Matrix Vesicles Research Articles

Ultrastructural evaluation of adverse effects on dentine formation from systemic fluoride application in an experimental mouse model.

Fluoride is widely used in dentistry for its caries prevention. To reduce dental caries, the optimal fluoride concentration of public water supplies in the United States is 0.7 ppm. However, excessive systemic fluoride consumption can lead to dental/enamel fluorosis. Numerous studies have explored the effects of fluoride on enamel and enamel-forming cells. However, research on systemic fluoride's impact on dentine is limited, particularly the effect of fluoride on the structure of the dentine-pulp complex. Therefore, this study aimed to identify how excessive fluoride affects dentine microstructure using an experimental mouse model. C57BL6/J male mice (6-9 weeks old) were randomized into four groups (Fluoride at 0, 50, 100, or 125 ppm in drinking water) (n = 4/group). Mice were provided water adlibitum for 6 weeks along with fluoride-free food. Thereafter, mandibular incisors were analysed. Enamel phenotypes were evaluated using light microscopy and quantitative light-induced fluorescence (QLF) to measure fluorosis levels. Dentine morphology was evaluated using micro-CT, scanning electron microscopy (SEM), SEM-EDX (energy-dispersive X-ray), microhardness test and histological imaging. Data were analysed using one-way ANOVA with Dunnett's multiple comparisons as a post hoc test and the Kruskal-Wallis test with Dunn's multiple comparisons post hoc test (p < .05). Mice treated with fluoride at 50-125 ppm developed enamel hypoplasia in their erupting incisors and micro-CT imaging revealed that fluoride 125 ppm caused external resorption of the growing incisor. Dentine mineral density, dentine volume decreased compared with the 0 ppm control, while pulp volume increased compared with the 0 ppm control group. SEM showed wider predentine layer and abnormalities in calcified matrix vesicles derived from odontoblasts in fluoride 100 and 125 ppm groups. Vickers microhardness of dentine significantly decreased in the high-dose group. Fluoride-induced dentine hypoplasia in a dose-dependent manner. Histological evaluation showed excessive fluoride 125 ppm induced micro abscess formation and inflammatory cell infiltration. Fluoride induced dentine dysplasia with a dentine microstructure resembling hypophosphatasia. High doses of systemic fluoride can cause dentine dysplasia. Both three-dimensional and microstructural analyses showed the structural, chemical and mechanical changes in the dentine and the mineralized tissue components, along with external resorption and pulp inflammation.

Matrix vesicles from osteoblasts promote atherosclerotic calcification

Atherosclerotic calcification often coincides with osteoporosis, suggesting a potential interplay between bone and vascular mineralization. Osteoblast-derived matrix vesicles (Ost-MVs), pivotal in bone mineralization, have emerged as potential contributors to ectopic vascular calcification. However, the precise role of Ost-MVs in vascular calcification and the underlying mechanisms remain elusive. In this study, we observed a concomitant increase in atherosclerotic calcification and bone loss, accompanied by elevated release of Ost-MVs into circulation. We demonstrate that circulating Ost-MVs target plaque lesions in the setting of atherosclerosis. Mechanistically, vascular injury facilitates transendothelial transport of Ost-MVs, collagen І remodeling promotes Ost-MVs aggregation, and vascular smooth muscle cell (VSMC) phenotypic switching enhances MV uptake. These pathological changes during atherosclerosis collectively contribute to Ost-MVs recruitment into the vasculature. Furthermore, Ost-MVs and VSMC-derived matrix vesicles (VSMC-MVs) exacerbate calcification via the Ras-Raf-ERK pathway. Our findings unveil a novel Ost-MVs-mediated mechanism participating in vascular calcification and enriching our understanding of bone-vascular crosstalk.

In-Stent Re-Endothelialization Strategies: Cells, Extracellular Matrix, and Extracellular Vesicles.

