Human Infrapatellar Fat Pad Mesenchymal Stem Cell-derived Extracellular Vesicles Purified by Anion Exchange Chromatography Suppress Osteoarthritis Progression in a Mouse Model.

BACKGROUND: Extracellular vesicles derived from mesenchymal stem cells (MSCs) show great promise in treating osteoarthritis (OA). However, studies from the perspective of clinical feasibility that consider an accessible cell source and a scalable preparation method for MSC-extracellular vesicles are lacking. QUESTIONS/PURPOSES: (1) Does an infrapatellar fat pad obtained from patients undergoing TKA provide a suitable source to provide MSC-extracellular vesicles purified by anion exchange chromatography? Using an in vivo mouse model for OA in the knee, (2) how does injection of the infrapatellar fat pad-derived MSC-extracellular vesicles alter gait, cartilage structure and composition, protein expression (Type II collagen, MMP13, and ADAMTS5), subchondral bone remodeling and osteophytes, and synovial inflammation? METHODS: The infrapatellar fat pad was collected from three patients (all female; 62, 74, 77 years) during TKA for infrapatellar fat pad-derived MSC culturing. Patients with infection, rheumatic arthritis, and age > 80 years were excluded. MSC-extracellular vesicles were purified by anion exchange chromatography. For the animal study, we used 30 male C57BL/6 mice aged 10 weeks, divided into six groups. MSC-extracellular vesicles were injected weekly into the joint of an OA mouse model during ACL transection (ACLT). To answer our first research question, we characterized MSCs based on their proliferative potential, differentiation capacity, and surface antigen expression, and we characterized MSC-extracellular vesicles by size, morphology, protein marker expression, and miRNA profile. To answer our second research question, we evaluated the effects of MSC-extracellular vesicles in the OA mouse model with quantitative gait analysis (mean pressure, footprint area, stride length, and propulsion time), histology (Osteoarthritis Research Society International Score based on histologic analysis [0 = normal to 24 = very severe degeneration]), immunohistochemistry staining of joint sections (protein expression of Type II collagen, MMP13, and ADAMTS5), and micro-CT of subchondral bone (BV/TV and Tb.Pf) and osteophyte formation. We also examined the mechanism of action of MSC-extracellular vesicles by immunofluorescent staining of the synovium membrane (number of M1 and M2 macrophage cells) and by analyzing their influence on the expression of inflammatory factors (relative mRNA level and protein expression of IL-1ß, IL-6, and TNF-α) in lipopolysaccharide-induced macrophages. RESULTS: Infrapatellar fat pads obtained from patients undergoing TKA provide a suitable cell source for producing MSC-extracellular vesicles, and anion exchange chromatography is applicable for isolating MSC-extracellular vesicles. Cultured MSCs were spindle-shaped, proliferative at Passage 4 (doubling time of 42.75 ± 1.35 hours), had trilineage differentiation capacity, positively expressed stem cell surface markers (CD44, CD73, CD90, and CD105), and negatively expressed hematopoietic markers (CD34 and CD45). MSC-extracellular vesicles purified by anion exchange chromatography had diameters between 30 and 200 nm and a typical cup shape, positively expressed exosomal marker proteins (CD63, CD81, CD9, Alix, and TSG101), and carried plentiful miRNA. Compared with the ACLT group, the ACLT + extracellular vesicle group showed alleviation of pain 8 weeks after the injection, indicated by increased area (0.67 ± 0.15 cm 2 versus 0.20 ± 0.03 cm 2 , -0.05 [95% confidence interval -0.09 to -0.01]; p = 0.01) and stride length (5.08 ± 0.53 cm versus 6.20 ± 0.33 cm, -1.12 [95% CI -1.86 to -0.37]; p = 0.005) and decreased propulsion time (0.22 ± 0.06 s versus 0.11 ± 0.04 s, 0.11 [95% CI 0.03 to 0.19]; p = 0.007) in the affected hindlimb. Compared with the ACLT group, the ACLT + extracellular vesicles group had lower Osteoarthritis Research Society International scores after 4 weeks (8.80 ± 2.28 versus 4.80 ± 2.28, 4.00 [95% CI 0.68 to 7.32]; p = 0.02) and 8 weeks (16.00 ± 3.16 versus 9.60 ± 2.51, 6.40 [95% CI 2.14 to 10.66]; p = 0.005). In the ACLT + extracellular vesicles group, there was more-severe OA at 8 weeks than at 4 weeks (9.60 ± 2.51 versus 4.80 ± 2.28, 4.80 [95% CI 0.82 to 8.78]; p = 0.02), indicating MSC-extracellular vesicles could only delay but not fully suppress OA progression. Compared with the ACLT group, the injection of MSC-extracellular vesicles increased Type II collagen expression, decreased MMP13 expression, and decreased ADAMTS5 expression at 4 and 8 weeks. Compared with the ACLT group, MSC-extracellular vesicle injection alleviated osteophyte formation at 8 weeks and inhibited bone loss at 4 weeks. MSC-extracellular vesicle injection suppressed inflammation; the ACLT + extracellular vesicles group had fewer M1 type macrophages than the ACLT group. Compared with lipopolysaccharide-treated cells, MSC-extracellular vesicles reduced mRNA expression and inhibited IL-1ß, IL-6, and TNF-α in cells. CONCLUSION: Using an OA mouse model, we found that infrapatellar fat pad-derived MSC-extracellular vesicles could delay OA progression via alleviating pain and suppressing cartilage degeneration, osteophyte formation, and synovial inflammation. The autologous origin of extracellular vesicles and scalable purification method make our strategy potentially viable for clinical translation. CLINICAL RELEVANCE: Infrapatellar fat pad-derived MSC-extracellular vesicles isolated by anion exchange chromatography can suppress OA progression in a mouse model. Further studies with large-animal models, larger animal groups, and subsequent clinical trials are necessary to confirm the feasibility of this technique for clinical OA treatment.

