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Exosomes are cell-derived nanovesicles that are involved in the intercellular transportation of materials. Therapeutics, such as small molecules or nucleic acid drugs, can be incorporated into exosomes and then delivered to specific types of cells or tissues to realize targeted drug delivery. Targeted delivery increases the local concentration of therapeutics and minimizes side effects. Here, we present a detailed review of exosomes engineering through genetic and chemical methods for targeted drug delivery. Although still in its infancy, exosome-mediated drug delivery boasts low toxicity, low immunogenicity, and high engineerability, and holds promise for cell-free therapies for a wide range of diseases.

Nonlinear variable interactions are essential for the development and evolution of extreme events. However, the conventional assimilation approaches, such as the ensemble Kalman filter (EnKF), tend to underestimate extreme events due to their inability to capture these nonlinear coupling features, given their reliance on linear background error covariance estimation. In this study, a nonlinear and machine learning‐based assimilation method is proposed to address this limitation and improve the quality of analysis ensemble for extreme events. This data‐driven approach effectively characterizes the time‐variant and complex multivariate relationships, thereby nonlinearly projecting the innovation onto the ensemble subspace. This significant improvement enables the ML‐based approach to increase the analysis accuracy for extreme phenomena by up to 66% over EnKF, and its ensemble increment distribution is well‐aligned with that of the target increments, showing the potential of data‐driven assimilation approach for advancing the capabilities of capturing and triggering the extreme events.

Osteoarthritis (OA) is a progressive joint disease characterized by inflammation and cartilage destruction, and its progression is closely related to imbalances in the M1/M2 synovial macrophages. A two‐pronged strategy for the regulation of intracellular/extracellular nitric oxide (NO) and hydrogen protons for reprogramming M1/M2 synovial macrophages is proposed. The combination of carbonic anhydrase IX (CA9) siRNA and NO scavenger in “two‐in‐one” nanocarriers (NAHA‐CaP/siRNA nanoparticles) is developed for progressive OA therapy by scavenging NO and inhibiting CA9 expression in synovial macrophages. In vitro experiments demonstrate that these NPs can significantly scavenge intracellular NO similar to the levels as those in the normal group and downregulate the expression levels of CA9 mRNA (≈90%), thereby repolarizing the M1 macrophages into the M2 phenotype and increasing the expression levels of pro‐chondrogenic TGF‐β1 mRNA (≈1.3‐fold), and inhibiting chondrocyte apoptosis. Furthermore, in vivo experiments show that the NPs have great anti‐inflammation, cartilage protection and repair effects, thereby effectively alleviating OA progression in both monoiodoacetic acid‐induced early and late OA mouse models and a surgical destabilization of medial meniscus‐induced OA rat model. Therefore, the siCA9 and NO scavenger “two‐in‐one” delivery system is a potential and efficient strategy for progressive OA treatment. The carbonic anhydrase IX siRNA and nitric oxide (NO) scavenger in “two‐in‐one” nanocarriers is developed for progressive osteoarthritis (OA) therapy. A two‐pronged strategy is proposed for the regulation of intracellular/extracellular NO and hydrogen protons for reprogramming M1/M2 synovial macrophages, which holds promising application prospects for clinical translation of progressive OA treatment.

