Matrix Mineralization Research Articles

Mechanical behavior of bio-aggregates based buildings materials

This Technical Letter examines the mechanical behaviour of bio-aggregate building materials (BBM), focusing on their performance under compressive, flexural and shear loading. The study synthesises the findings of various RILEM technical committees and recent research, highlighting the unique properties of BBM compared to conventional concrete. The paper discusses the factors influencing the mechanical behaviour of BBM, including bioaggregate type, volume fraction, morphology, mineral matrix, mix design, casting process and curing conditions. It presents detailed analyses of the BBM response under different loading conditions, highlighting the different phases observed during testing. The use of Digital Image Correlation (DIC) as an advanced measurement tool to capture BBM deformation is explored, providing insights into the heterogeneity and local behaviour of the material. The importance of the Interface Transition Zone (ITZ) between bio-aggregates and matrix is highlighted, with a focus on its formation and impact on mechanical properties. The paper also outlines the perspectives of a new technical committee aimed at harmonising test procedures and developing scientific data analysis methods for BBM. This comprehensive review provides valuable insights for researchers and practitioners working with bio-based building materials, paving the way for improved understanding and standardisation of the mechanical characterisation of BBM.

Dose-dependent enhancement of in vitro osteogenic activity on strontium-decorated polyetheretherketone

Polyetheretherketone (PEEK) is widely used in orthopedic and dental implants due to its excellent mechanical properties, chemical stability, and biocompatibility. However, its inherently bioinert nature makes it present weak osteogenic activity, which greatly restricts its clinical adoption. Herein, strontium (Sr) is incorporated onto the surface of PEEK using mussel-inspired polydopamine coating to improve its osteogenic activity. X-ray photoelectron spectroscopy and ion release assay results confirm that different concentrations of Sr are incorporated onto the PEEK substrate surfaces. The strontium-modified PEEK samples show a stable Sr ion release in 35 days of detection. Better results of MC3T3-E1 pre-osteoblasts adhesion, spreading, and proliferation can be observed in strontium-modified PEEK groups, which demonstrates strontium-modified PEEK samples with the improved MC3T3-E1 pre-osteoblasts compatibility. The boosted osteogenic activity of strontium-modified PEEK samples has been demonstrated by the better performed of ALP activity, extracellular matrix mineralization, collagen secretion, and the remarkable up-regulation of ALP, OCN, OPN, Runx2, Col-I, BSP, and OSX of the MC3T3-E1 pre-osteoblasts. Additionally, the strontium-modified PEEK samples exhibit a dose-dependent enhancement of osteoblasts compatibility and osteogenic activity, and the PEEK-Sr10 group shows the best. These findings indicate that strontium-decorated PEEK implants show promising application in orthopedic and dental implants.

SARS-CoV-2 Impairs Osteoblast Differentiation Through Spike Glycoprotein and Cytokine Dysregulation

Pulmonary and extrapulmonary manifestations have been reported following infection with SARS-CoV-2, the causative agent of COVID-19. The virus persists in multiple organs due to its tropism for various tissues, including the skeletal system. This study investigates the effects of SARS-CoV-2 infection, including both ancestral and Omicron viral strains, on differentiating mesenchymal stem cells (MSCs), the precursor cells, into osteoblasts. Although both viral strains can productively infect osteoblasts, precursor cell infection remained abortive. Viral exposure during osteoblast differentiation demonstrates that both variants inhibit mineral and organic matrix deposition. This is accompanied by reduced expression of runt-related transcription factor 2 (RUNX2) and increased levels of interleukin-6 (IL-6), a cytokine that negatively regulates osteoblast differentiation. Furthermore, the upregulation of receptor activator of nuclear factor kappa B ligand (RANKL) strongly suggests that the ancestral and Omicron variants may disrupt bone homeostasis by promoting osteoclast differentiation, ultimately leading to the formation of bone-resorbing cells. This process is dependent of spike glycoprotein since its neutralization significantly reduced the effect of infective SARS-CoV-2 and UV-C inactivated virus. This study underscores the capacity of ancestral and Omicron SARS-CoV-2 variants to disrupt osteoblast differentiation, a process essential for preserving the homeostasis and functionality of bone tissue.

