Arteries Of Pigs Research Articles

Solitaire Stentectomy Using a\xa0Stent-Retriever Technique in a\xa0Porcine Model

PurposeMechanical thrombectomy using the Solitaire device has become a standard treatment of ischemic stroke due to large vessel occlusions. Inadvertent detachment is a feared complication, which is associated with poor clinical outcome. The aim of this experimental study was to assess in a porcine model the feasibility and effectiveness of rescuing detached Solitaire devices using different stent retrievers.MethodsSolitaire FR devices (4 × 15/20 mm and 6 × 20/30 mm) were placed in the axillary artery of pigs. By means of 3 different stent retrievers (Trevo ProVue; EmboTrap II revascularization device; 3D revascularization device) a total of 24 rescue maneuvers (8 per retriever) were performed by deploying the retrievers within the deployed Solitaire devices and trapping parts of the Solitaire within the microcatheter. Rescue rates, rescue time and complications were assessed.ResultsOverall stentectomy of the Solitaire devices was successful in all cases (100%). Time of rescue was comparable using the applied stent retrievers (Trevo ProVue; EmboTrap II revascularization device; 3D revascularization device). Complications, such as entrapment of the Solitaire-retriever complex at the intermediate catheter, Solitaire migration, vasospasm, perforation, or dissection were not observed.ConclusionStentectomy of inadvertently detached Solitaire devices using different stent retrievers is a feasible and effective method. Rescue rates and times with the Trevo ProVue, EmboTrap II and 3D revascularization device were comparable.

Structure and Function of Porcine Arteries Are Preserved for up to 6 Days Using the HypoRP Cold-storage Solution.

Maintaining functional vessels during preservation of vascularized composite allografts (VCAs) remains a major challenge. The University of Wisconsin (UW) solution has demonstrated significant short-term benefits (4-6 h). Here we determined whether the new hypothermic resuscitation and preservation solution HypoRP improves both structure, survival, and function of pig arteries during storage for up to 6 days. Using porcine swine mesenteric arteries, the effects of up to 6-day incubation in a saline (PBS), UW, or HypoRP solution on the structure, cell viability, metabolism, and function were determined. After incubation at 4°C, for up to 6 days, the structures of the arteries were significantly disrupted, especially the tunica media, following incubation in PBS, in contrast with incubation in the HypoRP solution and to a lesser extent, in UW solution. Those disruptions were associated with increased active caspase 3 indicative of apoptosis. Additionally, while incubation in PBS led to a significant decrease in the metabolic activity, UW and HypoRP solutions allowed a stable to increased metabolic activity following 6 days of cold storage. Functional responsiveness to phenylephrine (PE) and sodium nitroprusside (SNP) decreased over time for artery rings stored in PBS and UW solution but not for those stored in HypoRP solution. Moreover, artery rings cold-stored in HypoRP solution were more sensitive to ATP. The HypoRP solution improved long-term cold storage of porcine arteries by limiting structural alterations, including the collagen matrix, reducing apoptosis, and maintaining artery contraction-relaxation functions for up to 6 days.

Aggravated endothelial endocrine dysfunction and intimal thickening of renal artery in high-fat diet-induced obese pigs following renal denervation

BackgroundRenal denervation (RDN) targeting the sympathetic nerves in the renal arterial adventitia as a treatment of resistant hypertension can cause endothelial injury and vascular wall injury. This study aims to evaluate the risk of atherosclerosis induced by RDN in renal arteries.MethodsA total of 15 minipigs were randomly assigned to 3 groups: (1) control group, (2) sham group, and (3) RDN group (n = 5 per group). All pigs were fed a high-fat diet (HFD) for 6 months after appropriate treatment. The degree of intimal thickening of renal artery and the conversion of endothelin 1 (ET-1) receptors were evaluated by histological staining. Western blot was used to assess the expression of nitric oxide (NO) synthesis signaling pathway, ET-1 and its receptors, NADPH oxidase 2 (NOX2) and 4-hydroxynonenal (4-HNE) proteins, and the activation of NF-kappa B (NF-κB).ResultsThe histological staining results suggested that compared to the sham treatment, RDN led to significant intimal thickening and significantly promoted the production of endothelin B receptor (ETBR) in vascular smooth muscle cells (VSMCs). Western blotting analysis indicated that RDN significantly suppressed the expression of AMPK/Akt/eNOS signaling pathway proteins, and decreased the production of NO, and increased the expression of endothelin system proteins including endothelin-1 (ET-1), endothelin converting enzyme 1 (ECE1), endothelin A receptor (ETAR) and ETBR; and upregulated the expression of NOX2 and 4-HNE proteins and enhanced the activation of NF-kappa B (NF-κB) when compared with the sham treatment (all p < 0.05). There were no significant differences between the control and sham groups (all p > 0.05).ConclusionsRDN aggravated endothelial endocrine dysfunction and intimal thickening, and increased the risk of atherosclerosis in renal arteries of HFD-fed pigs.