Background Astrocytes are crucial regulators in the central nervous system. Abnormal activation of astrocytes contributes to some behavior deficits. However, mechanisms underlying the effects remain unclear. Here, we studied the activation of A1 astrocytes and their contribution to murine behavior deficits. Methods A1 astrocytes were induced by treatment with lipopolysaccharide (LPS) in vitro. The functional phenotype of astrocytes was determined by quantitative RT-PCR, ELISA, and immunohistochemistry. To assess the role of A1 astrocytes in vivo, mice were injected intraperitoneally with LPS. Then, murine behaviors were tested, and the hippocampus and cortex were analyzed by quantitative RT-PCR, ELISA, and immunohistochemistry. The function of IL-10 and fluorocitrate on A1 astrocyte activation was also examined. Results Our results show that astrocytes isolated from B6.129S6-Il10 tm1Flv /J homozygotes (IL-10 tm1/tm1 ) were prone to characteristics of A1 reactive astrocytes. Compared with their wild-type counterparts, IL-10 tm1/tm1 astrocytes exhibited higher expression of glial fibrillary acidic protein (GFAP). Whether or not they were stimulated with LPS, IL-10 tm1/tm1 astrocytes exhibited enhanced expression of A1-specific transcripts and proinflammatory factors IL-1β, IL-6, and TNFα. In addition, IL-10 tm1/tm1 astrocytes demonstrated hyperphosphorylation of STAT3. Moreover, astrocytes from IL-10 tm1/tm1 mice showed attenuated phagocytic ability and were neurotoxic. IL-10 tm1/tm1 mice demonstrated increased immobility time in the forced swim test and defective learning and memory behavior in the Morris water maze test. Moreover, enhanced neuroinflammation was found in the hippocampus and cortex of IL-10 tm1/tm1 mice, accompanying with more GFAP-positive astrocytes and severe neuron loss in the hippocampus. Pretreatment IL-10 tm1/tm1 mice with IL-10 or fluorocitrate decreased the expression of proinflammatory factors and A1-specific transcripts in the hippocampus and cortex, and then alleviated LPS-induced depressive-like behavior. Conclusion These results demonstrate that astrocytes isolated from B6.129S6-Il10 tm1Flv /J homozygotes are prone to A1 phenotype and contribute to the depression-like behavior and memory deficits. Inhibiting A1 astrocyte activation may be an attractive therapeutic strategy in some neurodegenerative diseases.

Enzymatic reactions in living cells are highly dynamic but simultaneously tightly regulated. Enzyme engineers seek to construct multienzyme complexes to prevent intermediate diffusion, to improve product yield, and to control the flux of metabolites. Here we choose a pair of short peptide tags (RIAD and RIDD) to create scaffold-free enzyme assemblies to achieve these goals. In vitro, assembling enzymes in the menaquinone biosynthetic pathway through RIAD–RIDD interaction yields protein nanoparticles with varying stoichiometries, sizes, geometries, and catalytic efficiency. In Escherichia coli , assembling the last enzyme of the upstream mevalonate pathway with the first enzyme of the downstream carotenoid pathway leads to the formation of a pathway node, which increases carotenoid production by 5.7 folds. The same strategy results in a 58% increase in lycopene production in engineered Saccharomyces cerevisiae . This work presents a simple strategy to impose metabolic control in biosynthetic microbe factories. Metabolic enzymes often form supramolecular complexes to improve product yield. Here the authors use short peptide tags to create scaffold-free assemblies and synthetic metabolic nodes.

Background Senescent astrocytes play crucial roles in age-associated neurodegenerative diseases, including Parkinson’s disease (PD). Metformin, a drug widely used for treating diabetes, exerts longevity effects and neuroprotective activities. However, its effect on astrocyte senescence in PD remains to be defined. Methods Long culture-induced replicative senescence model and 1-methyl-4-phenylpyridinium/α-synuclein aggregate-induced premature senescence model, and a mouse model of PD were used to investigate the effect of metformin on astrocyte senescence in vivo and in vitro. Immunofluorescence staining and flow cytometric analyses were performed to evaluate the mitochondrial function. We stereotactically injected AAV carrying GFAP-promoter-cGAS-shRNA to mouse substantia nigra pars compacta regions to specifically reduce astrocytic cGAS expression to clarify the potential molecular mechanism by which metformin inhibited the astrocyte senescence in PD. Results We showed that metformin inhibited the astrocyte senescence in vitro and in PD mice. Mechanistically, metformin normalized mitochondrial function to reduce mitochondrial DNA release through mitofusin 2 (Mfn2), leading to inactivation of cGAS-STING, which delayed astrocyte senescence and prevented neurodegeneration. Mfn2 overexpression in astrocytes reversed the inhibitory role of metformin in cGAS-STING activation and astrocyte senescence. More importantly, metformin ameliorated dopamine neuron injury and behavioral deficits in mice by reducing the accumulation of senescent astrocytes via inhibition of astrocytic cGAS activation. Deletion of astrocytic cGAS abolished the suppressive effects of metformin on astrocyte senescence and neurodegeneration. Conclusions This work reveals that metformin delays astrocyte senescence via inhibiting astrocytic Mfn2-cGAS activation and suggest that metformin is a promising therapeutic agent for age-associated neurodegenerative diseases.