Exposure of Xenogeneic Biomaterial to the Oral Environment and Its Impact on Tissue Healing of Immediate Dental Implants: A Case–Control Study

This study evaluated the clinical and tomographic outcomes of socket healing. Immediate implants were placed in the molar area, and the gap was filled with either deproteinized bovine bone mineral (B) or collagen matrix (BM), n = 14/group. Scores of epithelization healing, immunoassay for VEGF, IL-1β, and FGF from wound exudate, keratinized mucosa variation (ΔKM), and bone levels were evaluated. The B group had slower tissue maturation than BM (p < 0.05), but gingival epithelialization was similar (p > 0.05). At the restorative phase, the B group exhibited greater ΔKM at prosthesis installation—1 to 2 months of postoperative (increase of 0.29 mm) compared to the BM group (reduction of −1.5 mm) (p < 0.05). Inflammatory tissue responses as well as vertical and horizontal bone remodeling were similar (p > 0.05). Crestal bone remodeling was limited to less than 0.8 mm for both groups. Taken together, the B and BM groups behaved similarly and promoted stable conditions for biomaterial incorporation in the socket healing after immediate implant placement in molar areas.

Palm Tocotrienol Activates the Wnt3a/β-Catenin Signaling Pathway, Protecting MC3T3-E1 Osteoblasts from Cellular Damage Caused by Dexamethasone and Promoting Bone Formation.

Background and aim: Prolonged glucocorticoid (GC) treatment increases oxidative stress, triggers apoptosis of osteoblasts, and contributes to osteoporosis. Tocotrienol, as an antioxidant, could protect the osteoblasts and preserve bone quality under glucocorticoid treatment. From this study, we aimed to determine the effects of tocotrienol on MC3T3-E1 murine pre-osteoblastic cells treated with GC. Methods: MC3T3-E1 cells were exposed to dexamethasone (150 µM), with or without palm tocotrienol (PTT; 0.25, 0.5, and 1 µg/mL). Cell viability was measured by the MTS assay. Alizarin Red staining was performed to detect calcium deposits. Cellular alkaline phosphatase activity was measured to evaluate osteogenic activity. The expression of osteoblastic differentiation markers was measured by an enzyme-linked immunoassay. Results: Enhanced matrix mineralization was observed in the cells treated with 0.5 µg/mL PTT, especially on day 18 (p < 0.05). The expression of Wnt3a, β-catenin, collagen 1α1, alkaline phosphatase, osteocalcin, low-density lipoprotein receptor-related protein 6, and runt-related transcription factor-2 were significantly increased in the PTT-treated groups compared to the vehicle control group, especially at 0.5 µg/mL of PTT (p < 0.05) and on day 6 of treatment. Conclusions: PTT maintains the osteogenic activity of the dexamethasone-treated osteoblasts by promoting their differentiation.

The proneural transcription factor Atoh1 promotes odontogenic differentiation in human dental pulp stem cells (DPSCs)

