a-microfluidic-system-for-modeling-endothelial-dysfunction-under

A Microfluidic System for Modeling Endothelial Dysfunction under Combined Physiological Pulsatile Shear Stress and Oscillatory Hyperglycemia

Endothelial dysfunction in diabetic vascular complications involves complex interactions between metabolic disturbances, specifically oscillatory glucose ...

Central Hospital of Dalian University of Technology

Dalian University of Technology

The biomechanical properties of single cells show great potential for early disease diagnosis and effective treatments. In this study, a microfluidic device was developed for quantifying the mechanical properties of a single cell. Micropipette aspiration was integrated into a microfluidic device that mimics a classical Wheatstone bridge circuit. This technique allows us not only to effectively alter the flow direction for single-cell trapping, but also to precisely control the pressure exerted on the aspirated cells, analogous to the feature of the Wheatstone bridge that can precisely control bridge voltage and current. By combining the micropipette aspiration technique into the microfluidic device, we can effectively trap the microparticles and Hela cells as well as measure the deformability of cells. The Young's modulus of Hela cells was evaluated to be 387 ± 77 Pa, which is consistent with previous micropipette aspiration studies. The simplicity, precision, and usability of our device show good potential for biomechanical trials in clinical diagnosis and cell biology research.

A Microfluidic Micropipette Aspiration Device to Study Single-Cell Mechanics Inspired by the Principle of Wheatstone Bridge.

Revealing the mechanisms underlying the intracellular calcium responses in vascular endothelial cells (VECs) induced by mechanical stimuli contributes to a better understanding for vascular diseases, including hypertension, atherosclerosis, and aneurysm. Combining with experimental measurement and Computational Fluid Dynamics simulation, we developed a mechanobiological model to investigate the intracellular [Ca] response in a single VEC being squeezed through narrow microfluidic channel. The time-dependent cellular surface tension dynamics was quantified throughout the squeezing process. In our model, the various Ca signaling pathways activated by mechanical stimulation is fully considered. The simulation results of our model exhibited well agreement with our experimental results. By using the model, we theoretically explored the mechanism of the two-peak intracellular [Ca] response in single VEC being squeezed through narrow channel and made some testable predictions for guiding experiment in the future.

The intracellular calcium dynamics in a single vascular endothelial cell being squeezed through a narrow microfluidic channel.

The mechanical properties of single cells have been recognized as biomarkers for identifying individual cells and diagnosing human diseases. Microfluidic devices based on the flow cytometry principle, which are not limited by the vision field of a microscope and can achieve a very high throughput, have been extensively adopted to measure the mechanical properties of single cells. However, these kinds of microfluidic devices usually required pressure-driven pumps with a very low flow rate and high precision. In this study, we developed a high-throughput microfluidic device inspired by the Wheatstone bridge principle for characterizing the mechanical properties of single cells. The microfluidic analogue of the Wheatstone bridge not only took advantage of flow cytometry, but also allowed precise control of a very low flow rate through the constricted channel with a higher input flow rate generated by a commercially available pressure-driven pump. Under different input flow rates of the pump, the apparent elastic moduli and the fluidity of osteosarcoma (U-2OS) cells and cervical carcinoma (HeLa) cells were measured by monitoring their dynamic deformations passing through the bridge-channel with different sizes of rectangular constrictions. The results showed that the input flow rate had little effect on measuring the mechanical properties of the cells, while the ratio of cell radius to effective constriction radius was different, , for U-2OS cells it was 1.20 and for HeLa cells it was 1.09. Under this condition compared with predecessors, our statistic results of cell mechanical properties exhibited minimal errors. Furthermore, the cell viability after measurements was kept above 90% that demonstrated the non-destructive property of our proposed method.

A high-throughput microfluidic device inspired by the Wheatstone bridge principle for characterizing the mechanical properties of single cells.

