Cavin-1/PTRF alters prostate cancer cell-derived extracellular vesicle content and internalization to attenuate extracellular vesicle-mediated osteoclastogenesis and osteoblast proliferation

The science of exosomes: Understanding their formation, capture, and role in cellular communication

Extracellular vesicles (EVs) serve as a crucial method for transferring information among cells, which is vital in multicellular organisms. Among these vesicles, exosomes are notable for their small size, ranging from 20 to 150 nm, and their role in cell-to-cell communication. They carry lipids, proteins, and nucleic acids between cells. The creation of exosomes begins with the inward budding of the cell membrane, which then encapsulates various macromolecules as cargo. Once filled, exosomes are released into the extracellular space and taken up by target cells via endocytosis and similar processes. The composition of exosomal cargo varies, encompassing diverse macromolecules with specific functions. Because of their significant roles, exosomes have been isolated from various cell types, including cancer cells, endothelial cells, macrophages, and mesenchymal cells, with the aim of harnessing them for therapeutic applications. Exosomes influence cellular metabolism, and regulate lipid, glucose, and glutamine pathways. Their role in pathogenesis is determined by their cargo, which can manipulate processes such as apoptosis, proliferation, inflammation, migration, and other molecular pathways in recipient cells. Non-coding RNA transcripts, a common type of cargo, play a pivotal role in regulating disease progression. Exosomes are implicated in numerous biological and pathological processes, including inflammation, cancer, cardiovascular diseases, diabetes, wound healing, and ischemic-reperfusion injury. As a result, they hold significant potential in the treatment of both cancerous and non-cancerous conditions.

Defining tropism and activity of natural and engineered extracellular vesicles

Extracellular vesicles (EVs) have important roles as mediators of cell-to-cell communication, with physiological functions demonstrated in various in vivo models. Despite advances in our understanding of the biological function of EVs and their potential for use as therapeutics, there are limitations to the clinical approaches for which EVs would be effective. A primary determinant of the biodistribution of EVs is the profile of proteins and other factors on the surface of EVs that define the tropism of EVs in vivo. For example, proteins displayed on the surface of EVs can vary in composition by cell source of the EVs and the microenvironment into which EVs are delivered. In addition, interactions between EVs and recipient cells that determine uptake and endosomal escape in recipient cells affect overall systemic biodistribution. In this review, we discuss the contribution of the EV donor cell and the role of the microenvironment in determining EV tropism and thereby determining the uptake and biological activity of EVs.

Neovascularization directed by CAVIN1/CCBE1/VEGFC confers TMZ-resistance in glioblastoma

Acquisition of resistance to temozolomide (TMZ) poses a significant challenge in glioblastoma (GBM) therapy. Neovascularization, a pivotal process in tumorigenesis and development, remains poorly understood in its contribution to chemoresistance in GBMs. This study unveils aberrant vascular networks within TMZ-resistant (TMZ-R) GBM tissues and identifies the extracellular matrix (ECM) protein CCBE1 as a potential mediator. Through in vivo and in vitro experiments involving gain and loss of function assessments, we demonstrate that high expression of CCBE1 promotes hyper-angiogenesis and orchestrates partial endothelial-to-mesenchymal transition (EndMT) in human microvascular endothelial cells (HCMEC/d3) within GBM. This is likely driven by VEGFC/Rho signaling. Intriguingly, CCBE1 overexpression substantially fails to promote tumor growth, but endows resistance to GBM cells in a vascular endothelial cell-dependent manner. Mechanically, the constitutive phosphorylation of SP1 at Ser101 drives the upregulation of CCBE1 transcription in TMZ resistant tumors, and the excretion of CCBE1 depends on caveolae associated protein 1 (CAVIN1) binding and assembling. Tumor cells derived CCBE1 promotes VEGFC maturation, activates VEGFR2/VEGFR3/Rho signaling in vascular endothelial cells, and ultimately results in hyper-angiogenesis in TMZ-R tumors. Collectively, the current study uncovers the cellular and molecular basis of abnormal angiogenesis in a chemo resistant microenvironment, implying that curbing CCBE1 is key to reversing TMZ resistance.

Glycobiology in osteoclast differentiation and function

Glycans, either alone or in complex with glycan-binding proteins, are essential structures that can regulate cell biology by mediating protein stability or receptor dimerization under physiological and pathological conditions. Certain glycans are ligands for lectins, which are carbohydrate-specific receptors. Bone is a complex tissue that provides mechanical support for muscles and joints, and the regulation of bone mass in mammals is governed by complex interplay between bone-forming cells, called osteoblasts, and bone-resorbing cells, called osteoclasts. Bone erosion occurs when bone resorption notably exceeds bone formation. Osteoclasts may be activated during cancer, leading to a range of symptoms, including bone pain, fracture, and spinal cord compression. Our understanding of the role of protein glycosylation in cells and tissues involved in osteoclastogenesis suggests that glycosylation-based treatments can be used in the management of diseases. The aims of this review are to clarify the process of bone resorption and investigate the signaling pathways mediated by glycosylation and their roles in osteoclast biology. Moreover, we aim to outline how the lessons learned about these approaches are paving the way for future glycobiology-focused therapeutics.

Acute Kidney Injury by Ischemia/Reperfusion and Extracellular Vesicles

Acute kidney injury (AKI) is often caused by ischemia-reperfusion injury (IRI). IRI significantly affects kidney metabolism, which elicits pro-inflammatory responses and kidney injury. The ischemia/reperfusion of the kidney is associated with transient high mitochondrial-derived reactive oxygen species (ROS) production rates. Excessive mitochondrial-derived ROS damages cellular components and, together with other pathogenic mechanisms, elicits a range of acute injury mechanisms that impair kidney function. Mitochondrial-derived ROS production also stimulates epithelial cell secretion of extracellular vesicles (EVs) containing RNAs, lipids, and proteins, suggesting that EVs are involved in AKI pathogenesis. This literature review focuses on how EV secretion is stimulated during ischemia/reperfusion and how cell-specific EVs and their molecular cargo may modify the IRI process. Moreover, critical pitfalls in the analysis of kidney epithelial-derived EVs are described. In particular, we will focus on how the release of kidney epithelial EVs is affected during tissue analyses and how this may confound data on cell-to-cell signaling. By increasing awareness of methodological pitfalls in renal EV research, the risk of false negatives can be mitigated. This will improve future EV data interpretation regarding EVs contribution to AKI pathogenesis and their potential as biomarkers or treatments for AKI.

The Bone Microenvironment Soil in Prostate Cancer Metastasis: An miRNA Approach

Bone metastatic prostate cancer (PCa) is associated with a high risk of mortality. Changes in the expression pattern of miRNAs seem to be related to early aspects of prostate cancer, as well as its establishment and proliferation, including the necessary steps for metastasis. Here we compiled, for the first time, the important roles of miRNAs in the development, diagnosis, and treatment of bone metastasis, focusing on recent in vivo and in vitro studies. PCa exosomes are proven to promote metastasis-related events, such as osteoblast and osteoclast differentiation and proliferation. Aberrant miRNA expression in PCa may induce abnormal bone remodeling and support tumor development. Furthermore, miRNAs are capable of binding to multiple mRNA targets, a dynamic property that can be harnessed for the development of treatment tools, such as antagomiRs and miRNA mimics, which have emerged as promising candidates in PCa treatment. Finally, miRNAs may serve as noninvasive biomarkers, as they can be detected in tissue and bodily fluids, are highly stable, and show differential expression between nonmetastatic PCa and bone metastatic samples. Taken together, the findings underscore the importance of miRNA expression profiles and miRNA-based tools as rational technologies to increase the quality of life and longevity of patients.