BackgroundBioengineering of human teeth for replacement is an appealing regenerative approach in the era of gene therapy. Developmentally regulated transcription factors hold promise in the quest because these transcriptional regulators constitute the gene regulatory networks driving cell fate determination. Atonal homolog 1 (Atoh1) is a transcription factor of the basic helix-loop-helix (bHLH) family essential for neurogenesis in the cerebellum, auditory hair cell differentiation, and intestinal stem cell specification. The functional versatility of Atoh1 prompted us to test the possibility that Atoh1 may intersect the dental pulp stem cell (DPSC) gene regulatory network governing odontogenic differentiation.MethodsWe isolated DPSCs from human dental pulps and treated the cells with a replication-deficient adenoviral vector to achieve robust ectopic expression of Atoh1, following which the growth and odontogenic differentiation profiles of DPSCs were characterized.ResultsDPSCs harboring the Atoh1 expression vector exhibited an approximately 3,000-fold increase in the expression of Atoh1 compared to the negative control, leading to increased DPSC proliferation in the growth medium (P < 0.05). In the odontogenic medium, Atoh1 caused an early induction of BMP2 (P < 0.001) followed by a late induction of BMP7 (P < 0.01) and increased Wnt signaling (P < 0.01). The increased BMP/Wnt signaling led to up to 8-fold increased expression of the master osteogenic transcription factor Osterix (P < 0.005) while exhibiting no significant effect on Runx2 or Dlx5, which are abundantly expressed in DPSCs. Atoh1 stimulated expression of type I collagen (P < 0.005) and small integrin-binding ligand, N-linked glycoproteins (SIBLINGs) such as bone sialoprotein (P < 0.001), dentin matrix protein 1 (P < 0.05), dentin sialophosphoprotein (P < 0.005), and osteopontin (P < 0.001), resulting in increased dentin matrix mineralization (P < 0.05). The odontogenic phenotype is associated with metabolic remodeling marked by enhanced glycolytic flux and attenuated mitochondrial metabolic enzyme activities.ConclusionsAtoh1, despite being a proneural transcription factor in development, possesses a novel odontogenic function upon ectopic expression in DPSCs. This in vitro study demonstrates a novel odontogenic mechanism mediated by ectopic expression of the transcription factor Atoh1 in human DPSCs. The finding may offer an innovative strategy for gene-based regeneration of the pulp-dentin complex.

Biomimetic Extracellular Vesicles Containing Biominerals for Targeted Osteoporosis Therapy.

Osteoporosis (OP) is a systemic skeletal disorder characterized by decreased bone mineral density and a heightened risk of fractures. Therapies for OP have primarily focused on balancing bone formation and bone resorption, but enhancing the remineralization of osteoporotic bone is also a key strategy for effective repair. Recent insights into biomineralization mechanisms have highlighted the essential role of mineral-containing extracellular vesicles (EVs) secreted by osteoblasts in promoting bone marrow mesenchymal stromal/stem cell (BMSC) differentiation and initiating matrix mineralization. Drawing from these principles, we developed a biomimetic approach to replicate the structure and function of the osteoblast-derived EVs by engineering biomimetic mitochondrial minerals with bone marrow homing cell membranes (CMs). This bone-targeted biomimetic system exhibits excellent biocompatibility, enhancing osteogenic differentiation and stimulating angiogenesis by regulating cellular energy metabolism. Additionally, the CM-coated structure shows affinity for collagen fibrils, effectively enhancing intrafibrillar collagen mineralization, thereby facilitating osteoporotic bone repair. Overall, the biomimetic system offers a safe and efficient therapeutic alternative, positioning it as a platform for bone tissue engineering and regenerative medicine.

Nanostructured TiO2 Surface Enriched with CeO2 over Ti Metal for Enhanced Cytocompatibility and Osseointegration for Biomedical Applications.

The present study aims to analyze the thermal regulation of the Ce3+/Ce4+ ratio on the nanonetwork titania layer over the titanium (Ti) surface developed by the alkali-mediated surface modification approach. The effect of sequential heat treatment from 200 to 800 °C was evaluated for its surface characteristics such as morphology, phase formation, roughness, hardness, hydrophilicity, etc. Surface oxidation by temperatures up to 600 °C demonstrated a progressive increase in the Ce4+ (CeO2) content with a rutile TiO2 network layer over the Ti surface. In contrast, a bulk reduction with increased Ce3+ (Ce2O3) content was observed at 800 °C. Heat treatment at 800 °C was also characterized by an improved nanohardness and roughness with a distorted surface network layer. The coexistence of Ce4+/Ce3+ (CeO2/Ce2O3) on a porous titania layer displayed a noticeable enhancement in antibacterial activity, which was evaluated against Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria. The surface-modified sample heat-treated at 600 °C and enriched with a high Ce4+/Ce3+ ratio revealed enhanced cell compatibility toward MG-63 in terms of cell adhesion, noncytotoxicity, and mitochondrial membrane potential with higher extracellular matrix mineralization. Further, in vivo bone defect investigations in a rat model using additively manufactured cancellous Ti scaffolds functionalized with surface incorporation of Ce ions heat-treated at 600 °C demonstrated significant enhancement in the osseointegration potential observed from histological and micro-computed tomography analyses. The upregulation of osteogenic marker genes (ALP, OCN, OPN, OSX, and RUNX2) at the implantation site evaluated by reverse transcription polymerase chain reaction confirmed the osteogenic potential of ceria surface functionalization. Hence, the Ce-incorporated nanostructured titania layer predominantly possessing a high Ce4+/Ce3+ ratio or CeO2 content on Ti metal is expected to reduce the risk of implant-related infections and improve cellular responses in orthopedic applications.

