. Their disorders are prevalent in mammals and significantly reduce the quality of life. These abnormalities in companion animals, specifically cats and dogs, commonly lead to elective euthanasia due to the poor quality of life. Multiple disorders of bones and jointsresult from genetic predisposition and are heritable, but other factors such as nutrition, growth rate, trauma, and physical activity affect how the disorder manifests. Treatments for cats and dogs are primarily to slow the progression of these disorders and assist in pain management. Therapeutic supplements such as Cosequin and formulated diets rich in amino acids are used commonly as treatments for companion animals to reduce pain and slow the progression of those diseases. Also, amino acids (e.g., taurine, arginine, glycine, proline, and 4-hydroxyproline), and glucosamine reduce inflammation and pain in animals with bone and joint disorders. Gaining insight into how amino acids function in maintaining bone and joint health can aid in developingpreventative diets and therapeutic supplementations of amino acids to improve the quality of life in companion animals.

Deep learning to overcome Zernike phase-contrast nanoCT artifacts for automated micro-nano porosity segmentation in bone.

Bone material contains a hierarchical network of micro- and nano-cavities and channels, known as the lacuna-canalicular network (LCN), that is thought to play an important role in mechanobiology and turnover. The LCN comprises micrometer-sized lacunae, voids that house osteocytes, and submicrometer-sized canaliculi that connect bone cells. Characterization of this network in three dimensions is crucial for many bone studies. To quantify X-ray Zernike phase-contrast nanotomography data, deep learning is used to isolate and assess porosity in artifact-laden tomographies of zebrafish bones. A technical solution is proposed to overcome the halo and shade-off domains in order to reliably obtain the distribution and morphology of the LCN in the tomographic data. Convolutional neural network (CNN) models are utilized with increasing numbers of images, repeatedly validated by `error loss' and `accuracy' metrics. U-Net and Sensor3D CNN models were trained on data obtained from two different synchrotron Zernike phase-contrast transmission X-ray microscopes, the ANATOMIX beamline at SOLEIL (Paris, France) and the P05 beamline at PETRA III (Hamburg, Germany). The Sensor3D CNN model with a smaller batch size of 32 and a training data size of 70 images showed the best performance (accuracy 0.983 and error loss 0.032). The analysis procedures, validated by comparison with human-identified ground-truth images, correctly identified the voids within the bone matrix. This proposed approach may have further application to classify structures in volumetric images that contain non-linear artifacts that degrade image quality and hinder feature identification.

Osteopontin as a marker of endometriosis - the current state of knowledge.

Endometriosis is a disease affecting mainly women of childbearing age, where ectopic endometrial lesions occur outside the uterine cavity. Its main symptoms are chronic pain, infertility and dysmenorrhea. These symptoms significantly reduce the quality of life of patients suffering from this disease. Despite advanced research, the exact etiopathogenesis of endometriosis is still unknown and various theories explaining its origin are postulated in the course of research. Osteopontin is a protein originally discovered in the bone matrix and then in various tissues and organs of the body such as the kidneys, lungs, reproductive organs, vascular epithelial cells or some cancer cells. It is involved in processes such as cell adhesion and migration, angiogenesis and the promotion of tumor cell metastasis. These processes play a role in the pathogenesis of endometriosis, hence intensive research on the role of osteopontin in the development of this disease is an interesting research direction.

Nanofibrous electrospun scaffold doped with hydroxyapatite derived from sand lobster shell (Panulirus homarus) for bone tissue engineering.

Healing of significant segmental bone defects remains a challenge, and various studies attempt to make materials that mimic bone structures and have biocompatibility, bioactivity, biodegradability, and osteoconductivity to native bone tissues. In this work, a nanofiber scaffold membrane of polyvinyl alcohol (PVA)/polyvinylpyrrolidone (PVP)/chitosan (CS) combined with hydroxyapatite (HAp) from sand lobster (SL; Panulirus homarus) shells, as a calcium source, was successfully synthesized to mimic the nanoscale extracellular matrix (ECM) in the native bone. The HAp from SL shells was synthesized by co-precipitation method with Ca/P of 1.67 and incorporated into the nanofiber membrane PVA/PVP/CS synthesized by the electrospinning method with varying concentrations, i.e. 0, 1, 3, and 5% (w/v). Based on the morphological and physicochemical analysis, the addition of HAp into the nanofiber successfully showed incorporation into the nanofiber with small agglomeration at HAp concentrations of 1, 3, and 5% (w/v). This led to a smaller fiber diameter with higher concentration of Hap, and incorporating HAp into the nanofiber could improve the mechanical properties of the nanofiber closer to the trabecula bone. Moreover, in general, swelling due to water absorption increases due to higher hydrophilicity at higher HAp concentrations and leads to the improvement of the degradation process and protein adsorption of the nanofiber. Biomineralization in a simulated body fluid (SBF) solution confirms that the HAp in the nanofiber increases bioactivity, and it can be seen that more apatite is formed during longer immersion in the SBF solution. The nanofiber PVA/PVP/CS HAp 5% has the most potential for osteoblast (MC3T3E1) cell viability after being incubated for 24 h, and it allowed the cell to attach and proliferate. Additionally, the higher HAp concentration in the nanofiber scaffold membrane can significantly promote the osteogenic differentiation of MC3T3E1 cells. Overall, the PVA/PVP/CS/HAp 5% nanofiber scaffold membrane has the most potential for bone tissue engineering.