Arterial stenosis caused by atherosclerosis often requires stent implantation to increase the patency of target artery. However, such external devices often lead to in-stent restenosis due to inadequate re-endothelialization and subsequent inflammatory responses. Therefore, re-endothelialization strategies after stent implantation have been developed to enhance endothelial cell recruitment or to capture circulating endothelial progenitor cells. Notably, recent research indicates that coating stent surfaces with biogenic materials enhances the long-term safety of implantation, markedly diminishing the risk of in-stent restenosis. In this review, we begin by describing the pathophysiology of coronary artery disease and in-stent restenosis. Then, we review the characteristics and materials of existing stents used in clinical practice. Lastly, we explore biogenic materials aimed at accelerating re-endothelialization, including extracellular matrix, cells, and extracellular vesicles. This review helps overcome the limitations of current stents for cardiovascular disease and outlines the next phase of research and development.

The comparison of extracellular vesicles with matrix vesicles derived from human vascular smooth muscle versus bone osteoblastic and osteosarcoma cells

The comparison of extracellular vesicles with matrix vesicles derived from human vascular smooth muscle versus bone osteoblastic and osteosarcoma cells

Preparation and biological characteristics of extracellular matrix vesicle mimetics

Objective: To investigate the characteristics of extracellular matrix vesicle mimetics prepared by mechanical extrusion and their effects on the cell viability and osteogenic differentiation potential of human periodontal ligament stem cells (PDLSC). Methods: PDLSC derived extracellular matrix vesicles were prepared by collagenase digestion, while the cell derived vesicle mimetics were simulated by mechanical extrusion. The obtained extracellular matrix vesicles and parental cell derived vesicle mimetics were divided into 4 groups: matrix vesicles derived from PDLSC cultured in basic medium for 7 days (PDLSC matrix vesicles, MVs), vesicle mimetics derived from PDLSC cultured in basic medium for 7 days (PDLSC vesicle mimetics, CVMs), matrix vesicles derived from PDLSC cultured in osteogenic inducing medium for 7 days (osteogenic-induced PDLSC matrix vesicles, O-MVs) and vesicle mimetics derived from PDLSC cultured in osteogenic inducing medium for 7 days (osteogenic-induced PDLSC vesicle mimetics, O-CVMs). Vesicles morphologies and sizes were observed by transmission electron microscopy and nanoparticle tracking analysis. Vesicles uptake was detected by immunofluorescence. With PDLSC as the control group, the effects of vesicles on the viability of PDLSC were detected by cell activity assay (cell counting kit-8), and the effects of vesicles on the osteogenic differentiation potential of PDLSC were detected by alizarin red staining and Western blotting. Results: Vesicles in MVs, O-MVs, CVMs and O-CVMs were all observed with a round structure (size 50-250 nm), and could be taken up by PDLSC without affecting the cell viability. Under osteogenic inducing conditions, PDLSC incubated with O-MVs or O-CVMs could produce more mineralized nodules than those in the control group (PDLSC). MVs, O-MVs, CVMs and O-CVMs could promote the expression of osteogenic-related proteins in PDLSC. PDLSC in group O-CVMs showed significant higher expressions of osteogenic-related proteins, including alkaline phosphatase (ALP) (1.571±0.348), osteopontin (OPN) (1.827±0.627) and osteocalcin (OCN) (1.798±0.537) compared to MVs (ALP: 1.156±0.170, OPN: 1.260±0.293, OCN: 1.286±0.302) (P<0.05). Compared to CMVs-incubated PDLSC, O-CVMs-incubated PDLSC expressed more Runt-related transcription factor 2 (1.632±0.455 vs 1.176±0.128) and OPN (1.827±0.627 vs 1.428±0.427) (P<0.05). Moreover, there was no significant difference in the expression levels of osteoblast-related proteins in PDLSC cultured with MVs, O-MVs and CVMs (P>0.05). Conclusions: The vesicle mimetics prepared by mechanical extrusion method are similar in shape and size to the extracellular matrix vesicles. MVs, O-MVs, CVMs and O-CVMs do not affect the cell viability of PDLSC, and can promote the osteogenic differentiation potential of PDLSC to a certain extent.

Enzyme-Activated Biomimetic Vesicles Confining Mineralization for Bone Maturation.