Autologous and Heterologous Minor and Major Bone Regeneration with Platelet-Derived Growth Factors.

This review aims to explore the clinical applications, biological mechanisms, and potential benefits of concentrated growth factors (CGFs), autologous materials, and xenografts in bone regeneration, particularly in dental treatments such as alveolar ridge preservation, mandibular osteonecrosis, and peri-implantitis. A systematic literature search was conducted using databases like PubMed, Scopus, and Web of Science, with keywords such as "bone regeneration" and "CGF" from 2014 to 2024. Only English-language clinical studies involving human subjects were included. A total of 10 studies were selected for qualitative analysis. Data were processed through multiple stages, including title and abstract screening and full-text evaluation. The findings of the reviewed studies underscore the potential of the CGF in enhancing bone regeneration through stimulating cell proliferation, angiogenesis, and extracellular matrix mineralization. Autologous materials have also demonstrated promising results due to their biocompatibility and capacity for seamless integration with natural bone tissue. When combined with xenografts, these materials show synergistic effects in improving bone quantity and quality, which are crucial for dental implant success. Future research should focus on direct comparisons of different techniques, the optimization of protocols, and broader applications beyond dental medicine. The integration of CGFs and autologous materials into routine clinical practice represents a significant advancement in regenerative dental medicine, with the potential for improved patient outcomes and satisfaction.

Adipose-Derived Stromal Cell Conditioned Medium on Bone Remodeling: Insights from a 3D Osteoblast-Osteoclast Co-Culture Model.

This study describes the potential of the conditioned medium (CM) from adipose-derived mesenchymal stromal cells (ASCs) to affect the response of bone cells and support bone remodeling. This was in particular assessed by an in vitro model represented by a 3D human osteoblast-osteoclast co-culture. It has been reported that the effects of ASCs are predominantly attributable to the paracrine effects of their secreted factors, that are present as soluble factors or loaded into extracellular vesicles. They may affect various biological processes, including bone turnover. Our interest was to provide further evidence to support ASC-CM as a promising cell-free therapeutic agent for the treatment of bone loss. ASC-CM was characterized using nanoparticle tracking analysis (NTA), cytofluorimetry, and proteomic analysis. Human osteoblasts (hOBs) from vertebral lamina were cultured with monocytes, as osteoclasts (hOCs) precursors, in a Rotary cell culture system for 14days. Histochemical analysis was performed to evaluate the effect of ASC-CM on bone-specific markers such as tartrate-resistant acid phosphatase (TRAP), osteopontin (OPN), RUNX2, Collagen 1 (COL1), and mineral matrix. ASC-CM characterization confirmed the content of CD63/CD81/CD9 positive extracellular vesicles. Proteomic dataset considering bone-remodeling-related keywords identified 16 processes significantly enriched. The exposure of hOBs/hOCs aggregates to ASC-CM induced increase of OPN, COL I, and RUNX2, and significantly induced mineral matrix deposition, while significantly reducing TRAP expression. These data demonstrated that CM from ASCs contains a complex of secreted factors able to control either bone resorption or bone formation and requires further investigations to deeply analyze their potential therapeutic effects.