Targeted therapy using engineered extracellular vesicles: principles and strategies for membrane modification.

Extracellular vesicles (EVs) are 30-150 nm membrane-bound vesicles naturally secreted by cells and play important roles in intercellular communication by delivering regulatory molecules such as proteins, lipids, nucleic acids and metabolites to recipient cells. As natural nano-carriers, EVs possess desirable properties such as high biocompatibility, biological barrier permeability, low toxicity, and low immunogenicity, making them potential therapeutic delivery vehicles. EVs derived from specific cells have inherent targeting capacity towards specific cell types, which is yet not satisfactory enough for targeted therapy development and needs to be improved. Surface modifications endow EVs with targeting abilities, significantly improving their therapeutic efficiency. Herein, we first briefly introduce the biogenesis, composition, uptake and function of EVs, and review the cargo loading approaches for EVs. Then, we summarize the recent advances in surface engineering strategies of EVs, focusing on the applications of engineered EVs for targeted therapy. Altogether, EVs hold great promise for targeted delivery of various cargos, and targeted modifications show promising effects on multiple diseases.

Photonic-assisted generation of a frequency-octupled triangular waveform based on spectrum manipulation.

A new photonic approach for generating a triangular waveform with octupled frequency, to the best of our knowledge, is presented. The core principle is the frequency octupling technique based on two cascaded dual-parallel Mach-Zehnder modulators(MZMs). A dual-electrode MZM and a single-mode fiber are subsequently applied to manipulate the signal spectrum to satisfy the characteristics of a triangular waveform. By applying a 2 GHz radio frequency signal, a full-duty-cycle triangular waveform with a repetition rate of 16 GHz is obtained. The high-frequency multiplying factor shows great potential in generating a cost-effective waveform. Additionally, the phase imbalance of a hybrid coupler and bias drift of the MZM have been considered in our simulation, which further verify the feasibility and stability of our proposal.

Modification of mesenchymal stem cells for cartilage-targeted therapy.