Inspired by the crucial role of matrix vesicles (MVs), a series of biomimetic vesicles (BVs) fabricated by calcium glycerophosphate (CaGP) modified polyurethane were designed to mediate the mineralization through in situ enzyme activation for bone therapy. In this study, alkaline phosphatase (ALP) was harbored in the porous BVs by adsorption (Ad-BVs) or entrapment (En-BVs). High encapsulation of ALP on En-BVs was effectively self-activating by calcium ions of CaGP-modified PU that specifically hydrolyzed the organophosphorus (CaGP) to inorganic phosphate, thus promoting the formation of the highly oriented bone-like apatite in vitro. Enzyme-catalyzed kinetics confirms the regulation of apatite crystallization by the synergistic action of self-activated ALP and the confined microcompartments of BVs. This leads to a supersaturated microenvironment, with the En-BVs group exhibiting inorganic phosphate (Pi) levels 4.19 times higher and Ca2+ levels 3.67 times higher than those of simulated body fluid (SBF). Of note, the En-BVs group exhibited excellent osteo-inducing differentiation of BMSCs in vitro and the highest maturity with reduced bone loss in rat femoral defect in vivo. This innovative strategy of biomimetic vesicles is expected to provide valuable insights into the enzyme-activated field of bone therapy.

Smooth muscle NF90 deficiency ameliorates diabetic atherosclerotic calcification in male mice via FBXW7-AGER1-AGEs axis

Hyperglycemia accelerates calcification of atherosclerotic plaques in diabetic patients, and the accumulation of advanced glycation end products (AGEs) is closely related to the atherosclerotic calcification. Here, we show that hyperglycemia-mediated AGEs markedly increase vascular smooth muscle cells (VSMCs) NF90/110 activation in male diabetic patients with atherosclerotic calcified samples. VSMC-specific NF90/110 knockout in male mice decreases obviously AGEs-induced atherosclerotic calcification, along with the inhibitions of VSMC phenotypic changes to osteoblast-like cells, apoptosis, and matrix vesicle release. Mechanistically, AGEs increase the activity of NF90, which then enhances ubiquitination and degradation of AGE receptor 1 (AGER1) by stabilizing the mRNA of E3 ubiquitin ligase FBXW7, thus causing the accumulation of more AGEs and atherosclerotic calcification. Collectively, our study demonstrates the effects of VSMC NF90 in mediating the metabolic imbalance of AGEs to accelerate diabetic atherosclerotic calcification. Therefore, inhibition of VSMC NF90 may be a potential therapeutic target for diabetic atherosclerotic calcification.

The Na+/Ca2+ exchanger NCX3 mediates Ca2+ entry into matrix vesicles to facilitate initial steps of mineralization in osteoblasts.

Matrix vesicles (MVs) provide the initial site for amorphous hydroxyapatite (HA) formation within mineralizing osteoblasts. Although Na+/Ca2+ exchanger isoform-3 (NCX3, SLC8A3) was presumed to function as major Ca2+ transporter responsible for Ca2+ extrusion out of osteoblast into the calcifying bone matrix, its presence and functional role in MVs have not been investigated. In this study, we investigated the involvement of NCX3 in MV-mediated mineralization process and its impact on bone formation. Using differentiated MC3T3-E1 cells, we demonstrated that NCX3 knockout in these cells resulted in a significant reduction of Ca2+ deposition due to reduced Ca2+ entry within the MVs, leading to impaired mineralization. Consequently, the capacity of MVs to promote extracellular HA formation was diminished. Moreover, primary osteoblast isolated from NCX3 deficient mice (NCX3-/-) exhibits reduced mineralization efficacy without any effect on osteoclast activity. To validate this in vitro finding, μCT analysis revealed a substantial decrease in trabecular bone mineral density in both genders of NCX3-/- mice, thus supporting the critical role of NCX3 in facilitating Ca2+ uptake into the MVs to initiate osteoblast-mediated mineralization. NCX3 expression was also found to be the target of downregulation by inflammatory mediators in vitro and in vivo. This newfound understanding of NCX3's functional role in MVs opens new avenues for therapeutic interventions aimed at enhancing bone mineralization and treating mineralization-related disorders.

Multifunctional Composite Scaffold with Nanosilver, Graphene Oxide, and Macrophage Membrane Vesicles for Sequential Treatment of Infected Bone Defects.