Skeletal and dental tissue mineralization: The potential role of the endoplasmic reticulum/Golgi complex and the endolysosomal and autophagic transport systems.

This paper presents a review of the potential role of the endoplasmic reticulum/Golgi complex and intracellular vesicles in mediating events leading to or associated with vertebrate tissue mineralization. The possible importance of these organelles in this process is suggested by observations that calcium ions accumulate in the tubules and lacunae of the endoplasmic reticulum and Golgi. Similar levels of calcium ions (approaching millimolar) are present in vesicles derived from endosomes, lysosomes and autophagosomes. The cellular level of phosphate ions in these organelles is also high (millimolar). While the source of these ions for mineral formation has not been identified, there are sound reasons for considering that they may be liberated from mitochondria during the utilization of ATP for anabolic purposes, perhaps linked to matrix synthesis. Published studies indicate that calcium and phosphate ions or their clusters contained as cargo within the intracellular organelles noted above lead to formation of extracellular mineral. The mineral sequestered in mitochondria has been documented as an amorphous calcium phosphate. The ion-, ion cluster- or mineral- containing vesicles exit the cell in plasma membrane blebs, secretory lysosomes or possibly intraluminal vesicles. Such a cell-regulated process provides a means for the rapid transport of ions or mineral particles to the mineralization front of skeletal and dental tissues. Within the extracellular matrix, the ions or mineral may associate to form larger aggregates and potential mineral nuclei, and they may bind to collagen and other proteins. How cells of hard tissues perform their housekeeping and other biosynthetic functions while transporting the very large volumes of ions required for mineralization of the extracellular matrix is far from clear. Addressing this and related questions raised in this review suggests guidelines for further investigations of the intracellular processes promoting the mineralization of the skeletal and dental tissues.

Comprehensive three-dimensional microCT and signaling analysis reveal the teratogenic effect of 2,3,7,8-tetrachlorodibenzo-p-dioxin on craniofacial bone development in mice.

Exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in utero can result in osteogenic defect during palatogenesis, but the effects on other craniofacial bones and underlying mechanisms remain to be characterized. By treating pregnant mice with TCDD (40 μg/kg) at the vital craniofacial patterning stages (embryonic day 8.5, 10.5 and 12.5), and scanning and reconstructing the skulls at embryonic day 18.5 using microCT, we found that TCDD exposure at the earlier and later patterning stages induced variable craniofacial malformations, including premature fusion of metopic and coronal sutures, truncated palatal processes of maxillary and palatine bones, as well as opening oriented pterygoid processes. Further in vitro determination of the underlying mechanisms using human fetal palatal mesenchymal cells (hFPMCs) revealed that TCDD suppressed a wide variety of osteogenic genes responsible for osteoblast commitment and bone matrix synthesis and mineralization, through activating aryl hydrocarbon receptor (AhR) signaling and subsequently inhibiting estrogen signaling. The attenuation of AhR signaling significantly blocked the osteogenic toxicity, and partly restored the expressing level of estrogen receptor α (ERα). Additional treatment with ERα agonist (PPT) significantly relieved the activation of AhR and rescued the impairment of osteogenesis caused by TCDD. Together, our findings demonstrated that TCDD was teratogenic in numerous cranial neural crest cell-derived craniofacial bone development, and disrupted multiple genes for osteogenic differentiation via the TCDD-mediated AhR/ ERα signaling cross-talk.

A novel chemical chaperone ameliorates osteoblast homeostasis and extracellular matrix in osteogenesis imperfecta.

