A novel methodology for rat aortic pulse wave velocity assessment by Doppler ultrasound: validation against invasive measurements

DCBLD2 deletion increases hyperglycemia and induces vascular remodeling by inhibiting insulin receptor recycling in endothelial cells

Discoidin, CUB, LCCL domain-containing 2 (DCBLD2) is a type I transmembrane protein with a similar structure to neuropilin, which acts as a co-receptor for certain receptor tyrosine kinases (RTKs). The insulin receptor is an RTK and plays a critical role in endothelial cell function and glycolysis. However, how and whether DCBLD2 regulates insulin receptor activity in endothelial cells is poorly understood. Diabetes was induced through treatment of Dcbld2 global-genome knockout mice and endothelium-specific knockout mice with streptozotocin. Vascular ultrasound, vascular tension test, and hematoxylin and eosin staining were performed to assess endothelial function and aortic remodeling. Glycolytic rate assays, real-time PCR and western blotting were used to investigate the effects of DCBLD2 on glycolytic activity and insulin receptor (InsR)/phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt) pathway in endothelial cells. Co-immunoprecipitation was used to assess the effects of DCBLD2 on insulin receptor endocytosis and recycling. Membrane and cytoplasmic proteins were isolated to determine whether DCBLD2 could affect the localization of the insulin receptor. We found that Dcbld2 deletion exacerbated endothelial dysfunction and vascular remodeling in diabetic mice. Both Dcbld2 knockdown and Dcbld2 deletion inhibited glycolysis and the InsR/PI3K/Akt signaling pathway in endothelial cells. Furthermore, Dcbld2 deletion inhibited insulin receptor recycling. Taken together, Dcbld2 deficiency exacerbated diabetic endothelial dysfunction and vascular remodeling by inhibiting the InsR/PI3K/Akt pathway in endothelial cells through the inhibition of Rab11-dependent insulin receptor recycling. Our data suggest that DCBLD2 is a potential therapeutic target for diabetes and cardiovascular diseases.

Long-term simulated microgravity fosters carotid aging-like changes via Piezo1

AIMS

Elucidating the impacts of long-term spaceflight on cardiovascular health is urgently needed in face of the rapid development of human space exploration. Recent reports including the NASA Twins Study on vascular deconditioning and aging of astronauts in spaceflight are controversial. The aims of this study were to elucidate whether long-term microgravity promotes vascular aging and the underlying mechanisms.

METHODS AND RESULTS

Hindlimb unloading (HU) by tail suspension was used to simulate microgravity in rats and mice. The dynamic changes of carotid stiffness in rats during 8 weeks of HU were determined. Simulated microgravity led to carotid artery aging-like changes as evidenced by increased stiffness, thickness, fibrosis, and elevated senescence biomarkers in the HU rats. Specific deletion of the mechanotransducer Piezo1 in vascular smooth muscles significantly blunted these aging-like changes in mice. Mechanistically, mechanical stretch-induced activation of Piezo1 elevated microRNA-582-5p in vascular smooth muscle cells, with resultant enhanced synthetic cell phenotype and increased collagen deposition via PTEN/PI3K/Akt signalling. Importantly, inhibition of miRNA-582-5p alleviated carotid fibrosis and stiffness not only in HU rats but also in aged rats.

CONCLUSIONS

Long-term simulated microgravity induces carotid aging-like changes via the mechanotransducer Piezo1-initiated and miRNA-mediated mechanism.

A Novel Methodology for Semi-automatic Measurement of Arterial Stiffness by Doppler Ultrasound: Clinical Feasibility and Reproducibility

The conventional manual approach to measurement of aortic pulse wave velocity (PWV) by Doppler ultrasonography is time consuming and operator dependent. Here we report a new semi-automated methodology for more efficient and objective measurement of aortic PWV and results of tests of its clinical feasibility and reproducibility. Carotid-femoral pulse wave velocity (cfPWV) was measured in 50 patients with suspected coronary artery disease (aged 59.2 ± 10.0 y, 36 males) by three independent observers, including two experienced sonographers and one cardiologist without ultrasonographic experience. The cfPWV measured by the semi-automatic method (cfPWV_A) was compared with reference values obtained by averaging measurements by two experienced sonographers using the conventional standard manual method (cfPWV_M). Measurements of cfPWV_A were feasible in all 50 patients and exhibited excellent agreement with averaged cfPWV_M from the two experienced sonographers, with an intraclass correlation coefficient (ICC) of 0.915 (95% confidence interval: 0.876-0.942). The inexperienced observer-measured cfPWV_A did not differ from the cfPWV_M measured by the two experienced sonographers (8.04 ± 1.29 vs. 8.14 ± 1.32 m/s, p > 0.05), with a high consistency by ICC of 0.877 (0.793-0.928). Bland-Altman plots further illustrated the good agreement between the two methods and good intra- and inter-observer reproducibility. Time consumption for cfPWV measurement using the new method was significantly less than that for the manual method (122 ± 35 s vs. 455 ± 105 s, p < 0.0001), saving about 73% of the time. This new semi-automatic methodology for aortic PWV measurement not only has an accuracy similar to that of the conventional standard manual method but is also highly feasible and time saving. It may provide a reliable, simple and reproducible approach to arterial stiffness evaluation in clinical settings.

