Complications and Peri-operative Characteristics of Flaps for Reconstruction of Defects after Ablation of Squamous Cell Carcinoma of the Floor of the Mouth.

OBJECTIVE: To determine the appropriate method to use to repair defects after ablation of squamous cell carcinoma (SCC) of the floor of the mouth (FOM). METHODS: A retrospective review of 119 patients who underwent surgical resections of SCC of the FOM and flap reconstructions was conducted. A Student t test was used to examine the statistical differences in operative time, length of hospital stay and complications among groups with different reconstructions. RESULTS: Advanced-stage patients were repaired with more free flaps than local pedicled flaps that provided more reconstructions for small-to-medium defects. The most common recipient complication was wound dehiscence, and patients in the anterolateral thigh flap group developed a greater number of overall recipient site complications compared with those in other groups. Patients undergoing local flap reconstructions had shorter operative times compared with those with free flap reconstructions. CONCLUSION: In contrast to a radial forearm free flap as a more appropriate reconstruction for defects involving the tongue, an anterolateral thigh flap was better suited for defects with dead spaces. A fibular flap was appropriate for massive complex defects involving the mandible, FOM and tongue. A pectoralis major musculocutaneous flap provided the last line of reconstruction for patients with relapsed SCC or high-risk factors for microsurgical reconstructions.

p-AKT/VPS4B regulates the small extracellular vesicle size in venous malformation endothelial cells.

OBJECTIVE: Small extracellular vesicle (sEV)-mediated intercellular communication is increasingly the key for the understanding of venous malformations (VMs). This study aims to clarify the detailed changes of sEVs in VMs. SUBJECTS AND METHODS: Fifteen VM patients without treatment history and twelve healthy donors were enrolled in the study. sEVs were isolated from both fresh lesions and cell supernatant, and were examined by western blotting, nanoparticle tracking analysis and transmission electron microscopy. Western blot analysis, immunohistochemistry and immunofluorescence were adopted to screening candidate regulator of sEV size. Specific inhibitors and siRNA were employed to validate the role of dysregulated p-AKT/vacuolar protein sorting-associated protein 4B (VPS4B) signaling on the size of sEVs in endothelial cells. RESULTS: The size of sEVs derived from both VM lesion tissues and cell model was significantly increased. VPS4B, whose expression level was mostly significantly downregulated in VM endothelial cells, was responsible for the size change of sEVs. Targeting abnormal AKT activation corrected the size change of sEVs by recovering the expression level of VPS4B. CONCLUSION: Downregulated VPS4B in endothelial cells, resulted from abnormally activated AKT signaling, contributed to the increased size of sEVs in VMs.

Real-Time Dissection of the Transportation and miRNA-Release Dynamics of Small Extracellular Vesicles.

Extracellular vesicles (EVs) are cell-derived membrane-enclosed structures that deliver biomolecules for intercellular communication. Developing visualization methods to elucidate the spatiotemporal dynamics of EVs' behaviors will facilitate their understanding and translation. With a quantum dot (QD) labeling strategy, a single particle tracking (SPT) platform is proposed here for dissecting the dynamic behaviors of EVs. The interplays between tumor cell-derived small EVs (T-sEVs) and endothelial cells (ECs) are specifically investigated based on this platform. It is revealed that, following a clathrin-mediated endocytosis by ECs, T-sEVs are transported to the perinuclear region in a typical three-stage pattern. Importantly, T-sEVs frequently interact with and finally enter lysosomes, followed by quick release of their carried miRNAs. This study, for the first time, reports the entire process and detailed dynamics of T-sEV transportation and cargo-release in ECs, leading to better understanding of their proangiogenic functions. Additionally, the QD-based SPT technique will help uncover more secrets of sEV-mediated cell-cell communication.

A histological study of vascular wall resident stem cells in venous malformations.

