Visualization of Nuclease- and Serum-Mediated Chromatin Degradation with DNA-Histone Mesostructures.

This study analyzed the nuclease- and serum-driven degradation of millimeter-scale, circular DNA-histone mesostructures (DHMs). DHMs are bioengineered chromatin meshes of defined DNA and histone compositions designed as minimal mimetics of physiological extracellular chromatin structures, such as neutrophil extracellular traps (NETs). Taking advantage of the defined circular shape of the DHMs, an automated time-lapse imaging and image analysis method was developed and used to track DHM degradation and shape changes over time. DHMs were degraded well by 10 U/mL concentrations of deoxyribonuclease I (DNase I) but not by the same level of micrococcal nuclease (MNase), whereas NETs were degraded well by both nucleases. These comparative observations suggest that DHMs have a less accessible chromatin structure compared to NETs. DHMs were degraded by normal human serum, although at a slower rate than NETs. Interestingly, time-lapse images of DHMs revealed qualitative differences in the serum-mediated degradation process compared to that mediated by DNase I. Importantly, despite their reduced susceptibility to degradation and compositional simplicity, the DHMs mimicked NETs in being degraded to a greater extent by normal donor serum compared to serum from a lupus patient with high disease activity. These methods and insights are envisioned to guide the future development and expanded use of DHMs, beyond the previously reported antibacterial and immunostimulatory analyses, to extracellular chromatin-related pathophysiological and diagnostic studies.

Development of a High-Fidelity Benchtop Model for Simultaneous Flow, Pressure, and Imaging Assessment of Transarterial Embolization Procedures.

PURPOSE: The development of new endovascular technologies for transarterial embolization has relied on animal studies to validate efficacy before clinical trials are undertaken. Because embolizations in animals and patients are primarily conducted with fluoroscopy alone, local hemodynamic changes are not assessed during testing. However, such hemodynamic metrics could be important indicators of procedure efficacy that could support improved patient outcomes, such as via the determination of procedural endpoints. The purpose of this study is to create a high-fidelity benchtop system for multiparametric (i.e., hemodynamic and imaging) assessment of transarterial embolization procedures. METHODS: The benchtop system consists of a 3D printed, anatomically accurate vascular phantom; a flow loop with a cardiac output simulator; a high-speed video camera; and pressure transducers and flow meters. This system enabled us to vary the heart rate and blood pressure and to simulate clinically relevant hemodynamic states, such as healthy adult, aortic regurgitation, and hypovolemic shock. RESULTS: With our radiation-free angiography-mimetic imaging system, we could simultaneously assess gauge pressure and flow values during transarterial embolization. We demonstrated the feasibility of recapitulating the digital subtraction angiography workflow. Finally, we highlighted the utility of this system by characterizing the relationship between an imaging-based metric of procedural endpoint and intravascular flow. We also characterized hemodynamic changes associated with particle embolization within a branch of the hepatic artery and found them to be within reported patient data. CONCLUSION: Our benchtop vascular system was low-cost and reproduced transarterial embolization-related hemodynamic phenomena with high fidelity. We believe that this novel platform enables the characterization of patient physiology, novel catheterization devices, and techniques.