Evaluation of the Effectiveness and Safety of Direct Oral Anticoagulants in Elderly Patients With Nonvalvular Atrial Fibrillation Who Are Not Candidates for Warfarin in Real-World Setting.

ABSTRACT: Limited literature has established the role of direct oral anticoagulants (DOAC) for elderly patients with nonvalvular atrial fibrillation who are unsuited for warfarin. Therefore, the objectives of this study were to assess the effectiveness and safety of DOAC use in this vulnerable patient population. This was a retrospective propensity score matching cohort study. Among all patients aged 75+ years who were not candidates for warfarin, we matched those who initiated DOAC between September 2017 and September 2018 with those who did not receive DOAC or warfarin in a 1:1 ratio. Effectiveness outcome was a composite measure of stroke, transient ischemic attack, and pulmonary embolism. Safety outcome was a composite measure of non-trauma-related intracranial hemorrhage and gastrointestinal bleed. Unless patients died or lost membership, follow-up period for the effectiveness outcome was until the end of 2019, whereas the safety outcome was for a period up to 1 year. Conditional logistic regression was used to analyze both outcomes. We identified 7818 patients who met the inclusion criteria and started DOAC, which matched to 7818 patients who did not receive anticoagulants. The mean age was 82.3 ± 5.1 years, and 51.5% male. The DOAC group had a lower hazard ratio of 0.37 (confidence interval, 0.24-0.57; P < 0.01) for composite effectiveness outcomes, whereas no difference in the composite safety outcome (hazard ratio, 0.91; confidence interval, 0.65-1.25; P = 0.55) when compared with matched control. In conclusion, DOAC was found to be effective in preventing thromboembolic events in patients aged 75+ years with nonvalvular atrial fibrillation who were not eligible for warfarin.

Cell-based biosensor to report DNA damage in micro- and nanosystems.

Understanding how newly engineered micro- and nanoscale materials and systems that interact with cells impact cell physiology is crucial for the development and ultimate adoption of such technologies. Reports regarding the genotoxic impact of forces applied to cells in such systems that can both directly or indirectly damage DNA emphasize the need for developing facile methods to assess how materials and technologies affect cell physiology. To address this need we have developed a TurboRFP-based DNA damage reporter cell line in NIH-3T3 cells that fluoresce to report genotoxic stress caused by a wide variety of agents, from chemical genotoxic agents to UV-C radiation. Our biosensor was successfully implemented in reporting the genotoxic impact of nanomaterials, demonstrating the ability to assess size dependent geno- and cyto-toxicity. The biosensor cells can be assayed in a high throughput, noninvasive manner, with no need for overly sophisticated equipment or additional reagents. We believe that this open-source biosensor is an important resource for the community of micro- and nanomaterials and systems designers and users who wish to evaluate the impact of systems and materials on cell physiology.

Controlled self-assembly of monodisperse niosomes by microfluidic hydrodynamic focusing.

Niosomes are synthetic membrane vesicles formed by self-assembly of nonionic surfactant, often in a mixture with cholesterol and dicetyl phosphate. Because of their inner aqueous core and bilayer membrane shell, niosomes are commonly used as carriers of treatment agents for pharmaceutical and cosmetic applications or contrast agents for clinical imaging applications. In those applications, niosomes are considered as a more economical and stable alternative to their biological counterpart (i.e., liposomes). However, conventional bulk method of niosome preparation requires bulk mixing of two liquid phases, which is time-consuming and not well-controlled. Such mixing conditions often lead to large niosomes with high polydispersity in size and thus affect the consistency of niosome dosage or imaging quality. In this study, we present a new method of niosome self-assembly by microfluidic hydrodynamic focusing to improve on the size and size distributions of niosomes. By taking advantage of the rapid and controlled mixing of two miscible fluids (i.e., alcohol and water) in microchannels, we were able to obtain in seconds nanoscaled niosomes with approximately 40% narrower size distributions compared to the bulk method. We further investigated different parameters that might affect on-chip assembly of niosomes, such as (1) conditions for the microfluidic mixing, (2) chemical structures of the surfactant used (i.e., sorbitan esters Span 20, Span 60, and Span 80), and (3) device materials for the microchannel fabrication. This work suggests that microfluidics may facilitate the development and optimization of biomimetic colloidal systems for nanomedicine applications.

Photopolymerized diffusion-defined polyacrylamide gradient gels for on-chip protein sizing.