Single cell RNA sequencing (scRNAseq) of severely atherosclerotic coronary artery from Ossabaw miniature swine with metabolic syndrome

IntroductionCoronary atherogenesis involves multiple signaling pathways and underlying gene expression. The atherogenic plasma milieu (excess lipoproteins, glucose, etc.) injures the endothelium, which is the initiating event of coronary plaque development. Subsequently, smooth muscle cells proliferate and migrate from the wall into the neointima, and blood cells and macrophages infiltrate the vessel wall and contribute to the growing plaque. Our goal was to characterize the gene expression in the heterogeneous cell population in this dynamic coronary artery pathology.MethodsWe performed single cell RNA sequencing (scRNAseq) on cells dispersed from the proximal 45 mm of the left anterior descending coronary artery of healthy pigs compared to separate plaque and wall cell dispersions from arteries of Ossabaw swine that had metabolic syndrome and were atherosclerotic for 23 months. Primary analysis scRNAseq data used t‐distributed stochastic neighbor embedding (T‐SNE) plots for an integrated analysis of the 3 cell preparations.ResultsMetabolic syndrome was confirmed by obesity, dyslipidemia, and hypertension. In vivo intravascular ultrasound (IVUS) of the entire artery revealed every stage of atherosclerosis from fatty streak to complex lesions having up to 70% occlusion with fibrofatty and calcified lesions. Cells (3,510) from healthy coronary artery expressed predominantly markers for endothelial (PECAM1), endocardial (CDH5, POSTN), and smooth muscle cells (ACTA2, TAGLN, CNN1, MYL9, CALD1, RGS5, MHY11). Overall, the healthy coronary artery cells were much more homogeneous than atherosclerotic plaque and wall cells. Wall cells (8,224) in atherosclerotic arteries expressed ~no (0.1%) endothelial, many smooth muscle, and fibroblast genes. Plaque cells (8,049) expressed ~no (0.1%) endothelial genes, robust smooth muscle marker genes, and a high abundance of early marker genes for chondrocytes, osteoblasts, monocytes, neutrophils, and macrophages.ConclusionProfound gene expression patterns were shown with scRNAseq in a clinically relevant model of coronary atherosclerosis. The striking heterogeneity of gene expression and marker genes for chondrocytes and osteoblasts in plaque cells indicate significant transdifferentiation and suggest further progression to severe coronary artery calcification.

Modelling, Fabrication by Photo-Chemical Etching and in Vivo Study of Magnesium AZ31 Stents