Aims: To determine floristic units and centres of plant species endemism using quantitative methods and different taxonomic groups. Location: The Qinghai-Tibetan Plateau in south-western China – the world's highest and geologically youngest plateau. Methods: The plateau was divided into 260 grid cells, each 1° × 1°, and the numbers of different seed-plant taxa, including genera, total species, endemic species and alpine species, were recorded in each cell. Hierarchical clustering and non-metric multidimensional scaling (NMDS) ordination were used to divide the flora quantitatively, and ANOSIM (analysis of similarities) was used to evaluate differences between the derived groups in the composition of taxa. The stress value was used to assess the fitness of the NMDS ordination. Species endemism was measured using corrected weighted endemism, and centres of species endemism were delimited on the basis of floristic units. Results: The plateau harbours a total of 12,058 seed-plant species and infraspecific taxa in 1619 genera; 38.2% of the species are endemic to the plateau and 27.7% are alpine plants. When two or four groups were considered, cluster analysis based on genera gave the best definition, whereas when 12 groups were considered, analysis of endemic species gave the best definition. The flora of the Qinghai-Tibetan Plateau represents two floristic subkingdoms, four floristic regions and 12 floristic subregions. Three centres of species endemism were identified, associated with five floristic subregions. Main conclusions: Quantitative analysis can reveal associations within a flora, and partly confirm intuitive classifications. Genera provide clear divisions of higher floristic ranks, and endemic species give the clearest classifications of lower floristic ranks. Alpine species are important taxa for classifying the flora of mountainous regions. A centre of species endemism based on a floristic unit can be conveniently identified and delimited, and the spatial scale of this centre is determined by the taxonomic rank used.

Essential oils (EOs) are primarily isolated from medicinal plants and possess various biological properties. However, their low water solubility and volatility substantially limit their application potential. Therefore, the aim of the current study was to improve the solubility and stability of the Mosla Chinensis (M. Chinensis) EO by forming an inclusion complex (IC) with β-cyclodextrin (β-CD). Furthermore, the IC formation process was investigated using experimental techniques and molecular modeling. The major components of M. Chinensis ‘Jiangxiangru’ EOs were carvacrol, thymol, o-cymene, and terpinene, and its IC with β-CD were prepared using the ultrasonication method. Multivariable optimization was studied using a Plackett-Burman design (step 1, identifying key parameters) followed by a central composite design for optimization of the parameters (step 2, optimizing the key parameters). SEM, FT-IR, TGA, and dissolution experiments were performed to analyze the physicochemical properties of the ICs. In addition, the interaction between EO and β-CD was further investigated using phase solubility, molecular docking, and molecular simulation studies. The results showed that the optimal encapsulation efficiency and loading capacity of EO in the ICs were 86.17% and 8.92%, respectively. Results of physicochemical properties were different after being encapsulated, indicating that the ICs had been successfully fabricated. Additionally, molecular docking and dynamics simulation showed that β-CD could encapsulate the EO component (carvacrol) via noncovalent interactions. In conclusion, a comprehensive methodology was developed for determining key parameters under multivariate conditions by utilizing two-step optimization experiments to obtain ICs of EO with β-CD. Furthermore, molecular modeling was used to study the mechanisms involved in molecular inclusion complexation.