Exosomes promote hFOB1.19 proliferation and differentiation via LINC00520

BACKGROUND

Osteoporosis remains a significant clinical challenge worldwide. Recent studies have shown that exosomes stimulate bone regeneration. Thus, it is worthwhile to explore whether exosomes could be a useful therapeutic strategy for osteoporosis. The purpose of this study was to investigate the effects of exosomes derived from human umbilical cord mesenchymal stem cells (hucMSCs) on osteoblast proliferation and differentiation.

METHODS

Exosomes were isolated from hucMSCs. Bioinformatics analysis was performed to identify the differentially expressed lncRNAs in myeloma-derived mesenchymal stem cells. Plasmids encoding LINC00520 or short hairpin RNA of LINC00520 were transfected into hucMSCs and then exosomes were isolated. After human osteoblasts hFOB1.19 were exposed to the obtained exosomes, cell survival, cell cycle, apoptosis and calcium deposits of hFOB1.19 cell were detected by MTT, 7-aminoactinomycin D, Annexin V-FITC/propidium iodide and Alizarin red staining, respectively.

RESULTS

In hFOB1.19 cells, 10 × 10⁹/mL hucMSC-derived exosomes inhibited cell proliferation, arrested cell cycle, and promoted apoptosis, while hucMSCs or 1 × 10⁹/mL exosomes promoted cell proliferation, accelerated cell cycle, and promoted calcium deposits and the expression of OCN, RUNX2, collagen I and ALP. In hFOB1.19 cells, exosomes from hucMSCs with LINC00520 knockdown reduced the survival and calcium deposits, arrested the cell cycle, and enhanced the apoptosis, while exosomes from hucMSCs overexpressing LINC00520 enhance the proliferation and calcium deposits and accelerated the cell cycle.

CONCLUSIONS

LINC00520 functions as a modulator of calcium deposits, and exosomes derived from hucMSCs overexpressing LINC00520 might be a novel therapeutic approach for osteoporosis.

Molecular and clinical characterization of PTRF in glioma via 1,022 samples

Polymerase I and transcript release factor (PTRF) plays a role in the regulation of gene expression and the release of RNA transcripts during transcription, which have been associated with various human diseases. However, the role of PTRF in glioma remains unclear. In this study, RNA sequencing (RNA-seq) data (n = 1022 cases) and whole-exome sequencing (WES) data (n = 286 cases) were used to characterize the PTRF expression features. Gene ontology (GO) functional enrichment analysis was used to assess the biological implication of changes in PTRF expression. As a result, the expression of PTRF was associated with malignant progression in gliomas. Meanwhile, somatic mutational profiles and copy number variations (CNV) revealed the glioma subtypes classified by PTRF expression showed distinct genomic alteration. Furthermore, GO functional enrichment analysis suggested that PTRF expression was associated with cell migration and angiogenesis, particularly during an immune response. Survival analysis confirmed that a high expression of PTRF is associated with a poor prognosis. In summary, PTRF may be a valuable factor for the diagnosis and treatment target of glioma.

Androgen-induced exosomal miR-379-5p release determines granulosa cell fate: cellular mechanism involved in polycystic ovaries

Polycystic ovarian syndrome (PCOS) is a complex multi-factorial syndrome associated with androgen excess and anovulatory infertility. In the current study, we investigated the role of dihydrotestosterone-induced exosomal miR-379-5p release in determining the destiny of the developing follicles. Our hypothesis was that androgen regulates granulosa cell miR-379-5p content by facilitating its exosomal release in a follicular-stage dependent manner, a process which determines granulosa cell fate. Compared to human non-PCOS subjects, individuals with PCOS exhibit higher follicular fluid free testosterone levels, lower exosomal miR-379-5p content and granulosa cell proliferation. Androgenized rats exhibited lower granulosa cell miR-379-5p but higher phosphoinositide-dependent kinase-1 (PDK1; a miR-379-5p target) content and proliferation. Androgen reduced granulosa cell miR-379-5p content by increasing its exosomal release in preantral follicles, but not in antral follicles in vitro. Studies with an exosomal release inhibitor confirmed that androgen-induced exosomal miR-379-5p release decreased granulosa cell miR-379-5p content and proliferation. Ovarian overexpression of miR-379-5p suppressed granulosa cell proliferation, and basal and androgen-induced preantral follicle growth in vivo. These findings suggest that increased exosomal miR-379-5p release in granulosa cells is a proliferative response to androgenic stimulation specific for the preantral stage of follicle development and that dysregulation of this response at the antral stage is associated with follicular growth arrest, as observed in human PCOS.

Caveolae Mechanotransduction at the Interface between Cytoskeleton and Extracellular Matrix

The plasma membrane (PM) is subjected to multiple mechanical forces, and it must adapt and respond to them. PM invaginations named caveolae, with a specific protein and lipid composition, play a crucial role in this mechanosensing and mechanotransduction process. They respond to PM tension changes by flattening, contributing to the buffering of high-range increases in mechanical tension, while novel structures termed dolines, sharing Caveolin1 as the main component, gradually respond to low and medium forces. Caveolae are associated with different types of cytoskeletal filaments, which regulate membrane tension and also initiate multiple mechanotransduction pathways. Caveolar components sense the mechanical properties of the substrate and orchestrate responses that modify the extracellular matrix (ECM) according to these stimuli. They perform this function through both physical remodeling of ECM, where the actin cytoskeleton is a central player, and via the chemical alteration of the ECM composition by exosome deposition. Here, we review mechanotransduction regulation mediated by caveolae and caveolar components, focusing on how mechanical cues are transmitted through the cellular cytoskeleton and how caveolae respond and remodel the ECM.

The biodistribution of placental and fetal extracellular vesicles during pregnancy following placentation

Human pregnancy is a highly orchestrated process requiring extensive cross-talk between the mother and the fetus. Extracellular vesicles released by the fetal tissue, particularly the placenta, are recognized as important mediators of this process. More recently, the importance of placental extracellular vesicle biodistribution studies in animal models has received increasing attention as identifying the organs to which extracellular vesicles are targeted to helps us understand more about this communication system. Placental extracellular vesicles are categorized based on their size into macro-, large-, and small-extracellular vesicles, and their biodistribution is dependent on the extracellular vesicle's particle size, the direction of blood flow, the recirculation of blood, as well as the retention capacity in organs. Macro-extracellular vesicles are exclusively localized to the lungs, while large- and small-extracellular vesicles show high levels of distribution to the lungs and liver, while there is inconsistency in the reporting of distribution to the spleen and kidneys. This inconsistency may be due to the differences in the methodologies employed between studies and their limitations. Future studies should incorporate analysis of placental extracellular vesicle biodistribution at the macroscopic level on whole animals and organs/tissues, as well as the microscopic cellular level.