The management of infected bone defects poses a significant clinical challenge, and current treatment modalities exhibit various limitations. This study focuses on the development of a multifunctional composite scaffold comprising nanohydroxyapatite/polyethyleneglycol diacrylate matrix, silver nanoparticles, graphene oxide (GO), sodium alginate, and M2-type macrophage membrane vesicles (MVs) to enhance the healing of infected bone defects. The composite scaffold demonstrates several key features: first, it releases sufficient quantities of silver ions to effectively eliminate bacteria; second, the controlled release of MVs leads to a notable increase in M2-type macrophages, thereby significantly mitigating the inflammatory response. Additionally, GO acts synergistically with nanohydroxyapatite to enhance osteoinductive activity, thereby fostering bone regeneration. Through meticulous in vitro and in vivo investigations, the composite scaffold exhibits broad-spectrum antimicrobial effects, robust immunomodulatory capabilities, and enhanced osteoinductive activity. This multifaceted composite scaffold presents a promising approach for the sequential treatment of infected bone defects, addressing the antimicrobial, immunomodulatory, and osteogenic aspects. This study introduces innovative perspectives and offers new and effective treatment alternatives for managing infected bone defects.

Comparative proteomic analysis of the ovarian fluid and eggs of Siberian sturgeon

BackgroundSturgeon species are living fossils that exhibit unique reproductive characteristics, and elucidation of the molecular processes governing the formation and quality of sturgeon eggs is crucial. However, comprehensive data on the protein composition of sturgeon ovarian fluid (OF) and eggs and their functional significance are lacking. To address this knowledge gap, the aim of the present study was to conduct a comprehensive comparative proteomic analysis of Siberian sturgeon OF and eggs using liquid chromatography–mass spectrometry (LC–MS/MS).ResultsA total of 617 proteins were identified in OF, and 565 proteins were identified in eggs. A total of 772 proteins showed differential abundance. Among the differentially abundant proteins, 365 were more abundant in OFs, while 407 were more abundant in eggs. We identified 339 proteins unique to OFs and 287 proteins specific to eggs, and further investigated the top 10 most abundant proteins in each. The functional annotation of the OF proteins highlighted their predominant association with immune system processes, including the complement and coagulation cascade, neutrophil and leukocyte-mediated immunity, cholesterol metabolism, and regulation of the actin cytoskeleton. Analysis of egg proteins revealed enrichment in metabolic pathways, such as oxidative phosphorylation and fatty acid metabolism, and protein ubiquitination and translation. OF-specific proteins included extracellular matrix and secretory vesicles, and eggs were enriched in proteins localized to mitochondria and ribosome components.ConclusionsThis study presents the first comprehensive characterization of the protein composition of sturgeon OF and eggs and elucidates their distinct functional roles. These findings advance our understanding of sturgeon reproduction, OF-egg signaling and the origin of OF proteins. The mass spectrometry proteomics data have been deposited in the ProteomeXchange Consortium with the dataset identifier PXD044168 to ensure accessibility for further research.

Lipids and Minerals, Interplay in Biomineralization: Nature's Alchemy.

The main focus of this article is the role of lipids in biomineralization. Much of the discussion on biomineralization focuses on proteins in these decades. Indeed, collagen and acidic noncollagenous proteins effectively serve as templates for mineralization. However, other macromolecules such as lipids and polysaccharides have received less attention despite their abundance at mineralization sites. The matrix vesicle (MV) theory is widely accepted as the induction of early mineralization. Although ion concentration within the vesicles has been discussed in the initial mineralization in this theory, the role of phospholipids that constitute the vesicle membrane has not been discussed much. Comprehensive considerations, including pathological mineralization, exist regardless of the localization of MVs, the involvement of bacteria in dental calculus formation, and biomineralization caused by marine organisms such as corals, suggesting that initial mineralization found in these biological conditions might be a common reaction relating to lipids. In contrast, despite the abundance of lipids, mineralization occurs only in the limited tissue within our body. In other words, gathering knowledge and creating a path to understanding about lipid-based mineralization is extremely important in proposing new bone disease treatment methods. This article describes how lipids influence nucleation, mineralization, and expansion during hard tissue formation.