Vascular endothelial cells (ECs) residing in the innermost layer of blood vessels are exposed to dynamic wall shear stress (WSS) induced by blood flow. The intracellular nitric oxide (NO) and reactive oxygen species (ROS) in ECs modulated by the dynamic WSS play important roles in endothelial functions. Mathematical modeling is a popular methodology for biophysical studies. It can not only explain existing cell experiments, but also reveal the underlying mechanism. However, the previous mathematical models of NO dynamics in ECs are limited to the static WSS induced by constant flow, while arterial blood flow is a periodic pulsatile flow with varying amplitude and frequency at different exercise intensities. In this study, a mathematical model of intracellular NO and ROS dynamics activated by dynamic WSS based on the in vitro cell experiments is developed. With the hypothesis of the viscoelastic body, the Kelvin model is adopted to simulate the mechanosensors on EC. Thus, the NO dynamics activated by dynamic shear stresses induced by constant flow, pulsatile flow, and oscillatory flow are analyzed and compared. Moreover, the roles of ROS have been considered for the first time in the modeling of NO dynamics in ECs based on the analysis of cell experiments. The predictions of the proposed model coincide fairly well with the experimental data when ECs are subjected to exercise-induced WSS. The mechanism is elucidated that WSS induced by moderate-intensity exercise is most favorable to NO production in ECs. This study can provide valuable insights for further study of NO and ROS dynamics in ECs and help develop appropriate exercise regimens for improving endothelial functions.

A mathematical model for intracellular NO and ROS dynamics in vascular endothelial cells activated by exercise-induced wall shear stress.

The temperature is often a critical factor affecting the diffusion of nanoparticles in complex physiological media, but its specific effects are still to be fully understood. Here, we constructed a temperature-regulated model of semidilute polymer solution and experimentally investigated the temperature-mediated diffusion of nanoparticles using the particle tracking method. By examining the ensemble-averaged mean square displacements (MSDs), we found that the MSD grows gradually as the temperature increases while the transition time from sublinear to linear stage in MSD decreases. Meanwhile, the temperature-dependent measured diffusivity of the nanoparticles shows an exponential growth. We revealed that these temperature-mediated changes are determined by the composite effect of the macroscale property of polymer solution and the microscale dynamics of polymer chain as well as nanoparticles. Furthermore, the measured non-Gaussian displacement probability distributions were found to exhibit non-Gaussian fat tails, and the tailed distribution is enhanced as the temperature increases. The non-Gaussianity was calculated and found to vary in the same trend with the tailed distribution, suggesting the occurrence of hopping events. This temperature-mediated non-Gaussian feature validates the recent theory of thermally induced activated hopping. Our results highlight the temperature-mediated changes in diffusive transport of nanoparticles in polymer solutions and may provide the possible strategy to improve drug delivery in physiological media.

Temperature-mediated diffusion of nanoparticles in semidilute polymer solutions.

Enhanced external counterpulsation (EECP) is a mechanically assisted circulation technique widely used in the rehabilitation and management of ischemic cardiovascular diseases. It contributes to cardiovascular functions by regulating the afterload of ventricle to improve hemodynamic effects, including increased diastolic blood pressure at aortic root, increased cardiac output and enhanced blood perfusion to multiple organs including coronary circulation. However, the effects of EECP on the coupling of the ventricle and the arterial system, termed ventricular-arterial coupling (VAC), remain elusive. We aimed to investigate the acute effect of EECP on the dynamic interaction between the left ventricle and its afterload of the arterial system from the perspective of ventricular output work.

Hemodynamics of ventricular-arterial coupling under enhanced external counterpulsation: An optimized dual-source lumped parameter model.

Type 2 diabetes mellitus (T2DM) is a chronic metabolic disorder affecting people worldwide. It is characterized by several key features, including hyperinsulinemia, hyperglycemia, hyperlipidemia, and dysbiosis. Epidemiologic studies have shown that T2DM is closely associated with the development and progression of cancer. T2DM-related hyperinsulinemia, hyperglycemia, and hyperlipidemia contribute to cancer progression through complex signaling pathways. These factors increase drug resistance, apoptosis resistance, and the migration, invasion, and proliferation of cancer cells. Here, we will focus on the role of hyperinsulinemia, hyperglycemia, and hyperlipidemia associated with T2DM in cancer development. Additionally, we will elucidate the potential molecular mechanisms underlying their effects on cancer progression. We aim to identify potential therapeutic targets for T2DM-related malignancies and explore relevant directions for future investigation.

Effects of T2DM on cancer progression: pivotal precipitating factors and underlying mechanisms.