A cell-specific delivery vehicle is required to achieve gene editing of the disease-associated cells, so the hereditable genome editing reactions are confined within these cells without affecting healthy cells. A hybrid exosome-based nano-sized delivery vehicle derived by fusion of engineered exosomes and liposomes will be able to encapsulate and deliver CRISPR/Cas9 plasmids selectively to chondrocytes embedded in articular cartilage and attenuate the condition of cartilage damage. Chondrocyte-targeting exosomes (CAP-Exo) were constructed by genetically fusing a chondrocyte affinity peptide (CAP) at the N-terminus of the exosomal surface protein Lamp2b. Membrane fusion of the CAP-Exo with liposomes formed hybrid CAP-exosomes (hybrid CAP-Exo) which were used to encapsulate CRISPR/Cas9 plasmids. By intra-articular (IA) administration, hybrid CAP-Exo/Cas9 sgMMP-13 entered the chondrocytes of rats with cartilage damages that mimicked the condition of osteoarthritis. The hybrid CAP-Exo entered the deep region of the cartilage matrix in arthritic rats on IA administration, delivered the plasmid Cas9 sgMMP-13 to chondrocytes, knocked down the matrix metalloproteinase 13 ( ), efficiently ablated the expression of in chondrocytes, and attenuated the hydrolytic degradation of the extracellular matrix proteins in the cartilage. Chondrocyte-specific knockdown of mitigates or prevents cartilage degradation in arthritic rats, showing that hybrid CAP-Exo/Cas9 sgMMP-13 may alleviate osteoarthritis.

Background Droplet digital PCR (ddPCR) has emerged as a promising tool of pathogen detection in bloodstream infections (BSIs) in critical care medicine. However, different ddPCR platforms have variable sensitivity and specificity for diverse microorganisms at various infection sites. There is still a lack of prospective clinical studies aimed at validating and interpreting the discrepant ddPCR results for diagnosing BSI in intensive care unit (ICU) practice. Methods A prospective diagnostic study of multiplex ddPCR panels was conducted in a general ICU from May 21, 2021, to December 22, 2021. Paired blood cultures (BCs) and ddPCRs (2.5 h) were obtained synchronously to detect the 12 most common BSI pathogens and three antimicrobial resistance (AMR) genes. Firstly, ddPCR performance was compared to definite BSI. Secondly, clinical validation of ddPCR was compared to composite clinical diagnosis. Sensitivity, specificity, and positive and negative predictive values were calculated. Thirdly, the positive rate of AMR genes and related analysis was presented. Results A total of 438 episodes of suspected BSIs occurring in 150 critical patients were enrolled. BC and ddPCR were positive for targeted bacteria in 40 (9.1%) and 180 (41.1%) cases, respectively. There were 280 concordant and 158 discordant. In comparison with BCs, the sensitivity of ddPCR ranged from 58.8 to 86.7% with an aggregate of 72.5% in different species, with corresponding specificity ranging from 73.5 to 92.2% with an aggregate of 63.1%. Furthermore, the rate of ddPCR+/BC− results was 33.6% (147/438) with 87.1% (128 of 147) cases was associated with probable ( n  = 108) or possible ( n  = 20) BSIs. When clinically diagnosed BSI was used as true positive, the final sensitivity and specificity of ddPCR increased to 84.9% and 92.5%, respectively. In addition, 40 bla KPC , 3 bla NDM , and 38 mec A genes were detected, among which 90.5% were definitely positive for bla KPC . Further, 65.8% specimens were predicted to be mec A-positive in Staphylococcus sp. according to all microbiological analysis. Conclusions The multiplexed ddPCR is a flexible and universal platform, which can be used as an add-on complementary to conventional BC. When combined with clinical infection evidence, ddPCR shows potential advantages for rapidly diagnosing suspected BSIs and AMR genes in ICU practice.