Inducing myointimal hyperplasia versus atherosclerosis in mice: an introduction of two valid models

Beta1-receptor blockade attenuates atherosclerosis progression following traumatic brain injury in apolipoprotein E deficient mice

Traumatic brain injury (TBI) is associated with cardiovascular mortality in humans. Enhanced sympathetic activity following TBI may contribute to accelerated atherosclerosis. The effect of beta1-adrenergic receptor blockade on atherosclerosis progression induced by TBI was studied in apolipoprotein E deficient mice. Mice were treated with metoprolol or vehicle following TBI or sham operation. Mice treated with metoprolol experienced a reduced heart rate with no difference in blood pressure. Six weeks following TBI, mice were sacrificed for analysis of atherosclerosis. Total surface area and lesion thickness, analyzed at the level of the aortic valve, was found to be increased in mice receiving TBI with vehicle treatment but this effect was ameliorated in TBI mice receiving metoprolol. No effect of metoprolol on atherosclerosis was observed in mice receiving only sham operation. In conclusion, accelerated atherosclerosis following TBI is reduced with beta-adrenergic receptor antagonism. Beta blockers may be useful to reduce vascular risk associated with TBI.

Role of Bevacizumab on Vascular Endothelial Growth Factor in Apolipoprotein E Deficient Mice after Traumatic Brain Injury

Traumatic brain injury (TBI) disrupts the blood–brain barrier (BBB). Vascular endothelial growth factor (VEGF) is believed to play a key role in TBI and to be overexpressed in the absence of apolipoprotein E (ApoE). Bevacizumab, a VEGF inhibitor, demonstrated neuroprotective activity in several models of TBI. However, the effects of bevacizumab on Apo-E deficient mice are not well studied. The present study aimed to evaluate VEGF expression and the effects of bevacizumab on BBB and neuroinflammation in ApoE^−/− mice undergoing TBI. Furthermore, for the first time, this study evaluates the effects of bevacizumab on the long-term consequences of TBI, such as atherosclerosis. The results showed that motor deficits induced by controlled cortical impact (CCI) were accompanied by increased brain edema and VEGF expression. Treatment with bevacizumab significantly improved motor deficits and significantly decreased VEGF levels, as well as brain edema compared to the control group. Furthermore, the results showed that bevacizumab preserves the integrity of the BBB and reduces the neuroinflammation induced by TBI. Regarding the effects of bevacizumab on atherosclerosis, it was observed for the first time that its ability to modulate VEGF in the acute phase of head injury prevents the acceleration of atherosclerosis. Therefore, the present study demonstrates not only the neuroprotective activity of bevacizumab but also its action on the vascular consequences related to TBI.

STUDY OF THE PHARMACOLOGICAL ACTIVITY OF NOVEL EPOR/CD131 HETERORECEPTOR AGONISTS IN MICE WITH ENDOTHELIAL-SPECIFIC EXPRESSION OF MUTANT POLG GENE

The aim of the research was to study antiatherosclerotic and endothelial kinds of a protective activity of peptides mimicking an erythropoietin a-helix B tertiary structure with laboratory codes EP-11-1 (UEHLERALNSS), EP-11-2. (UEQLERALNCS), EP-11-3 (UEQLERALNTS).

Materials and methods. The study was conducted on 96 C57Bl/6J male double transgenic Polgmut/mut/Cdh5-CRE mice. Atherosclerosis was induced by a balloon injury accompanied by Western diet. Then, for 27 days, the drugs under study were administered once per 3 days at the dose of 20 μg/kg. On the 28th day, the animals were euthanized and the area of atherosclerotic plaques was collected for an assessment. The expression of genes associated with the processes of inflammation, apoptosis, and angiogenesis was determined in the tissues of the aorta. In addition, the endothelial protective effect of peptides in isolated segments of the thoracic aorta of wild and transgenic ransgenic Polgmut/mut mice was studied.

Results. The assessment of the plaque size in the animals with the Polgmut/mut/Cdh5-CRE genotype against the background of the peptides under study did not reveal statistically significant differences in comparison to control. However, a quantitative PCR showed a statistically significant decreased expression of pro-apoptotic factors p-53 and Bax, and also increase the expression of anti-apoptotic factor Bcl-2 against the background of the peptides EP-11-1 and EP-11-2 administration. The administration of EP-11-1 and the original peptide pHBSP resulted in a statistically significant decrease in the Bax/Bcl-2 ratio. Compounds EP-11-1, EP-11-2, and EP-11-3 were more effective than the original peptide pHBSP, in reducing the increased expression of genes for inflammatory markers iNos, intercellular adhesion molecules Icam-1, Vcam-1 and E-selectin. The use of EP-11-1 led to a more efficient, in comparison with pHBSP, restoration of endothelial-dependent vasodilation of the aortic segments in mice with endothelial-specific overexpression of the mutant Polg gene.

Conclusion. The study carried out on a murine model of the endothelial-specific expression of mutant gamma polymerase has shown that derivatives of the pHBSP peptide with laboratory codes EP-11-1, EP-11-2, EP-11-3, obtained by BLAST-searching for groups of pHBSP related peptides, have atheroprotective and endothelial protective kinds of a protective activity, which is more pronounced in comparison with the original peptide pHBSP.