Osteoarthritis (OA) is a chronic degenerative joint disease characterized by the destruction of the articular cartilage, sclerosis of the subchondral bone, and joint dysfunction. Its pathogenesis is attributed to direct damage and mechanical destruction of joint tissues. Mesenchymal stem cells (MSCs), suggested as a potential strategy for the treatment of OA, have shown therapeutic effects on OA. However, the specific fate of MSCs after intraarticular injection, including cell attachment, proliferation, differentiation, and death, is still unclear, and there is no guarantee that stem cells can be retained in the cartilage tissue to enact repair. Direct homing of MSCs is an important determinant of the efficacy of MSC-based cartilage repair. Recent studies have revealed that the unique homing capacity of MSCs and targeted modification can improve their ability to promote tissue regeneration. Here, we comprehensively review the homing effect of stem cells in joints and highlight progress toward the targeted modification of MSCs. In the future, developments of this targeting system that accelerate tissue regeneration will benefit targeted tissue repair.

Photonic generation of millimeter-wave and multi-waveform signals based on external modulation and polarization control.

An approach for photonic generation of multi-function microwave/pulse signals has been proposed and verified, which is capable of achieving Nyquist/triangular pulse signals and frequency quadrupling/12-tupling microwave signals. Based on optical carrier suppressed modulation in a dual-parallel Mach-Zehnder modulator, a four-line optical frequency comb and a Nyquist pulse are generated. Subsequently, polarization controlling using an optical interleaver and a linear polarizer is conducted to manipulate spectra, after which a pulse signal with triangular shape and a microwave signal with high-frequency multiplication factor are generated. By applying a 10-GHz RF driving signal, a Nyquist pulse and a full-duty-cycle triangular pulse with repetition frequency of 40 GHz, and 40-/120-GHz millimeter-wave signals can be obtained. This proposal provides the potential of higher-frequency multi-waveform and millimeter-wave signals generator for an all-optical network.

Identification of differentially expressed genes by single-cell transcriptional profiling of umbilical cord and synovial fluid mesenchymal stem cells.

The purpose of this study was to measure the heterogeneity in human umbilical cord-derived mesenchymal stem cells (hUC-MSCs) and human synovial fluid-derived mesenchymal stem cells (hSF-MSCs) by single-cell RNA-sequencing (scRNA-seq). Using Chromium™ technology, scRNA-seq was performed on hUC-MSCs and hSF-MSCs from samples that passed our quality control checks. In order to identify subgroups and activated pathways, several bioinformatics tools were used to analyse the transcriptomic profiles, including clustering, principle components analysis (PCA), t-Distributed Stochastic Neighbor Embedding (t-SNE), gene set enrichment analysis, as well as Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses. scRNA-seq was performed on the two sample sets. In total, there were 104 761 163 reads for the hUC-MSCs and 6 577 715 for the hSF-MSCs, with >60% mapping rate. Based on PCA and t-SNE analyses, we identified 11 subsets within hUC-MSCs and seven subsets within hSF-MSCs. Gene set enrichment analysis determined that there were 533, 57, 32, 44, 10, 319, 731, 1037, 90, 25 and 230 differentially expressed genes (DEGs) in the 11 subsets of hUC-MSCs and 204, 577, 30, 577, 16, 57 and 35 DEGs in the seven subsets of hSF-MSCs. scRNA-seq was not only able to identify subpopulations of hUC-MSCs and hSF-MSCs within the sample sets, but also provided a digital transcript count of hUC-MSCs and hSF-MSCs within a single patient. scRNA-seq analysis may elucidate some of the biological characteristics of MSCs and allow for a better understanding of the multi-directional differentiation, immunomodulatory properties and tissue repair capabilities of MSCs.

Repair of articular cartilage defects with intra-articular injection of autologous rabbit synovial fluid-derived mesenchymal stem cells.

BACKGROUND: The role of rabbit synovial fluid-derived mesenchymal stem cells (rbSF-MSCs) in cartilage defect repair remains undefined. This work evaluates the in vivo effects of rbSF-MSCs to repair knee articular cartilage defects in a rabbit model. METHODS: Cartilage defects were made in the patellar grooves of New Zealand white rabbits. The rbSF-MSCs were generated from the knee cavity by arthrocentesis. Passage 5 rbSF-MSCs were assayed by flow cytometry. The multipotency of rbSF-MSCs was confirmed after 3 weeks induction in vitro and the autologous rbSF-MSCs and predifferentiated rbSF-MSCs were injected into the synovial cavity. The intra-articular injection was performed once a week for 4 weeks. The animals were euthanized and the articular surfaces were subjected to macroscopic and histological evaluations at 8 and 12 weeks after the first intra-articular injection. RESULTS: Hyaline-like cartilage was detected in the defects treated with rbSF-MSCs, while fibrocartilage tissue formed in the defects treated with chondrocytes induced from rbSF-MSCs. CONCLUSIONS: Our results suggest that autologous undifferentiated rbSF-MSCs are favorable to articular cartilage regeneration in treating cartilage defects.

