Chitosan-based hydrogel dressings for diabetic wound healing via promoting M2 macrophage-polarization.

A long-term inflammatory phase of diabetic wounds is the primary cause to prevent their effective healing. Bacterial infection, excess reactive oxygen species (ROS), especially failure of M2-phenotype macrophage polarization can hinder the transition of diabetic wounds from an inflammation phase to a proliferation one. Herein, a chitosan-based hydrogel dressing with the ability of regulating M2 macrophage polarization was reported. The PAAc/CFCS-Vanillin hydrogel dressing was synthesized by one step thermal polymerization of catechol-functionalized chitosan (CFCS), acrylic acid, catechol functional methacryloyl chitosan­silver nanoparticles (CFMC-Ag NPs) and bioactive vanillin. The PAAc/CFCS-Vanillin hydrogel possessed sufficient mechanical strength and excellent adhesion properties, which helped rapidly block bleeding of wounds. Thanks to CFCS, CFMC-Ag NPs and vanillin in the hydrogel, it displayed excellent antibacterial infection in the wounds. Vanillin helped scavenge excess ROS and regulate the levels of inflammatory factors to facilitate the polarization of macrophages into the M2 phenotype. A full-thickness skin defect diabetic wound model showed that the wounds treated by the PAAc/CFCS-Vanillin hydrogel exhibited the smallest wound area, and superior granulation tissue regeneration, remarkable collagen deposition, and angiogenesis were observed in the wound tissue. Therefore, the PAAc/CFCS-Vanillin hydrogel could hold promising potential as a dressing for the treatment of diabetic chronic wounds.

Highly Flexible, High-Performance, and Stretchable Piezoelectric Sensor Based on a Hierarchical Droplet-Shaped Ceramics with Enhanced Damage Tolerance.

Stretchable self-powered sensors are of significant interest in next-generation wearable electronics. However, current strategies for creating stretchable piezoelectric sensors based on piezoelectric polymers or 0-3 piezoelectric composites face several challenges such as low piezoelectric activity, low sensitivity, and poor durability. In this paper, a biomimetic soft-rigid hybrid strategy is used to construct a new form of highly flexible, high-performance, and stretchable piezoelectric sensor. Inspired by the hinged bivalve Cristaria plicata, hierarchical droplet-shaped ceramics are manufactured and used as rigid components, where computational models indicate that the unique arched curved surface and rounded corners of this bionic structure can alleviate stress concentrations. To ensure electrical connectivity of the piezoelectric phase during stretching, a patterned liquid metal acts as a soft circuit and a silicone polymer with optimized wettability and stretchability serves as a soft component that forms a strong mechanical interlock with the hierarchical ceramics. The novel sensor design exhibits excellent sensitivity and durability, where the open circuit voltage remains stable after 5000 stretching cycles at 60% strain and 5000 twisting cycles at 180°. To demonstrate its potential in heathcare applications, this new stretchable sensor is successfully used for wireless gesture recognition and assessing the progression of knee osteoarthritis.

Dielectric Properties of Benzocyclobutene-Based Resin: A Molecular Dynamics Study.

Benzocyclobutene (BCB)-based resins have garnered considerable attention because of their remarkable dielectric properties and thermal stability. However, in molecular dynamics (MD) simulations, progress in BCB-based resin research has yet to keep pace with experimental advancements, resulting in a shortage of theoretical underpinnings at the molecular level. This study focuses on a novel homopolymer, poly(2-(4-benzocyclobutenyl)-divinylbenzene(DVB-S-BCB)), and devises an interactive methodology suitable for BCB-based resins. We implemented a Python script for the joint relaxation method to construct a three-dimensional model of the cured polymer using MadeA and LAMMPS. We conducted MD simulations to investigate how the cross-linking degree and resin molecular weight influence the dielectric properties of the cured polymer. Furthermore, we analyzed the thermodynamic properties through simulation. The results illustrate that augmenting the cross-linking degree and resin molecular weight results in a higher cross-linking density and reduced free volume, thereby increasing the dielectric constant of the resin. The cross-link density does not increase indefinitely with molecular weight, and after a certain threshold is reached, it cannot have a significant effect on the dielectric constant. The degree of cross-linking exerts a more pronounced impact on the dielectric constant than the molecular weight of the resin. In addition, the simulation results denote the excellent thermodynamic properties of the cured polymer. This study also examines the dielectric and thermodynamic properties of the resin samples that were experimentally prepared. The obtained data successfully confirm the reliability of the simulation results. This study offers novel insights for future simulation research on benzocyclobutene-based resins. Additionally, it provides theoretical support for exploring experimental work on low-dielectric materials in the electronic field.

