Fluid Shear Stress Research Articles

Muscarinic acetylcholine receptor 3 localized to primary endothelial cilia regulates blood pressure and cognition

We previously demonstrated that the inability of primary endothelial cilia to sense fluid shear stress can lead to nitric oxide (NO) deficiency and cause hypertension (HTN). Decreased biosynthesis of NO contributes to cerebral amyloid angiopathy in Alzheimer’s disease (AD) patients through increased deposition of amyloid beta (Aβ). However, the molecular mechanisms underlying the pathogenesis of HTN and AD are incompletely understood. The objective of this study was to examine the pathophysiological roles of vascular primary cilia and muscarinic acetylcholine receptor 3 (CHRM3) in HTN and AD. We discovered, for the first time, that CHRM3 was localized to primary cilia of endothelial and cerebrovascular cells, and that CHRM3 expression was downregulated in cilialess cells. Moreover, CHRM3 activation enhanced cilia length and sensory function in terms of eNOS activation. To further examine the role of vascular CHRM3 in vivo, we showed that endothelial CHRM3 knockout was associated with increased BP and attenuated acetylcholine-mediated vascular relaxation. In addition, endothelial CHRM3 knockout resulted in altered fear behavior. This demonstrates the physiological significance of endothelial CHRM3 signaling and primary cilia-derived NO production as an important mechanism in the control of BP and cognition.

SARS-CoV-2 S-protein expression drives syncytia formation in endothelial cells

SARS-CoV-2 is a viral infection, best studied in the context of epithelial cell infection. Epithelial cells, when infected with SARS-CoV-2 express the viral S-protein, which causes host cells to fuse together into large multi-nucleated cells known as syncytia. Because SARS-CoV-2 infections also frequently present with cardiovascular phenotypes, we sought to understand if S-protein expression would also result in syncytia formation in endothelial cells. S-protein expression in endothelial cells was sufficient to induce the formation of multi-nucleated cells, with an average of 10% of all cells forming syncytia with an average of 6 nuclei per syncytia after 72 h of S-protein expression. Formation of syncytia was associated with the formation of gaps between cells, suggesting the potential for syncytia formation to compromise barrier function. Inhibition of myosin light chain kinase (MLCK), but not Rho-associated protein kinase, inhibited the formation of syncytia, suggesting a role for MLCK in syncytia formation. Further supporting the role of cellular contractility in syncytia formation, we also observed a reduction in the occurrence of syncytia for endothelial cells grown on substrates with reduced stiffness. Because endothelial cells are exposed to physiological forces due to blood flow, we examined the effects of cyclic biaxial stretch and fluid shear stress. While biaxial stretch did not affect syncytia formation, endothelial cells exposed to fluid shear stress were more resistant to syncytia formation. Finally, we observed that endothelial cells are suitable host cells for SARS-CoV-2 viral infection and replication, and that viral infection also causes syncytia formation. Our studies indicate that endothelial cells, in addition to epithelial cells, should also be considered a target for SARS-CoV-2 infection and a driver of COVID-19-associated pathology.

Exploring markers in nursing care of prostate cancer.

Prostate cancer is epithelial malignant prostate hyperplasia caused by a tumor. We found prostate cancer GSE141551 and GSE200879 profiles from gene expression omnibus database, followed by differentially expressed genes (DEGs) analysis, weighted gene co-expression network analysis, protein-protein interaction analysis, gene function enrichment analysis, and comparative toxicology database analysis. Finally, the gene expression heat map was drawn, and miRNA information regulating core DEGs was retrieved. A total of 1151 DEGs were found, most of them focusing on systematic development, cell development, cell differentiation, regulation of multicellular biological processes, anatomical morphogenesis, MAPK signaling pathway, proteoglycans in cancer, fluid shear stress, and atherosclerosis. The core genes (MYL9, TAGLN, SMTN, CNN1, MYH11, MYLK, MYOCD, ACTC1, LMOD1, and TPM2) obtained in end are all lowly expressed in prostate cancer samples and are associated with hypertension, tumor metastasis, prostate tumors, and tumor aggressiveness. LMOD1 and SMTN are lowly expressed in prostate cancer and may be used as markers in prostate cancer nursing.