Osteogenesis imperfecta (OI) is a collagen I-related heritable family of skeletal diseases associated to extreme bone fragility and deformity. Its classical forms are caused by dominant mutations in COL1A1 and COL1A2, which encode for the protein α chains, and are characterized by impairment in collagen I structure, folding, and secretion. Mutant collagen I assembles in an altered extracellular matrix affecting mineralization and bone properties and partially accumulating inside the cells, leading to impaired trafficking and cellular stress. Recently, the chemical chaperone 4-phenylbutyrate (4-PBA) has been proposed as an innovative drug for OI based on its ability to restore intracellular homeostasis, stimulate secretion, and ameliorate collagen-producing cell functions, positively affecting bone properties. However, the limited half-life of the molecule represents a serious hurdle for its use. To efficiently target cellular stress as OI treatment, two new compounds were designed by molecular modelling based on the 4-PBA structure to increase its stability and its ability to implement protein secretion. The short butyryl fatty acid chain of 4-PBA was substituted with a nitro functional group or with a glycine, respectively. The latter, N-benzyl glycine (N-BG), showed the best docking score, less toxicity, and higher stability than 4-PBA. N-BG improved extracellular matrix quality and mineral content together with ameliorating OI cells' homeostasis by increasing ER-associated degradation pathway, reducing apoptosis, and stimulating protein secretion, thus facilitating intracellular clearance from accumulated misfolded proteins. In conclusion, N-BG represents a novel potential available compound to target altered homeostasis in OI with the aim to ameliorate the disease phenotype.

Ano5Cys360Tyr mutation leads to bone dysfunction of gnathodiaphyseal dysplasia via disturbing Akt signaling.

Gnathodiaphyseal dysplasia (GDD) is a rare autosomal dominant genetic disease characterized by osteosclerosis of the tubular bones and cemento-osseous lesions of the mandibles. Anoctamin 5 (ANO5) is the pathogenic gene, however, the specific molecular mechanism of GDD remains unclear. Herein, a knockin (Ano5 KI/KI ) mouse model expressing the human mutation p.Cys360Tyr was used to investigate the role of Akt signaling in enhanced osteogenesis and decreased osteoclastogenesis in GDD. Bone marrow-derived macrophages (BMMs) and mouse calvarial osteoblasts (mCOBs) were isolated from homozygous Ano5 KI/KI mice and treated with SC79, a specific Akt activator. The differentiation and F-actin ring formation of osteoclasts were examined by TRAP and phalloidin staining, respectively. Osteoblast differentiation and mineralization were examined by ALP and alizarin red staining. The expression of bone remodeling-related factors was measured by qRT-PCR. Akt activation promoted the generation of TRAP-positive multinucleated osteoclasts and the formation of actin rings in Ano5 KI/KI BMMs cultures, accompanied by increased expression of Nfatc1, Trap, Dc-stamp, Mmp9, Ctsk, and Atp6v0d2. Additionally, Ano5 Cys360Tyr mutation down-regulated the Akt phosphorylation level in osteoblast. ALP activity and matrix mineralization capacity in Ano5 KI/KI osteoblast cultures were inhibited after SC79 stimulation, with reduced expression of Runx2, Opn, Col1a1, and Ocn. Akt activation by SC79 stimulation can obviously rescue abnormal increased osteogenesis and decreased osteoclastogenesis in Ano5 KI/KI mouse model, which demonstrated that disturbed Akt signaling pathway may play a pivotal role in the pathogenesis of GDD, and an Akt activator is probable a therapeutic target for GDD.

PTX3-assembled pericellular hyaluronan matrix enhances endochondral ossification during fracture healing and heterotopic ossification.