Isolation and characterization of human mesenchymal stem cells derived from synovial fluid by magnetic-activated cell sorting (MACS).

Mesenchymal stem cells (MSCs) are the primary source of cells used for cell-based therapy in tissue engineering. MSCs are found in synovial fluid, a source that could be conveniently used for cartilage tissue engineering. However, the purification and characterization of SF-MSCs has been poorly documented in the literature. Here, we outline an easy-to-perform approach for the isolation and culture of MSCs derived from human synovial fluid (hSF-MSCs). We have successfully purified hSF-MSCs using magnetic-activated cell sorting (MACS) using the MSC surface marker, CD90. Purified SF-MSCs demonstrate significant renewal capacity following several passages in culture. Furthermore, we demonstrated that MACS-sorted CD90+ cells could differentiated into osteoblasts, adipocytes, and chondrocytes in vitro. In addition, we show that these cells can generate cartilage tissue in micromass culture as well. This study demonstrates that MACS is a useful tool that can be used for the purification of hSF-MSCs from synovial fluid. The proliferation properties and ability to differentiate into chondrocytes make these hSF-MSCs a promising source of stem cells for applications in cartilage repair.

An In-tether Chiral Center Modulates the Helicity, Cell Permeability, and Target Binding Affinity of a Peptide.

The addition of a precisely positioned chiral center in the tether of a constrained peptide is reported, yielding two separable peptide diastereomers with significantly different helicity, as supported by circular dichroism (CD) and NMR spectroscopy. Single crystal X-ray diffraction analysis suggests that the absolute configuration of the in-tether chiral center in helical form is R, which is in agreement with theoretical simulations. The relationship between the secondary structure of the short peptides and their biochemical/biophysical properties remains elusive, largely because of the lack of proper controls. The present strategy provides the only method for investigating the influence of solely conformational differences upon the biochemical/biophysical properties of peptides. The significant differences in permeability and target binding affinity between the peptide diastereomers demonstrate the importance of helical conformation.

Crosslinked Aspartic Acids as Helix-Nucleating Templates.

Described is a facile helix-nucleating template based on a tethered aspartic acid at the N-terminus [terminal aspartic acid (TD)]. The nucleating effect of the template is subtly influenced by the substituent at the end of the side-chain-end tether as indicated by circular dichroism, nuclear magnetic resonance, and molecular dynamics simulations. Unlike most nucleating strategies, the N-terminal amine is preserved, thus enabling further modification. Peptidomimetic estrogen receptor modulators (PERMs) constructed using this strategy show improved therapeutic properties. The current strategy can be regarded as a good complement to existing helix-stabilizing methods.

Structural Insights on the bacteriolytic and self-protection mechanism of muramidase effector Tse3 in Pseudomonas aeruginosa.

The warfare among microbial species as well as between pathogens and hosts is fierce, complicated, and continuous. In Pseudomonas aeruginosa, the muramidase effector Tse3 (Type VI secretion exported 3) can be injected into the periplasm of neighboring bacterial competitors by a Type VI secretion apparatus, eventually leading to cell lysis and death. However, P. aeruginosa protects itself from lysis by expressing immune protein Tsi3 (Type six secretion immunity 3). Here, we report the crystal structure of the Tse3-Tsi3 complex at 1.8 Å resolution, revealing that Tse3 possesses one open accessible, goose-type lysozyme-like domain with peptidoglycan hydrolysis activity. Calcium ions bind specifically in the Tse3 active site and are identified to be crucial for its bacteriolytic activity. In combination with biochemical studies, the structural basis of self-protection mechanism of Tsi3 is also elucidated, thus providing an understanding and new insights into the effectors of Type VI secretion system.

Molecular evolution and sequence divergence of plant chalcone synthase and chalcone synthase-Like genes.