Convective forces contribute to post‐traumatic degeneration after spinal cord injury

AbstractSpinal cord injury (SCI) initiates a complex cascade of chemical and biophysical phenomena that result in tissue swelling, progressive neural degeneration, and formation of a fluid‐filled cavity. Previous studies show fluid pressure above the spinal cord (supraspinal) is elevated for at least 3 days after injury and contributes to a phase of damage called secondary injury. Currently, it is unknown how fluid forces within the spinal cord itself (interstitial) are affected by SCI and if they contribute to secondary injury. We find spinal interstitial pressure increases from −3 mmHg in the naive cord to a peak of 13 mmHg at 3 days post‐injury (DPI) but relatively normalizes to 2 mmHg by 7 DPI. A computational fluid dynamics model predicts interstitial flow velocities up to 0.9 μm/s at 3 DPI, returning to near baseline by 7 DPI. By quantifying vascular leakage of Evans Blue dye after a cervical hemi‐contusion in rats, we confirm an increase in dye infiltration at 3 DPI compared to 7 DPI, suggestive of higher fluid velocities at the time of peak fluid pressure. In vivo expression of the apoptosis marker caspase‐3 is strongly correlated with regions of interstitial flow at 3 DPI, and exogenously enhancing interstitial flow exacerbates tissue damage. In vitro, we show overnight exposure of neuronal cells to low pathological shear stress (0.1 dynes/cm2) significantly reduces cell count and neurite length. Collectively, these results indicate that interstitial fluid flow and shear stress may play a detrimental role in post‐traumatic neural degeneration.

Numerical Simulation of Fluid Shear Stress Distribution in Microcracks of Trabecular Bone.

Bone is one of the hardest tissues in the human body, but it can undergo microcracks under long-term and periodic mechanical loads. The Newton iterative method was used to calculate the steady state, and the effects of different inlet and outlet pressures, trabecular gap width and height, and microcrack's depth and width on the fluid shear stress (FSS) were studied, and the gradient of FSS inside the microcrack was analyzed. The results show that the pressure difference and trabecular gap heigh are positively correlated with the FSS (the linear correlation coefficients R 2 were 0.9768 and 0.96542, respectively). When the trabecular gap width was 100 μm, the peak of FSS decreased by 28.57% compared with 800 and 400 μm, and the gradient of FSS inside the microcrack was 0.1-0.4 Pa/mm. This study can help people more intuitively understand the internal fluid distribution of trabecular bone and provide a reliable theoretical basis for the subsequent construction of gradient FSS devices in vitro.

Injury-on-a-chip for modelling microvascular trauma-induced coagulation.

Blood coagulation is a highly regulated injury response that features polymerization of fibrin fibers to prevent the passage of blood from a damaged vascular endothelium. A growing body of research seeks to monitor coagulation in microfluidic systems but fails to capture coagulation as a response to disruption of the vascular endothelium. Here we present a device that allows compression injury of a defined segment of a microfluidic vascular endothelium and the assessment of coagulation at the injury site. This pressure injury-on-a-chip (PINCH) device allows visualization of coagulation as the accumulation of fluorescent fibrin at injury sites. Quantification of fluorescent fibrin levels upstream of and at injury sites confirm that pre-treating vascular endothelium with fluid shear stress helps capture coagulation as an injury response. We leverage the PINCH devices to demonstrate the limited coagulation response of type A hemophiliacs and evaluate the performance of hemostatic microparticles and fibrinolytic nanoparticles. Our findings and the straightforward fabrication of the PINCH devices make it a promising choice for additional screening of hemostatic therapeutics.