Vascular wall resident stem cells (VW-SCs) play a key role in vascular formation and remodeling under both physiological and pathological situations. They not only serve as a reservoir to supply all types of vascular cells needed, but also regulate vascular homeostasis by paracrine effects. Venous malformations (VMs) are common congenital vascular malformations which are just characterized by the deficient quantity and abnormal function of vascular cells. However, the existence and role of VW-SCs in VMs is still unclear at present. In this study, the level and distribution of VW-SCs in 22 specimens of VMs were measured by immunochemistry, double-labeling immunofluorescence, and qPCR, followed by the Spearman rank correlation test. We found that both the protein and mRNA expression levels of CD34, vWF, VEGFR2, CD44, CD90, and CD105 were significantly downregulated in VMs compared with that in normal venules. VW-SCs were sporadically distributed or even absent within and outside the endothelium of VMs. The expression of the VW-SC-related markers was positively correlated with the density of both endothelial cells and perivascular cells. All those results and established evidence indicated that VW-SCs were more sporadically distributed with fewer amounts in VMs, which possibly contributing to the deficiency of vascular cells in VMs.

Endothelial cells induce degradation of ECM through enhanced secretion of MMP14 carried on extracellular vesicles in venous malformation.

Venous malformations (VMs), featuring localized dilated veins, are the most common developmental vascular anomalies. Aberrantly organized perivascular extracellular matrix (ECM) is one of the prominent pathological hallmarks of VMs, accounting for vascular dysfunction. Although previous studies have revealed various proteins involved in ECM remodeling, the detailed pattern and molecular mechanisms underlying the endothelium-ECM interplay have not been fully elucidated. Our previous studies revealed drastically elevated extracellular vesicle (EV) secretion in VM lesions. Here, we identified increased EV-carried MMP14 in lesion fluids of VMs and culture medium of TIE2-L914F mutant endothelial cells (ECs), along with stronger ECM degradation. Knockdown of RAB27A, a required regulator for vesicle docking and fusion, led to decreased secretion of EV-carried MMP14 in vitro. Histochemical analysis further demonstrated a highly positive correlation between RAB27A in the endothelium and MMP14 in the perivascular environment. Therefore, our results proved that RAB27A-regulated secretion of EV-MMP14, as a new pattern of endothelium-ECM interplay, contributed to the development of VMs by promoting ECM degradation.

In Situ Membrane Biotinylation Enables the Direct Labeling and Accurate Kinetic Analysis of Small Extracellular Vesicles in Circulation.

Circulating small extracellular vesicles (sEVs) are naturally occurring nanosized membrane vesicles that convey bioactive molecules between cells. Conventionally, to evaluate their behaviors in vivo, circulating sEVs have to be isolated from the bloodstream, then labeled with imaging materials in vitro, and finally injected back into the circulation of animals for subsequent detection. The tedious isolation-labeling-reinfusion procedures might have an undesirable influence on the natural properties of circulating sEVs, thereby changing their behaviors and the detected kinetics in vivo. Herein, we proposed an in situ biotinylation strategy to directly label circulating sEVs with intravenously injected DSPE-PEG-Biotin, aiming to evaluate the in vivo kinetics of circulating sEVs more biofriendly and accurately. Such an analysis strategy is free of isolation-labeling-reinfusion procedures and has no unfavorable influence on the natural behaviors of sEVs. The results showed that the lifetime of generic circulating sEVs in mice was around 3 days. Furthermore, we, for the first time, revealed the distinct in vivo kinetics of circulating sEV subpopulations with different cell sources, among which erythrocyte-derived sEVs showed the longest lifespan. Moreover, compared with circulating sEVs in situ or used as autograft, circulating sEVs used as allograft had the shortest lifetime. In addition, the in situ biotinylation strategy also provides a way for the enrichment of biotinylated circulating sEVs. In summary, this study provides a novel strategy for in situ labeling of circulating sEVs, which would facilitate the accurate characterization of their kinetics in vivo, thereby accelerating their future application as biomarkers and theranositic vectors.