Magnesium metal (Mg) is a promising material for stent applications due to its biocompatibility and ability to be resorbed by the body. Manufacturing of stents by laser cutting has become an industry standard. However, this expensive approach has challenges. Our alternative approach uses photo-chemical etching to transfer a pattern of the stent onto a Mg sheet. Such a stent has been characterized in vitro and the results are published elsewhere by our group. In this study, we present three stages of creating and validating a stent prototype, which includes design and simulation using finite element analysis, followed by fabrication based on AZ31 alloy and, finally, in vivo testing in peripheral arteries of domestic pigs. Six stents were implanted in two domestic farm pigs weighing 25-28 kg and were allowed to survive for 28 days, with an interim follow-up on day 14. The left and right superficial femoral, the left iliac, and the right renal artery were selected for this study. The diameters of the stented segments were evaluated at the time of implantation, on day 14 and then, finally, on day 28, by quantitative vessel analysis (QVA) using fluoroscopic imaging. Post-implantation angiograms showed good acute gain within the stented segments for all the implanted devices. However, a reduction in lumenal diameter was observed at both the 14th and 28th-day time points. Mean stent stenosis and late lumen loss was recorded as 37 % ± 11 and 1.2 ± 0.55 mm, respectively. Optical Coherence Tomography (OCT) confirmed that although there was a decrease in mean lumenal diameter at 28 days compared to post-implantation, an increase in this diameter was recorded between the interim (14th-day) and terminal (28th-day) time points. OCT imaging displayed some malposition, breaks, stacking, and protrusion into the lumen at the proximal, distal, and mid-sections of the stented arteries. The stents degraded with time, but simultaneously became embedded in the intima. After 28 days, the animals were euthanized, and explanted vessels were fixed for micro-CT imaging and histology studies. Micro-CT imaging revealed stent morphological and volumetric changes due to the in-body degradation. An in vivo corrosion rate of 0.75 mm/year was obtained by the CT evaluation. The histology suggested no-life threatening effects, although moderate injury, inflammation, and endothelialization scores were observed. Additionally, the fibrin score was very low with a high neointimal maturity score at proximal, mid, and distal parts of the vessel with direct contact to the stent. No other stent-related sequelae were reported, including mural thrombus, fibrin deposition in the tunica media (middle layer of the blood vessel) or on the adventitia (outer most layer of the blood vessel), necrosis, nor other potentially adverse findings. The extracted remains of the stents were found to be covered with Mg corrosion by-products typical of the physiological environment.

Neural regulation of the contractility of nutrient artery in the guinea pig tibia.

Nutrient arteries provide the endosteal blood supply to maintain bone remodelling and energy metabolism. Here, we investigated the distribution and function of perivascular nerves in regulating the contractility of the tibial nutrient artery. Changes in artery diameter were measured using a video tracking system, while the perivascular innervation was investigated using fluorescence immunohistochemistry. Nerve-evoked phasic constrictions of nutrient arteries were suppressed by phentolamine (1μM), an α-adrenoceptor antagonist, guanethidine (10μM), a blocker of sympathetic transmission, or fluoxetine (10μM), a serotonin (5-hydroxytryptamine, 5-HT) reuptake inhibitor. In arteries pretreated with guanethidine, residual nerve-evoked constrictions were abolished by a high concentration of propranolol (10μM) that is known to inhibit 5-HT receptors, or ketanserin (100nM), a 5-HT2 receptor antagonist, but not SB207216 (1μM), an antagonist of 5-HT3 and 5-HT4 receptors. Bath-applied 5-HT (100nM) induced arterial constriction that was suppressed by propranolol (10μM) or ketanserin (100nM). Nerve-evoked arterial constrictions were enhanced by spantide (1μM), a substance P (SP) receptor antagonist, or L-nitro arginine (L-NA; 100μM), an inhibitor of nitric oxide synthase (NOS). Immunohistochemistry revealed 5-HT-positive nerves running along the arteries that are distinct from perivascular sympathetic or substance P-positive primary afferent nerves. For the first time, functional serotonergic nerves are identified in the tibial nutrient artery of the guinea pig. Thus, it appears that tibial nutrient arterial calibre is regulated by the balance between sympathetic and serotonergic vasoconstrictor nerves and vasodilator afferent nerves that release substance P-stimulating endothelial nitric oxide (NO) release.

Unmodified autologous stem cells at point of care for chronic myocardial infarction.

