Harnessing exosomes as therapeutic drug delivery vehicles requires a better understanding of exosomal composition and their mode of action. A full appreciation of all the exosomal components ...(proteins, lipids, and RNA content) will be important for the design of effective exosome-based or exosome-mimicking drug carriers. In this review we describe the presence of rarely studied, non-coding RNAs that exist in high numbers in exosomes. We discuss the implications of the molecular composition and heterogeneity of exosomes on their biological and therapeutic effects. Finally, we highlight outstanding questions with regard to RNA loading into exosomes, analytical methods to sort exosomes and their sub-populations, and the effects of exosomal proteins and lipids on recipient cells. Investigations into these facets of exosome biology will further advance the field, could lead to the clinical translation of exosome-based therapeutics, and aid in the reverse-engineering of synthetic exosomes. Although synthetic exosomes are still an underexplored area, they could offer researchers a way to manufacture exosomes with highly defined structure, composition, and function.
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Bronchoscopy is frequently nondiagnostic in patients with pulmonary lesions suspected to be lung cancer. This often results in additional invasive testing, although many lesions are benign. We sought ...to validate a bronchial-airway gene-expression classifier that could improve the diagnostic performance of bronchoscopy.
Current or former smokers undergoing bronchoscopy for suspected lung cancer were enrolled at 28 centers in two multicenter prospective studies (AEGIS-1 and AEGIS-2). A gene-expression classifier was measured in epithelial cells collected from the normal-appearing mainstem bronchus to assess the probability of lung cancer.
A total of 639 patients in AEGIS-1 (298 patients) and AEGIS-2 (341 patients) met the criteria for inclusion. A total of 43% of bronchoscopic examinations were nondiagnostic for lung cancer, and invasive procedures were performed after bronchoscopy in 35% of patients with benign lesions. In AEGIS-1, the classifier had an area under the receiver-operating-characteristic curve (AUC) of 0.78 (95% confidence interval CI, 0.73 to 0.83), a sensitivity of 88% (95% CI, 83 to 92), and a specificity of 47% (95% CI, 37 to 58). In AEGIS-2, the classifier had an AUC of 0.74 (95% CI, 0.68 to 0.80), a sensitivity of 89% (95% CI, 84 to 92), and a specificity of 47% (95% CI, 36 to 59). The combination of the classifier plus bronchoscopy had a sensitivity of 96% (95% CI, 93 to 98) in AEGIS-1 and 98% (95% CI, 96 to 99) in AEGIS-2, independent of lesion size and location. In 101 patients with an intermediate pretest probability of cancer, the negative predictive value of the classifier was 91% (95% CI, 75 to 98) among patients with a nondiagnostic bronchoscopic examination.
The gene-expression classifier improved the diagnostic performance of bronchoscopy for the detection of lung cancer. In intermediate-risk patients with a nondiagnostic bronchoscopic examination, a negative classifier score provides support for a more conservative diagnostic approach. (Funded by Allegro Diagnostics and others; AEGIS-1 and AEGIS-2 ClinicalTrials.gov numbers, NCT01309087 and NCT00746759.).
Aptamers are single-stranded nucleic acid ligands that bind to target molecules with high affinity and specificity. They are typically discovered by searching large libraries for sequences with ...desirable binding properties. These libraries, however, are practically constrained to a fraction of the theoretical sequence space. Machine learning provides an opportunity to intelligently navigate this space to identify high-performing aptamers. Here, we propose an approach that employs particle display (PD) to partition a library of aptamers by affinity, and uses such data to train machine learning models to predict affinity in silico. Our model predicted high-affinity DNA aptamers from experimental candidates at a rate 11-fold higher than random perturbation and generated novel, high-affinity aptamers at a greater rate than observed by PD alone. Our approach also facilitated the design of truncated aptamers 70% shorter and with higher binding affinity (1.5 nM) than the best experimental candidate. This work demonstrates how combining machine learning and physical approaches can be used to expedite the discovery of better diagnostic and therapeutic agents.