Synthesis of new alendronate analogs for bone-targeted drug delivery strategies

1-Hydroxymethylene-1,1-bisphosphonate (HMBP) derivatives bearing a tunable side-chain function (azide, amine or maleimide) were developed to be used as bone vectors for imagery and bioactive compounds.

Management of unicameral bone cysts by intramedullary flexible nails: a series of 18 children

Abstract Introduction The intracystic injection of methylprednisolone acetate, curettage with bone grafting, osteoinductive treatments employing demineralized bone matrix, and intramedullary fixation with flexible nails are being used to treat unicameral bone cysts (UBC) in children. The purpose of this study was to assess the functional results of elastic stable intramedullary nails for symptomatic UBC with or without a fracture. Methods From March 2012 to March 2022, 18 patients with UBC were treated with intramedullary flexible nails. Pathological fractures were present at the cyst site in 6 individuals. 12 patients had discomfort and swelling in the afflicted extremity. Cysts were found in the humerus in 13 (72%) patients and the femur in 5 (28%) cases. The average age of the patient at the time of surgery was 7.8 (6–12 years), and the average follow-up period was 16 months. The Capanna et al. criteria were used to do the radiographic evaluation. Results According to radiological evaluation by Capanna et al., 5 cysts healed completely (Stage I), 5 cysts healed with residual radiolucent areas visible on radiographs that were less than 3 cm in size (Stage II), and 7 cysts healed with residual radiolucent areas that were visible on radiographs that were larger than 3 cm in size (Stage III). An infection at the surgery site affected one patient. A 12 (60%) patients had their implants removed. Conclusion Elastic stable intramedullary nailing promotes early stabilization, enables early mobilization, eliminates the need for a plaster cast, and reduces the occurrence of a pathological fracture with early return to functional activity.

The ontogenetic status of a small hadrosauroid dinosaur from the uppermost Cretaceous of Bulgaria, and implications for the paleobiogeography and assembly of European island faunas

During the latest Cretaceous hadrosauroids were the most numerous and taxonomically diverse herbivorous dinosaurs on the European island archipelago, including diminutive non-hadrosaurid hadrosauroids and lambeosaurine immigrants from Asia and, possibly, from North America. In recent years the existence of small-bodied adult hadrosauroids (or ‘island dwarfs’) in the Maastrichtian of Romania and Spain has been confirmed by histological study of their bones. The first fossils attributable to Hadrosauroidea discovered in Bulgaria (from the upper Maastrichtian Kaylaka Formation) are also of diminutive size, but it has been unclear whether the bones belonged to small adults or simply to juveniles. Here, we subjected a tibia, fibula, indeterminate long bone diaphyseal fragment, and six indeterminate bone fragments, which are associated with the hadrosauroid hind limb elements and assumed to had been broken off from one or more of them during excavation, to a histological analysis. The analysis shows that the specimens belong to a young, actively growing individual(s), as evidenced by the presence of highly vascularized primary tissues in the outer cortex, secondary remodelling mostly restricted to certain areas of the bone sections, and absence of annual growth lines or an external fundamental system that would signify skeletal maturity. The bone matrix of the periosteal tissues exhibits high amounts of parallel-fibered and lamellar bone, similar to the long bones of other European island-living non-avian dinosaurs, a feature probably linked to lower growth rates. In general, the histomorphology and size of the Bulgarian hadrosauroid correspond well with ‘late juveniles’ and young ‘subadults’ in the osteohistologically well-studied hadrosauroid Maiasaura peeblesorum. The presence of a medium-sized hadrosauroid in the south-eastern part of the Late Cretaceous European archipelago suggests a dispersal route that allowed large-bodied terrestrial fauna to populate emergent islands in the region.