Preparation of black phosphorus@sodium alginate microspheres with bone matrix vesicle structure via electrospraying for bone regeneration

Bone matrix vesicles are commonly acknowledged as the primary site of biomineralization in human skeletal tissue. Black phosphorus has exhibited favorable properties across various chemical and physical domains. In this investigation, a novel composite microsphere was synthesized through the amalgamation of sodium alginate (ALG) with black phosphorus nanosheets (BP) utilizing the electrospray (ES) technique. These microspheres were tailored to mimic the regulatory function of matrix vesicles (MV) upon exposure to a biomimetic mineralization fluid (SBF) during the biomineralization process. Results revealed that black phosphorus nanosheets facilitated the generation of hydroxyapatite (HA) on the microsphere surface. Live-dead assays and cell proliferation experiments showcased a cell survival rate exceeding 85 %. Moreover, wound healing assessments unveiled that M-ALG-BP microspheres exhibited superior migration capacity, with a migration rate surpassing 50 %. Furthermore, after 7 days of osteogenic induction, M-ALG-BP microspheres notably stimulated osteoblast differentiation. Particularly noteworthy, M-ALG-BP microspheres significantly enhanced osteogenic differentiation of osteoblasts and induced collagen production in vitro. Additionally, experiments involving microsphere implantation into mouse skeletal muscle demonstrated the potential for ectopic mineralization by ALG-BP microspheres. This investigation underscores the outstanding mineralization properties of ALG-BP microspheres and their promising clinical prospects in bone tissue engineering.

Vascular Calcification: Molecular Networking, Pathological Implications and Translational Opportunities.

Calcification is a process of accumulation of calcium in tissues and deposition of calcium salts by the crystallization of PO43- and ionized calcium (Ca2+). It is a crucial process in the development of bones and teeth. However, pathological calcification can occur in almost any soft tissue of the organism. The better studied is vascular calcification, where calcium salts can accumulate in the intima or medial layer or in aortic valves, and it is associated with higher mortality and cardiovascular events, including myocardial infarction, stroke, aortic and peripheral artery disease (PAD), and diabetes or chronic kidney disease (CKD), among others. The process involves an intricate interplay of different cellular components, endothelial cells (ECs), vascular smooth muscle cells (VSMCs), fibroblasts, and pericytes, concurrent with the activation of several signaling pathways, calcium, Wnt, BMP/Smad, and Notch, and the regulation by different molecular mediators, growth factors (GFs), osteogenic factors and matrix vesicles (MVs). In the present review, we aim to explore the cellular players, molecular pathways, biomarkers, and clinical treatment strategies associated with vascular calcification to provide a current and comprehensive overview of the topic.

Integrated transcriptomic and metabolomic analyses reveal potential regulatory pathways regulating bone metabolism pre- and postsexual maturity in hens

At the onset of sexual maturity, the increasing circulating estrogen stimulates the formation of medullary bone, which provides available calcium for eggshell formation. The bone loss of laying hens is caused by the continuous dynamic changes of structure bone leading to bone fragility and susceptibility. The degree of medullary bone mineralization in sexual maturity is positively correlated with bone quality in the late laying stage. This study aimed to explore the molecular regulation mechanism of bone metabolism pre- and postsexual maturity in hens based on the joint analysis of transcriptome and metabolome. A total of 50 Hy-line Sonia pullets with comparable body weight at 13 wk were selected. Eight pullets were killed at 15 wk (juvenile hens, JH) and 19 wk (laying hens, LH), and LHs were killed within 3 h after oviposition. Differentially expressed genes and metabolites in tibia were analyzed based on transcriptome and metabolome, and then combined to construct the relevant metabolisms and hub genes. In the LH hens, plasma levels of estrogen and tartrate-resistant acid phosphatase were significantly elevated by 1.7 and 1.3 times. In addition, the midpoint diameter, bone mineral density and bone mineral content of the tibia and femur were higher at 19 wk of age. A total of 580 differentially expressed genes were found between the JH and LH group in the tibia, including 280 up-regulated, and 300 down-regulated genes in the LH group. Gene set enrichment analysis (GSEA) showed that the intracellular biosynthesis and secretion of matrix vesicles were significantly enrichment in the LH hens. A total of 21 differential metabolites were identified between JH and LH group. Estradiol valerate positively correlated with L-theanine, tryptophan betaine, dopamine, and perindopril. Joint analysis showed that the top 20 hub genes were enriched in cholesterol biosynthesis and phospholipid metabolism, which played a key regulatory role in bone metabolism during pre- and postsexual maturity. These results provide a theoretical foundation for maintaining efficient egg production and reducing bone health problems in laying hens.

