Human cerebrospinal fluid microRNA: temporal changes following subarachnoid hemorrhage.

Aneurysmal subarachnoid hemorrhage (aSAH) is a devastating form of hemorrhagic stroke with 30-day mortality between 33 and 45%. Delayed cerebral ischemia (DCI) is the chief cause of morbidity and mortality in patients who survive the initial aSAH. DCI accounts for almost 50% of deaths in patients surviving to treatment of the ruptured aneurysm. The mechanisms for brain injury after aSAH and the brain's response to this injury are not fully understood in humans. MicroRNAs (miRs) are 22- to 25-nucleotide single-stranded RNA molecules that inhibit the expression of specific messenger RNA targets. In this work, miR profiling of human cerebrospinal fluid from eight patients after aSAH was performed daily for 10 days with the goal of identifying changes in miR abundance. Using the nanoString nCounter Expression Assay, we identified two specific clusters of miR that were differentially regulated over time. Quantitative RT-PCR was performed on select miRs from each cluster. The first cluster contained miRs known to be present in blood and decreased in abundance over time. miRs in this group include miR-92a and let-7b. The second cluster contained several poorly characterized miRs that increased in abundance over time. miRs in this group included miR-491. This second cluster of miRs may be released into the CSF by the brain itself as a result of the initial SAH. Temporal changes in the abundance of specific miRs in human CSF after aSAH may provide novel insight into the role of miRs in brain injury and the brain's response.

Gelation chemistries for the encapsulation of nanoparticles in composite gel microparticles for lung imaging and drug delivery.

The formation of 10-40 µm composite gel microparticles (CGMPs) comprised of ∼100 nm drug containing nanoparticles (NPs) in a poly(ethylene glycol) (PEG) gel matrix is described. The CGMP particles enable targeting to the lung by filtration from the venous circulation. UV radical polymerization and Michael addition polymerization reactions are compared as approaches to form the PEG matrix. A fluorescent dye in the solid core of the NP was used to investigate the effect of reaction chemistry on the integrity of encapsulated species. When formed via UV radical polymerization, the fluorescence signal from the NPs indicated degradation of the encapsulated species by radical attack. The degradation decreased fluorescence by 90% over 15 min of UV exposure. When formed via Michael addition polymerization, the fluorescence was maintained. Emulsion processing using controlled shear stress enabled control of droplet size with narrow polydispersity. To allow for emulsion processing, the gelation rate was delayed by adjusting the solution pH. At a pH = 5.4, the gelation occurred at 3.5 h. The modulus of the gels was tuned over the range of 5 to 50 kPa by changing the polymer concentration between 20 and 70 vol %. NP aggregation during polymerization, driven by depletion forces, was controlled by the reaction kinetics. The ester bonds in the gel network enabled CGMP degradation. The gel modulus decreased by 50% over 27 days, followed by complete gel degradation after 55 days. This permits ultimate clearance of the CGMPs from the lungs. The demonstration of uniform delivery of 15.8 ± 2.6 µm CGMPs to the lungs of mice, with no deposition in other organs, is shown, and indicates the ability to concentrate therapeutics in the lung while avoiding off-target toxic exposure.