Integrated network pharmacology and experimental validation to explore the mechanisms of Coregonus peled-derived myosin ACE-inhibiting peptides for the treatment of hypertension

Coregonus peled is rich in protein and is a plentiful resource of bioactive peptides. This study was aimed at extracting novel Angiotensin I-converting enzyme (ACE) inhibitory peptides from Coregonus peled and revealing their potential hypotensive mechanisms. This paper screened six ACE inhibitory peptides with high bioactivity, good water solubility, and ADMET properties by computerized enzyme digestion of myosin-heavy chain from Coregonus peled, and LCYPR had the greatest ACE inhibition activity (IC50 = 47.8782 μM). There were 47 potentially critical targets of LCYPR for hypertension treatment, involving 135 biological processes (BP), 30 cellular components (CC), and 30 molecular functions (MF). The results of KEGG pathway analyse showed that the LCYPR participated in 50 pathways including the renin-angiotensin system, renin secretion, lipid and atherosclerosis, relaxin signaling pathway, IL-17 signaling pathway, atherosclerosis, fluid shear stress, and others, through the key targets such as AGT, AKT1, ACE, REN, CTSB, STAT3, PLG, SRC, MMP2, and F2 to regulate the blood pressure of organisms. In conclusion, the study obtained a novel ACE inhibitory peptide from the myosin-heavy chain of Coregonus peled and revealed the potential target and pathway of LCYPR to improve hypertension. The study provides new ideas and methods for developing novel antihypertensive peptides. The results provide a theoretical basis for developing functional foods of the Xinjiang specialty cold-water fish.

Signatures of the speed of sound on the gravitational wave power spectrum from sound waves

Future space-based interferometers offer an unprecedented opportunity to detect signals from the stochastic gravitational wave background originating from a first-order phase transition at the electroweak scale. The phase transition is accompanied by a change of the equation of state from that of pure radiation. In this work we study the effect of this change on the power spectrum of gravitational waves generated by the sound waves in the plasma during the acoustic phase of the transition. We carry out an analytic calculation assuming that the sound speed and the fluid shear-stress that sources tensor perturbations remain approximately constant during the acoustic phase. The effect of a softer equation of state is twofold:(i) a scale-independent suppression of the power spectrum at all scales, due to the modified propagation of both sound and gravitational waves and(ii) the peak of the spectrum moves to smaller frequencies as the equation of state becomes softer.The power-law indices of the spectrum at small and large scales are unaffected by the softening of the equation of state. Our work improves the current estimation of the gravitational waves power spectrum from first order phase transitions and expands the possible scenarios of transitions that can be tested by gravitational wave detectors.

Development of a bioreactor to examine the response of corneal cells to fluid shear stress

Development of a bioreactor to examine the response of corneal cells to fluid shear stress

Development of a bioreactor to examine the response of corneal cells to fluid shear stress

Development of a bioreactor to examine the response of corneal cells to fluid shear stress

A bioreactor for in vitro studies of lymphatic endothelial cells with simultaneous fluid shear stress and membrane strain

A bioreactor for in vitro studies of lymphatic endothelial cells with simultaneous fluid shear stress and membrane strain

Immunomechanobiology: Engineering the Activation and Function of Immune Cells With the Mechanical Signal of Fluid Shear Stress

Immunomechanobiology: Engineering the Activation and Function of Immune Cells With the Mechanical Signal of Fluid Shear Stress

Force Nanoscopy Demonstrates Stress-Activated Adhesion between Staphylococcus aureus Iron-Regulated Surface Determinant Protein B and Host Toll-like Receptor 4.

The Staphylococcus aureus iron-regulated surface determinant protein B (IsdB) has recently been shown to bind to toll-like receptor 4 (TLR4), thereby inducing a strong inflammatory response in innate immune cells. Currently, two unsolved questions are (i) What is the molecular mechanism of the IsdB-TLR4 interaction? and (ii) Does it also play a role in nonimmune systems? Here, we use single-molecule experiments to demonstrate that IsdB binds TLR4 with both weak and extremely strong forces and that the mechanostability of the molecular complex is dramatically increased by physical stress, sustaining forces up to 2000 pN, at a loading rate of 105 pN/s. We also show that TLR4 binding by IsdB mediates time-dependent bacterial adhesion to endothelial cells, pointing to the role of this bond in cell invasion. Our findings point to a function for IsdB in pathogen-host interactions, that is, mediating strong bacterial adhesion to host endothelial cells under fluid shear stress, unknown until now. In nanomedicine, this stress-dependent adhesion represents a potential target for innovative therapeutics against S. aureus-resistant strains.