Surviving Inhibition Induces Cell Cycle Arrest and Disrupts Multipotency in Haemangioma Stem Cells.

OBJECTIVE: To explore the potential therapies for infantile haemangiomas by targeting survivin, a member of the inhibitor of apoptosis protein family, using its specific small molecule inhibitor YM155. METHODS: The expression of survivin in human haemangioma tissue was explored using immunohistochemistry and immunohistofluorescence. Cell cycle analysis and EdU assays were used to measure cell proliferation. Heochst33342 and Annexin V/PI double staining were performed to measure cell apoptosis. The capacity for self-renewal and multilineage differentiation potential of haemangioma stem cells (HemSCs) were measured by clone formation assays and multiple differentiation assays. Murine haemangioma models were established to explore the therapeutic efficacy of YM155 in vivo. RESULTS: Strong staining of survivin in stromal cells was observed in the proliferative haemangioma tissue. In vitro studies demonstrated that YM155 induced cell cycle arrest and proliferation suppression of HemSCs, and also caused cell apoptosis at a higher concentration. YM155 impaired the self-renewal capacities and damaged multiple differentiation potentials of HemSCs. Importantly, YM155 suppressed blood vessel formation and cell proliferation, and induced cell apoptosis in murine haemangioma models. CONCLUSION: The present study demonstrated that targeting survivin using its specific suppressant, YM155, prevented the progression of infantile haemangioma by suppressing cell proliferation, inducing cell apoptosis and disrupting the differentiation potential of HemSCs. These results indicate a novel and promising therapeutic approach for the treatment of infantile haemangioma.

 Neothelaxespileata, a new species from China (Hemiptera, Sternorrhyncha, Aphididae, Thelaxinae).

Neothelaxespileata Qiao sp. nov., found on Pileamartinii (Urticaceae) in China, is described and illustrated. Neothelaxes Chakrabarti & Quednau is also a new generic record for China.

Chlorophyll-Based Near-Infrared Fluorescent Nanocomposites: Preparation and Optical Properties.

Near-infrared (NIR) fluorescence has attracted much attention in biomedical fields because it offers deep tissue penetration and high spatial resolution. Herein, a method is developed for the preparation of NIR fluorescent nanocomposites (NCs) by encapsulating natural chlorophyll (Chl) into the micelles of octylamine-modified poly(acrylic acid) (OPA). Both femtosecond transient absorption spectra and isothermal titration calorimetry thermogram reveal that the micelles of OPA provide a hydrophobic environment for the improved fluorescence efficiency. Hence the resulted Chl NCs possess unique properties such as ultrasmall size, outstanding photostability, good biocompatibility, and superbright NIR fluorescence emission. In vivo imaging of sentinel lymph node is achieved in nude mice, demonstrating the potential of Chl NCs in biomedical applications. This work provides a new strategy for the preparation of highly biocompatible NIR fluorescence labeling nanocomposites.

Three new methylated Δ8-pregnene steroids from the Polyalthia laui-derived fungus Stemphylium sp. AZGP4-2.

Three new methylated Δ8-pregnene steroids, stemphylisteroids A-C (1-3) were isolated from the medicinal plant Polyalthia laui-derived fungus Stemphylium sp. AZGP4-2. Their structures were elucidated by the detailed analysis of comprehensive spectroscopic data. The absolute configuration of 1 was determined by X-ray crystallographic analysis. Compound 1 show antibacterial activity against Escherichia coli with the MIC value of 6.25 µg/mL, and 2 exhibited a broad spectrum of antibacterial activities against six pathogenic bacteria with the MIC values ranging from 12.5 to 50 µg/mL. The discovery of three methylated Δ8-pregnene steroids 1-3 are a further addition to diverse and complex array of methylated steroids.

Effects of bleomycin on tooth eruption: a novel potential application.