Plant chalcone synthase (CHS) and CHS-Like (CHSL) proteins are polyketide synthases. In this study, we evaluated the molecular evolution of this gene family using representative types of CHSL genes, including stilbene synthase (STS), 2-pyrone synthase (2-PS), bibenzyl synthase (BBS), acridone synthase (ACS), biphenyl synthase (BIS), benzalacetone synthase, coumaroyl triacetic acid synthase (CTAS), and benzophenone synthase (BPS), along with their CHS homologs from the same species of both angiosperms and gymnosperms. A cDNA-based phylogeny indicated that CHSLs had diverse evolutionary patterns. STS, ACS, and 2-PS clustered with CHSs from the same species (late diverged pattern), while CTAS, BBS, BPS, and BIS were distant from their CHS homologs (early diverged pattern). The amino-acid phylogeny suggested that CHS and CHSL proteins formed clades according to enzyme function. The CHSs and CHSLs from Polygonaceae and Arachis had unique evolutionary histories. Synonymous mutation rates were lower in late diverged CHSLs than in early diverged ones, indicating that gene duplications occurred more recently in late diverged CHSLs than in early diverged ones. Relative rate tests proved that late diverged CHSLs had unequal rates to CHSs from the same species when using fatty acid synthase, which evolved from the common ancestor with the CHS superfamily, as the outgroup, while the early diverged lineages had equal rates. This indicated that late diverged CHSLs experienced more frequent mutation than early diverged CHSLs after gene duplication, allowing obtaining new functions in relatively short period of time.

Deciphering m6A methylation in monocyte-mediated cardiac fibrosis and monocyte-hitchhiked erythrocyte microvesicle biohybrid therapy.

Rationale: Device implantation frequently triggers cardiac remodeling and fibrosis, with monocyte-driven inflammatory responses precipitating arrhythmias. This study investigates the role of m6A modification enzymes METTL3 and METTL14 in these responses and explores a novel therapeutic strategy targeting these modifications to mitigate cardiac remodeling and fibrosis. Methods: Peripheral blood mononuclear cells (PBMCs) were collected from patients with ventricular septal defects (VSD) who developed conduction blocks post-occluder implantation. The expression of METTL3 and METTL14 in PBMCs was measured. METTL3 and METTL14 deficiencies were induced to evaluate their effect on angiotensin II (Ang II)-induced myocardial inflammation and fibrosis. m6A modifications were analyzed using methylated RNA immunoprecipitation followed by quantitative PCR. NF-κB pathway activity and levels of monocyte migration and fibrogenesis markers (CXCR2 and TGF-ß1) were assessed. An erythrocyte microvesicle-based nanomedicine delivery system was developed to target activated monocytes, utilizing the METTL3 inhibitor STM2457. Cardiac function was evaluated via echocardiography. Results: Significant upregulation of METTL3 and METTL14 was observed in PBMCs from patients with VSD occluder implantation-associated persistent conduction block. Deficiencies in METTL3 and METTL14 significantly reduced Ang II-induced myocardial inflammation and fibrosis by decreasing m6A modification on MyD88 and TGF-ß1 mRNAs. This disruption reduced NF-κB pathway activation, lowered CXCR2 and TGF-ß1 levels, attenuated monocyte migration and fibrogenesis, and alleviated cardiac remodeling. The erythrocyte microvesicle-based nanomedicine delivery system effectively targeted inflamed cardiac tissue, reducing inflammation and fibrosis and improving cardiac function. Conclusion: Inhibiting METTL3 and METTL14 in monocytes disrupts the NF-κB feedback loop, decreases monocyte migration and fibrogenesis, and improves cardiac function. Targeting m6A modifications of monocytes with STM2457, delivered via erythrocyte microvesicles, reduces inflammation and fibrosis, offering a promising therapeutic strategy for cardiac remodeling associated with device implantation.

[Pseudotargeted metabolomics analysis of pine pollen intervention in the liver of premature ovarian failure rats].