BACKGROUNDNumerous studies investigated cell-based therapies for myocardial infarction (MI). The conflicting results of these studies have established the need for developing innovative approaches for applying cell-based therapy for MI. Experimental studies on animal models demonstrated the potential of fresh, uncultured, unmodified, autologous adipose-derived regenerative cells (UA-ADRCs) for treating acute MI. In contrast, studies on the treatment of chronic MI (CMI; > 4 wk post-MI) with UA-ADRCs have not been published so far. Among several methods for delivering cells to the myocardium, retrograde delivery into a temporarily blocked coronary vein has recently been demonstrated as an effective option.AIMTo test the hypothesis that in experimentally-induced chronic myocardial infarction (CMI; > 4 wk post-MI) in pigs, retrograde delivery of fresh, uncultured, unmodified, autologous adipose-derived regenerative cells (UA-ADRCs) into a temporarily blocked coronary vein improves cardiac function and structure.METHODSThe left anterior descending (LAD) coronary artery of pigs was blocked for 180 min at time point T0. Then, either 18 × 106 UA-ADRCs prepared at “point of care” or saline as control were retrogradely delivered via an over-the-wire balloon catheter placed in the temporarily blocked LAD vein 4 wk after T0 (T1). Effects of cells or saline were assessed by cardiac magnetic resonance (CMR) imaging, late gadolinium enhancement CMR imaging, and post mortem histologic analysis 10 wk after T0 (T2).RESULTSUnlike the delivery of saline, delivery of UA-ADRCs demonstrated statistically significant improvements in cardiac function and structure at T2 compared to T1 (all values given as mean ± SE): Increased mean LVEF (UA-ADRCs group: 34.3% ± 2.9% at T1 vs 40.4 ± 2.6% at T2, P = 0.037; saline group: 37.8% ± 2.6% at T1 vs 36.2% ± 2.4% at T2, P > 0.999), increased mean cardiac output (UA-ADRCs group: 2.7 ± 0.2 L/min at T1 vs 3.8 ± 0.2 L/min at T2, P = 0.002; saline group: 3.4 ± 0.3 L/min at T1 vs 3.6 ± 0.3 L/min at T2, P = 0.798), increased mean mass of the left ventricle (UA-ADRCs group: 55.3 ± 5.0 g at T1 vs 71.3 ± 4.5 g at T2, P < 0.001; saline group: 63.2 ± 3.4 g at T1 vs 68.4 ± 4.0 g at T2, P = 0.321) and reduced mean relative amount of scar volume of the left ventricular wall (UA-ADRCs group: 20.9% ± 2.3% at T1 vs 16.6% ± 1.2% at T2, P = 0.042; saline group: 17.6% ± 1.4% at T1 vs 22.7% ± 1.8% at T2, P = 0.022).CONCLUSIONRetrograde cell delivery of UA-ADRCs in a porcine model for the study of CMI significantly improved myocardial function, increased myocardial mass and reduced the formation of scar tissue.

Reduced histologic neo in-stent restenosis after use of a paclitaxel-coated cutting balloon in porcine coronary arteries.

The incidence of in-stent restenosis (ISR) has declined dramatically, but once it develops, no current treatment option, such as drug-eluting stents, drug-coated balloons, or cutting balloons (CBs), prevents re-narrowing of the stented atherosclerotic artery. In this preclinical study, we aimed to improve the efficacy of ISR treatment by coating CBs with paclitaxel (paclitaxel-eluting cutting balloon; PECB) and to characterize the histological features of neo-ISRs that arise after ISR treatment. ISR was induced by bare metal stent (BMS) implantation in coronary arteries in pigs. After one month of follow-up, the BMS-induced ISR was treated with either CB or PECB. After another month, we performed quantitative coronary angiography, explanted the treated arteries and assessed histopathological and histomorphometric parameters. In addition, we compared the histological features of neo-ISRs with pre-treatment ISRs. Injury, inflammation, fibrin deposition, and endothelialization scores were similar between the CB and PECB groups at one month after ISR treatment. Neointimal area (0.87±0.61 vs. 1.95±1.14 mm², p=0.02), mean neointimal thickness (0.40±0.39 vs. 0.99±0.56 mm, p=0.01), and percent area stenosis (27.3±20.4 vs. 48.3±22.9%, p=0.04) were decreased in PECB-treated coronary arteries compared to CB-treated arteries, respectively. Density of cells (predominantly smooth muscle cells; SMCs) was increased in neo-ISRs (3.51±3.05×10³ vs. 6.35±2.57×10³ cells/mm², p<0.01), but significantly more CD68⁺ and CD20⁺ cells were found in the pre-treatment ISRs. In conclusion, PECB treatment of ISRs led to better results in terms of smaller neointimal area and %area stenosis of the neo-ISR. SMC density was increased in neo-ISRs in contrast with higher percentage of CD68⁺ and CD20⁺ cells in pre-treatment ISRs.