Endochondral ossification (EO) is a pivotal process during fracture healing and traumatic heterotopic ossification (HO), involving the cartilaginous matrix synthesis and mineralization. Unlike the extracellular matrix, the hyaluronan (HA)-rich pericellular matrix (PCM) directly envelops chondrocytes, serving as the frontline for extracellular signal reception and undergoing dynamic remodeling. Pentraxin 3 (PTX3), a secreted glycoprotein, facilitates HA matrix assembly and remodeling. However, it remains unclear whether PTX3 affects EO by regulating HA-rich PCM assembly of chondrocytes, thereby impacting fracture healing and traumatic HO. This study demonstrates that PTX3 deficiency impairs fracture healing and inhibits traumatic HO, but dose not affect growth plate development in mice. PTX3 expression is up-regulated during chondrocyte matrix synthesis and maturation and is localized in the HA-rich PCM. PTX3 promotes the assembly of HA-rich PCM in a serum- and TSG-6-dependent manner, fostering CD44 receptor clustering, activating the FAK/AKT signaling pathway, and promoting chondrocyte matrix synthesis and maturation. Local injection of PTX3/TSG-6 matrix protein mixture effectively promotes fracture healing in mice. In conclusion, PTX3-assembled HA-rich PCM promotes chondrocyte matrix synthesis and maturation via CD44/FAK/AKT signaling. This mechanism facilitates EO during fracture healing and traumatic HO in mice.

SPP1-ITGα5/β1 Accelerates Calcification of Nucleus Pulposus Cells by Inhibiting Mitophagy via Ubiquitin-Dependent PINK1/PARKIN Pathway Blockade.

Low back pain (LBP) caused by nucleus pulposus degeneration and calcification leads to great economic and social burden worldwide. Unexpectedly, no previous studies have demonstrated the association and the underlying mechanism between nucleus pulposus tissue degeneration and calcification formation. Secreted Phosphoprotein 1 (SPP1) exerts crucial functions in bone matrix mineralization and calcium deposition. Here, a novel function of SPP1 is reported, namely that it can aggravate nucleus pulposus cells (NPs) degeneration by negatively regulating extracellular matrix homeostasis. The degenerated NPs have a higher mineralization potential, which is achieved by SPP1. Mechanistically, SPP1 can accelerate the degeneration of nucleus pulposus cells by activating integrin α5β1 (ITGα5/β1), aggravating mitochondrial damage and inhibiting mitophagy. SPP1-ITGα5/β1 axis inhibits mitophagy by PINK1/PARKIN pathway blockade. In conclusion, SPP1 activates ITGα5/β1 to inhibit mitophagy, accelerates NPs degeneration, and induces calcification, thereby leading to intervertebral disc degeneration (IVDD) and calcification, identifying the potentially unknown mechanism and relationship between IVDD and calcification. Important insights are provided into the role of SPP1 in nucleus pulposus calcification in IVDD by inducing nucleus pulposus cell senescence through inhibition of mitophagy and may help develop potential new strategies for IVDD treatment.

Identification of osteoid and chondroid matrix mineralization in primary bone tumors using a deep learning fusion model based on CT and clinical features: a multi-center retrospective study

We retrospectively collected CT scan data from 276 patients with pathologically confirmed primary bone tumors from 4 medical centers in Guangdong Province between January, 2010 and August, 2021. A convolutional neural network (CNN) was employed as the deep learning architecture. The optimal baseline deep learning model (R-Net) was determined through transfer learning, and an optimized model (S-Net) was obtained through algorithmic improvements. Multivariate logistic regression analysis was used to screen the clinical features such as sex, age, mineralization location, and pathological fractures, which were then connected with the imaging features to construct the deep learning fusion model (SC-Net). The diagnostic performance of the SC-Net model and machine learning models were compared with radiologists' diagnoses, and their classification performance was evaluated using the area under the receiver operating characteristic curve (AUC) and F1 score. In the external test set, the fusion model (SC-Net) achieved the best performance with an AUC of 0.901 (95% CI: 0.803-1.00), an accuracy of 83.7% (95% CI: 69.3%-93.2%) and an F1 score of 0.857, and outperformed the S-Net model with an AUC of 0.818 (95% CI: 0.694-0.942), an accuracy of 76.7% (95% CI: 61.4%-88.2%), and an F1 score of 0.828. The overall classification performance of the fusion model (SC-Net) exceeded that of radiologists' diagnoses. The deep learning fusion model based on multi-center CT images and clinical features is capable of accurate classification of osseous and chondroid matrix mineralization and may potentially improve the accuracy of clinical diagnoses of osteogenic versus chondrogenic primary bone tumors.