Mesenchymal stem cell (MSC)-derived exosomes mediate tissue regeneration in a variety of diseases including ischemic heart injury, liver fibrosis, and cerebrovascular disease. Despite an increasing ...number of studies reporting the therapeutic effects of MSC exosomes, the underlying molecular mechanisms and their miRNA complement are poorly characterized. Here we microRNA (miRNA)-profiled MSC exosomes and conducted a network analysis to identify the dominant biological processes and pathways modulated by exosomal miRNAs. At a system level, miRNA-targeted genes were enriched for (cardio)vascular and angiogenesis processes in line with observed cardiovascular regenerative effects. Targeted pathways were related to Wnt signaling, pro-fibrotic signaling via TGF-β and PDGF, proliferation, and apoptosis. When tested, MSC exosomes reduced collagen production by cardiac fibroblasts, protected cardiomyocytes from apoptosis, and increased angiogenesis in HUVECs. The intrinsic beneficial effects were further improved by virus-free enrichment of MSC exosomes with network-informed regenerative miRNAs capable of promoting angiogenesis and cardiomyocyte proliferation. The data presented here help define the miRNA landscape of MSC exosomes, establish their biological functions through network analyses at a system level, and provide a platform for modulating the overall phenotypic effects of exosomes.
The capacity to achieve rapid, sensitive, specific, quantitative, and multiplexed genetic detection of pathogens via a robust, portable, point-of-care platform could transform many diagnostic ...applications. And while contemporary technologies have yet to effectively achieve this goal, the advent of microfluidics provides a potentially viable approach to this end by enabling the integration of sophisticated multistep biochemical assays (e.g., sample preparation, genetic amplification, and quantitative detection) in a monolithic, portable device from relatively small biological samples. Integrated electrochemical sensors offer a particularly promising solution to genetic detection because they do not require optical instrumentation and are readily compatible with both integrated circuit and microfluidic technologies. Nevertheless, the development of generalizable microfluidic electrochemical platforms that integrate sample preparation and amplification as well as quantitative and multiplexed detection remains a challenging and unsolved technical problem. Recognizing this unmet need, we have developed a series of microfluidic electrochemical DNA sensors that have progressively evolved to encompass each of these critical functionalities. For DNA detection, our platforms employ label-free, single-step, and sequence-specific electrochemical DNA (E-DNA) sensors, in which an electrode-bound, redox-reporter-modified DNA "probe" generates a current change after undergoing a hybridization-induced conformational change. After successfully integrating E-DNA sensors into a microfluidic chip format, we subsequently incorporated on-chip genetic amplification techniques including polymerase chain reaction (PCR) and loop-mediated isothermal amplification (LAMP) to enable genetic detection at clinically relevant target concentrations. To maximize the potential point-of-care utility of our platforms, we have further integrated sample preparation via immunomagnetic separation, which allowed the detection of influenza virus directly from throat swabs and developed strategies for the multiplexed detection of related bacterial strains from the blood of septic mice. Finally, we developed an alternative electrochemical detection platform based on real-time LAMP, which not is only capable of detecting across a broad dynamic range of target concentrations, but also greatly simplifies quantitative measurement of nucleic acids. These efforts represent considerable progress toward the development of a true sample-in-answer-out platform for genetic detection of pathogens at the point of care. Given the many advantages of these systems, and the growing interest and innovative contributions from researchers in this field, we are optimistic that iterations of these systems will arrive in clinical settings in the foreseeable future.
Dietary nitrate supplementation increases circulating nitrite concentration, and the subsequent reduction of nitrite to nitric oxide is promoted in hypoxic environments. Given that PO2 is lower in ...Type II compared with Type I muscle, this article examines the hypothesis that the ergogenicity of nitrate supplementation is linked to specific effects on vascular, metabolic, and contractile function in Type II muscle.
Single‐step DNA detection: A microfluidic electrochemical loop mediated isothermal amplification platform is reported for rapid, sensitive, and quantitative detection of pathogen genomic DNA at the ...point of care (see picture). DNA amplification was electrochemically monitored in real time within a monolithic microfluidic device, thus enabling the detection of as few as 16 copies of Salmonella genomic DNA through a single‐step process in less than an hour.