Developing a Flow-Resistance Module for Elucidating Cell Mechanotransduction on Multiple Shear Stresses.

Fluid shear stress plays a pivotal role in regulating cellular behaviors, maintaining tissue homeostasis, and driving disease progression. Cells in various tissues are specifically adapted to physiological levels of shear stress and exhibit sensitivity to variations in its magnitude, highlighting the requirement for a comprehensive understanding of cellular responses to both physiologically and pathologically relevant levels of shear stress. In this study, we developed an independent upstream flow-resistance module with high fluidic resistances comprising three microchannels. The validity of the flow-resistance module was confirmed via computational fluid dynamics (CFD) simulations and flow calibration experiments, resulting in the generation of steady wall shear stresses ranging from 0.06 to 11.57 dyn/cm2 within the interconnected cell culture chips. Gene expression profiles, cytoskeletal remodeling, and morphological changes, as well as Yes-associated protein (YAP) nuclear translocation, were investigated in response to various shear stresses to authenticate the reliability of our experimental platform, indicating an increasing trend as the shear stress increases, reaching its maximum at various shear stresses. Our findings suggest that this flow-resistance module can be readily employed for precise characterization of cellular responses under various shear stresses.

Multiscale interstitial fluid computation modeling of cortical bone to characterize the hydromechanical stimulation of lacunar-canalicular network.

Bone tissue is a biological composite material with a complex hierarchical structure that could continuously adjust its internal structure to adapt to the alterations in the external load environment. The fluid flow within bone is the main route of osteocyte metabolism, and the pore pressure as well as the fluid shear stress generated by it are important mechanical stimuli perceived by osteocytes. Owing to the irregular multiscale structure of bone tissue, the fluid stimulation that lacunar-canalicular network (LCN) in different regions of the tissue underwent remained unclear. In this study, we constructed a multiscale conduction model of fluid flow stimulus signals in bone tissue based on the poroelasticity theory. We analyzed the fluid flow behaviors at the macro-scale (whole bone tissue), macro-meso scale (periosteum, interstitial bone, osteon and endosteum), and micro-scale (lacunar-osteocyte-canalicular) levels. We explored how fluid stimulation at the tissue level correlated with that at the cellular level in cortical bone and characterized the distributions of the pore pressure, fluid velocity and fluid shear stress that the osteocytes experienced across the entire tissue structure. The results showed that the initial conditions of intramedullary pressure had a significant impact on the pore pressure of Haversian systems, but had a relatively small influence on the fluid velocity. The osteocyte which were located at different positions in the bone tissue received very distinct fluid stimuli. Osteocytes in the vicinity of the Haversian Canals experienced higher fluid shear stress stimulation. When the permeability of the LCN was within the range from 10-21m2 to 10-18m2, the distribution of pressure, fluid velocity and fluid shear stress within the osteon near the periosteum and endosteum was significantly different from that in other parts of the bone. However, when the permeability was less than 10-22m2, such a difference did not exist. Particularly, the flow velocity at the lacunae was markedly higher than that in the canaliculi. Meanwhile, the pore pressure and fluid shear stress were conspicuously lower than those in the canaliculi. In this study, we considered the interconnections of different biofunctional units at different scales of bone tissue, construct a more complete multiscale model of bone tissue, and propose that osteocytes at different locations receive different fluid stimuli, which provides a reference for a deeper understanding of bone mechanotransduction.