Diabetic vascular complications (DVCs) are diabetes-induced vascular dysfunction and pathologies, leading to the major causes of morbidity and mortality in millions of diabetic patients worldwide. DVCs are provoked by endothelial dysfunction which is closely coordinated with two important hallmarks: one is the insufficient insulin secretion or insulin resistance, and another is the decrease in intracellular nitric oxide (NO) influenced by dynamic wall shear stress (WSS). Although the intracellular NO dynamics in endothelial cells (ECs) is crucial for endothelial function, the regulation of NO production by dynamic WSS and insulin is still poorly understood. In this study, we have proposed a mathematical model of intracellular NO production in ECs under the stimulation of dynamic WSS combined with insulin. The model integrates simultaneously the biochemical signaling pathways of insulin and the mechanotransduction pathways induced by dynamic WSS. The accuracy and reliability of the model to quantitatively describe NO production in ECs were compared and validated with reported experimental data. According to the validated model, inhibition of protein kinase B (AKT) phosphorylation and Ca influx by dynamic oscillatory WSS disrupts the dual nature of endothelial nitric oxide synthase (eNOS) enzyme activation. This disruption leads to the decrease in NO production and the bimodal disappearance of NO waveforms. Moreover, the results reveal that dynamic WSS combined with insulin promote endothelial NO production through negative synergistic effects, which is resulted from the temporal differences in mechanical and biochemical signaling. In brief, the proposed model elucidates the mechanism of NO generation activated by dynamic WSS combined with insulin, providing a potential target and theoretical framework for future treatment of DVCs.

Unveiling the Negative Synergistic Effect of Wall Shear Stress and Insulin on Endothelial NO Dynamics by Mathematical Modeling.

The dramatic hemodynamic disturbances induced by arteriovenous fistula (AVF) creation are universally acknowledged as the triggering factors for AVF dysfunction. The postoperative blood redistribution is greatly relevant with the flow disturbances of the AVF, such as disturbed flow, low wall shear stress (WSS), and oscillating WSS. However, the relationship between blood redistribution and hemodynamic disturbances of AVF remains unexamined. The role of clinically observed retrograde blood flow at the distal radial artery is rarely understood.

Adjusting blood redistribution to suppress flow disturbances of hemodialysis arteriovenous fistula: a computational fluid dynamics analysis.

Dysglycemia causes arterial endothelial damage, which is an early critical event in vascular complications for diabetes patients. Physiologically, moderate shear stress (SS) helps maintain endothelial cell health and normal function. Reactive oxygen species (ROS) and calcium ions (Ca) signals are involved in dysglycemia-induced endothelial dysfunction and are also implicated in SS-mediated regulation of endothelial cell function. Therefore, it is urgent to establish  models for studying endothelial biomechanics and mechanobiology, aiming to seek interventions that utilize appropriate SS to delay or reverse endothelial dysfunction. Microfluidic technology, as a novel approach, makes it possible to replicate blood glucose environment and accurate pulsatile SS . Here, we reviewed the progress of microfluidic systems used for SS-mediated repair of dysglycemia-induced endothelial cell damage (ECD), revealing the crucial roles of ROS and Ca during the processes. It holds significant implications for finding appropriate mechanical intervention methods, such as exercise training, to prevent and treat cardiovascular complications in diabetes.

Microfluidic investigation for shear-stress-mediated repair of dysglycemia-induced endothelial cell damage.

A comprehensive understanding of cellular mechanical heterogeneity is essential for identifying phenotypic variations. Impedance flow cytometry offers a high-throughput, label-free approach to assess single-cell electrical properties, yet current methods focus primarily on undeformed cells and overlook mechanical perturbations that may alter cytoskeletal structure and membrane behavior. Here, we present an integrated system that combines controlled mechanical compression with impedance measurement to quantify mechanical opacity-an electrical metric reflecting membrane permeability under dynamic deformation. This parameter correlates with cytoskeletal integrity and reveals how mechanical stimuli influence electrical responses. Theoretical modeling shows that membrane permittivity and conductivity critically shape frequency-dependent impedance, supporting the use of dual-frequency (500 kHz and 5 MHz) measurements to probe both intra- and extracellular properties. We define a four-parameter feature set (, , , ) to capture impedance changes during deformation and relaxation, offering a compact and interpretable mechanical signature. Using this system, we demonstrate distinct mechanical opacity profiles among three human cancer cell lines (HeLa, SW1990, BxPC-3), reflecting their inherent biomechanical differences. Fluorescence assays confirm that lower mechanical opacity corresponds to increased membrane permeability, linking electrical measurements to underlying structural changes. Our work establishes mechanical opacity as a dynamic, label-free marker for single-cell mechanics, bridging mechanical stimulation and electrical detection. This approach expands the capability of impedance flow cytometry for applications in cell classification, drug screening, and disease diagnostics.