Improved renal outcomes after revascularization of the stenotic renal artery in pigs by prior treatment with low-energy extracorporeal shockwave therapy.

Revascularization does not restore renal function in most patients with atherosclerotic renal artery stenosis (RAS), likely because of inflammation and fibrosis within the stenotic kidney. Low-energy shockwave therapy (LE-SWT) stimulates angiogenesis in the stenotic kidney, but its ability to improve renal function and structure after revascularization remains unexplored. We tested the hypothesis that a LE-SWT regimen before percutaneous transluminal renal angioplasty (PTRA) would enable PTRA to restore renal function in hypercholesterolemic pigs with RAS (HC+RAS), and that this would be associated with attenuation of renal inflammation and fibrosis. Twenty-six pigs were studied after 16 weeks of HC+RAS, HC+RAS treated with PTRA with or without a preceding LE-SWT regimen (bi-weekly for 3 weeks), and controls. Single-kidney renal blood flow (RBF), glomerular filtration rate (GFR), and oxygenation were assessed in vivo using imaging 4 weeks after PTRA, and then inflammation and fibrosis ex vivo.Four weeks after successful PTRA, blood pressure fell similarly in both revascularized groups. Yet, stenotic-kidney GFR remained lower in HC+RAS and HC+RAS+PTRA (P < 0.01 vs. normal), but was improved in HC+RAS+PTRA+SW (P > 0.05 vs. normal). Furthermore, reduced inflammation, medullary fibrosis, and cortical hypoxia were only shown in swine stenotic kidneys pretreated with LE-SWT before PTRA 4 weeks later. LE-SWT delivery before revascularization permitted PTRA to improve function and decrease cortical and medullary damage in the stenotic swine kidney. This study, therefore, supports the use of an adjunct SW pretreatment to enhance the success of PTRA in blunting loss of kidney function in experimental HC+RAS.

2381Low-intensity pulsed ultrasound ameliorates DES-induced coronary adventitial inflammation and hyperconstricting responses in pigs in vivo - A novel non-invasive therapy for coronary inflammation

Abstract Background We previously demonstrated that coronary adventitial inflammation plays important roles in the pathogenesis of coronary artery spasm, including drug-eluting stent (DES)-induced coronary hyperconstricting responses, in pigs and humans. Indeed, the coronary adventitia has recently attracted much attention as the important site for vascular inflammation. However, a direct therapeutic approach to the coronary adventitia remains to be developed. We have developed a non-invasive low-intensity pulsed ultrasound (LIPUS) therapy for angina, which exerts anti-inflammatory effects through improved coronary microcirculation. Purpose In this study, we aimed to examine whether our LIPUS therapy ameliorates DES-induced coronary hyperconstricting responses in pigs in vivo, and if so, what mechanisms are involved. Methods An everolimus-eluting stent (EES) was implanted into the left anterior descending (LAD) coronary artery in normal male pigs. They were randomly assigned to the LIPUS or the sham therapy groups. After EES implantation, in the LIPUS group, LIPUS (32 cycles, 193 mW/cm2) was applied to the heart at 3 different levels (proximal and distal stent edges and middle portion of the stent) through X-ray for 20 min at each level for every other day for 2 weeks (6 days in total) (Figs. 1A, 1B). The sham therapy group was treated in the same manner but without LIPUS. At 4 weeks after the procedure, we performed coronary angiography to examine coronary vasoconstricting responses to intracoronary serotonin in vivo. Finally, stented coronary vessels were harvested for immunohistochemistry of vasa vasorum, lymphatic vessels (LYVE-1), sympathetic nerve fibers (SNF), vascular inflammation (macrophages and IL-1β expression), Rho-kinase expression and activity as evaluated by phosphorylated myosin phosphatase target subunit-1 (pMYPT-1). Results Coronary vasoconstricting responses to intracoronary serotonin were significantly enhanced in the sham therapy group but were significantly suppressed in the LIPUS group at the DES edges in the LAD, whereas those responses were comparable at the non-DES implanted segments in the left circumflex (LCx) coronary arteries between the 2 groups. (Figs. 1C, 1D). Furthermore, in vivo lymph transport speed was significantly faster in the LIPUS group than in sham group (Figs. 1E–1G). Histological analysis showed that except vasa vasorum formation, the number of lymphatic vessels, adventitial inflammatory cells infiltration, Rho-kinase expression and activity were all significantly enhanced in the sham therapy group and were significantly suppressed in the LIPUS group (Figs. 1G–1K). Figure 1 Conclusion We were able to develop a non-invasive LIPUS therapy for coronary functional abnormalities caused by chronic adventitial inflammation in pigs in vivo, for which multiple beneficial effects appear to be involved (Fig. 1L).