There are many kinds of potentially undesirable teeth. At present, surgical extraction is the most efficient way to eliminate these teeth, but it's very complex and invasive. In this study, we investigated the effects of bleomycin (BLM) on dental follicle and tooth eruption as a potential conservative therapy for undesirable teeth. Our data showed that local injection of 0.2 U/kg BLM had no significant effects on tooth eruption compared to the control group in Wistar rats. With higher dose of BLM (0.5 or 2 U/kg), the eruption of treated teeth was interrupted and their root formation failed until 4 weeks postnatal without significant systemic toxicity. Additionally, those effects were not depending on the toxicity of overdose evidenced by TUNEL assay. In summary, injecting BLM into dental follicle at an early stage could interrupt tooth development and eruption, and may prevent the potentially clinical problems resulting from undesirable teeth instead of surgical removal.

Tunneling nanotubes mediate intercellular communication between endothelial progenitor cells and osteoclast precursors.

Tunneling nanotube (TNT)-mediated cell communication play pivotal roles in a series of physiological and pathological processes in multicellular organism. This study was designed to investigate the existence of TNTs between EPCs and osteoclast precursors and evaluate their effects on the differentiation of osteoclast precursors. For these purposes, EPCs and osteoclast precursors (RAW264.7 cells) were stained with different fluorescent dyes before direct co-culture; then, the co-cultured cells were sorted by fluorescence activated cell sorter (FACS), and the differentiation of co-cultured RAW264.7 cells was evaluated. The results showed that the differentiation potential of RAW264.7 cells was significantly inhibited after their co-culture with EPCs. Additionally, the expression of macrophage migration inhibitory factor (MIF) was up-regulated in RAW264.7 cells after co-culture. Moreover, the MIF inhibitor ISO-1 could rescue the formation of TRAP-positive multinuclear osteoclasts and the expression of osteoclastogenesis-associated genes in the co-cultured RAW264.7 cells. The present study demonstrates that EPCs can affect the differentiation of osteoclast precursors through the TNT-like structures formed across these two types of cells and might inform new therapeutic strategies for osteolytic diseases.

Controversies Regarding the Management of Teeth Associated with Cystic Lesions of the Jaws.

The continual growth of cystic lesions of the jaws can cause bone expansion, facial deformity, impacted teeth, occlusal disorder and displacement and loosening of the originating tooth or adjacent teeth. The management of teeth associated with cystic lesions of the jaws has been widely debated. When standing teeth with vital pulp are associated with cystic lesions, especially when tooth roots protrude into the cyst cavity, different treatment options have been recommended to support tooth preservation. However, there is no consensus about the extraction of the affected tooth in cases of root involvement by odontogenic keratocyst (OKC). In addition, there is controversy around whether root canal therapy should be considered a necessary treatment to be carried out prior to or after enucleation when standing teeth are associated with cystic lesions. An impacted tooth enclosed in the cavity of a developmental cyst may be treated by various approaches such as marsupialisation or decompression, or enucleation in combination with extraction or coronectomy, depending on the patient's age, root development and the angle and depth of the tooth in the jaw. Successful results obtained in pulp revascularisation after autotransplantation or endodontic regeneration treatments have been reported and pulp tissue functionality after cyst enucleation or apicetomy is a serious concern. In this article, we present an overview of the management of teeth associated with cystic lesions of the jaws.

In vitro assessment of PD-L1+ microvesicles in the cyst fluid of non-syndromic odontogenic keratocysts.