The Effect of Sleep on Metabolism, Musculoskeletal Disease, and Mortality in the General US Population: Analysis of Results From the National Health and Nutrition Examination Survey.

BACKGROUND: Sleep is an important physiological behavior in humans that is associated with the occurrence and development of various diseases. However, the association of sleep duration with health-related outcomes, including obesity-related factors, musculoskeletal diseases, and mortality because of different causes, has not been systematically reported. OBJECTIVE: This study aims to systematically investigate the effect of sleep duration on health-related outcomes. METHODS: Overall, 54,664 participants with sleep information from 8 survey cycles of the National Health and Nutrition Examination Survey (2005-2020) were included in the analysis. Health-related outcomes comprised obesity-related outcomes (ie, BMI, obesity, waist circumference, and abdominal obesity), metabolism-related outcomes (ie, uric acid, hyperuricemia, and bone mineral density [BMD]), musculoskeletal diseases (ie, osteoarthritis [OA] and rheumatoid arthritis [RA]), and mortality because of different causes. The baseline information of participants including age, sex, race, educational level, marital status, total energy intake, physical activity, alcohol consumption, smoking, hypertension, and diabetes was also collected as covariates. Information about the metabolism index, disease status, and covariates was acquired from the laboratory, examination, and questionnaire data. Survival information, including survival status, duration, and cause of death, was obtained from the National Death Index records. Quantile regression models and Cox regression models were used for association analysis between sleep duration and health-related outcomes. In addition, the threshold effect analysis, along with smooth curve fitting method, was applied for the nonlinear association analysis. RESULTS: Participants were divided into 4 groups with different sleep durations. The 4 groups showed significant differences in terms of baseline data (P<.001). The quantile regression analysis indicated that participants with increased sleep duration showed decreased BMI (ß=-.176, 95% CI -.220 to -.133; P<.001), obesity (odds ratio [OR] 0.964, 95% CI 0.950-0.977; P<.001), waist circumference (ß=-.219, 95% CI -.320 to -.117; P<.001), abdominal obesity (OR 0.975, 95% CI 0.960-0.990; P<.001), OA (OR 0.965, 95% CI 0.942-0.990; P=.005), and RA (OR 0.940, 95% CI 0.912-0.968; P<.001). Participants with increased sleep duration also showed increased BMD (ß=.002, 95% CI .001-.003; P=.005), as compared with participants who slept <5.5 hours. A significant saturation effect of sleep duration on obesity, abdominal obesity, and hyperuricemia was detected through smooth curve fitting and threshold effect analysis (sleep duration>inflection point). In addition, a significant threshold effect of sleep duration on BMD (P<.001); OA (P<.001); RA (P<.001); and all-cause (P<.001), cardiovascular disease-cause (P<.001), cancer-cause (P=.005), and diabetes-cause mortality (P<.001) was found. The inflection point was between 6.5 hours and 9 hours. CONCLUSIONS: The double-edged sword effect of sleep duration on obesity-related outcomes, embolism-related diseases, musculoskeletal diseases, and mortality because of different causes was detected in this study. These findings provided epidemiological evidence that proper sleep duration may be an important factor in the prevention of multisystem diseases.

High Thermal Stability and Low Dielectric Constant of BCB Modified Silicone Resins.

Based on the excellent physical properties and flexible molecular modifiability, modified silicone resins have received favorable attention in the field of microelectronics, and recently a number of modified silicone resins have appeared while few breakthroughs have been made in low dielectric constant (low-k) materials field due to the limitations of structure or the curing process. In this work, functional silicone resin with different BCB contents was prepared with two monomers. The resins showed low dielectric constant (k = 2.77 at 10 MHz) and thermal stability (T5% = 495.0 °C) after curing. Significant performance changes were observed with the increase in BCB structural units, and the functional silicone obtained does not require melting and dissolution during processing because of good fluidity at room temperature. Moreover, the mechanical properties of silicone resins can be also controlled by adjusting the BCB content. The obtained silicone resins could be potentially used in the field of electronic packaging materials.

The exposure to volatile organic chemicals associates positively with rheumatoid arthritis: a cross-sectional study from the NHANES program.