Development of drug-coated balloon for the treatment of multiple peripheral artery segments

ObjectivePeripheral artery disease is the second most common cardiovascular disease. It can often occur in complex form when there is a presence of long, diffuse, and multiple lesions. Current treatments use either single long drug-coated balloons (DCBs) or multiple DCBs; however, treatment success is limited. The purpose of this study was to investigate the preclinical feasibility of our multiple-release Tailored Medical Devices DCB (MR-TMD-DCB) to treat multiple arterial segments using a single DCB. MethodsThe MR-TMD-DCBs were developed using a two-layer coating approach. The DCBs were developed in a certified Current Good Manufacturing Practices facility using presterilized materials and reagent and then characterized for coating morphology, thermal and chemical changes, and in vitro particulate shedding. The drug loss, tissue uptake, and undelivered drug amounts were analyzed using an in vitro peripheral artery flow model and explanted pig arteries. Then, an in vivo survival study was performed using a healthy porcine model to measure the short-term drug uptake (seven swine; 14 treatments at day 1) and retention (seven swine; 14 treatments at day 7) in two different arterial segments after treatment with a single MR-TMD-DCB. ResultsThe coating on the MR-TMD-DCB was smooth and homogeneous with paclitaxel molecularly dispersed in its amorphous state. A negligible number of particulates were shed from the MR-TMD-DCB coating. A similar amount of drug was accurately delivered into two separate explanted arteries using a single MR-TMD-DCB during the in vitro flow model testing (707 ± 109 ng/mg in the first explanted artery and 783 ± 306 ng/mg in the second explanted artery). The MR-TMD-DCB treatment resulted in equivalent drug amounts in the two arterial segments at day 1 (63 ± 19 ng/mg in the first treatment site and 59 ±19 ng/mg in the second treatment site) and at day 7 (9 ± 6 ng/mg in the first treatment site and 10 ± 6 ng/mg in the second treatment site). In addition, the drug levels at each time point were in the clinically relevant range to prevent neointimal hyperplasia. ConclusionsThe MR-TMD-DCBs provided equivalent and clinically relevant drug retention levels into two different arterial segments. Thus, MR-TMD-DCBs can be used to accurately deliver drug into multiple arterial segments with the use of a single DCB. The clinical outcomes of these findings need further investigation. Future long-term pharmacokinetics and safety studies will be performed to evaluate the safety and efficacy of the MR-TMD-DCB.

Poly-l-lactide Polymer-Based Triple Drug-Eluting Stent with Abciximab, Alpha-Lipoic Acid and Sirolimus in Porcine Coronary Restenosis Model

