Bio-Inspired Microdevices that Mimic the Human Vasculature

Research progress of electrochemical oxidation and self-action of electric field for medical wastewater treatment

A large number of pathogenic microorganisms exist in medical wastewater, which could invade the human body through the water and cause harm to human health. With the global pandemic coronavirus (COVID-19), public health safety become particularly important, and medical wastewater treatment is an important part of it. In particular, electrochemical disinfection technology has been widely studied in medical wastewater treatment due to its greenness, high efficiency, convenient operation, and other advantages. In this paper, the development status of electrochemical disinfection technology in the treatment of medical wastewater is reviewed, and an electrochemical three-stage disinfection system is proposed for the treatment of medical wastewater. Moreover, prospects for the electrochemical treatment of medical wastewater will be presented. It is hoped that this review could provide insight and guidance for the research and application of electrochemical disinfection technology to treat medical wastewater.GRAPHICAL ABSTRACT.

Combinatorial approaches for novel cardiovascular drug discovery: a review of the literature

INTRODUCTION

In this article, authors report an inclusive discussion about the combinatorial approach for the treatment of cardiovascular diseases (CVDs) and for counteracting the cardiovascular risk factors. The mentioned strategy was demonstrated to be useful for improving the efficacy of pharmacological treatments and in CVDs showed superior efficacy with respect to the classical monotherapeutic approach.

AREAS COVERED

According to this topic, authors analyzed the combinatorial treatments that are available on the market, highlighting clinical studies that demonstrated the efficacy of combinatorial drug strategies to cure CVDs and related risk factors. Furthermore, the review gives an outlook on the future perspective of this therapeutic option, highlighting novel drug targets and disease models that could help the future cardiovascular drug discovery.

EXPERT OPINION

The use of specifically designed and increasingly rational and effective drug combination therapies can therefore be considered the evolution of polypharmacy in cardiometabolic and CVDs. This approach can allow to intervene on multiple etiopathogenetic mechanisms of the disease or to act simultaneously on different pathologies/risk factors, using the combinations most suitable from a pharmacodynamic, pharmacokinetic, and toxicological perspective, thus finding the most appropriate therapeutic option.

Automated Classification of Left Ventricular Hypertrophy on Cardiac MRI

Left ventricular hypertrophy is an independent predictor of coronary artery disease, stroke, and heart failure. Our aim was to detect LVH cardiac magnetic resonance (CMR) scans with automatic methods. We developed an ensemble model based on a three-dimensional version of ResNet. The input of the network included short-axis and long-axis images. We also introduced a standardization methodology to unify the input images for noise reduction. The output of the network is the decision whether the patient has hypertrophy or not. We included 428 patients (mean age: 49 ± 18 years, 262 males) with LVH (346 hypertrophic cardiomyopathy, 45 cardiac amyloidosis, 11 Anderson–Fabry disease, 16 endomyocardial fibrosis, 10 aortic stenosis). Our control group consisted of 234 healthy subjects (mean age: 35 ± 15 years; 126 males) without any known cardiovascular diseases. The developed machine-learning-based model achieved a 92% F1-score and 97% recall on the hold-out dataset, which is comparable to the medical experts. Experiments showed that the standardization method was able to significantly boost the performance of the algorithm. The algorithm could improve the diagnostic accuracy, and it could open a new door to AI applications in CMR.

Optimization of RNA extraction methods from human metabolic tissue samples of the COMET biobank

Constitution of biobank of human tissues requires careful handling and storage of biological material, to guarantee the quality of samples. Tissue preparation is also critical for further applications such as transcriptomic profiling. In this study, our aim was to evaluate the impact of different disruption techniques (FastPrep-24 instrument, GentleMACS dissociator, and syringe/needle) and homogenizing buffers (RLT versus QIAzol) on RNA purity and quality of metabolic tissues (adipose tissues, liver and skeletal muscle) present in the COMET Biobank. For all homogenization methods used and tissue types, the A260/280 ratios reached values ≥ 1.8, which are in the range of what is found in human tissues and cell lines, while the A260/230 ratios were however ≤ 1.8, with the lowest value obtained with GentleMACS Dissociator. In addition, GentleMACS Dissociator combined with QIAzol reagent gave the highest RIN value and 28S/18S ratio for all tissues tested, except for muscle. Performing RT-qPCR, Ct values for different housekeeping genes can be influenced by extraction methods and RNA quality of samples. In conclusion, we have demonstrated that different disruption techniques and homogenizing buffers impact the purity and some quality markers of RNA, and can also impact quantification of mRNAs by RT-qPCR in human metabolic tissues.