Caveolae sense oxidative stress through membrane lipid peroxidation and cytosolic release of CAVIN1 to regulate NRF2

Caveolae have been linked to many biological functions, but their precise roles are unclear. Using quantitative whole-cell proteomics of genome-edited cells, we show that the oxidative stress response is the major pathway dysregulated in cells lacking the key caveola structural protein, CAVIN1. CAVIN1 deletion compromised sensitivity to oxidative stress in cultured cells and in animals. Wound-induced accumulation of reactive oxygen species and apoptosis were suppressed in Cavin1-null zebrafish, negatively affecting regeneration. Oxidative stress triggered lipid peroxidation and induced caveolar disassembly. The resulting release of CAVIN1 from caveolae allowed direct interaction between CAVIN1 and NRF2, a key regulator of the antioxidant response, facilitating NRF2 degradation. CAVIN1-null cells with impaired negative regulation of NRF2 showed resistance to lipid-peroxidation-induced ferroptosis. Thus, caveolae, via lipid peroxidation and CAVIN1 release, maintain cellular susceptibility to oxidative-stress-induced cell death, demonstrating a crucial role for this organelle in cellular homeostasis and wound response.

Morinda officinalis polysaccharide enable suppression of osteoclastic differentiation by exosomes derived from rat mesenchymal stem cells

CONTEXT

Morinda officinalis F.C. How. (MO) (Rubiaceae) can strengthen bone function.

OBJECTIVE

To examine the functional mechanism and effect of MO polysaccharides (MOPs) in rats with glucocorticoid-induced osteoporosis (GIOP).

MATERIALS AND METHODS

Rats with GIOP were treated with 5, 15 or 45 mL/kg of MOP [n = 15 for each dose, intraperitoneal (i.p.) injection every other day for 8 weeks]. The body weight of rats and histomorphology of bone tissues were examined. Bone marrow mesenchymal stem cells (BMSCs)-derived exosomes (Exo) were collected and identified. Bone marrow-derived macrophages (BMMs) were induced to differentiate into osteoclasts and treated with BMSC-Exo for in vitro studies.

RESULTS

MOP reduced the body weight (5, 15, or 45 mg/kg MOP vs. phosphate-buffered saline: 8%, 15% and 25%, p < 0.01), elevated the bone volume to tissue volume (BV/TV), mean trabecular thickness (Tb.Th), mean trabecular number (Tb.N) and mean connectivity density (Conn.D) (40-86%, p < 0.01), decreased the mean trabecular separation/spacing (Tb.Sp) (22-37%, p < 0.01), increased the cortical bone continuity (35-90%, p < 0.01) and elevated RUNX family transcription factor 2 and RANK levels (5-12%, p < 0.01), but suppressed matrix metallopeptidase 9 and cathepsin K levels (9-20%, p < 0.01) in femur tissues. BMSC-Exo from MOP-treated rats (MOP-Exo) suppressed osteoclastic differentiation and proliferation of BMMs. The downregulation of microRNA-101-3p (miR-101-3p) or the upregulation of prostaglandin-endoperoxide synthase 2 (PTGS2) blocked the functions of MOP-Exo.

DISCUSSION AND CONCLUSIONS

MOP inhibits osteoclastic differentiation and could potentially be used for osteoporosis management. This suppression may be enhanced by the upregulation of miR-101-3p or the inhibition of PTGS2.

Exosomal miR-328 originated from pulmonary adenocarcinoma cells enhances osteoclastogenesis via downregulating Nrp-2 expression

Osseous metastases of pulmonary carcinoma and the detailed mechanisms remain unclear, and the effects of exosomes (Exos) originated from pulmonary adenocarcinoma cells in this process have received a lot of attentions. Our study revealed that the Exos secreted from A549 cells (A549-Exos) enhanced osteoclastogenesis and osseous resorption in vitro. In addition, A549-Exos showed a targeted effect on bones to enhance osseous resorption in vivo. A549-exosomal miR-328 enhanced osseous resorption via downregulating neuropilin 2 (Nrp-2) expression, and A549-Exos miR-328 inhibitors suppressed osseous resorption in vivo. Therefore, A549-exosomal miR-328 enhances osteoclastogenesis via downregulating Nrp-2 expression, thus A549-Exos ^{miR-328 inhibitors} can be used as a potential nanodrug for treating osseous metastases.

Extracellular vesicles and particles impact the systemic landscape of cancer

Intercellular cross talk between cancer cells and stromal and immune cells is essential for tumor progression and metastasis. Extracellular vesicles and particles (EVPs) are a heterogeneous class of secreted messengers that carry bioactive molecules and that have been shown to be crucial for this cell-cell communication. Here, we highlight the multifaceted roles of EVPs in cancer. Functionally, transfer of EVP cargo between cells influences tumor cell growth and invasion, alters immune cell composition and function, and contributes to stromal cell activation. These EVP-mediated changes impact local tumor progression, foster cultivation of pre-metastatic niches at distant organ-specific sites, and mediate systemic effects of cancer. Furthermore, we discuss how exploiting the highly selective enrichment of molecules within EVPs has profound implications for advancing diagnostic and prognostic biomarker development and for improving therapy delivery in cancer patients. Altogether, these investigations into the role of EVPs in cancer have led to discoveries that hold great promise for improving cancer patient care and outcome.

Targeting regulation of stem cell exosomes: Exploring novel strategies for aseptic loosening of joint prosthesis

Periprosthetic osteolysis is a major long-term complication of total joint replacement. A series of biological reactions caused by the interaction of wear particles at the prosthesis bone interface and surrounding bone tissue cells after artificial joint replacement are vital reasons for aseptic loosening. Disorder of bone metabolism and aseptic inflammation induced by wear particles are involved in the occurrence and development of aseptic loosening of the prosthesis. Promoting osteogenesis and angiogenesis and mediating osteoclasts and inflammation may be beneficial in preventing the aseptic loosening of the prosthesis. Current research about the prevention and treatment of aseptic loosening of the prosthesis focuses on drug, gene, and stem cell therapy and has not yet achieved satisfactory clinical efficacy or has not been used in clinical practice. Exosomes are a kind of typical extracellular vehicle. In recent years, stem cell exosomes (Exos) have been widely used to regulate bone metabolism, block inflammation, and have broad application prospects in tissue repair and cell therapy.

Exosomes in urological diseases - Biological functions and clinical applications

Exosomes are extracellular vesicles with a variety of biological functions that exist in various biological body fluids and exert their functions through proteins, nucleic acids, lipids, and metabolites. Recent discoveries have revealed the functional and biomarker roles of miRNAs in urological diseases, including benign diseases and malignancies. Exosomes have several uses in the diagnosis, treatment, and monitoring of urological diseases, especially cancer. Proteins and nucleic acids can be used as alternative biomarkers for detecting urological diseases. Additionally, exosomes can be detected in most body fluids, thereby avoiding pathogenesis. More importantly, for urological tumors, exosomes display a higher sensitivity than circulating tumor cells and tumor-derived DNA in body fluid biopsies because of their low immunogenicity and high stability. These advantages have made it a research hotspot in recent years. In this review, we focus on the biological characteristics and functions of exosomes and summarize their advantages and the latest progress in the diagnosis and treatment of urological diseases.