This study evaluated the effect of a novel triple drug-eluting stent containing antithrombotic abciximab, antioxidative alpha-lipoic acid (ALA), and antiproliferative sirolimus in a porcine model. The coronary arteries of pigs were randomized into three groups: triple drug-eluting stent (TES; n=10), sirolimus-eluting stent (SES; n=10), and bare metal stent (BMS; n=10). At 28 days after stent implantation, a histopathologic analysis was performed. There were no significant differences in the injury score. There were significant differences in the neointimal area (2.3±0.6 mm2 in TES vs. 2.5±0.88 mm2 in SES vs. 3.3±0.58 mm2 in BMS, p<0.0001), percent area of stenosis (37.1±9.26% in TES vs. 46.1±15.9% in SES vs. 66.2±10.12% in BMS, p<0.0001), inflammation score (1.0 [range, 0.0-1.0] in TES vs. 1.5 [range, 1.0-2.0] in SES vs. 1.0 [range, 1.0-2.0] in BMS, p<0.05), and fibrin score (2.0 [range, 1.0-2.0] in TES vs. 2.0 [range, 1.0-2.5] in SES vs. 0.0 [range, 0.0-1.0] in BMS, p<0.0001) among the three groups. The occlusion rates using micro-computed tomography showed similar restenosis rates based on histologic analysis (35.4±8.39% in TES vs. 43.4±10.12% in SES vs. 71.4±4.38% in BMS, p<0.0001). TES demonstrated an inhibitory effect on the smooth muscle cells compared to the other stents. It also suppressed inflammation in the stented lesion compared to SES as evidenced by the inflammation score.

Mesenchymal Stromal Cells Are Retained in the Porcine Renal Cortex Independently of Their Metabolic State After Renal Intra-Arterial Infusion.

The regenerative capacities of mesenchymal stromal cells (MSCs) make them suitable for renal regenerative therapy. The most common delivery route of MSC is through intravenous infusion, which is associated with off-target distribution. Renal intra-arterial delivery offers a targeted therapy, but limited knowledge is available regarding the fate of MSCs delivered through this route. Therefore, we studied the efficiency and tissue distribution of MSCs after renal intra-arterial delivery to a porcine renal ischemia-reperfusion model. MSCs were isolated from adipose tissue of healthy male pigs, fluorescently labeled and infused into the renal artery of female pigs. Flow cytometry allowed MSC detection and quantification in tissue and blood. In addition, quantitative polymerase chain reaction was used to trace MSCs by their Y-chromosome. During infusion, a minor number of MSCs left the kidney through the renal vein, and no MSCs were identified in arterial blood. Ischemic and healthy renal tissues were analyzed 30 min and 8 h after infusion, and 1-4 × 104 MSCs per gram of tissue were detected, predominantly, in the renal cortex, with a viability >70%. Confocal microscopy demonstrated mainly glomerular localization of MSCs, but they were also observed in the capillary network around tubuli. The infusion of heat-inactivated (HI) MSCs, which are metabolically inactive, through the renal artery showed that HI-MSCs were distributed in the kidney in a similar manner to regular MSCs, suggesting a passive retention mechanism. Long-term MSC survival was analyzed by Y-chromosome tracing, and demonstrated that a low percentage of the infused MSCs were present in the kidney 14 days after administration, while HI-MSCs were completely undetectable. In conclusion, renal intra-arterial MSC infusion limited off-target engraftment, leading to efficient MSC delivery to the kidney, most of them being cleared within 14 days. MSC retention was independent of the metabolic state of MSC, indicating a passive mechanism.

Premature Vascular Aging in Guinea Pigs Affected by Fetal Growth Restriction

Cardiovascular risk associated with fetal growth restriction (FGR) could result from an early impaired vascular function. However, whether this effect results in premature vascular aging has not been addressed. We studied the ex vivo reactivity of carotid and femoral arteries in fetal (near term), adults (eight months-old) and aged (16 months-old) guinea pigs in normal (control) and FGR offspring. Additionally, an epigenetic marker of vascular aging (i.e., LINE-1 DNA methylation) was evaluated in human umbilical artery endothelial cells (HUAEC) from control and FGR subjects. Control guinea pig arteries showed an increased contractile response (KCl-induced) and a progressive impairment of NO-mediated relaxing responses as animals get older. FGR was associated with an initial preserved carotid artery reactivity as well as a later significant impairment in NO-mediated responses. Femoral arteries from FGR fetuses showed an increased contractility but a decreased relaxing response compared with control fetuses, and both responses were impaired in FGR-adults. Finally, FGR-HUAEC showed decreased LINE-1 DNA methylation compared with control-HUAEC. These data suggest that the aging of vascular function occurs by changes in NO-mediated responses, with limited alterations in contractile capacity. Further, these effects are accelerated and imposed at early stages of development in subjects exposed to a suboptimal intrauterine environment.