Quantitative Monitoring of Dynamic Blood Flows Using Coflowing Laminar Streams in a Sensorless Approach

Determination of blood viscosity requires consistent measurement of blood flow rates, which leads to measurement errors and presents several issues when there are continuous changes in hematocrit changes. Instead of blood viscosity, a coflowing channel as a pressure sensor is adopted to quantify the dynamic flow of blood. Information on blood (i.e., hematocrit, flow rate, and viscosity) is not provided in advance. Using a discrete circuit model for the coflowing streams, the analytical expressions for four properties (i.e., pressure, shear stress, and two types of work) are then derived to quantify the flow of the test fluid. The analytical expressions are validated through numerical simulations. To demonstrate the method, the four properties are obtained using the present method by varying the flow patterns (i.e., constant flow rate or sinusoidal flow rate) as well as test fluids (i.e., glycerin solutions and blood). Thereafter, the present method is applied to quantify the dynamic flows of RBC aggregation-enhanced blood with a peristaltic pump, where any information regarding the blood is not specific. The experimental results indicate that the present method can quantify dynamic blood flow consistently, where hematocrit changes continuously over time.

A permeable on-chip microvasculature for assessing the transport of macromolecules and polymeric nanoconstructs

HYPOTHESIS

The selective permeation of molecules and nanomedicines across the diseased vasculature dictates the success of a therapeutic intervention. Yet, in vitro assays cannot recapitulate relevant differences between the physiological and pathological microvasculature. Here, a double-channel microfluidic device was engineered to comprise vascular and extravascular compartments connected through a micropillar membrane with tunable permeability.

EXPERIMENTS

The vascular compartment was coated by endothelial cells to achieve permeability values ranging from ~0.1 μm/sec, following a cyclic adenosine monophosphate (cAMP) pre-treatment (25 μg/mL), up to ~2 μm/sec, upon exposure to Mannitol, Lexiscan or in the absence of cells. Fluorescent microscopy was used to monitor the vascular behavior of 250 kDa Dextran molecules, 200 nm polystyrene nanoparticles (PB), and 1,000 × 400 nm discoidal polymeric nanoconstructs (DPN), under different permeability and flow conditions.

FINDINGS

In the proposed on-chip microvasculature, it was confirmed that permeation enhancers could favor the perivascular accumulation of ~200 nm, in a dose and time dependent fashion, while have no effect on larger particles. Moreover, the microfluidic device was used to interrogate the role of particle deformability in vascular dynamics. In the presence of a continuous endothelium, soft DPN attached to the vasculature more avidly at sub-physiological flows (100 μm/sec) than rigid DPN, whose deposition was larger at higher flow rates (1 mm/sec). The proposed double-channel microfluidic device can be efficiently used to systematically analyze the vascular behavior of drug delivery systems to enhance their tissue specific accumulation.

High-Throughput Magnetic Actuation Platform for Evaluating the Effect of Mechanical Force on 3D Tumor Microenvironment

Accurately replicating and analyzing cellular responses to mechanical cues is vital for exploring metastatic disease progression. However, many of the existing in vitro platforms for applying mechanical stimulation seed cells on synthetic substrates. To better recapitulate physiological conditions, a novel actuating platform is developed with the ability to apply tensile strain on cells at various amplitudes and frequencies in a high-throughput multi-well culture plate using a physiologically-relevant substrate. Suspending fibrillar fibronectin across the body of the magnetic actuator provides a matrix representative of early metastasis for 3D cell culture that is not reliant on a synthetic substrate. This platform enables the culturing and analysis of various cell types in an environment that mimics the dynamic stretching of lung tissue during normal respiration. Metabolic activity, YAP activation, and morphology of breast cancer cells are analyzed within one week of cyclic stretching or static culture. Further, matrix degradation is significantly reduced in breast cancer cell lines with metastatic potential after actuation. These new findings demonstrate a clear suppressive cellular response due to cyclic stretching that has implications for a mechanical role in the dormancy and reactivation of disseminated breast cancer cells to macrometastases.