Introduction: Rheumatoid arthritis (RA) is an autoimmune disease and closely associated with both genetic and environmental factors. Volatile organic chemicals (VOC), a common environment pollutant, was associated with some autoimmune diseases, while whether VOC exposure or which VOC leads to RA is yet clarified. Methods: A cross-sectional study using data from the 6 survey cycles (2005-2006, 2011-2012, 2013-2014, 2015-2016, 2017-2018, 2017-2020) of NHANES program was performed. The RA or non-arthritis status of participant was identified through a questionnaire survey. The quantile logistic regression method was used for correlation analysis between VOC metabolites (VOCs) in urine and RA. The covariates included age, gender, race, educational level, marital status, total energy intake, physical activity, smoking, hypertension, diabetes, urine creatinine, albumin and marihuana use. Results: A total of 9536 participants (aged 20 to 85) with 15 VOCs, comprising 618 RA and 8918 non-arthritis participants, was finally included for analysis. Participants in the RA group showed higher VOCs in urine than that in the non-arthritis group. A positive association between 2 VOCs (AMCC: Q4: OR=2.173, 95%CI: 1.021, 4.627. 3HPMA: Q2: OR=2.286, 95%CI: 1.207 - 4.330; Q4: OR=2.663, 95%CI: 1.288 -5.508.) and RA was detected in the model 3, which was independent of all the covariates. The relative parent compounds of the two VOCs included N,N-Dimethylformamide and acrolein. Discussion: These findings suggested that the VOC exposure significantly associated with RA, providing newly epidemiological evidence for the establishment that environmental pollutants associated with RA. And also, more prospective studies and related experimental studies are needed to further validate the conclusions of this study.

Comprehensive evaluation of serum cotinine on human health: Novel evidence for the systemic toxicity of tobacco smoke in the US general population.

BACKGROUND: Accumulating epidemiological studies have demonstrated that smoking caused damage to human health. However, these studies almost focused on the individual smoking pattern rather than the toxic ingredients of tobacco smoke. Despite the exact accuracy of cotinine as a smoking exposure biomarker, there were few studies investigating the association between serum cotinine and human health. This study aimed to provide novel evidence about the harmful effect of smoking on systemic health from the perspective of serum cotinine. METHODS: All used data was acquired from 9 survey cycles (2003-2020) of the National Health and Nutrition Examination Survey (NHANES) program. The mortality information of participants was derived from the National Death Index (NDI) website. The disease status of participants, including respiratory, cardiovascular, and musculoskeletal diseases, was obtained from questionnaire surveys. The metabolism-related index, including obesity, bone mineral density (BMD), and serum uric acid (SUA), was obtained from examination data. Multiple regression methods, smooth curve fitting, and threshold effect models were used for association analyses. RESULTS: With a total of 53,837 subjects included, we detected an L-shaped association between serum cotinine and obesity-related index, a negative association between serum cotinine and BMD, a positive association between serum cotinine and nephrolith and coronary heart disease (CHD), a threshold effect of serum cotinine on hyperuricemia (HUA), osteoarthritis (OA), chronic obstructive pulmonary disease (COPD), and stroke, as well as a positive saturate effect of serum cotinine on asthma, rheumatoid arthritis (RA), all-cause, cardiovascular disease (CVD)-cause, cancer-cause, and diabetes-cause mortality. CONCLUSIONS: In this study, we investigated the association between serum cotinine and multiple health outcomes, indicating the systematic toxicity of smoking exposure. These findings provided novel epidemiological evidence about how passive exposure to tobacco smoke affects the health condition of the general US population.

Dissection of Cellular Communication between Human Primary Osteoblasts and Bone Marrow Mesenchymal Stem Cells in Osteoarthritis at Single-Cell Resolution.