Regulatory Pathways in Growth Plate Chondrocytes that Are Impacted by Matrix Vesicle microRNA Identified by Targeted RISC Pulldown and Sequencing of the Resulting Transcriptome.

During endochondral bone formation, growth plate chondrocytes are differentially regulated by various factors and hormones. As the cellular phenotype changes, the composition of the extracellular matrix is altered, including the production and composition of matrix vesicles (MV) and their cargo of microRNA. The regulatory functions of these MV microRNA in the growth plate are still largely unknown. To address this question, we undertook a targeted bioinformatics approach. A subset of five MV microRNA was selected for analysis based on their specific enrichment in these extracellular vesicles compared to the parent cells (miR-1-3p, miR-22-3p, miR-30c-5p, miR-122-5p, and miR-133a-3p). Synthetic biotinylated versions of the microRNA were produced using locked nucleic acid (LNA) and were transfected into rat growth plate chondrocytes. The resulting LNA to mRNA complexes were pulled down and sequenced, and the transcriptomic data were used to run pathway analysis pipelines. Bone and musculoskeletal pathways were discovered to be regulated by the specific microRNA, notably those associated with transforming growth factor beta (TGFβ) and Wnt pathways, cell differentiation and proliferation, and regulation of vesicles and calcium transport. These results can help with understanding the maturation of the growth plate and the regulatory role of microRNA in MV.

Comprehensive analysis of the effects of the cuprotosis-associated gene SLC31A1 on patient prognosis and tumor microenvironment in human cancer.

Solute carrier family 31 (copper transporter), member 1 (SLC31A1) is a key factor in maintaining intracellular copper concentration and an important factor affecting cancer energy metabolism. Therefore, exploring the potential biological function and value of SLC31A1 could provide a new direction for the targeted therapy of tumors. This study assessed gene expression levels, survival, clinicopathology, gene mutations, methylation levels, the tumor mutational burden (TMB), microsatellite instability (MSI), and the immune cell infiltration of SLC31A1 in pan-cancer using the Tumor Immune Estimation Resource 2.0 (TIMER2.0), Gene Expression Profiling Interactive Analysis (GEPIA), University of Alabama at Birmingham CANcer (UALCAN) data analysis portal, and cBioPortal databases. To further understand the potential biological mechanisms of SLC31A1 in different cancers, single-cell level sequencing and a Gene Ontology/Kyoto Encyclopedia of Genes and Genomes (GO/KEGG) enrichment analysis of SLC31A1 were also performed. Finally, real-time quantitative polymerase chain reaction (RT-qPCR) and western blotting (WB) were used to validate the expression of SLC31A1 in cancers, such as gastric cancer. SLC31A1 was expressed in most cancer tissues. In kidney renal clear cell carcinoma (KIRC), the high expression of SLC31A1 was associated with good overall survival (OS), while in adrenocortical carcinoma (ACC), breast invasive carcinoma (BRCA), lower grade glioma (LGG), mesothelioma (MESO), and skin cutaneous melanoma (SKCM), the low expression of SLC31A1 was associated with good OS. The highest frequency of SLC31A1 amplification was observed in ACC. In addition, missense mutations accounted for a major portion of the mutation types. The truncation mutation S105Y may be a putative cancer driver. SLC31A1 affected methylation levels in cancer and was associated with the TMB, MSI, and the level of infiltration of various immune cells. Additionally, the single-cell sequencing results showed that SLC31A1 was associated with multiple biological functions in cancer. Finally, the SLC31A1 enrichment analysis revealed that the SLC31A1-related genes were mainly enriched in the mitochondrial matrix and envelope vesicles. The RT-qPCR and WB results were consistent with the predicted results. SLC31A1 may be a potential target related to cancer energy metabolism and may have prognostic value.