Coral reef rehabilitation following Hurricane Irma using nano-engineered artificial reefs in Sint Maarten.

Artificial reefs are being increasingly deployed as a coral reef restoration strategy. Additional reef habitats made from conventional substrates (e.g., metal, concrete, etc.) have had limited success in addressing conservation objectives on degraded coral reefs due to structure size and lack of standardized monitoring, and inability to enhance select ecological, and species variables. Technological advances and new restoration methods must be quickly tested and applied on a large scale to curb further deterioration of coral reefs. Here, we present the results of the first deployment of Oceanite artificial reefs (ARs). We compare the composition of the benthic community and associated fish assemblages on Oceanite ARs 14 months after deployment in a marine protected area (MPA) and two unprotected sites in Philipsburg, Sint Maarten. We also examined fish abundance and behaviour on the ARs. The initial results from this pilot study suggest that Oceanite mineral matrices can enhance local biodiversity, attract coral recruits, provide food and protection for large fish communities, and develop an early stage, healthy coral reef community in 14 months. We suggest that further research and testing of Oceanite capabilities will allow us to develop site-, species-, and function-specific nanotechnology-enabled substrates to optimize AR conservation goals. Oceanite mix designs can be tuned to precise parameters to promote reef restoration and stressor mitigation (e.g., pH, leachate emissions, surface texture, porosity, void structure, and hydrophobic, heat-absorbing, and disease-fighting properties). Using both bottom-up and top-down restoration processes, we suggest that deploying bio-enhancing habitats with targeted microclimate stressor treatments on the world's critical reefs will allow to build global refuges resilient to climate change and provide much needed ecosystem services.

Improvement of bone properties in children with osteogenesis imperfecta after pamidronate: a bone biopsy study.

OI, or bone brittle disease, is characterized by increased mineralization of bone matrix independently of clinical severity. So, a beneficial effect of antiresorptive treatments such as bisphosphonates (BP) is questionable. We aim to compare the bone matrix characteristics before and after BP pamidronate (PAM). Fifty-eight children (9 ± 5yr-old) with OI (Type I, III, IV, V, VI, XI, or unknown) received intravenous PAM for 2yr and underwent transiliac bone biopsies before (n = 57) and after (n = 35) treatment. Compared with age-matched controls, untreated OI was characterized by cortical and cancellous rarefaction. Two years of PAM in OI patients significantly decreased bone remodeling activity, increased cortical thickness, improved the maturation of both organic and mineral matrix, and most of the nanomechanical properties, despite further increase in the degree of mineralization. Overall, in addition to a gain in bone mass, our results showed for the first time that PAM is able to increase the maturation of mineral crystals and collagen matrix contributing to its antifracture efficacy in OI patients.

Two-sided function of osteopontin during osteoblast differentiation.

Osteopontin (OPN) is expressed in various cell types including osteoblasts. OPN expression level is robustly increased during osteoblast differentiation. Although OPN was initially found as a secretory protein (sOPN), recent reports identified the intracellular isoform of OPN (iOPN). Distinct functions of each OPN isoform in osteoblasts, however, are not well established. Here, using the Tet-On inducible expression system, we examined the role of each OPN isoform during osteoblast differentiation. Induced overexpression of wild type OPN (wtOPN), which includes both sOPN and iOPN, significantly increased matrix mineralization and osteogenic marker gene expression during osteogenic differentiation induced by either ascorbic acid or bone morphogenetic protein (BMP) 9. In contrast, these osteogenic differentiation processes were significantly inhibited by the specific overexpression of iOPN. Furthermore, the addition of recombinant OPN or neutralizing anti-OPN antibody to the culture medium exerted promotive or inhibitory effect on osteoblast differentiation, respectively. These data strongly indicate that iOPN exerts inhibitory effects on osteoblast differentiation, whereas sOPN exerts positive effects. We also found that the secretion process of OPN is positively regulated by c-Jun N-terminal kinase (JNK) activity in osteoblasts.