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Inorganic nitrate (NO3−) supplementation with beetroot juice (BR) in humans lowers blood pressure and the O2 cost of exercise and may improve exercise tolerance following its reduction ...to nitrite (NO2−) and nitric oxide (NO).
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The effect of inorganic NO3− supplementation with BR on skeletal muscle blood flow (BF) and vascular conductance (VC) within and among locomotory muscles during exercise is unknown.
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Inorganic NO3− supplementation with BR in rats resulted in lower exercising mean arterial pressure, lower blood lactate, and higher total skeletal muscle hindlimb BF and VC during submaximal treadmill running.
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The greater BF and VC was found in muscles and muscle parts containing primarily type IIb + d/x muscle fibres.
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These data demonstrate that inorganic NO3− supplementation improves vascular control and elevates skeletal muscle O2 delivery during exercise predominantly in fast‐twitch type II muscles, and provide a potential mechanism by which NO3− supplementation improves metabolic control.
Dietary nitrate (NO3−) supplementation, via its reduction to nitrite (NO2−) and subsequent conversion to nitric oxide (NO) and other reactive nitrogen intermediates, reduces blood pressure and the O2 cost of submaximal exercise in humans. Despite these observations, the effects of dietary NO3− supplementation on skeletal muscle vascular control during locomotory exercise remain unknown. We tested the hypotheses that dietary NO3− supplementation via beetroot juice (BR) would reduce mean arterial pressure (MAP) and increase hindlimb muscle blood flow in the exercising rat. Male Sprague–Dawley rats (3–6 months) were administered either NO3− (via beetroot juice; 1 mmol kg−1 day−1, BR n= 8) or untreated (control, n= 11) tap water for 5 days. MAP and hindlimb skeletal muscle blood flow and vascular conductance (radiolabelled microsphere infusions) were measured during submaximal treadmill running (20 m min−1, 5% grade). BR resulted in significantly lower exercising MAP (control: 137 ± 3, BR: 127 ± 4 mmHg, P < 0.05) and blood lactate (control: 2.6 ± 0.3, BR: 1.9 ± 0.2 mm, P < 0.05) compared to control. Total exercising hindlimb skeletal muscle blood flow (control: 108 ± 8, BR: 150 ± 11 ml min−1 (100 g)−1, P < 0.05) and vascular conductance (control: 0.78 ± 0.05, BR: 1.16 ± 0.10 ml min−1 (100 g)−1 mmHg−1, P < 0.05) were greater in rats that received BR compared to control. The relative differences in blood flow and vascular conductance for the 28 individual hindlimb muscles and muscle parts correlated positively with their percentage type IIb + d/x muscle fibres (blood flow: r= 0.74, vascular conductance: r= 0.71, P < 0.01 for both). These data support the hypothesis that NO3− supplementation improves vascular control and elevates skeletal muscle O2 delivery during exercise predominantly in fast‐twitch type II muscles, and provide a potential mechanism by which NO3− supplementation improves metabolic control.
Declarations of Dependencerethinks the historical relationship between money and aesthetics in an effort to make critical theory newly answerable to politics. Scott Ferguson regrounds critical theory ...in the alternative conception of money articulated by the contemporary heterodox school of political economy known as Modern Monetary Theory. Applying the insights of this theory, Ferguson contends that money, rather than representing a private, finite, and alienating technology, is instead a public and fundamentally unlimited medium that harbors still-unrealized powers for inclusion, cultivation, and care.Ferguson calls Modern Monetary Theory's capacious ontology of money the "unheard-of center" of modern life. Here he installs this unheard-of center at the heart of critique to inaugurate a new critical theory that aims to actualize money's curative potential in a sensuous here-and-now.Declarations of Dependencereimagines the relation between money and aesthetics in a manner that points beyond neoliberal privation and violence and, by doing so, lends critical theory fresh relevance and force.
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