Static magnetic field enhances the bone remodelling capacity of human demineralized bone matrix in a rat animal model of cranial bone defects.

The regeneration of bone defects that exceed 2 cm is a challenge for the human body, necessitating interventional therapies. Demineralized bone matrices (DBM) derived from biological tissues have been employed for bone regeneration and possess notable osteoinductive and osteoconductive characteristics. Nevertheless, their efficiency in regenerating critically sized injuries is limited, and therefore additional signaling cues are required. Thanks to the piezoelectric properties of the bone, external physical stimulation is shown to accelerate tissue healing. We have implanted human DBM in critically sized cranial bone defects in rat animal models and exposed them to an external magnetic field (1 T) to enhance endogenous bone formation. Our in vitro experiments showed the superior cytocompatibility of DBM compared to cell culture plates. Furthermore, alkaline phosphatase activity after 14 days and Alizarin red staining at 28 days demonstrated differentiation of rat bone marrow mesenchymal stem cells into bone lineage on DBM. Computer tomography images together with histological analyses showed that implanting DBM in the injured rats significantly enhanced bone regeneration. Notably, combining DBM transplantation with a 2 h daily exposure to a 1 T magnetic field for 2 weeks (day 7 to 21 post-surgery) significantly improved bone regeneration compared to DBM transplantation alone. This research indicates that utilizing external magnetic stimulation significantly enhances the potential of bone allografts to regenerate critically sized bone defects.

Preparation and Characterization of Demineralised Bone Matrix from Fish Waste

Due to its osteoinductive and osteoconductive qualities, demineralized bone matrix (DBM) is a desirable biomaterial frequently utilised in tissue engineering and regenerative medicine. As a sustainable alternative to conventional sources like mammalian bones, we set out to create and characterise DBM made from fish waste, primarily fish bones. Several methodologies were used to thoroughly characterise the generated DBM. The chemical composition was examined using Fourier-transform infrared spectroscopy (FTIR), which also served to confirm the removal of mineral components. In order to analyse the DBM's microstructure and surface morphology, scanning electron microscopy (SEM) was performed. According to FTIR measurement, the DBM showed a considerable decrease in mineral content, demonstrating successful demineralization. A porous structure with linked pores was visible in SEM images, allowing for nutrition diffusion and cell penetration. Additionally, the DBM's biological characteristics were assessed. Studies using in vitro cell cultures showed that the DBM might help human mesenchymal stem cells adhere, proliferate, and differentiate into osteogenic cells. Through in vivo animal studies, the osteoinductive ability of the DBM was evaluated. The implanted DBM stimulated new bone production in a rat calvarial deficiency model. As a result of our study's successful preparation and characterisation of DBM from fish waste, we now have a reliable and affordable supply for this important biomaterial. Positive characteristics of the demineralized fish bone matrix included reduced mineral content, porosity structure, and osteoinductive capability. These results demonstrate the possibility of DBM generated from fish waste as a promising substitute for bone regeneration applications.

Biomechanical Study of 3 Osteoconductive Materials Applied in Pedicle Augmentation and Revision for Osteoporotic Vertebrae: Allograft Bone Particles, Calcium Phosphate Cement, Demineralized Bone Matrix.

This study assessed biomechanical properties of pedicle screws enhanced or revised with 3 materials. We aimed to compare the efficacy of these materials in pedicle augmentation and revision. One hundred twenty human cadaveric vertebrae were utilized for in vitro testing. Vertebrae bone density was evaluated. Allograft bone particles (ABP), calcium phosphate cement (CPC), and demineralized bone matrix (DBM) were used to augment or revise pedicle screw. Post the implantation of pedicle screws, parameters such as insertional torque, pullout strength, cycles to failure and failure load were measured using specialized instruments. ABP, CPC, and DBM significantly enhanced biomechanical properties of the screws. CPC augmentation showed superior properties compared to ABP or DBM. ABP-augmented screws had higher cycles to failure and failure loads than DBM-augmented screws, with no difference in pullout strength. CPC-revised screws exhibited similar strength to the original screws, while ABP-revised screws showed comparable cycles to failure and failure loads but lower pullout strength. DBM-revised screws did not match the original screws' strength. ABP, CPC, and DBM effectively improve pedicle screw stability for pedicle augmentation. CPC demonstrated the highest efficacy, followed by ABP, while DBM was less effective. For pedicle revision, CPC is recommended as the primary choice, with ABP as an alternative. However, using DBM for pedicle revision is not recommended.