STUDY OF ANTIATHEROSCLEROTIC AND ENDOTHELIOPROTECTIVE ACTIVITY OF PEPTIDE AGONISTS OF EPOR/CD131 HETERORECEPTOR

Introduction. The drugs affecting a mitochondrial dysfunction, oxidative stresses, apoptosis and inflammation of the vascular wall, have a high potential for the prevention and treatment of atherosclerotic lesions. In this regard, the use of EPOR/CD131 heteroreceptor agonists which have a similar spectrum of pharmacological effects, is one of the promising strategies in the treatment of cardiovascular diseases.

Materials and Methods. The study was carried out on 68 C57Bl/6J male mice. Atherosclerosis was simulated in transgenic animals with an endotheliospecific knockdown of the Polg gene by simulating a balloon injury and keeping on a Western diet. Then, the studied drugs were injected once every 3 days at the dose of 20 μg/kg for 27 days. On the 28-th day, the animals were euthanized and the area of atherosclerotic plaques was assessed. The gene expression associated with the processes of inflammation, antioxidant protection, apoptosis, and angiogenesis was also determined in the aortic tissues. In addition, the endothelium protective effect of peptides on primary cultures of endothelial cells of wild and transgenic Polg-D257A mice was studied.

Results. No statistically significant effect of drugs on the area of lipid infiltration have been found. However, the studied peptides have significantly reduced the expression of proinflammatory genes (iNos, Icam1, Vcam1, Sele, Il6, Tnfa), the genes associated with angiogenesis (Vegfa, Kdr, and Hif1a), the expression of proapoptic factors; they decreased the Bax/Bcl-2 ratio by more than 1.5 times. In addition, when supplemented with H2 O2  in vitro, peptides dose-dependently increased endothelial cell survival.

Conclusion. The erythropoietin-based peptides can be used to improve the functional state of the vascular wall against the background of atherosclerotic lesions and have a depressing effect on pathobiological processes associated with a mitochondrial dysfunction. In addition, the studied peptides have a significant endothelial protective effect in the induction of oxidative stress in vitro.

Traumatic Brain Injury Leads to Accelerated Atherosclerosis in Apolipoprotein E Deficient Mice

Traumatic brain injury (TBI) has been associated with atherosclerosis and cardiovascular mortality in humans. However the causal relationship between TBI and vascular disease is unclear. This study investigated the direct role of TBI on vascular disease using a murine model of atherosclerosis. Apolipoprotein E deficient mice were placed on a western diet beginning at 10 weeks of age. Induction of TBI or a sham operation was performed at 14 weeks of age and mice were sacrificed 6 weeks later at 20 weeks of age. MRI revealed evidence of uniform brain injury in all mice subjected to TBI. There were no differences in total cholesterol levels or blood pressure between the groups. Complete blood counts and flow cytometry analysis performed on peripheral blood 6 weeks following TBI revealed a higher percentage of Ly6C-high monocytes in mice subjected to TBI compared to sham-treated mice. Mice with TBI also showed elevated levels of plasma soluble E-selectin and bone marrow tyrosine hydroxylase. Analysis of atherosclerosis at the time of sacrifice revealed increased atherosclerosis with increased Ly6C/G immunostaining in TBI mice compared to sham-treated mice. In conclusion, progression of atherosclerosis is accelerated following TBI. Targeting inflammatory pathways in patients with TBI may reduce subsequent vascular complications.

Balloon-based Injury to Induce Myointimal Hyperplasia in the Mouse Abdominal Aorta

The use of animal models is essential for a better understanding of MH, one major cause for arterial stenosis.In this article, we demonstrate a murine balloon denudation model, which is comparable with established vessel injury models in large animals. The aorta denudation model with balloon catheters mimics the clinical setting and leads to comparable pathobiological and physiological changes. Briefly, after performing a horizontal incision in the aorta abdominalis, a balloon catheter will be inserted into the vessel, inflated, and introduced retrogradely. Inflation of the balloon will lead to intima injury and overdistension of the vessel. After removing the catheter, the aortic incision will be closed with single stiches. The model shown in this article is reproducible, easy to perform, and can be established quickly and reliably. It is especially suitable for evaluating expensive experimental therapeutic agents, which can be applied in an economical fashion. By using different knockout-mouse strains, the impact of different genes on MH development can be assessed.

Vein Interposition Model: A Suitable Model to Study Bypass Graft Patency

Bypass grafting is an established treatment method for coronary artery disease. Graft patency continues to be the Achilles heel of saphenous vein grafts. Research models for bypass graft failure are essential for a better understanding of pathobiological and pathophysiological processes during graft patency loss. Large animal models, such as pigs or sheep, resemble human anatomical structures but require special facilities and equipment. This video describes a rat vein interposition model to investigate vein graft patency loss. Rats are inexpensive and easy to handle. Compared to mouse models, the convenient size of rats permits better operability and enables a sufficient amount of material to be obtained for further diverse analysis. In brief, the inferior epigastric vein of a donor rat is harvested and used to replace a segment of the femoral artery. Anastomosis is conducted via single stitches and sealed with fibrin glue. Graft patency can be monitored non-invasively using duplex sonography. Myointimal hyperplasia, which is the main cause for graft patency loss, develops progressively over time and can be calculated from histological cross sections.