Background and Objectives: Osteoblasts are derived from bone marrow mesenchymal stem cells (BMMSCs) and play important role in bone remodeling. While our previous studies have investigated the cell subtypes and heterogeneity in osteoblasts and BMMSCs separately, cell-to-cell communications between osteoblasts and BMMSCs in vivo in humans have not been characterized. The aim of this study was to investigate the cellular communication between human primary osteoblasts and bone marrow mesenchymal stem cells. Methods and Results: To investigate the cell-to-cell communications between osteoblasts and BMMSCs and identify new cell subtypes, we performed a systematic integration analysis with our single-cell RNA sequencing (scRNA-seq) transcriptomes data from BMMSCs and osteoblasts. We successfully identified a novel preosteoblasts subtype which highly expressed ATF3, CCL2, CXCL2 and IRF1. Biological functional annotations of the transcriptomes suggested that the novel preosteoblasts subtype may inhibit osteoblasts differentiation, maintain cells to a less differentiated status and recruit osteoclasts. Ligand-receptor interaction analysis showed strong interaction between mature osteoblasts and BMMSCs. Meanwhile, we found FZD1 was highly expressed in BMMSCs of osteogenic differentiation direction. WIF1 and SFRP4, which were highly expressed in mature osteoblasts were reported to inhibit osteogenic differentiation. We speculated that WIF1 and sFRP4 expressed in mature osteoblasts inhibited the binding of FZD1 to Wnt ligand in BMMSCs, thereby further inhibiting osteogenic differentiation of BMMSCs. Conclusions: Our study provided a more systematic and comprehensive understanding of the heterogeneity of osteogenic cells. At the single cell level, this study provided insights into the cell-to-cell communications between BMMSCs and osteoblasts and mature osteoblasts may mediate negative feedback regulation of osteogenesis process.

Phosphorus-Containing Flame-Retardant Benzocyclobutylene Composites with High Thermal Stability and Low CTE.

As a component of printed circuit substrate, copper clad laminate (CCL) needs to meet the performance requirements of heat resistance, flame retardancy, and low coefficient of thermal expansion (CTE), which, respectively, affects the stability, safety, and processability of terminal electronic products. In this paper, benzocyclobutylene (BCB)-functionalized phosphorus-oxygen flame retardant composites were prepared through introducing the BCB groups, and the performance was researched by thermogravimetric analysis, microcombustion calorimetry, and thermomechanical analysis. The research results show that these phosphorus oxide compounds containing BCB groups show good thermal stability and low total heat release (THR) after thermal curing, and the more BCB groups on the phosphorus oxide monomers, the better the thermal stability and flame retardancy of cured resins. The Td5 and THR of the composite (M3) are as high as 443 °C and 23.1 kJ/g, respectively. In addition, the CTE of M3 is as low as 16.71 ppm/°C. Introduction of BCB groups which can be crosslinked through heat to improve the thermal stability, flame retardancy, and reduced CTE of traditional organophosphorus flame retardant materials. These materials are expected to be good candidates for CCL substrates for electronic circuits.

Iridium-catalyzed selective amination of B(4)-H for the synthesis of o-carborane-fused indolines.

An iridium-catalyzed selective amination of B(4)-H via dehydrogenative cross-coupling of B-H/N-H bonds for the synthesis of o-carborane-fused indolines has been developed for the first time. Various types of unprecedented o-carborane-fused indolines have been synthesized, which would be potential candidates for applications in drug discovery, pharmaceutical chemistry and functional materials. This work offers a valuable reference for the designing and synthesis of o-carborane-fused heterocycles.

The association analysis between exposure to volatile organic chemicals and obesity in the general USA population: A cross-sectional study from NHANES program.

BACKGROUND: Increasing evidence have been provided that the exposure to environment pollutants was associated obesity, while whether the exposure to volatile organic chemicals (VOC) was associated with obesity or abdominal obesity is yet to be clarified. METHOD: A cross-sectional study using data from the 6 survey cycles (2005-2006, 2011-2018, 2017-2020) of NHANES program was performed. Obesity and abdominal obesity were identified as a BMI >30 and a waist circumference >102 cm for men or >88 cm for women respectively. The quantile logistic regression method was used to analyze the association between VOC metabolites (VOCs) in urine and obesity, and the quantile regression method was used for the association analysis between VOCs in urine and BMI, as well as waist circumference. RESULTS: A total of 17 524 participants (4965 obesity, 7317 abdominal obesity) were included, and participants in the obesity or abdominal obesity groups showed higher VOCs in urine than that in the control group. The CEMA was identified as the risk factor for obesity and abdominal obesity in all the 4 models, and its detected OR for obesity in the Q2 to Q4 of model 3 was 1.169 (Q2, p < 0.05), 1.306 (Q3, p < 0.001) and 1.217 (Q4, p < 0.01) respectively. And its OR for abdominal obesity in the Q2 to Q4 of model 3 was 1.222 (Q2, p < 0.01), 1.448 (Q3, p < 0.001) and 1.208 (Q4, p < 0.05) respectively. A significantly positive association between CEMA and BMI, as well as waist circumference, was also detected. CONCLUSION: In this study, we found that the exposure to VOC (Acrolein, Acrylamide, Acrylonitrile, 1,3-Butadiene, Crotonaldehyde, Cyanide, N,N-Dimethylformamide, Ethylbenzene, styrene, Propylene oxide, Toluene and Xylene) was significantly associated with obesity or abdominal obesity. And also, more prospective studies and related experimental researches should be carried out to further demonstrate the conclusion of this study.

