Browsing by Subject "microparticles"

Now showing 1 - 3 of 3
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    ItemOpen Access
    A standardized method to determine the concentration of extracellular vesicles using tunable resistive pulse sensing.
    (J Extracell Vesicles, 2016) Vogel, Robert; Coumans, Frank AW; Maltesen, Raluca G; Böing, Anita N; Bonnington, Katherine E; Broekman, Marike L; Broom, Murray F; Buzás, Edit I; Christiansen, Gunna; Hajji, Najat; Kristensen, Søren R; Kuehn, Meta J; Lund, Sigrid M; Maas, Sybren LN; Nieuwland, Rienk; Osteikoetxea, Xabier; Schnoor, Rosalie; Scicluna, Benjamin J; Shambrook, Mitch; de Vrij, Jeroen; Mann, Stephen I; Hill, Andrew F; Pedersen, Shona
    BACKGROUND: Understanding the pathogenic role of extracellular vesicles (EVs) in disease and their potential diagnostic and therapeutic utility is extremely reliant on in-depth quantification, measurement and identification of EV sub-populations. Quantification of EVs has presented several challenges, predominantly due to the small size of vesicles such as exosomes and the availability of various technologies to measure nanosized particles, each technology having its own limitations. MATERIALS AND METHODS: A standardized methodology to measure the concentration of extracellular vesicles (EVs) has been developed and tested. The method is based on measuring the EV concentration as a function of a defined size range. Blood plasma EVs are isolated and purified using size exclusion columns (qEV) and consecutively measured with tunable resistive pulse sensing (TRPS). Six independent research groups measured liposome and EV samples with the aim to evaluate the developed methodology. Each group measured identical samples using up to 5 nanopores with 3 repeat measurements per pore. Descriptive statistics and unsupervised multivariate data analysis with principal component analysis (PCA) were used to evaluate reproducibility across the groups and to explore and visualise possible patterns and outliers in EV and liposome data sets. RESULTS: PCA revealed good reproducibility within and between laboratories, with few minor outlying samples. Measured mean liposome (not filtered with qEV) and EV (filtered with qEV) concentrations had coefficients of variance of 23.9% and 52.5%, respectively. The increased variance of the EV concentration measurements could be attributed to the use of qEVs and the polydisperse nature of EVs. CONCLUSION: The results of this study demonstrate the feasibility of this standardized methodology to facilitate comparable and reproducible EV concentration measurements.
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    Characterization of Blast-Induced Activation of Human Immune Cells
    (2012) Garrett, Joel Frederick

    Blast related injuries have become a common occurrence among soldiers and civilians serving in Iraq and Afghanistan, and minor traumatic brain injuries associated with such incidents have increased correspondingly. Advances in protection and treatment have allowed many individuals to survive what would have previously been deadly blasts but there is a concern that there are additional negative side effects associated with such exposure. This study hypothesizes that human T leukocytes and promyelocytes respond to blasts by initiating cell death processes and releasing microparticles that could lead to further systemic inflammation. It was found that there was a significant (p<0.05) increase in lactase dehydrogenase activity and microparticle release in HL-60 cells blasted using a shock tube (with an incident blast overpressure of either 1000 or 1300 kPA and a duration of 2 ms) compared to control populations after 24 hours. There were no corresponding increases in Jurkat cells exposed to similar conditions.

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    Microfluidics-Generated Biodegradable Polymeric Microparticles for Controlled Drug Delivery
    (2014) Roberts, Emily Remsen Hogan

    While drug-loaded biodegradable polymer microparticles have found many therapeutic applications, bulk manufacturing methods produce heterogeneous populations of particles. A more highly controlled manufacturing method may provide the ability improve the microparticle characteristics such as the drug release profile. Microfluidic droplet-makers manipulate liquids on the scale of tens of microns and can produce highly regular and controlled emulsions. However, microfluidic droplet manufacturing is not typically designed for clinical translation and the chemicals used are often not biocompatible.

    I developed a two-chip PDMS-based microfluidic device that can manufacture PLGA microparticle loaded with hydrophilic or hydrophobic drugs. I characterized protein-loaded microparticles made using this device and compared them with bulk-generated microparticles. The microfluidics-generated microparticles had similar release curves and encapsulation efficiencies as bulk-generated microparticles but a much narrower size distribution. I generated peanut protein-loaded microparticles with this device and tested them in a mouse model of peanut allergy, improving the particles as the project evolved to have a higher loading level and lower burst release. The microparticles improved the safety and efficacy of an immunotherapy protocol. I also encapsulated hydrophilic and hydrophobic chemotherapeutic drugs for a brain cancer model.