Effects of lacunocanalicular morphology and network architecture on fluid dynamic environments of osteocytes and bone mechanoresponses

Osteocytes, situated within the lacunocanalicular network (LCN) of the bone matrix, play crucial roles in sensing mechanical signals and orchestrating bone adaptive responses. Alterations in LCN structure could significantly modify the fluid dynamic microenvironment of osteocytes, thereby influencing bone mechanoresponses (BMRs). However, a comprehensive understanding of this tissue remains elusive. In this study, a multi-scale model of whole bone-LCN was developed to systematically investigate the effects of lacunocanalicular morphology (lacunar volume [Lc.V] and canalicular area [Ca.S]) and network architecture (lacunar density [Lc.ρ] and canalicular density [Ca.ρ]) on fluid shear stress (FSS) within the LCN and BMR predicted by fluid flow. Furthermore, the relationships between fluid flow within the LCN and BMRs were examined in two specific scenarios: aging and lactation. Results demonstrated that changes in lacunocanalicular morphology (Lc.V and Ca.S) primarily influenced the intensity of fluid flow, while alterations in the LCN (Lc.ρ and Ca.ρ) largely affected the distribution of fluid flow. Increases in Lc.V or decreases in Ca.S increased FSS, whereas decreases in Lc.ρ or increases in Ca.ρ reduced FSS. Compared with other structural parameters, alterations in Ca.ρ had the greatest effect on FSS, while BMR primarily depended on changes in Lc.V and Ca.S. In agreement with experimental observations, aging- or lactation-induced changes in LCN structure (and fluid dynamics) were associated with reduced (−50%) or increased (+20%) bone responses to mechanical loading, respectively. These findings suggest that modifications in lacunocanalicular morphology and network architecture can substantially impact the fluid dynamic microenvironment for mechanosensing osteocytes and, consequently, BMRs.

Pesticide exposures and 10-year atherosclerotic cardiovascular disease risk: Integrated epidemiological and bioinformatics analysis.

Recent studies link pesticide exposures to cardiovascular disease risk factors. However, research on the combined effects of multiple pesticides on atherosclerotic cardiovascular disease (ASCVD) is limited, particularly in rural areas. Despite advances in toxicogenomics, the mechanisms underlying these effects remain unclear. This study aims to investigate the combined effects and mechanisms of pesticide exposures on ASCVD. In the cross-sectional study section, 2291 participants were included. Variables were filtered using machine learning models, and associations between mixed exposure to multiple pesticides and ASCVD were explored using environmental mixed exposure models (weighted quartile sum (WQS) regression and quantile-based g-computation (QGC)). In the bioinformatics analysis section, the GEO, CTD, Malacards, and GeneCards databases were used to retrieve target genes for pesticide exposure and atherosclerotic diseases. Enrichment analysis was then performed to identify the biological pathways associated with these genes. Three machine models screened 34 pesticides. Single pesticide exposures, such as atrazine, oxadiazon, p,p'-DDE, α-BHC, β-BHC, fenitrothion, malathion, fenitrothion, cypermethrin, cypermethrin, and cypermethrin might increase the 10-year ASCVD risk (all P < 0.05). Total mixed pesticide exposure was positively associated with 10-year ASCVD risk in both the QGC (3.223(2.196, 4.730)) and WQS models (4.642(3.070, 7.020)). Notably, there was a linear relationship between totalQGC (P_overal < 0.001; P_nonlinearity = 0.864) and high 10-year ASCVD risk. In toxicogenomic bioinformatics analysis, we identified 112 potential atherosclerosis target genes affected by pesticide exposure. Pathway enrichment analysis suggests pesticide-induced atherosclerosis is linked to pathways such as metabolic pathways, lipid metabolism, MAPK, AMPK, FoxO signaling, apoptosis, fluid shear stress, endocrine resistance, TNF, and PI3K-Akt. Key genes were identified based on maximal clique centrality, including AKT1, TP53, IL6, BCL2, TNF, JUN, PTGS2, CASP3, MAPK3, and CASP9. Individual and combined exposure to pesticides increased the 10-year ASCVD risk, especially in patients with T2DM. Mixed levels of pesticide exposure were linearly and positively associated with high 10-year ASCVD risk. The mechanism of atherogenesis by mixed pesticide exposure may involve pathways such as lipid metabolism, MAPK, AMPK, FoxO signaling, apoptosis, fluid shear stress, endocrine resistance, TNF, and PI3K-Akt.