Odontogenic keratocysts (OKCs) are jaw cystic lesions which are characterized by local invasion and high recurrence rate. The majority of OKCs are exposed to microorganisms and occur along with focal inflammatory infiltrates. Cyst fluids are biological fluids that contain a large content of cytokines and immune globulins. Inhibitory receptor such as programmed death receptor 1 (PD-1) and its ligand programmed death-ligand 1 (PD-L1), which can induce a coinhibitory signal in activated T cells, plays a vital role in the differentiation, exhaustion and apoptosis of T cells. Cell derived microvesicles, carrying a cargo of functional proteins, nucleic acids and lipids, are important communication tools in the development of diseases. However, the expression of PD-L1 in OKCs tissues and whether PD-L1 could be carried by microvesicles are unexplored. Presently, we have isolated cyst fluid microvesicles and identified cell derived PD-L1+ cyst fluid microvesicles. PD-L1 was located in the membrane of the cyst fluid microvesicles. The main cellular origins of PD-L1+ cyst fluid microvesicles were dendritic cells followed by lymphocytes. Elevated PD-L1+ cyst fluid microvesicles were detected in the OKCs compared with dentigerous cysts. Isolated cyst fluid microvesicles could bind to the membrane of activated CD8 T cells and inhibit proliferation of stimulated peripheral blood CD8 T cells. In conclusion, the present study suggests that elevated PD-L1+ cyst fluid microvesicles might be related with the cyst development of OKCs.

Increased salivary microvesicles are associated with the prognosis of patients with oral squamous cell carcinoma.

Microvesicles (MVs), which are cell-derived membrane vesicles present in body fluids, are closely associated with the development of malignant tumours. Saliva, one of the most versatile body fluids, is an important source of MVs. However, the association between salivary MVs (SMVs) and oral squamous cell carcinoma (OSCC), which is directly immersed in the salivary milieu, remains unclear. SMVs from 65 patients with OSCC, 21 patients with oral ulcer (OU), and 42 healthy donors were purified, quantified and analysed for their correlations with the clinicopathologic features and prognosis of OSCC patients. The results showed that the level of SMVs was significantly elevated in patients with OSCC compared to healthy donors and OU patients. Meanwhile, the level of SMVs showed close correlations with the lymph node status, and the clinical stage of OSCC patients. Additionally, the ratio of apoptotic to non-apoptotic SMVs was significantly decreased in OSCC patients with higher pathological grade. Consistently, poorer overall survival was observed in patients with lower ratio of apoptotic to non-apoptotic SMVs. In conclusion, the elevated level of SMVs is associated with clinicopathologic features and decreased survival in patients with OSCC, suggesting that SMVs are a potential biomarker and/or regulator of the malignant progression of OSCC.

Lymphotoxin-α promotes tumor angiogenesis in HNSCC by modulating glycolysis in a PFKFB3-dependent manner.

Tumor angiogenesis is critical for tumor progression as the new blood vessels supply nutrients and facilitate metastasis. Previous studies indicate tumor associated lymphocytes, including B cells and T cells, contribute to tumor angiogenesis and tumor progression. The present study aims to identify the function of Lymphotoxin-α (LT-α), which is secreted by the activated lymphocytes, in the tumor angiogenesis of head and neck squamous cell carcinoma (HNSCC). The coculture system between HNSCC cell line Cal27 and primary lymphocytes revealed that tumor cells promoted the LT-α secretion in the cocultured lymphocytes. In vitro data further demonstrated that LT-α promoted the proliferation, migration and tube formation of human umbilical vein endothelial cells (HUVECs) by enhancing the PFKFB3-mediated glycolytic flux. Genetic and pharmacological inhibition of PFKFB3 suppressed the enhanced proliferation and migration of HUVECs. We further identified that LT-α induced PFKFB3 expression was dependent on the TNFR/NF-κB signaling pathway. In addition, we proved that PFKFB3 blockade decreased the density of CD31 positive blood vessels in HNSCC xenografts. Finally, the results from the human HNSCC tissue array revealed that the expression of LT-α in HNSCC samples positively correlated with microvessel density, lymphocytes infiltration and endothelial PFKFB3 expression. In conclusion, infiltrated lymphocyte secreted LT-α enhances the glycolysis of ECs in a PFKFB3-dependent manner through the classical NF-κB pathway and promotes the proliferation and migration of ECs, which may contribute to the aberrant angiogenesis in HNSCCs. Our study suggests that PFKFB3 blockade is a promising therapeutic approach for HNSCCs by targeting tumor angiogenesis.