Evaluation of Plaque Characteristics and Inflammation Using Magnetic Resonance Imaging

Atherosclerosis is an inflammatory disease of large and medium-sized arteries, characterized by the growth of atherosclerotic lesions (plaques). These plaques often develop at inner curvatures of arteries, branchpoints, and bifurcations, where the endothelial wall shear stress is low and oscillatory. In conjunction with other processes such as lipid deposition, biomechanical factors lead to local vascular inflammation and plaque growth. There is also evidence that low and oscillatory shear stress contribute to arterial remodeling, entailing a loss in arterial elasticity and, therefore, an increased pulse-wave velocity. Although altered shear stress profiles, elasticity and inflammation are closely intertwined and critical for plaque growth, preclinical and clinical investigations for atherosclerosis mostly focus on the investigation of one of these parameters only due to the experimental limitations. However, cardiovascular magnetic resonance imaging (MRI) has been demonstrated to be a potent tool which can be used to provide insights into a large range of biological parameters in one experimental session. It enables the evaluation of the dynamic process of atherosclerotic lesion formation without the need for harmful radiation. Flow-sensitive MRI provides the assessment of hemodynamic parameters such as wall shear stress and pulse wave velocity which may replace invasive and radiation-based techniques for imaging of the vascular function and the characterization of early plaque development. In combination with inflammation imaging, the analyses and correlations of these parameters could not only significantly advance basic preclinical investigations of atherosclerotic lesion formation and progression, but also the diagnostic clinical evaluation for early identification of high-risk plaques, which are prone to rupture. In this review, we summarize the key applications of magnetic resonance imaging for the evaluation of plaque characteristics through flow sensitive and morphological measurements. The simultaneous measurements of functional and structural parameters will further preclinical research on atherosclerosis and has the potential to fundamentally improve the detection of inflammation and vulnerable plaques in patients.

Acute Changes in Carotid-Femoral Pulse-Wave Velocity Are Tracked by Heart-Femoral Pulse-Wave Velocity

Background: Carotid-femoral pulse-wave velocity (cfPWV) is the reference standard measure of central arterial stiffness. However, it requires assessment of the carotid artery, which is technically challenging, and subject-level factors, including carotid artery plaque, may confound measurements. A promising alternative that overcomes these limitations is heart-femoral PWV (hfPWV), but it is not known to what extent changes in cfPWV and hfPWV are associated.

Objectives: To determine, (1) the strength of the association between hfPWV and cfPWV; and (2) whether change in hfPWV is associated with change in cfPWV when central arterial stiffness is perturbed.

Methods: Twenty young, healthy adults [24.0 (SD: 3.1) years, 45% female] were recruited. hfPWV and cfPWV were determined using Doppler ultrasound at baseline and following a mechanical perturbation in arterial stiffness (120 mmHg thigh occlusion). Agreement between the two measurements was determined using mixed-effects regression models and Bland-Altman analysis.

Results: There was, (1) strong (ICC > 0.7) agreement between hfPWV and cfPWV (ICC = 0.82, 95%CI: 0.69, 0.90), and, (2) very strong (ICC > 0.9) agreement between change in hfPWV and cfPWV (ICC = 0.92, 95%CI: 0.86, 0.96). cfPWV was significantly greater than hfPWV at baseline and during thigh occlusion (both P < 0.001). Inspection of the Bland-Altman plot, comparing cfPWV and corrected hfPWV, revealed no measurement magnitude bias.

Discussion: The current findings indicate that hfPWV and cfPWV are strongly associated, and that change in cfPWV is very strongly associated with change in hfPWV. hfPWV may be a simple alternative to cfPWV in the identification of cardiovascular risk in clinical and epidemiological settings.

Potential therapeutic effects of endothelial cells trans-differentiated from Wharton's Jelly-derived mesenchymal stem cells on altered vascular functions in aged diabetic rat model

BACKGROUND

Diabetes mellitus in elderly represents an exceptional subset in the population vulnerable to cardiovascular events. As aging, diabetes mellitus and hypertension share common pathways, an ideal treatment should possess the ability to counter more than one of, if not all, the underlying mechanisms. Stem cells emerged as a potential approach for complicated medical problems. We tested here the possible role of trans-differentiated endothelial cells (ECs) in the treatment of diabetes mellitus in old rats.

METHODS

Mesenchymal stem cells where isolated from umbilical cord Wharton's Jelly and induced to differentiate into endothelial like-cells using vascular endothelial growth factor-enriched media. Thirty aged male Wistar albino rats were used in the present study. Rats were divided (10/group) into: control group (18-20 months old, weighing 350-400 g, received single intraperitoneal injection as well as single intravenous injection via tail vein of the vehicles), aged diabetic group (18-20 months old, weighing 350-400 g, received single intraperitoneal injection of 50 mg/kg streptozotocin, and also received single intravenous injection of saline via tail vein), and aged diabetic + ECs group (18-20 months old, weighing 350-400 g, received single intraperitoneal injection of 50 mg/kg streptozotocin, and also received single intravenous injection of 2*10⁶ MSC-derived ECs in 0.5 ml saline via tail vein) groups. Assessment of SBP, aortic PWV, and renal artery resistance was performed. Serum levels of ET1, ANG II, IL-6, TNF-α, MDA, ROS, and VEGF were evaluated, as well as the aortic NO tissue level and eNOS gene expression. Histopathological and immunostaining assessments of small and large vessels were also performed.

RESULTS

Induction of diabetes in old rats resulted in significant increase in SBP, aortic PWV, renal artery resistance, and serum levels of ET1, ANG II, IL-6, TNF-α, MDA, ROS, and VEGF. While there was significant decrease in aortic NO tissue level and eNOS gene expression in the aged diabetic group when compared to aged control group. ECs treatment resulted in significant improvement of endothelial dysfunction, inflammation and oxidative stress.

CONCLUSION

We report here the potential therapeutic role of trans-differentiated ECs in aged diabetics. ECs demonstrated anti-inflammatory, antioxidant, gene modifying properties, significantly countered endothelial dysfunction, and improved vascular insult.