Mechanical Signal Transduction: A Key Role of Fluid Shear Forces in the Development of Osteoarthritis.

Globally, osteoarthritis is a common and highly disabling disease that places a heavy burden on society and medical systems. The role of biomechanical factors in the development of osteoarthritis has gradually received more attention. As a key biomechanical stimulus, fluid shear force is becoming the focus of research for its dual role in maintaining cartilage health and disease progression. This paper conducts an in-depth discussion on the mechanism of fluid shear force in osteoarthritis and its impact on the disease process, aiming to reveal how fluid shear stress affects the development of osteoarthritis by regulating the physiological function and signal transduction pathways of chondrocytes.

The impact of ciliary length on the mechanical response of osteocytes to fluid shear stress.

Osteocytes are crucial for detecting mechanical stimuli and translating them into biochemical responses within the bone. The primary cilium, a cellular 'antenna,' plays a vital role in this process. However, there is a lack of direct correlation between cilium length changes and osteocyte mechanosensitivity changes. This study aims to reveal the relationship between ciliary length and nitric oxide (NO) release in osteocytes to show how primary cilia may be involved in reducing osteocyte mechanosensitivity caused by microgravity. We used the MLO-Y4 cell line and primary osteoblasts to adjust the ciliary length using chloral hydrate (CH) for shortening and lithium ions (Li+) for elongation. We then examined the impact of varied ciliary lengths on osteocyte response to fluid shear stress, focusing on the PC1/PC2-Ca2+-NO signaling pathway. Co-culture systems assessed downstream effects on osteoblast function, including collagen secretion and mineralization. We observed a significant correlation between ciliary length and osteocyte mechanosensitivity, with longer primary cilia enhancing Ca2+ influx and NO release in response to fluid shear stress. However, contrary to expectations, calmodulin (CaM) expression did not increase with ciliary length, suggesting alternative pathways, such as PKC or Akt/PKB, may modulate p-eNOS activity. Co-cultured osteoblasts showed altered osteogenic functions regulated by osteocyte-derived signals influenced by primary cilia length. Our findings clarify the role of primary cilia length in modulating osteocyte mechanosensitivity and their influence on osteoblast function, highlighting a complex regulatory network that may not solely rely on CaM for NO release. These insights contribute to a deeper understanding of bone mechanotransduction and could have implications for developing therapeutic targets for osteocyte-related disorders.

PIEZO1 overexpression in hereditary hemorrhagic telangiectasia arteriovenous malformations.

Hereditary hemorrhagic telangiectasia (HHT) is an inherited vascular disorder characterized by arteriovenous malformations (AVMs). Loss-of-function mutations in Activin receptor-like kinase 1 (ALK1) cause type 2 HHT and Alk1 knockout (KO) mice develop AVMs due to overactivation of VEGFR2/PI3K/AKT signaling pathways. However, the full spectrum of signaling alterations in Alk1 mutants remains unknown and means to combat AVM formation in patients are yet to be developed. Single-cell RNA sequencing of endothelial-specific Alk1 KO mouse retinas and controls identified a cluster of endothelial cells (ECs) that was unique to Alk1 mutants and that overexpressed fluid shear stress (FSS) signaling signatures including upregulation of the mechanosensitive ion channel PIEZO1. PIEZO1 overexpression was confirmed in human HHT lesions, and genetic and pharmacological PIEZO1 inhibition was tested in Alk1 KO mice, as well as downstream PIEZO1 signaling. Pharmacological PIEZO1 inhibition, and genetic Piezo1 deletion in Alk1 -deficient mice effectively mitigated AVM formation. Furthermore, we identified that elevated VEGFR2/AKT, ERK5-p62-KLF4, hypoxia and proliferation signaling were significantly reduced in Alk1 - Piezo1 double ECKO mice. PIEZO1 overexpression and signaling is integral to HHT2, and PIEZO1 blockade reduces AVM formation and alleviates cellular and molecular hallmarks of ALK1-deficient cells. This finding provides new insights into the mechanistic underpinnings of ALK1-related vascular diseases and identifies potential therapeutic targets to prevent AVMs.