Premature ovarian failure (POF) is a prevalent gynecological disease. In traditional Chinese medicine, it is believed that POF is directly related to abnormal function of the liver and kidneys. As such, regulation of the liver metabolism through the use of medicinal and edible substances is important for the treatment of POF. Pine pollen, a traditional Chinese medicinal and edible pollen variety, contains various active substances, such as sex hormones and phytohormones, which have been used to inhibit inflammation, regulate the immune system, and protect reproductive tissues. Using ultra-high performance liquid chromatography-triple quadrupole mass spectrometry (UHPLC-MS/MS), this study examined the influence of pine pollen on the liver metabolome of cyclophosphamide-induced POF model Sprague Dawley (SD) rats. The variations in the metabolites present in the liver tissue of control SD rats, model SD rats, and SD rats treated with various doses of pine pollen or estrogen were analyzed using principal component analysis (PCA) in combination with orthogonal partial least squares discriminant analysis (OPLS-DA) and other multivariate statistical methods to reveal the mechanism of pine pollen intervention in the livers of POF SD rats. An animal model experiment was conducted using six groups of ten-week-old rats. Cyclophosphamide was administered intraperitoneally to the model group and four intervention groups at a dosage of 60 mg/kg for 1 d followed by a dosage of 10 mg/kg for 14 d. Within the following four weeks, each of the four intervention groups received the intragastric administration of 0.1, 0.5, or 1.5 g/kg bodyweight (BW) of pine pollen, or 0.075 g/kg BW of conjugated estrogens (positive control). Equal quantities of normal saline were administered to the control and cyclophosphamide-treated model groups. Subsequently, the rat livers were subject to pseudotargeted metabolomics, and a total of 687 liver metabolites were discovered using both positive and negative ions. The metabolites differing in content were screened using the t-test (p<0.05) and the fold change (FC>2 or <0.5) in univariate analysis, and the variable importance in projection (VIP>1) in multivariate analysis. It was found that in comparison with the control group, the contents of 32 metabolites significantly increased, while those of 28 metabolites significantly decreased in the model group. The majority of these metabolites were involved α-linolenic acid metabolism, vitamin B6 metabolism, and purine metabolism, along with the lysine degradation and glycolysis/gluconeogenesis metabolic pathways. Compared with the cyclophosphamide-induced model group, the estrogen group exhibited increased levels of 47 metabolites and decreased levels of 29 metabolites, wherein 34 metabolites were restored to the levels found in the control group. These metabolites mainly involved the vitamin B6, lysine, glycolysis/gluconeogenesis, arginine and proline, and cysteine and methionine metabolic pathways. In the low/medium/high-dose pine pollen groups, the contents of 34/32/34 metabolites increased, the contents of 30/37/24 metabolites decreased, and the contents of 47/38/34 metabolites were restored to the levels found in the control group, respectively. These metabolites were mainly involved in vitamin B6 metabolism, purine metabolism, and the glycolysis/gluconeogenesis metabolic pathway. These results therefore indicate that the restoring effect of pine pollen is equivalent or superior to that of conjugated estrogen. Additionally, based on the known metabolic pathways, it appears that when estrogen interferes with the liver metabolism, the key metabolic pathways that become affected are the arginine and proline metabolism and cysteine and methionine metabolism pathways. In contrast, pine pollen intervention affected existing metabolic pathways that were known to be disordered by cyclophosphamide. The use of pine pollen may therefore restore the levels of many metabolites. It should be noted that 23 overlaps exist between the estrogen-restored metabolites and the pine pollen-restored metabolites, including a variety of acylcarnitines, such as ACar 10∶0. As a result, pine pollen extract may be able to normalize the liver metabolic abnormalities induced by POF. This study therefore establishes a theoretical reference for the development of functional applications for pine pollen and for the treatment of POF.

Axial Compressive Loading Attenuates Early Osteoarthritis by Reducing Subchondral Bone Remodeling.