Quantifying mechanical opacity as a novel indicator for single-cell phenotyping  integrated dynamic mechanical compression and impedance flow cytometry.

Pulsatile blood flow generates complex wall shear stress (WSS) patterns at the carotid bifurcation, which critically regulate endothelial function and structure. While physiological pulsatile WSS (PWSS) is essential for maintaining vascular health, low oscillatory WSS (OWSS) near the carotid sinus is closely associated with endothelial dysfunction, atherosclerotic plaque formation, and stenosis. Reproducing these hemodynamic conditions in vitro is therefore crucial for investigating endothelial mechanobiology and elucidating the pathogenesis of atherosclerosis. Although microfluidic technologies have emerged as promising platforms for simulating either pulsatile or oscillatory WSS, a system capable of simultaneously replicating both characteristic waveforms-as found in vivo at the carotid bifurcation-remains undeveloped. In this study, we designed a variable cross-section microfluidic channel using Computational Fluid Dynamics (CFD) simulations. Numerical results demonstrate that the optimized channel accurately reproduces low OWSS at a stepped section emulating the carotid sinus, alongside high PWSS in a downstream uniform section. Vortex formation induced by the step structure is identified as key to generating low OWSS, influenced by step height, channel width ratio, and input flow rate. This work provides a novel and robust methodology for designing microfluidic systems that mimic complex hemodynamic microenvironments, facilitating future studies on the interplay between distinct WSS patterns and endothelial dysfunction.

A Variable Cross-Section Microfluidic Channel for Simultaneous Reproduction of Low Oscillatory and Pulsatile Wall Shear Stress at the Carotid Bifurcation: A Computational Fluid Dynamics-Based Study.

Article	Year
A Microfluidic Micropipette Aspiration Device to Study Single-Cell Mechanics Inspired by the Principle of Wheatstone Bridge. Micromachines\| PubMed ID: 30781497	2019
The intracellular calcium dynamics in a single vascular endothelial cell being squeezed through a narrow microfluidic channel. Biomechanics and modeling in mechanobiology\| PubMed ID: 32710185	2021
A high-throughput microfluidic device inspired by the Wheatstone bridge principle for characterizing the mechanical properties of single cells. Analytical methods : advancing methods and applications\| PubMed ID: 36382629	2022
A mathematical model for intracellular NO and ROS dynamics in vascular endothelial cells activated by exercise-induced wall shear stress. Mathematical biosciences\| PubMed ID: 37086782	2023
Temperature-mediated diffusion of nanoparticles in semidilute polymer solutions. Electrophoresis\| PubMed ID: 37736676	2023
Hemodynamics of ventricular-arterial coupling under enhanced external counterpulsation: An optimized dual-source lumped parameter model. Computer methods and programs in biomedicine\| PubMed ID: 38677079	2024
Effects of T2DM on cancer progression: pivotal precipitating factors and underlying mechanisms. Frontiers in endocrinology\| PubMed ID: 39290325	2024
Unveiling the Negative Synergistic Effect of Wall Shear Stress and Insulin on Endothelial NO Dynamics by Mathematical Modeling. Bulletin of mathematical biology\| PubMed ID: 39969626	2025
Adjusting blood redistribution to suppress flow disturbances of hemodialysis arteriovenous fistula: a computational fluid dynamics analysis. Frontiers in bioengineering and biotechnology\| PubMed ID: 40182996	2025
Microfluidic investigation for shear-stress-mediated repair of dysglycemia-induced endothelial cell damage. Mechanobiology in medicine\| PubMed ID: 40395495	2024
Quantifying mechanical opacity as a novel indicator for single-cell phenotyping integrated dynamic mechanical compression and impedance flow cytometry. Lab on a chip\| PubMed ID: 40613747	2025
A Variable Cross-Section Microfluidic Channel for Simultaneous Reproduction of Low Oscillatory and Pulsatile Wall Shear Stress at the Carotid Bifurcation: A Computational Fluid Dynamics-Base... Biosensors\| PubMed ID: 41149300	2025

Chun-Dong Xue

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