Imputation of Human Primary Osteoblast Single Cell RNA-Seq Data Identified Three Novel Osteoblastic Subtypes.

BACKGROUND: Recently, single-cell RNA sequencing (scRNA-seq) technology was increasingly used to study transcriptomics at a single-cell resolution, scRNA-seq analysis was complicated by the "dropout", where the data only captures a small fraction of the transcriptome. This phenomenon can lead to the fact that the actual expressed transcript may not be detected. We previously performed osteoblast subtypes classification and dissection on freshly isolated human osteoblasts. MATERIALS AND METHODS: Here, we used the scImpute method to impute the missing values of dropout genes from a scRNA-seq dataset generated on freshly isolated human osteoblasts. RESULTS: Based on the imputed gene expression patterns, we discovered three new osteoblast subtypes. Specifically, these newfound osteoblast subtypes are osteoblast progenitors, and two undetermined osteoblasts. Osteoblast progenitors showed significantly high expression of proliferation related genes (FOS, JUN, JUNB and JUND). Analysis of each subtype showed that in addition to bone formation, these undetermined osteoblasts may involve osteoclast and adipocyte differentiation and have the potential function of regulate immune activation. CONCLUSIONS: Our findings provided a new perspective for studying the osteoblast heterogeneity and potential biological functions of these freshly isolated human osteoblasts at the single-cell level, which provides further insight into osteoblasts subtypes under various (pathological) physiological conditions.

Surface Engineering of Ni wires and Rapid Growth Strategy of Ni-MOF Synergistically Contribute to High-Performance Fiber-Shaped Aqueous Battery.

The fiber-shaped aqueous battery (FSAB) has the advantages of flexibility, portability and safety making it promising for energy storage applications. In particular, FSABs based on metal wire current collectors with good electrical conductivity can provide excellent energy storage properties. However, the low adhesion caused by the smooth surface of the metal wire and the unavailability of many electrochemically active materials for use in FSAB is holding back their development. Herein, a substrate is effectively constructed for the strongly applicable growth of the active material via a Ni wire etching strategy. In addition, core-shell structured nanorod arrays consisting of NiCo2 O4 and Ni-metal-organic frameworks (MOFs) are constructed, where Ni-MOF can be obtained rapidly via ß-Ni(OH)2 intermediates. The NCO/NM-15 electrode obtained by structural regulation exhibits high capacity and outstanding cycling stability. De calculations further demonstrate that the formation of NiCo2 O4 and Ni-MOF heterostructures results in a significant increase in the Fermi level leading to more active internal electrons, which facilitates electron transfer in electrochemical reactions. An assembled FSAB device can provide an energy density of 158.33 µWh cm-2 and the devices can provide power for a calculator and an electronic watch screen, demonstrating a wide application prospect in the field of energy storage.

Cu(OTf)2/NBS-Mediated Tandem Reaction of 1-Cinnamyl Alcohol-o-Carboranes via Ring Opening of Oxetane with Arenes: An Alternative Approach for the Synthesis of C-Alkenyl-o-Carboranes.

The Cu(OTf)2/NBS-mediated tandem reaction of 1-cinnamyl alcohol-o-carboranes for the synthesis of C-alkenyl-o-carboranes has been developed. Mechanism studies demonstrated that the Cu(OTf)2-promoted ring opening of oxetane with electron-rich arenes as soft nucleophiles was involved and was the key step for the transformation. This work provided an alternative strategy for the synthesis of C-alkenyl-o-carboranes, which has an important reference for the synthesis of o-carborane derivatives with diversity.

High performance low dielectric polybenzocyclobutene nanocomposites with organic-inorganic hybrid silicon nanoparticles.