Insight into Extracellular Vesicle-Cell Communication: From Cell Recognition to Intracellular Fate

Extracellular vesicles (EVs) are heterogamous lipid bilayer-enclosed membranous structures secreted by cells. They are comprised of apoptotic bodies, microvesicles, and exosomes, and carry a range of nucleic acids and proteins that are necessary for cell-to-cell communication via interaction on the cells surface. They initiate intracellular signaling pathways or the transference of cargo molecules, which elicit pleiotropic responses in recipient cells in physiological processes, as well as pathological processes, such as cancer. It is therefore important to understand the molecular means by which EVs are taken up into cells. Accordingly, this review summarizes the underlying mechanisms involved in EV targeting and uptake. The primary method of entry by EVs appears to be endocytosis, where clathrin-mediated, caveolae-dependent, macropinocytotic, phagocytotic, and lipid raft-mediated uptake have been variously described as being prevalent. EV uptake mechanisms may depend on proteins and lipids found on the surfaces of both vesicles and target cells. As EVs have been shown to contribute to cancer growth and progression, further exploration and targeting of the gateways utilized by EVs to internalize into tumor cells may assist in the prevention or deceleration of cancer pathogenesis.

Bone Cell Exosomes and Emerging Strategies in Bone Engineering

Bone tissue remodeling is a highly regulated process balancing bone formation and resorption through complex cellular crosstalk between resident bone and microenvironment cells. This cellular communication is mediated by direct cell and cell–matrix contact, autocrine, endocrine, and paracrine receptor mediated mechanisms such as local soluble signaling molecules and extracellular vesicles including nanometer sized exosomes. An impairment in this balanced process leads to development of pathological conditions. Bone tissue engineering is an emerging interdisciplinary field with potential to address bone defects and disorders by synthesizing three-dimensional bone substitutes embedded with cells for clinical implantation. However, current cell-based therapeutic approaches have faced hurdles due to safety and ethical concerns, challenging their clinical translation. Recent studies on exosome-regulated bone homeostasis and regeneration have gained interest as prospective cell free therapy in conjugation with tissue engineered bone grafts. However, exosome research is still in its nascent stages of bone tissue engineering. In this review, we specifically describe the role of exosomes secreted by cells within bone microenvironment such as osteoblasts, osteocytes, osteoclasts, mesenchymal stem cell cells, immune cells, endothelial cells, and even tumor cells during bone homeostasis and crosstalk. We also review exosome-based osteoinductive functionalization strategies for various bone-based biomaterials such as ceramics, polymers, and metals in bone tissue engineering. We further highlight biomaterials as carrier agents for exosome delivery to bone defect sites and, finally, the influence of various biomaterials in modulation of cell exosome secretome.

Microglial glutaminase 1 deficiency mitigates neuroinflammation associated depression

Glutaminase 1 (GLS1) has recently been reported to be expressed in microglia and plays a crucial role in neuroinflamation. Significantly increased level of GLS1 mRNA expression together with neuroinflammation pathway were observed in postmortem prefrontal cortex from depressed patients. To find out the function of microglial GLS1 in depression and neuroinflammation, we generated transgenic mice (GLS1 cKO), postnatally losing GLS1 in microglia, to detect changes in the lipopolysaccharide (LPS)-induced depression model. LPS-induced anxiety/depression-like behavior was attenuated in GLS1 cKO mice, paralleled by a significant reduction in pro-inflammatory cytokines and an abnormal microglia morphological phenotype in the prefrontal cortex. Reduced neuroinflammation by GLS1 deficient microglia was a result of less reactive astrocytes, as GLS1 deficiency enhanced miR-666-3p and miR-7115-3p levels in extracellular vesicles released from microglia, thus suppressing astrocyte activation via inhibiting Serpina3n expression. Together, our data reveal a novel mechanism of GLS1 in neuroinflammation and targeting GLS1 in microglia may be a novel strategy to alleviate neuroinflammation-related depression and other disease.

Effect of Sample Concentration on Nanoparticle Tracking Analysis of Small Extracellular Vesicles and Liposomes Mimicking the Physicochemical Properties of Exosomes

For quantitative analysis, data should be obtained at a sample concentration that is within the range of linearity. We examined the effect of sample concentration on nanoparticle tracking analysis (NTA) of small extracellular vesicles (sEVs), including exosomes, by comparing NTA results of sEVs with those obtained for polystyrene nanoparticles (PSN) and liposomes, which mimic lipid composition and physicochemical properties of exosomes. Initially, NTA of PSN at different concentrations was performed and the particle sizes determined were validated by dynamic light scattering. The major peak maxima for PSN mixtures of different sizes at the higher particle numbers were similar, with some fluctuation of the minor peak maxima observed at the lower particle number, which was also observed for sEVs. Sample concentration is critical for obtaining reproducible data for liposomes and exosomes and increasing the sample concentration caused an increase in data variability because of particle interactions. The inter-day repeatability of particles sizes and concentration for sEVs were 7.47 and 4.51%, respectively. Analysis of the linearity range revealed that this was narrower for sEVs when compared with that of liposomes. Owing to the use of liposomes that mimic the lipid composition and physicochemical properties of exosomes and proteinase-treated sEVs, it was demonstrated that these different analytical results could be possibly caused by the protein corona of sEVs. Consideration of the sample concentration and linearity range is important for obtaining reproducible and reliable data of sEVs.

Potential Role of Exercise Induced Extracellular Vesicles in Prostate Cancer Suppression

Physical exercise is increasingly recognized as a valuable treatment strategy in managing prostate cancer, not only enhancing supportive care but potentially influencing disease outcomes. However, there are limited studies investigating mechanisms of the tumor-suppressive effect of exercise. Recently, extracellular vesicles (EVs) have been recognized as a therapeutic target for cancer as tumor-derived EVs have the potential to promote metastatic capacity by transferring oncogenic proteins, integrins, and microRNAs to other cells and EVs are also involved in developing drug resistance. Skeletal muscle has been identified as an endocrine organ, releasing EVs into the circulation, and levels of EV-containing factors have been shown to increase in response to exercise. Moreover, preclinical studies have demonstrated the tumor-suppressive effect of protein and microRNA contents in skeletal muscle-derived EVs in various cancers, including prostate cancer. Here we review current knowledge of the tumor-derived EVs in prostate cancer progression and metastasis, the role of exercise in skeletal muscle-derived EVs circulating levels and the alteration of their contents, and the potential tumor-suppressive effect of skeletal muscle-derived EV contents in prostate cancer. In addition, we review the proposed mechanism of exercise in the uptake of skeletal muscle-derived EVs in prostate cancer.

Exosomes as mediators of intercellular crosstalk in metabolism

Exosomes are nanoparticles secreted by all cell types and are a large component of the broader class of nanoparticles termed extracellular vesicles (EVs). Once secreted, exosomes gain access to the interstitial space and ultimately the circulation, where they exert local paracrine or distal systemic effects. Because of this, exosomes are important components of an intercellular and intraorgan communication system capable of carrying biologic signals from one cell type or tissue to another. The exosomal cargo consists of proteins, lipids, miRNAs, and other RNA species, and many of the biologic effects of exosomes have been attributed to miRNAs. Exosomal miRNAs have also been used as disease biomarkers. The field of exosome biology and metabolism is rapidly expanding, with new discoveries and reports appearing on a regular basis, and it is possible that potential therapeutic approaches for the use of exosomes or miRNAs in metabolic diseases will be initiated in the near future.