BACKGROUND: Mechanical loading and alendronate (ALN) can be used as noninvasive physical therapy methods for osteoarthritis (OA). However, the timing and efficacy for treatments are unknown. PURPOSE: To determine whether the timing of mechanical loading and ALN influences the pathobiological changes of OA. STUDY DESIGN: Controlled laboratory study. METHODS: Mice with OA induced by anterior cruciate ligament transection were subjected to early (1-3 weeks) or late (5-7 weeks) axial compressive dynamic load or intraperitoneal injection of ALN. Changes in gait were analyzed using gait analysis system, pathobiological changes in subchondral bone, cartilage, osteophyte, and synovitis were assessed using micro-computed tomography, tartrate-resistant acid phosphatase staining, pathologic section staining, and immunohistochemistry at 1, 2, 4, and 8 weeks. RESULTS: At 1, 2, and 4 weeks, the OA limb had lower mean footprint pressure intensity, lower bone volume per tissue volume (BV/TV) in the subchondral bone, and more osteoclasts. At 4 weeks, the early loading, ALN, and load + ALN treatments induced less cartilage destruction, with a corresponding reduction in Osteoarthritis Research Society International score and increased hyaline cartilage thickness. The treatments also resulted in fewer osteoclasts and higher BV/TV and bone mineral density of subchondral bone and suppressed inflammation and interleukin 1ß- and tumor necrosis factor α-positive cells in synovium. At 8 weeks, early loading or load + ALN improved the mean footprint pressure intensity and knee flexion. At 8 weeks, early load + ALN had a synergistic effect on protecting hyaline cartilage and proteoglycans. Footprint pressure intensity and cartilage destruction were worse in late loading limbs, and no differences in BV/TV, bone mineral density, osteophyte formation, and synovium inflammation were found between the late load, ALN, and load + ALN groups and the anterior cruciate ligament transection group. CONCLUSION: Dynamic axial mechanical loading or ALN in the early stages of knee trauma protected against OA by suppressing subchondral bone remodeling. However, late loading promoted cartilage degeneration in advanced OA, indicating that reduced loading should be performed in the late stages of OA to avoid the acceleration of OA. CLINICAL RELEVANCE: Early low-level functional exercise or antiosteoporotic drugs could clearly slow or prevent the progression of early OA. For patients with mild to severe OA, loading reduction via brace protection or maintenance of joint stability via early ligament reconstruction surgery may ameliorate OA exacerbation.

Nanomaterials for mRNA-based therapeutics: Challenges and opportunities.

Messenger RNA (mRNA) holds great potential in developing immunotherapy, protein replacement, and genome editing. In general, mRNA does not have the risk of being incorporated into the host genome and does not need to enter the nucleus for transfection, and it can be expressed even in nondividing cells. Therefore, mRNA-based therapeutics provide a promising strategy for clinical treatment. However, the efficient and safe delivery of mRNA remains a crucial constraint for the clinical application of mRNA therapeutics. Although the stability and tolerability of mRNA can be enhanced by directly retouching the mRNA structure, there is still an urgent need to improve the delivery of mRNA. Recently, significant progress has been made in nanobiotechnology, providing tools for developing mRNA nanocarriers. Nano-drug delivery system is directly used for loading, protecting, and releasing mRNA in the biological microenvironment and can be used to stimulate the translation of mRNA to develop effective intervention strategies. In the present review, we summarized the concept of emerging nanomaterials for mRNA delivery and the latest progress in enhancing the function of mRNA, primarily focusing on the role of exosomes in mRNA delivery. Moreover, we outlined its clinical applications so far. Finally, the key obstacles of mRNA nanocarriers are emphasized, and promising strategies to overcome these obstacles are proposed. Collectively, nano-design materials exert functions for specific mRNA applications, provide new perception for next-generation nanomaterials, and thus revolution of mRNA technology.

Tracking tools of extracellular vesicles for biomedical research.

Imaging of extracellular vesicles (EVs) will facilitate a better understanding of their biological functions and their potential as therapeutics and drug delivery vehicles. In order to clarify EV-mediated cellular communication in vitro and to track the bio-distribution of EV in vivo, various strategies have been developed to label and image EVs. In this review, we summarized recent advances in the tracking of EVs, demonstrating the methods for labeling and imaging of EVs, in which the labeling methods include direct and indirect labeling and the imaging modalities include fluorescent imaging, bioluminescent imaging, nuclear imaging, and nanoparticle-assisted imaging. These techniques help us better understand the mechanism of uptake, the bio-distribution, and the function of EVs. More importantly, we can evaluate the pharmacokinetic properties of EVs, which will help promote their further clinical application.

Crosslinking effect of dialdehyde cholesterol modified starch nanoparticles on collagen hydrogel.