In this study, benzocyclobutene-functionalized organic-inorganic hybrid spherical silicon nanoparticles (BCBNPs) with controllable size (200-600 nm) and good dispersion were synthesized by a one-step sol-gel method in aqueous solution. The effect of the reaction conditions (time, precursor concentration, pH value and temperature) on the particle size of the BCBNPs and the formation mechanism of the BCBNPs were studied. What is more, homogeneously dispersed BCBNPs/divinyltetramethyldisiloxane-bis(benzocyclobutene) (BCBNPs/PDVSBCB) nanocomposites were prepared and the influence of the incorporation of BCBNPs on the properties of the nanocomposites was investigated. The dielectric constants of the BCBNPs/PDVSBCB nanocomposites were drastically reduced relative to neat PDVSBCB, and were as low as 2.25 (30 MHz). Besides, the thermal and mechanical properties of the BCBNPs/PDVSBCB nanocomposites were significantly improved, evidencing their potential applications in the field of high-performance dielectric materials.

Dietary inflammation index and osteoarthritis in the elderly: is there a mediating role of physical activity?

We examined whether physical activity (PA) explains the association between dietary inflammatory potential and osteoarthritis (OA) in the elderly. A total of 1249 elderly people (≥65 years) were eligible for this study from the National Health and Nutrition Examination Survey (NHANES) from 2011 to 2016. The semi-quantitative Food Frequency Questionnaire (FFQ) and Global PA Questionnaire (GPAQ) were used to evaluate the diet and PA of the elderly, respectively. The multivariable logistic regression model estimated the odds ratio (OR) and 95% confidence interval (CI) between Energy-adjusted Dietary Inflammatory Index (E-DII) and OA. The interaction of E-DII and PA on depressive events was tested, and the mediation analysis of PA was performed. The average E-DII in this study was +0.68 (SE 0.08), and the score ranges from -5.32 (most anti-inflammatory) to +4.26 (most pro-inflammatory). In comparison with the first quartile, the elderly from the second quartile (OR: 1.16 [95% CI: 1.06, 1.68]) to the fourth quartile (OR: 1.64 [95% CI: 1.13, 2.37]) had a higher risk of OA before adjustment for PA. An interaction was observed between E-DII and PA in terms of the risk of OA (PInteraction < 0.001). The whole related part was mediated by PA (20.08%). Our findings indicated that the higher pro-inflammatory potential of diet was associated with a higher risk of OA, and low PA was an important part of the mediating factor in the relationship between systemic low-grade dietary inflammation and the risk of OA.

Low dielectric resins derived from hyperbranched carbosilane oligmers functionalized by benzocyclobutene groups.

Polycarbosilanes have been considered as potential materials used in electronic packaging and circuit boards owing to their excellent low-dielectric performance. In this work, we prepared new hyperbranched carbosilane oligomers (HCBOs) which were functionalized by benzocyclobutene (BCB) groups. HCBOs can be thermally cured to produce transparent (HCBRs) with low dielectric constant and high thermostability.

Exosomes From Human Urine-Derived Stem Cells Encapsulated Into PLGA Nanoparticles for Therapy in Mice With Particulate Polyethylene-Induced Osteolysis.

Background: Periprosthetic osteolysis is the primary reason for arthroplasty failure after total joint replacement because of the generation of wear particles and subsequent bone erosion around the prosthesis, which leads to aseptic loosening. Periprosthetic osteolysis is often treated with revision surgery because of the lack of effective therapeutic agents. As key messengers of intercellular interactions, exosomes can be independently used as therapeutic agents to promote tissue repair and regeneration. In this study, we fabricated poly(lactic-co-glycolic acid) (PLGA) nanoparticles (NPs) that carry exosomes derived from human urine stem cells (USC-Exos) and explored their effects on polyethylene-induced osteolysis. Methods: USCs were identified by multipotent differentiation and flow cytometry analyses. USC-Exos were isolated and identified by transmission electron microscopy (TEM), dynamic light scattering (DLS), and western blotting. PLGA microspheres containing USC-Exos were fabricated to synthesize NPs using the mechanical double-emulsion method. The obtained NPs were characterized in terms of stability, toxicity, exosome release, and cell uptake. Then, these NPs were implanted into the murine air pouch model, and their effects on polyethylene-induced osteolysis were evaluated by microcomputed tomography (micro-CT) and histological analyses. Results: The average NP diameter was ~282 ± 0.4 nm, and the zeta potential was -2.02 ± 0.03 mV. After long-term storage at room temperature and 4°C, the NP solution was stable without significant coaggregation. In vitro release profiles indicated sustained release of exosomes for 12 days. In vivo, injection of NPs into the murine air pouch caused less osteolysis than that of USC-Exos, and NPs significantly reduced bone absorption, as indicated by histology and micro-CT scanning. Conclusion: Our findings suggest that USC-Exo-based PLGA NPs can prevent particulate polyethylene-induced osteolysis and bone loss.