We report on a facile diffusion-based photopatterning technique for generating linear and non-linear decreasing pore-size gradients in cross-linked polyacrylamide gels. Diffusion of low viscosity polymer precursor solutions and a two-step photopatterning process were used to define the decreasing pore-size gradient gels in a microfluidic format, thus eliminating the need for controlled mixing and delivery of polymer precursor solutions. We present an analytical model of the non-steady state diffusion process and numerically evaluate that model for direct comparison with empirical characterizations of the gradient gels. We show that the analytical model provides an effective means to predict the steepness and linearity of a desired gradient gel prior to fabrication. To assess electrophoretic assay performance in the microfluidic gradient gels, on-chip sizing of protein samples (20-116 kDa) was investigated. Baseline resolution of six proteins was demonstrated in 4 s using 3.5% to 10% polyacrylamide gradient gels. The demonstrated ability to conduct efficient protein sizing in ultra-short separation lengths (0.3 cm) means low applied electric potentials are needed to achieve the electric field strengths required for protein separations. The low required electric potentials relax operating constraints on electrical components, as is especially important for translation of the assay into pre-clinical and clinical settings. The gradient gel fabrication method reported is amenable to adaptation to non-sizing protein assays, as well as integration with upstream sample preparation steps and subsequent orthogonal downstream assays.

Profiling lymphocyte interactions at the single-cell level by microfluidic cell pairing.

Establishing a successful immune response requires cell-cell interactions, where the nature of antigen presentation dictates functional outcomes. Methods to study these interactions, however, suffer from limited throughput and a lack of control over cell pairing. Here we describe a microfluidic platform that achieves high-throughput deterministic pairing of lymphocytes with a defined contact time, thereby allowing accurate assessment of early activation events for each pair in controlled microenvironments. More importantly, the platform allows the capture of dynamic processes and static parameters from both partners simultaneously, thus enabling pairwise-correlated multiparametric profiling of lymphocyte interactions over hundreds of pairs in a single experiment. Using our platform, we characterized early activation dynamics of CD8 T cells (OT-1 and TRP1 transnuclear (TN)) and investigated the extent of heterogeneity in T-cell activation and the correlation of multiple readouts. The results establish our platform as a promising tool for quantitative investigation of lymphocyte interactions.

Poly(lactide-co-glycolide) nanoparticle assembly for highly efficient delivery of potent therapeutic agents from medical devices.

Controlled delivery of therapeutic agents from medical devices can improve their safety and effectiveness in vivo, by ameliorating the surrounding tissue responses and thus maintaining the functional integrity of the devices. Previously, we presented a new method for providing simultaneous controlled delivery from medical devices, by surface assembly of biodegradable polymer nanoparticles (NPs) encapsulating fluorescent dyes. Here, we continue our investigation with NPs loaded with therapeutic agents, dexamethasone (DEX) or plasmid DNA, and evaluated the bioactivity of the released molecules with macrophage cells associated with inflammation. Over a period of one week, NPs encapsulating DEX released 24.9+/-0.8ng from the probe surface and was successful at suppressing macrophage cell growth by 40+/-10%. This percentage of suppression corresponded to approximately 100% drug delivery efficiency, in comparison with the unencapsulated drug. DNA NP coatings, in contrast, released approximately 1ng of plasmid DNA and were effective at transfecting macrophage cells to express the luciferase gene at 300+/-200 relative luminescence/mg total protein. This amount of luciferase activity corresponded to 100% gene delivery efficiency. Thus, NP coatings were capable of providing continuous release of bioactive agents in sufficient quantities to induce relevant biological effects in cell culture studies. These coatings also remained intact, even after 14 days of incubation with phosphate buffered saline. Although the maximum loading for NP coatings is inherently lower than the more established matrix coating, our study suggests that the NP coatings are a more versatile and efficient approach toward drug delivery or gene delivery from a medical device surface and are perhaps best suited for continuous release of highly potent therapeutic agents.

Simultaneous release of multiple molecules from poly(lactide-co-glycolide) nanoparticles assembled onto medical devices.

Cell and tissue responses to implanted biomaterials often limit their effectiveness and lifetime. This is particularly true for materials implanted into the brain. We present here a new approach for the modification of materials to enable release of multiple agents, which might be useful in modulating tissue responses, without changing the properties of the underlying material, in this case, a silicon probe. Poly(lactide-co-glycolide) nanoparticles (NPs) were assembled onto silicon probe surfaces by electrostatic interactions. Charged NPs were fabricated by altering the properties of the surfactant. NPs formed with poly(ethylene-alt-maleic anhydride) (PEMA) were strongly negatively charged; these NPs assembled onto probes best when suspended at nearly physiological conditions (surface density approximately 83,600+/-3000 particles/mm(2)). The percentage of surface area coverage by the NPs was estimated to be approximately 13% and was maintained over two weeks during constant exposure to PBS. Multiple fluorescent NP populations were attached to the same probe to allow visualization of simultaneous delivery of multiple agents by fluorescence microscopy. Release from NP coatings was reproducible and controllable. The distinct release profiles of each agent from the coatings were preserved upon attachment to the surfaces. The unique feature of this new system is that NPs encapsulating various molecules (i.e. drugs, proteins, or DNA) can be fabricated separately, in advance, and simply mixed prior to attachment. The versatility of this delivery system, therefore, makes it suitable for many applications.