Lymphocyte­derived microparticles stimulate osteoclastogenesis by inducing RANKL in fibroblasts of odontogenic keratocysts.

Leukocyte­derived microparticles (LMPs) include neutrophil­, lymphocyte­ and monocyte­derived MPs. LMPs act as proinflammatory mediators in autoimmune diseases, infectious diseases and vascular diseases. The present study examined the hypothesis that the percentage of LMPs was increased in patients with inflamed odontogenic keratocysts (OKCs), and investigated the biological effects of Jurkat cell­derived MPs on the fibroblasts of OKCs in vitro. Cyst fluid MPs, obtained by centrifugation of samples from 20 patients with inflamed OKCs, 3 patients with uninflamed OKCs, 15 patients with radicular cysts (RCs) and 12 patients with inflamed dentigerous cysts (DCs), were analyzed by transmission electron microscopy, dynamic light scattering and immunofluorescence staining. The percentages and concentrations of cyst fluid LMPs were further determined by flow cytometry. The cytokine levels of apoptotic Jurkat cell­derived MPs and Jurkat cell supernatants were compared by cytokine antibody arrays. Fibroblasts were isolated from 3 patients with OKC and co­cultured with apoptotic Jurkat cell­derived MPs with or without interleukin (IL)­15Rα to detect the levels of matrix metallopeptidase 9 (MMP­9) and receptor activator of nuclear factor­κB ligand (RANKL) by reverse transcription­quantitative polymerase chain reaction and enzyme­linked immunosorbent assay. The supernatant from Jurkat MPs­treated fibroblasts was collected to make conditioned medium in which the osteoclastogenesis of Raw264.7 cells was determined. Antibodies against human soluble (s)RANKL were added to the conditioned medium to investigate the inhibitory effects. Mean percentages of lymphocyte­ and neutrophil­derived MPs were significantly higher in inflamed OKCs than in DCs. Significant elevations in IL­15 were detected in apoptotic Jurkat cell­derived MPs compared with that in Jurkat cell supernatant. Furthermore, higher levels of MMP­9 and RANKL were detected in Jurkat cell MP­treated OKC fibroblasts, and this was partially blocked by IL­15Rα. Increased osteoclast­like cell formation was observed in the Jurkat MPs­treated fibroblast supernatant and Raw264.7 co­culture groups. The anti­human sRANKL antibody in the Jurkat MPs­treated fibroblast supernatant group decreased the osteoclastogenesis of the Raw264.7 cells. These results indicate that LMPs serve as novel communication tools that contribute toward the bone resorption of inflamed OKCs by inducing RANKL of OKC fibroblasts via IL­15.

Tumor associated macrophages induce epithelial to mesenchymal transition via the EGFR/ERK1/2 pathway in head and neck squamous cell carcinoma.

The development of head and neck squamous cell carcinoma (HNSCC) is closely associated with inflammation. Tumor associated macrophages (TAMs), the largest population of inflammatory cells in the tumor stroma, serve an important role in accelerating cancer progression. The present study aimed to investigate the role of TAMs in the metastasis of HNSCC. TAM biomarkers and epithelial to mesenchymal transition (EMT)­associated proteins were detected using immunohistochemical and immunofluorescence staining in HNSCC. Then, direct and indirect co­culture systems of TAMs and HNSCC cells were established. The EMT­associated proteins and associated signaling pathways in HNSCC cells of the co­culture system were measured by reverse transcription­quantitative polymerase chain reaction and western blotting. Finally, hierarchical clustering was performed to analyze associations among TAM biomarkers, epidermal growth factor receptor (EGFR), activated extracellular signal­regulated protein kinase 1/2 (ERK1/2) and EMT­associated proteins in HNSCC tissues. The results indicated that the expression of EMT­associated proteins was positively associated with M2 macrophage biomarkers in HNSCC tissues. Cal27 cells were isolated from the co­culture system by fluorescence­activated cell sorting, and it was identified that E­cadherin was downregulated in Cal27 cells, while Vimentin and Slug were upregulated. Furthermore, the results indicated that EGF released by M2 macrophages in the co­culture served an important role by activating ERK1/2. The correlation and cluster analyses indicated that activated ERK1/2 was positively correlated with cluster of differentiation­163, EGFR, Vimentin and Slug. This suggested that TAMs may induce the EMT of cancer cells by activating the EGFR/ERK1/2 signaling pathway in HNSCC, which may be a promising approach to suppressing cancer metastasis.