Extracellular Vesicles from Human Urine-Derived Stem Cells Ameliorate Particulate Polyethylene-Induced Osteolysis.

PURPOSE: Wear debris particle-induced periprosthetic osteolysis is a severe complication of total joint replacement that results in aseptic loosening and subsequent arthroplasty failure. No effective therapeutic agents or drugs have been approved to prevent or treat osteolysis; thus, revision surgery is often needed. Extracellular vesicles (EVs) are vital nanosized regulators of intercellular communication that can be directly applied to promote tissue repair and regeneration. In this study, we assessed the therapeutic potential of EVs from human urine-derived stem cells (USCs) (USC-EVs) in preventing ultrahigh-molecular-weight polyethylene (UHMWPE) particle-induced osteolysis. METHODS: USCs were characterized by measuring induced multipotent differentiation and flow cytometry. USC-EVs were isolated and characterized using transmission electron microscopy (TEM), dynamic light scattering (DLS) and Western blotting. RAW264.7 cells and bone marrow mesenchymal stem cells (BMSCs) were cultured with USC-EVs to verify osteoclast differentiation and osteoblast formation, respectively, in vitro. The effects of USC-EVs were investigated on a UHMWPE particle-induced murine calvarial osteolysis model by assessing bone mass, the inflammatory reaction, and osteoblast and osteoclast formation. RESULTS: USCs differentiated into osteogenic, adipogenic and chondrogenic cells in vitro and were positive for CD44, CD73, CD29 and CD90 but negative for CD34 and CD45. USC-EVs exhibited a cup-like morphology with a double-layered membrane structure and were positive for CD63 and TSG101 and negative for calnexin. In vitro, USC-EVs promoted the osteogenic differentiation of BMSCs and reduced proinflammatory factor production and osteoclastic activity in RAW264.7 cells. In vivo, local injection of USC-EVs around the central sites of the calvaria decreased inflammatory cytokine generation and osteolysis compared with the control groups and significantly increased bone formation. CONCLUSION: Based on our findings, USC-EVs prevent UHMWPE particle-induced osteolysis by decreasing inflammation, suppressing bone resorption and promoting bone formation.

Single-cell RNA sequencing deconvolutes the in vivo heterogeneity of human bone marrow-derived mesenchymal stem cells.

Bone marrow-derived mesenchymal stem cells (BM-MSCs) are multipotent stromal cells that have a critical role in the maintenance of skeletal tissues such as bone, cartilage, and the fat in bone marrow. In addition to providing microenvironmental support for hematopoietic processes, BM-MSCs can differentiate into various mesodermal lineages including osteoblast/osteocyte, chondrocyte, and adipocyte that are crucial for bone metabolism. While BM-MSCs have high cell-to-cell heterogeneity in gene expression, the cell subtypes that contribute to this heterogeneity in vivo in humans have not been characterized. To investigate the transcriptional diversity of BM-MSCs, we applied single-cell RNA sequencing (scRNA-seq) on freshly isolated CD271+ BM-derived mononuclear cells (BM-MNCs) from two human subjects. We successfully identified LEPRhiCD45low BM-MSCs within the CD271+ BM-MNC population, and further codified the BM-MSCs into distinct subpopulations corresponding to the osteogenic, chondrogenic, and adipogenic differentiation trajectories, as well as terminal-stage quiescent cells. Biological functional annotations of the transcriptomes suggest that osteoblast precursors induce angiogenesis coupled with osteogenesis, and chondrocyte precursors have the potential to differentiate into myocytes. We also discovered transcripts for several clusters of differentiation (CD) markers that were either highly expressed (e.g., CD167b, CD91, CD130 and CD118) or absent (e.g., CD74, CD217, CD148 and CD68) in BM-MSCs, representing potential novel markers for human BM-MSC purification. This study is the first systematic in vivo dissection of human BM-MSCs cell subtypes at the single-cell resolution, revealing an insight into the extent of their cellular heterogeneity and roles in maintaining bone homeostasis.