An engineered CD81-based combinatorial library for selecting recombinant binders to cell surface proteins: Laminin binding CD81 enhances cellular uptake of extracellular vesicles

The research of extracellular vesicles (EVs) has boomed in the last decade, with the promise of them functioning as target-directed drug delivery vehicles, able to modulate proliferation, migration, differentiation, and other properties of the recipient cell that are vital for health of the host organism. To enhance the ability of their targeted delivery, we employed an intrinsically overrepresented protein, CD81, to serve for recognition of the desired target antigen. Yeast libraries displaying mutant variants of the large extracellular loop of CD81 have been selected for binders to human placental laminin as an example target. Their specific interaction with laminin was confirmed in a mammalian display system. Derived sequences were reformatted to full-length CD81 and expressed in EVs produced by HeLa cells. These EVs were examined for the presence of the recombinant protein and were shown to exhibit an enhanced uptake into laminin-secreting mammalian cell lines. For the best candidate, the specificity of antigen interaction was demonstrated with a competition experiment. To our knowledge, this is the first example of harnessing an EV membrane protein as mediator of de novo target antigen recognition via in vitro molecular evolution, opening horizons to a broad range of applications in various therapeutic settings.

Isolation of extracellular vesicle with different precipitation-based methods exerts a tremendous impact on the biomarker analysis for clinical plasma samples

BACKGROUND

Extracellular vesicles(EVs) is an emerging approach of cancer liquid biopsy. Although the precipitation-based method with commercial kits has gained popularity as the second most commonly used technique, these protocols vary tremendously with many included reagents still unknown to the community.

METHODS

In this study, we assigned each of the 3 clinical plasma samples into 6 aliquots to assess five commercial EV isolation kits, in comparison with ultracentrifugation(UC). We implemented a standardized EV preparation and transcriptome analysis workflow except the EV isolation methods used. The metrics of EVs and its RNA cargo (evRNA) were compared to assess the technical variations versus the biological variations in the clinical setting.

RESULTS

Although the size range of the isolated EVs demonstrated a similar distribution, we found significant technical variability among these methods, in terms of EV amount, purity, subpopulations and RNA integrity. Such variabilities were further relayed to a drastic divergence of evRNA expression on a transcriptome-wide fashion.

CONCLUSIONS

Our study demonstrated a highly variable result from polymeric precipitation-based EV isolation methods, making EVs based biomarker analysis difficult to interpret and reproduce. We highlighted the importance of benchmarking and transparent reporting of the precipitation-based protocols in the liquid biopsy research.

Extracellular Vesicles: An Emerging Regenerative Treatment for Oral Disease

Extracellular Vesicles (EVs) are small lipid-enclosed particles containing biological molecules such as RNA and proteins that have emerged as vital modulators of intercellular communication. Increasingly, studies have shown that EVs play an essential role in the occurrence and prognosis of oral diseases. EVs are increasingly considered a research hotspot of oral diseases. In addition, the characteristics of carrying active molecules have also been studied in oral tissue regeneration. Evidence has shown that EVs regulate the homeostasis of the inflammatory microenvironment, promote angiogenesis, and repair damaged tissues. In this review, we summarized the characteristics of EVs and highlighted the role of EVs in oral tissue regeneration, including dental pulp, periodontal tissue, cartilage, and bone. We also discussed their deficiencies and prospects as a potential therapeutic role in the regeneration treatment of oral disease.

Neuroretinal-Derived Caveolin-1 Promotes Endotoxin-Induced Inflammation in the Murine Retina

Purpose

The immune-privileged environment and complex organization of retinal tissue support the retina's essential role in visual function, yet confound inquiries into cell-specific inflammatory effects that lead to dysfunction and degeneration. Caveolin-1 (Cav1) is an integral membrane protein expressed in several retinal cell types and is implicated in immune regulation. However, whether Cav1 promotes or inhibits inflammatory processes in the retina (as well as in other tissues) remains unclear. Previously, we showed that global-Cav1 depletion resulted in reduced retinal inflammatory cytokine production but paradoxically elevated retinal immune cell infiltration. We hypothesized that these disparate responses are the result of differential cell-specific Cav1 functions in the retina.

Methods

We used Cre/lox technology to deplete Cav1 specifically in the neural retinal (NR) compartment to clarify the role NR-specific Cav1 (NR-Cav1) in the retinal immune response to intravitreal inflammatory challenge induced by activation of Toll-like receptor-4 (TLR4). We used multiplex protein suspension array and flow cytometry to evaluate innate immune activation. Additionally, we used bioinformatics assessment of differentially expressed membrane-associated proteins to infer relationships between NR-Cav1 and immune response pathways.

Results

NR-Cav1 depletion, which primarily affects Müller glia Cav1 expression, significantly altered immune response pathway regulators, decreased retinal inflammatory cytokine production, and reduced retinal immune cell infiltration in response to LPS-stimulated inflammatory induction.

Conclusions

Cav1 expression in the NR compartment promotes the innate TLR4-mediated retinal tissue immune response. Additionally, we have identified novel potential immune modulators differentially expressed with NR-Cav1 depletion. This study further clarifies the role of NR-Cav1 in retinal inflammation.

Extracellular Vesicle-Mediated Bone Remodeling and Bone Metastasis: Implications in Prostate Cancer

Bone metastasis is the tendency of certain primary tumors to spawn and dictate secondary neoplasia in the bone. The process of bone metastasis is regulated by the dynamic crosstalk between metastatic cancer cells, cellular components of the bone marrow microenvironment (osteoblasts, osteoclasts, and osteocytes), and the bone matrix. The feed-forward loop mechanisms governs the co-option of homeostatic bone remodeling by cancer cells in bone. Recent developments have highlighted the discovery of extracellular vesicles (EVs) and their diverse roles in distant outgrowths. Several studies have implicated EV-mediated interactions between cancer cells and the bone microenvironment in synergistically promoting pathological skeletal metabolism in the metastatic site. Nevertheless, the potential role that EVs serve in arbitrating intricate sequences of coordinated events within the bone microenvironment remains an emerging field. In this chapter, we review the role of cellular participants and molecular mechanisms in regulating normal bone physiology and explore the progress of current research into bone-derived EVs in directly triggering and coordinating the processes of physiological bone remodeling. In view of the emerging role of EVs in interorgan crosstalk, this review also highlights the multiple systemic pathophysiological processes orchestrated by the EVs to direct organotropism in bone in prostate cancer. Given the deleterious consequences of bone metastasis and its clinical importance, in-depth knowledge of the multifarious role of EVs in distant organ metastasis is expected to open new possibilities for prognostic evaluation and therapeutic intervention for advanced bone metastatic prostate cancer.