Vascularized Microfluidics and the Blood-Endothelium Interface

The microvasculature is the primary conduit through which the human body transmits oxygen, nutrients, and other biological information to its peripheral tissues. It does this through bidirectional communication between the blood, consisting of plasma and non-adherent cells, and the microvascular endothelium. Current understanding of this blood-endothelium interface has been predominantly derived from a combination of reductionist two-dimensional in vitro models and biologically complex in vivo animal models, both of which recapitulate the human microvasculature to varying but limited degrees. In an effort to address these limitations, vascularized microfluidics have become a platform of increasing importance as a consequence of their ability to isolate biologically complex phenomena while also recapitulating biochemical and biophysical behaviors known to be important to the function of the blood-endothelium interface. In this review, we discuss the basic principles of vascularized microfluidic fabrication, the contribution this platform has made to our understanding of the blood-endothelium interface in both homeostasis and disease, the limitations and challenges of these vascularized microfluidics for studying this interface, and how these inform future directions.

Advice for starting a mechanobiology lab

Starting a new lab in mechanobiology and a new lab in general can be an exciting, yet daunting experience. Depending on your previous position, you have now found yourself with significantly more responsibility in more ways than one. For those considering taking such a career path, I present in this commentary advice that will hopefully be useful and provide food for thought.

Cardiovascular disease models: A game changing paradigm in drug discovery and screening

Cardiovascular disease is the leading cause of death worldwide. Although investment in drug discovery and development has been sky-rocketing, the number of approved drugs has been declining. Cardiovascular toxicity due to therapeutic drug use claims the highest incidence and severity of adverse drug reactions in late-stage clinical development. Therefore, to address this issue, new, additional, replacement and combinatorial approaches are needed to fill the gap in effective drug discovery and screening. The motivation for developing accurate, predictive models is twofold: first, to study and discover new treatments for cardiac pathologies which are leading in worldwide morbidity and mortality rates; and second, to screen for adverse drug reactions on the heart, a primary risk in drug development. In addition to in vivo animal models, in vitro and in silico models have been recently proposed to mimic the physiological conditions of heart and vasculature. Here, we describe current in vitro, in vivo, and in silico platforms for modelling healthy and pathological cardiac tissues and their advantages and disadvantages for drug screening and discovery applications. We review the pathophysiology and the underlying pathways of different cardiac diseases, as well as the new tools being developed to facilitate their study. We finally suggest a roadmap for employing these non-animal platforms in assessing drug cardiotoxicity and safety.

Probing Endothelial Cell Mechanics Through Connexin 43 Disruption

The endothelium has been established to generate intercellular stresses and suggested to transmit these intercellular stresses through cell-cell junctions, such as VE-Cadherin and ZO-1, for example. Although the previously mentioned molecules reflect the appreciable contributions both adherens junctions and tight junctions are believed to have in endothelial cell intercellular stresses, in doing so they also reveal the obscure relationship that exists between gap junctions and intercellular stresses. Therefore, to bring clarity to this relationship we disrupted expression of the endothelial gap junction connexin 43 (Cx43) by exposing confluent human umbilical vein endothelial cells (HUVECs) to a low (0.2 μg/mL) and high (2 μg/mL) concentration of 2,5-dihydroxychalcone (chalcone), a known Cx43 inhibitor. To evaluate the impact Cx43 disruption had on endothelial cell mechanics we utilized traction force microscopy and monolayer stress microscopy to measure cell-substrate tractions and cell-cell intercellular stresses, respectively. HUVEC monolayers exposed to a low concentration of chalcone produced average normal intercellular stresses that were on average 17% higher relative to control, while exposure to a high concentration of chalcone yielded average normal intercellular stresses that were on average 55% lower when compared to control HUVEC monolayers. HUVEC maximum shear intercellular stresses were observed to decrease by 16% (low chalcone concentration) and 66% (high chalcone concentration), while tractions exhibited an almost 2-fold decrease under high chalcone concentration. In addition, monolayer cell velocities were observed to decrease by 19% and 35% at low chalcone and high chalcone concentrations, respectively. Strain energies were also observed to decrease by 32% and 85% at low and high concentration of chalcone treatment, respectively, when compared to control. The findings we present here reveal for the first time the contribution Cx43 has to endothelial biomechanics.

Microfluidic technologies for vasculature biomimicry

An overview of microfluidic technologies for vascular studies and fabrication of vascular structures.