Overexpression of Fra-1, c-Jun and c-Fos in odontogenic keratocysts: potential correlation with proliferative and anti-apoptotic activity.

AIMS: The purpose of this study was to explore the potential involvement of Fra-1, c-Jun and c-Fos, three vital members of the AP-1 complex, in the pathogenesis of odontogenic keratocysts (OKCs). METHODS AND RESULTS: Tissue samples, containing 10 normal oral mucosa (OM), 10 dentigerous cysts (DC) and 32 OKC specimens, were applied to investigate the expression levels of Fra-1, c-Jun and c-Fos by immunohistochemistry and real-time-quantitative polymerase chain reaction (RT-qPCR). The association between Fra-1, c-Jun and c-Fos expression levels and markers of proliferation [Ki-67, proliferating cell nuclear antigen (PCNA)], anti-apoptosis (Bcl-2) was then investigated in the OKC serial tissue sections. The results showed that Fra-1, c-Jun and c-Fos expression levels were increased significantly in OKCs compared to these in OM and DC tissue samples. Meanwhile, the expression levels of Fra-1, c-Jun and c-Fos were associated positively with the expression levels of Ki-67, PCNA and Bcl-2, as confirmed further by double-labelling immunofluorescence analysis and hierarchical analysis. CONCLUSIONS: This study revealed for the first time that Fra-1, c-Jun and c-Fos were overexpressed in OKCs and had a close correlation with proliferation and anti-apoptosis potential of OKCs.

Increased level of cell-derived microparticles in the cyst fluids of odontogenic keratocysts.

The aim of this study was to examine the level and basic characteristics of cell­derived microparticles (MPs) in the cyst fluids of odontogenic keratocysts (OKCs). For this purpose, MPs from the cyst fluids (CFMPs) of OKCs were purified by a classic differential centrifugation method and characterized by a transmission electron microscope and fluorescence microscope. Flow cytometric analysis was used to determine the size, concentration and cellular origins of the CFMPs. Moreover, the expression level of receptor activator for nuclear factor­κB ligand in the OKCs was evaluated by immunohistochemical staining and then analyzed for its correlation with the concentration of CFMPs by Spearman's rank correlation test. In addition, reverse transcription­quantitative polymerase chain reaction (RT­qPCR) and tartaric­resistant acid phosphatase (TRAP) staining were performed to examine the osteoclastogenesis of mouse bone marrow­derived macrophages (BMMs) in response to CFMPs. The results revealed that the levels of total CFMPs were significantly elevated in OKCs compared with dentigerous cysts (DCs) and radicular cysts (RCs). In addition, in vitro experiments further revealed that CFMPs derived from the OKCs of patients could be taken up by BMMs, leading to a significant increase in the mRNA expression levels of nuclear factor of activated T­cells 1 (NFATc1) and TRAP. Moreover, TRAP­positive multinucleated osteoclasts were successfully cultured in the presence of macrophage colony­stimulating factor (M­CSF) and CFMPs with BMMs. On the whole, our findings indicate that patients with OKCs have higher levels of CFMPs compared with patients with DCs and RCs, which may be associated with the bone resorption of OKCs.