Extracellular Vesicles: An Emerging Mechanism Governing the Secretion and Biological Roles of Tenascin-C

ECM composition and architecture are tightly regulated for tissue homeostasis. Different disorders have been associated to alterations in the levels of proteins such as collagens, fibronectin (FN) or tenascin-C (TnC). TnC emerges as a key regulator of multiple inflammatory processes, both during physiological tissue repair as well as pathological conditions ranging from tumor progression to cardiovascular disease. Importantly, our current understanding as to how TnC and other non-collagen ECM components are secreted has remained elusive. Extracellular vesicles (EVs) are small membrane-bound particles released to the extracellular space by most cell types, playing a key role in cell-cell communication. A broad range of cellular components can be transported by EVs (e.g. nucleic acids, lipids, signalling molecules and proteins). These cargoes can be transferred to target cells, potentially modulating their function. Recently, several extracellular matrix (ECM) proteins have been characterized as bona fide EV cargoes, exosomal secretion being particularly critical for TnC. EV-dependent ECM secretion might underpin diseases where ECM integrity is altered, establishing novel concepts in the field such as ECM nucleation over long distances, and highlighting novel opportunities for diagnostics and therapeutic intervention. Here, we review recent findings and standing questions on the molecular mechanisms governing EV–dependent ECM secretion and its potential relevance for disease, with a focus on TnC.

Extracellular vesicles in prostate cancer: a narrative review

Over the past decade, there has been remarkable progress in prostate cancer biomarker discovery using urine- and blood-based assays. A liquid biopsy is a minimally invasive procedure to investigate the cancer-related molecules in circulating tumor cells (CTCs), cell-free DNA, and extracellular vesicles (EVs). Liquid biopsies have the advantage of detecting heterogeneity as well as acquired resistance in cancer. EVs are cell-derived vesicles enclosed by a lipid bilayer and contain various molecules, such as nucleic acids, proteins, and lipids. In patients with cancer, EVs derived from tumors can be isolated from urine, plasma, and serum. The advances in isolation techniques provide the opportunity to use EVs as biomarkers in the clinic. Emerging evidence suggests that EVs can be useful biomarkers for the diagnosis of prostate cancer, especially high-grade cancer. EVs can also be potent biomarkers for the prediction of disease progression in patients with castration-resistant prostate cancer (CRPC). EVs shed from cancer and stromal cells are involved in the development of tumor microenvironments, enhancing cancer progression, metastasis, and drug resistance. Here, we provide an overview of the use of EVs for the diagnosis of clinically significant prostate cancer as well as for predicting disease progression. We also discuss the biological function of EVs, which regulate cancer progression.

Caveolin-1-driven membrane remodelling regulates hnRNPK-mediated exosomal microRNA sorting in cancer

BACKGROUND

Caveolae proteins play diverse roles in cancer development and progression. In prostate cancer, non-caveolar caveolin-1 (CAV1) promotes metastasis, while CAVIN1 attenuates CAV1-induced metastasis. Here, we unveil a novel mechanism linking CAV1 to selective loading of exosomes with metastasis-promoting microRNAs.

RESULTS

We identify hnRNPK as a CAV1-regulated microRNA binding protein. In the absence of CAVIN1, non-caveolar CAV1 drives localisation of hnRPNK to multi-vesicular bodies (MVBs), recruiting AsUGnA motif-containing miRNAs and causing their release within exosomes. This process is dependent on the lipid environment of membranes as shown by cholesterol depletion using methyl-β-cyclodextrin or by treatment with n-3 polyunsaturated fatty acids. Consistent with a role in bone metastasis, knockdown of hnRNPK in prostate cancer PC3 cells abolished the ability of PC3 extracellular vesicles (EV) to induce osteoclastogenesis, and biofluid EV hnRNPK is elevated in metastatic prostate and colorectal cancer.

CONCLUSIONS

Taken together, these results support a novel pan-cancer mechanism for CAV1-driven exosomal release of hnRNPK and associated miRNA in metastasis, which is modulated by the membrane lipid environment.

Small extracellular vesicles deliver osteolytic effectors and mediate cancer-induced osteolysis in bone metastatic niche

Extracellular vesicles (EVs) play critical roles in regulating bone metastatic microenvironment through mediating intercellular crosstalks. However, little is known about the contribution of EVs derived from cancer cells to the vicious cycle of bone metastasis. Here, we report a direct regulatory mode between tumour cells and osteoclasts in metastatic niche of prostate cancer via vesicular miRNAs transfer. Combined analysis of miRNAs profiles both in tumour‐derived small EVs (sEVs) and osteoclasts identified miR‐152‐3p as a potential osteolytic molecule. sEVs were enriched in miR‐152‐3p, which targets osteoclastogenic regulator MAFB. Blocking miR‐152‐3p in sEVs upregulated the expression of MAFB and impaired osteoclastogenesis in vitro. In vivo experiments of xenograft mouse model found that blocking of miR‐152‐3p in sEVs significantly slowed down the loss of trabecular architecture, while systemic inhibition of miR‐152‐3p using antagomir‐152‐3p reduced the osteolytic lesions of cortical bone while preserving basic trabecular architecture. Our findings suggest that miR‐152‐3p carried by prostate cancer‐derived sEVs deliver osteolytic signals from tumour cells to osteoclasts, facilitating osteolytic progression in bone metastasis.

Caveola-forming proteins and prostate cancer

Caveolae are specialised and dynamic plasma membrane subdomains, involved in many cellular functions including endocytosis, signal transduction, mechanosensing and lipid storage, trafficking, and metabolism. Two protein families are indispensable for caveola formation and function, namely caveolins and cavins. Mutations of genes encoding these caveolar proteins cause serious pathological conditions such as cardiomyopathies, skeletal muscle diseases, and lipodystrophies. Deregulation of caveola-forming protein expression is associated with many types of cancers including prostate cancer. The distinct function of secretion of the prostatic fluid, and the unique metabolic phenotype of prostate cells relying on lipid metabolism as a main bioenergetic pathway further suggest a significant role of caveolae and caveolar proteins in prostate malignancy. Accumulating in vitro, in vivo, and clinical evidence showed the association of caveolin-1 with prostate cancer grade, stage, metastasis, and drug resistance. In contrast, cavin-1 was found to exhibit tumour suppressive roles. Studies on prostate cancer were the first to show the distinct function of the caveolar proteins depending on their localisation within the caveolar compartment or as cytoplasmic or secreted proteins. In this review, we summarise the roles of caveola-forming proteins in prostate cancer and the potential of exploiting them as therapeutic targets or biological markers.

Exosome-Derived Noncoding RNAs as a Promising Treatment of Bone Regeneration

The reconstruction of large bone defects remains a crucial challenge in orthopedic surgery. The current treatments including autologous and allogenic bone grafting and bioactive materials have their respective drawbacks. While mesenchymal stem cell (MSC) therapy may address these limitations, growing researches have demonstrated that the effectiveness of MSC therapy depends on paracrine factors, particularly exosomes. This aroused great focus on the exosome-based cell-free therapy in the treatment of bone defects. Exosomes can transfer various cargoes, and noncoding RNAs are the most widely studied cargo through which exosomes exert their ability of osteoinduction. Here, we review the research status of the exosome-derived noncoding RNAs in bone regeneration, the potential application of exosomes, and the existing challenges.