Crosslinking is frequently used to improve the inherent poor physicochemical properties of collagen. However, local flocculation and irregular crosslinking of collagen would be unavoidably occurred once contacting with crosslinking agents due to widespread complex interactions. Herein, dialdehyde starch-based nanoparticles were developed to crosslink collagen as a new strategy. Starch was conjugated with cholesterol chloroformate before periodate oxidation to obtain dialdehyde cholesterol modified starch (DACS). DACS self-assembled into nanoparticles (DACSNPs) and crosslinked with collagen to fabricate collagen hydrogels (DACSNPs-Col). DACSNPs-Col hydrogels exhibited faster gelation rate, better uniform porous structure, higher mechanical properties and better degradation stability than dialdehyde starch crosslinked hydrogels. Significantly, DACSNPs-Col hydrogels show homogeneous structure, improved mechanical properties, low cytotoxicity, well blood compatibility, high cell adhesion and proliferation. Overall, the oxidized polysaccharide nanoparticles crosslinked collagen hydrogels have homogeneous and compact microstructure and improved physicochemical properties, which show potential application prospect in the field of tissue engineering scaffold.

Effect of Impregnation with Natural Shellac Polymer on the Mechanical Properties of Fast-Growing Chinese Fir.

Fast-growing Chinese fir wood has shortfalls such as loose structure and low strength because it grows faster than natural trees. Resin impregnation is a great way to increase the strength of fast-growing fir. However, the resin used for impregnation is a kind of urea-formaldehyde resin, phenolic formaldehyde resin, melamine formaldehyde resin, and the like, which introduce harmful substances such as formaldehyde or phenolic into the wood. In this paper, Chinese fir wood was impregnated with natural shellac polymer, and the effects of impregnation variables on the mechanical properties of the wood were examined. The increase in strength in compression perpendicular to grain (SCPG) of wood samples impregnated with 15% shellac solution achieved a maximum value of 39.01%, but the modulus of rupture (MOR) was slightly reduced. The effects of the impregnation pressure, time, and their interaction were investigated by the response surface method (RSM). ANOVA analysis revealed that the impregnation pressure and time and the interaction between the two seemed to have a significant effect on ∆SCPG. Based on the response face model, the corresponding optimal parameters obtained are 1.0 MPa and 16.0 min for impregnation pressure and time, respectively. By impregnating fir wood with the above optimal conditions, the SCPG increased by 85.78%, whereas the MOR decreased by the least amount.

Predicting nanoemulsion formulation and studying the synergism mechanism between surfactant and cosurfactant: A combined computational and experimental approach.

Nanoemulsion (NE) is a dosage form widely used in pharmaceutical, food, agrochemical, cosmetics, and personal care industries. NE systems are usually formulated through trial and error via numerous semi-empirical experiments. Moreover, the complex interaction mechanisms between the formulation surfactant and cosurfactant are difficult to understand. Dissipative particle dynamics (DPD) may be helpful in solving these formulation problems. Silibinin is a flavonolignan isolated from milk thistle, which has demonstrated antioxidant and antimicrobial effects. For this project, silibinin-loaded nanoemulsion (SBNE) was formulated by DPD, including surfactant and cosurfactant screening, pseudo-ternary phase construction, and SBNE characterization, all of which were verified by experimentation. Most importantly, this work shows that DPD can be adopted to explore the synergetic mechanisms between the surfactant and cosurfactant, including emulsification efficiency, distance, angle, arrangement, and order parameter. Additional verification experiments on the antioxidant and antimicrobial applications of simulation-designed SBNE were also carried out and confirmed DPD-predicted results. As such, predicting NE formulation by DPD has been proven to be feasible. For SBNE, the addition of PEG400 cosurfactant stretches the Cremophor RH40 surfactant molecules and assists in a more orderly arrangement. An enhanced interfacial thickness in SBNE could be attributed to the stretched hydrophilic head group and the decreased angle between the molecular axis and interface normal. These DPD and experimentally-verified results indicated that a proper cosurfactant will enhance the interfacial thickness, decrease the consumption of surfactant, and benefit NE formation. This new computationally applied knowledge should facilitate optimizing, designing, and understanding NE formulation more rationally and scientifically.