The Inhibition of Vessel Co-Option as an Emerging Strategy for Cancer Therapy.

Vessel co-option (VCO) is a non-angiogenic mechanism of vascularization that has been associated to anti-angiogenic therapy. In VCO, cancer cells hijack the pre-existing blood vessels and use them to obtain oxygen and nutrients and invade adjacent tissue. Multiple primary tumors and metastases undergo VCO in highly vascularized tissues such as the lungs, liver or brain. VCO has been associated with a worse prognosis. The cellular and molecular mechanisms that undergo VCO are poorly understood. Recent studies have demonstrated that co-opted vessels show a quiescent phenotype in contrast to angiogenic tumor blood vessels. On the other hand, it is believed that during VCO, cancer cells are adhered to basement membrane from pre-existing blood vessels by using integrins, show enhanced motility and a mesenchymal phenotype. Other components of the tumor microenvironment (TME) such as extracellular matrix, immune cells or extracellular vesicles play important roles in vessel co-option maintenance. There are no strategies to inhibit VCO, and thus, to eliminate resistance to anti-angiogenic therapy. This review summarizes all the molecular mechanisms involved in vessel co-option analyzing the possible therapeutic strategies to inhibit this process.

PHOSPHO1-mNeonGreen reporter cells are a robust model to study matrix vesicle biogenesis during osteoblast-driven mineralisation

PHOSPHO1-mNeonGreen reporter cells are a robust model to study matrix vesicle biogenesis during osteoblast-driven mineralisation

Do Media Extracellular Vesicles and Extracellular Vesicles Bound to the Extracellular Matrix Represent Distinct Types of Vesicles?

Mineralization-competent cells, including hypertrophic chondrocytes, mature osteoblasts, and osteogenic-differentiated smooth muscle cells secrete media extracellular vesicles (media vesicles) and extracellular vesicles bound to the extracellular matrix (matrix vesicles). Media vesicles are purified directly from the extracellular medium. On the other hand, matrix vesicles are purified after discarding the extracellular medium and subjecting the cells embedded in the extracellular matrix or bone or cartilage tissues to an enzymatic treatment. Several pieces of experimental evidence indicated that matrix vesicles and media vesicles isolated from the same types of mineralizing cells have distinct lipid and protein composition as well as functions. These findings support the view that matrix vesicles and media vesicles released by mineralizing cells have different functions in mineralized tissues due to their location, which is anchored to the extracellular matrix versus free-floating.

Additional Insights Into the Role of Osteocalcin in Osteoblast Differentiation and in the Early Steps of Developing Alveolar Process of Rat Molars.

This study investigated whether osteocalcin (OCN) is present in osteoblast precursors and its relationship with initial phases of alveolar process formation. Samples of maxillae of 16-, 18-, and 20-day-old rat embryos (E16, E18, and E20, respectively), and 05-, 10-, and 15-day-old postnatal rats (P05, P10, and P15, respectively) were fixed and embedded in paraffin or araldite. Immunohistochemistry for osterix (Osx), alkaline phosphatase (ALP), and OCN detection was performed and the number of immunolabelled cells was computed. Non-decalcified sections were subjected to the von Kossa method combined with immunohistochemistry for Osx or OCN detection. For OCN immunolocalization, samples were fixed in 0.5% glutaraldehyde/2% formaldehyde and embedded in LR White resin. The highest number of ALP- and OCN-immunolabelled cells was observed in dental follicle of E16 specimens, mainly in basal portions of dental alveolus. In corresponding regions, osteoblasts in differentiation adjacent to von Kossa-positive bone matrix exhibited Osx and OCN immunoreactivity. Ultrastructural analysis revealed OCN immunoreactive particles inside osteoblast in differentiation, and in bone matrix associated with collagen fibrils and within matrix vesicles, at early stages of alveolar process formation. Our results indicate that OCN plays a role in osteoblast differentiation and may regulate calcium/phosphate precipitation during early mineralization of the alveolar process.