Extracellular vesicles in bone and periodontal regeneration: current and potential therapeutic applications

Oral mesenchymal stem cells (MSCs) and their secretomes are considered important factors in the field of medical tissue engineering and cell free biotherapy due to their ease of access, differentiation potential, and successful therapeutic outcomes. Extracellular vesicles (EVs) and the conditioned medium (CM) from MSCs are gaining more attraction as an alternative to cell-based therapies due to the less ethical issues involved, and their easier acquisition, preservation, long term storage, sterilization, and packaging. Bone and periodontal regenerative ability of EVs and CM have been the focus of some recent studies. In this review, we looked through currently available literature regarding MSCs' EVs or conditioned medium and their general characteristics, function, and regenerative potentials. We will also review the novel applications in regenerating bone and periodontal defects.

Extracellular Vesicles in Tumors: A Potential Mediator of Bone Metastasis

As one of the most common metastatic sites, bone has a unique microenvironment for the growth and prosperity of metastatic tumor cells. Bone metastasis is a common complication for tumor patients and accounts for 15-20% of systemic metastasis, which is only secondary to lung and liver metastasis. Cancers prone to bone metastasis include lung, breast, and prostate cancer. Extracellular vesicles (EVs) are lipid membrane vesicles released from different cell types. It is clear that EVs are associated with multiple biological phenomena and are crucial for intracellular communication by transporting intracellular substances. Recent studies have implicated EVs in the development of cancer. However, the potential roles of EVs in the pathological exchange of bone cells between tumors and the bone microenvironment remain an emerging area. This review is focused on the role of tumor-derived EVs in bone metastasis and possible regulatory mechanisms.

Exosomes derived from osteogenic tumor activate osteoclast differentiation and concurrently inhibit osteogenesis by transferring COL1A1-targeting miRNA-92a-1-5p

In patients with prostate cancer (PCa), bone lesions appear osteoblastic in radiographs; however, pathological fractures frequently occur in PCa patients, and bone resorption is observed in all metastatic lesions under histopathologic assessment. The mechanisms that balance the activities of osteoblasts and osteoclasts in PCa patients remain unclear. We unexpectedly discovered that PCa exosomes are critical mediators in the regulation of bone homeostasis that results in osteoclastic lesions and thereby promotes tumor growth in bone. We evaluated how exosomes derived from osteoblastic, osteoclastic, and mixed PCa cell lines affect osteoblast and osteoclast differentiation, revealing that all three types of PCa exosomes promoted osteoclastogenesis in vitro and induced osteolysis in vivo. Mechanistically, microRNAs (miRNAs) delivered by PCa exosomes were found to play several key roles in bone homeostasis. Among the delivered miRNAs, miR-92a-1-5p, the most abundant miRNA, downregulated type I collagen expression by directly targeting COL1A1, and thus promoting osteoclast differentiation and inhibiting osteoblastogenesis. Furthermore, PCa exosomes also markedly reduced type I collagen expression in vivo. Our findings not only offer a novel perspective on tumor bone metastasis, where-contrary to our initial hypothesis-exosomes derived from an osteoblastic tumor induce osteoclast differentiation, but also suggest potential therapeutic targets for PCa bone metastasis.

microRNA exchange via extracellular vesicles in cancer

Cells utilize different means of inter-cellular communication to function properly. Here, we review the crosstalk between cancer cells and their surrounding environment through microRNA (miRNA)-containing extracellular vesicles (EVs). The current findings suggest that the export of miRNAs and uptake of miRNA-containing EVs might be an active process. As post-transcriptional regulators of gene expression, cancer-derived miRNAs that are taken up by normal cells can change the translational profile of the recipient cell towards a transformed proteome. Stromal cells can also deliver miRNAs via EVs to cancer cells to support tumour growth and cancer progression. Therefore, gaining a better understanding of EV-mediated inter-cellular communication in the tumour microenvironment might lead to the development of novel diagnostic and therapeutic strategies.

Emerging Players in Prostate Cancer-Bone Niche Communication

Patients with advanced prostate cancer (PCa) frequently develop skeletal metastases that are associated with fractures, disability, and increased mortality. Within the bone metastatic niche, mutual interactions between tumor cells and osteoblasts have been proposed as major contributors of osteotropism by PCa. Here, we highlight the emerging role of PCa-derived extracellular vesicles (EVs) in reprogramming osteoblasts and support of premetastatic niche formation. We also develop the concept of cancer-associated osteoblasts (CAOs) and outline the potential of PCa cells to acquire an osteoblastic phenotype, termed osteomimicry, as two strategies that PCa utilizes to create a favorable protected niche. Finally, we delineate future research that may help to deconstruct the complexity of PCa osteotropism.

Exosomes as a Novel Approach to Reverse Osteoporosis: A Review of the Literature

Osteoporosis is a chronic disease requiring long-term, sometimes lifelong, management. With the aging population, the prevalence of osteoporosis is increasing, and with it so is the risk of hip fracture and subsequent poor quality of life and higher mortality. Current therapies for osteoporosis have various significant side effects limiting patient compliance and use. Recent evidence has demonstrated the significant role of exosomes in osteoporosis both in vivo and in vitro. In this review, we summarize the pathogenesis of senile osteoporosis, highlight the properties and advantages of exosomes, and explore the recent literature on the use of exosomes in osteogenesis regulation. This is a very helpful review as several exosomes-based therapeutics have recently entered clinical trials for non-skeletal applications, such as pancreatic cancer, renal transplantation, and therefore it is urgent for bone researchers to explore whether exosomes can become the next class of orthobiologics for the treatment of osteoporosis.

Extracellular Vesicles in Bone Metastasis: Key Players in the Tumor Microenvironment and Promising Therapeutic Targets

Extracellular vesicles (EVs) are lipid membranous vesicles that are released from every type of cell. It has become clear that EVs are involved in a variety of biological phenomena, including cancer progression, and play critical roles in intracellular communication through the horizontal transfer of cellular cargoes such as proteins, DNA fragments, RNAs including mRNA and non-coding RNAs (microRNA, piRNA, and long non-coding RNA) and lipids. The most common cause of death associated with cancer is metastasis. Recent investigations have revealed that EVs are deeply associated with metastasis. Bone is a preferred site of metastasis, and bone metastasis is generally incurable and dramatically affects patient quality of life. Bone metastasis can cause devastating complications, including hypercalcemia, pathological fractures, spinal compression, and bone pain, which result in a poor prognosis. Although the mechanisms underlying bone metastasis have yet to be fully elucidated, increasing evidence suggests that EVs in the bone microenvironment significantly contribute to cancer progression and cancer bone tropism. Emerging evidence on EV functions in bone metastasis will facilitate the discovery of novel treatments. In this review, we will discuss the remarkable effects of EVs, especially on the tumor microenvironment in bone.

Switching Homes: How Cancer Moves to Bone

Bone metastases (BM) are a very common complication of the most prevalent human cancers. BM are extremely painful and may be life-threatening when associated with hypercalcaemia. BM can lead to kidney failure and cardiac arrhythmias and arrest, but why and how do cancer cells decide to "switch homes" and move to bone? In this review, we will present what answers science has provided so far, with focus on the molecular mechanisms and cellular aspects of well-established findings, such as the concept of "vicious cycle" and "osteolytic" vs. "osteosclerotic" bone metastases; as well as on novel concepts, such as cellular dormancy and extracellular vesicles. At the molecular level, we will focus on hypoxia-associated factors and angiogenesis, the Wnt pathway, parathyroid hormone-related peptide (PTHrP) and chemokines. At the supramolecular/cellular level, we will discuss tumour dormancy, id est the mechanisms through which a small contingent of tumour cells coming from the primary site may be kept dormant in the endosteal niche for many years. Finally, we will present a potential role for the multimolecular mediators known as extracellular vesicles in determining bone-tropism and establishing a premetastatic niche by influencing the bone microenvironment.

Homotrimer cavin1 interacts with caveolin1 to facilitate tumor growth and activate microglia through extracellular vesicles in glioma

Background: Intercellular communication via extracellular vesicles (EVs) plays a critical role in glioma progression. However, little is known about the precise mechanism regulating EV secretion and function. Our previous study revealed that Cavin1 was positively correlated with malignancy grades of glioma patients, and that overexpressing Cavin1 in glioma cells enhanced the malignancy of nearby glioma cells via EVs.

Methods: The current study used bioinformatics to design a variant Cavin1 (vCavin1) incapable of interacting with Caveolin1, and compared the effects of overexpressing Cavin1 and vCavin1 in glioma cells on EV production and function.

Results: Remarkably, our results indicated that Cavin1 expression enhanced the secretion, uptake, and homing ability of glioma-derived EVs. EVs expressing Cavin1 promoted glioma growth in vitro and in vivo. In addition, Cavin1 expressing murine glioma cells recruited and activated microglia via EVs. However, vCavin1 neither was loaded onto EVs nor altered EV secretion and function.

Conclusion: Our findings suggested that Cavin1-Caveolin1 interaction played a significant role in regulating production and function of glioma-EVs, and may act as a promising therapeutic target in gliomas that express high levels of Cavin1.

Exosomes: A Novel Therapeutic Agent for Cartilage and Bone Tissue Regeneration

Despite traditionally treating autologous and allogeneic transplantation and emerging tissue engineering (TE)-based therapies, which have commonly performed in clinic for skeletal diseases, as the "gold standard" for care, undesirably low efficacy and other complications remain. Therefore, exploring new strategies with better therapeutic outcomes and lower incidences of unfavorable side effect is imperative. Recently, exosomes, secreted microvesicles of endocytic origin, have caught researcher's eyes in tissue regeneration fields, especially in cartilage and bone-related regeneration. Multiple researchers have demonstrated the crucial roles of exosomes throughout every developing stage of cartilage and bone tissue regeneration, indicating that there may be a potential therapeutic application of exosomes in future clinical use. Herein, we summarize the function of exosomes derived from the primary cells functioning in skeletal diseases and their restoration processes, therapeutic exosomes used to promote cartilage and bone repairing in recent research, and applications of exosomes within the setting of the TE matrix.

Tumour-Derived Extracellular Vesicles (EVs): A Dangerous "Message in A Bottle" for Bone

Several studies have shown the importance of Extracellular Vesicles (EVs) in the intercellular communication between tumour and resident cells. Through EVs, tumour cells can trigger cell-signalling molecules and shuttle exogenous information to target cells, thus promoting spread of the disease. In fact, many processes are fuelled by EVs, such as tumour invasion and dormancy, drug-resistance, immune-surveillance escape, extravasation, extracellular matrix remodelling and metastasis. A key element is certainly the molecular profile of the shed cargo. Understanding the biochemical basis of EVs would help to predict the ability and propensity of cancer cells to metastasize a specific tissue, with the aim to target the release of EVs and to manipulate their content as a possible therapeutic approach. Moreover, EV profiling could help monitor the progression of cancer, providing a useful tool for more effective therapy. This review will focus on all the EV-mediated mentioned mechanisms in the context of both primary bone cancers and bone metastases.

Role of tumor-derived exosomes in bone metastasis

Tight coupling between bone resorption and formation is essential for bone remodeling. Disruption of this equilibrium can lead to skeletal disorders. Osseous metastatic disease is a severe consequence of tumor cell dissemination from numerous primary cancer sites, including the prostate, lungs and breasts. Metastatic disease is one of the most common causes of mortality in patients with cancer. Rapid advances in the therapeutic options for bone disease, including the use of bisphosphonates, have achieved effective clinical effects. However, the overall survival time of patients with bone metastatic has not significantly improved. Exosomes, which originate from tumor tissue and preferentially the bone, provide a reasonable way to understand the mechanism of neoplastic bone metastasis. Recently, several studies have indicated that tumor-derived exosomes are involved in cancer progression. However, the potential role that exosomes serve in the pathological communication between tumor and bone cells within the skeletal microenvironment remains an emerging field. The present review reports some recent findings on the detrimental roles of exosomes in bone metastasis. In addition, since exosomes are involved in metabolic organ cross-talk, this review highlights the involvement of cancer-derived exosomes in the regulation of skeletal metastatic diseases. Lastly, the potential promising clinical applications and emerging therapeutic opportunities targeting exosomes are discussed as novel strategies for cancer therapy.

Assessing the role of surface glycans of extracellular vesicles on cellular uptake

Extracellular vesicles (EVs) are important mediators of cell-cell communication in a broad variety of physiological contexts. However, there is ambiguity around the fundamental mechanisms by which these effects are transduced, particularly in relation to their uptake by recipient cells. Multiple modes of cellular entry have been suggested and we have further explored the role of glycans as potential determinants of uptake, using EVs from the murine hepatic cell lines AML12 and MLP29 as independent yet comparable models. Lectin microarray technology was employed to define the surface glycosylation patterns of EVs. Glycosidases PNGase F and neuraminidase which cleave N-glycans and terminal sialic acids, respectively, were used to analyze the relevance of these modifications to EV surface glycans on the uptake of fluorescently labelled EVs by a panel of cells representing a variety of tissues. Flow cytometry revealed an increase in affinity for EVs modified by both glycosidase treatments. High-content screening exhibited a broader range of responses with different cell types preferring different vesicle glycosylation states. We also found differences in vesicle charge after treatment with glycosidases. We conclude that glycans are key players in the tuning of EV uptake, through charge-based effects, direct glycan recognition or both, supporting glycoengineering as a toolkit for therapy development.

Exosomes in the Repair of Bone Defects: Next-Generation Therapeutic Tools for the Treatment of Nonunion

Nonunion with bone defects, a common complication after long bone fracture, is a major challenge for orthopaedic surgeons worldwide because of the high incidence rate and difficulties in achieving successful treatment. Bone defects are the main complications of nonunion. The conventional biological treatments for nonunion with bone defects involve the use of autologous bone grafts or bone graft substitutes and cell-based therapy. Traditional nonunion treatments have always been associated with safety issues and various other complications. Bone grafts have limited autologous cancellous bone and there is a risk of infection. Additionally, problems with bone graft substitutes, including rejection and stimulation of bone formation, have been noted, and the health of the stem cell niche is a major consideration in cell-based therapy. In recent years, researchers have found that exosomes can be used to deliver functional RNA and mediate cell-to-cell communication, suggesting that exosomes may repair bone defects by regulating cells and cytokines involved in bone metabolism. In this review, we highlight the possible relationships between risk factors for nonunion and exosomes. Additionally, we discuss the roles of exosomes in bone metabolism and bone regeneration.