Structural changes in the uterine artery of the domestic pig (Sus scrofa domesticus) in the first trimester of pregnancy

Background Adaptation of the uterine artery in pregnancy involves changes in anatomy that include widening of the lumen medial thickening elastic lamina degradation and smooth muscle cell hypertrophy Early remodeling of the uterine vascular system is needed to maintain pregnancy and ensure desired pregnancy outcome The trigger mechanisms for uterine artery remodeling are uncertain Also unclear are the regional variations in the uterine artery in the first trimester of pregnancy Methods domestic pigs Sus scrofa in the first trimester of pregnancy and non gravid were sacrificed to examine the structure of the uterine artery The specimens were prepared for paraffin wax embedding and stained with Masson rsquo s Trichrome Weigert rsquo s Resorcin Fuschscin counterstained with Van Gieson stain and Hematoxylin and Eosin Slides were examined with a light microscope at x x and X magnification Observations made were recorded and photomicrographs taken Results The Uterine artery of the domestic pig in the first trimester showed marked reduction in the thickness of the tunica intima a prominent internal elastic lamina and elastic fibres The tunica media had hypertrophied vascular smooth muscle with zonation of the media into inner circular and outer longitudinal smooth muscle layers in the proximal regions of the artery There was also prominence of the Vasa vasorum in the adventitia of these uterine arteries that reduced distally along the artery Conclusion The proximal sections of the uterine artery shows unique physical mechanical adaptation in the first trimester of pregnancy related to increased demand of blood to the feto placental unit

Pathologic and hemodynamic changes of common carotid artery in obstructive sleep apnea hypopnea syndrome in a porcine model

Background/aim To prepare a porcine model of obstructive sleep apnea-hypopnea syndrome (OSAHS) and observe the pathological and hemodynamic changes in the common carotid artery.Materials and methods Twelve male miniature pigs were randomly divided into the model and control group (n = 6). Pigs in the model group were kept in an air-flow negative pressure chamber at 0.96 ± 0.01 kPa, and the air oxygen content, temperature, and humidity were kept at normal culture conditions in both groups. After pigs in the model group presented symptoms of OSAHS, changes in the hemodynamics and morphology of the carotid artery were analyzed using color Doppler, and light and electron microscopy.Results An animal model of OSAHS was successfully created. The internal diameter of the carotid artery of pigs in the model group was decreased, while the intima thickness, peak-systolic mean velocity, and resistance index were increased when compared to the control group (P < 0.05). The results of the light and electron microscopy revealed an incomplete elastic plate, increased media thickness, irregular morphology of the smooth muscle cells, increased collagen fiber bundles, partially disordered elastic fibers, and smooth muscle layers. The quantitative analysis showed significantly increased elastic fibers in the media of the carotid artery in the model group (P < 0.01).Conclusion Pathological changes in the tissue structure and hemodynamics in the negative pressure-induced pig OSAHS model were observed. We suggest that alterations in the upper airway pressure during OSAHS may lead to cardiovascular conditions through its pathological effects on the carotid artery.

Responses of retinal arterioles and ciliary arteries in pigs with acute respiratory distress syndrome (ARDS)

Acute respiratory distress syndrome (ARDS) is a clinical syndrome of acute lung failure in critically sick patients, which severely compromises the function of multiple organs, including the brain. Although, the optic nerve and the retina are a part of the central nervous system, the effects of ARDS on these ocular structures are completely unknown. Thus, the major goal of this study was to test the hypothesis that ARDS affects vascular function in the eye. ARDS was induced in anesthetized pigs by intratracheal injection of lipopolysaccharide (LPS). Sham-treated animals served as controls. Pigs were monitored for 8 h and then sacrificed. Subsequently, retinal arterioles and short posterior ciliary arteries were isolated and cannulated with micropipettes to measure vascular responses by videomicroscopy. Levels of reactive oxygen species (ROS) were quantified in isolated vessels using dihydroethidium (DHE). Messenger RNA expression of hypoxic, inflammatory, prooxidative, and antioxidative genes was assessed by real-time PCR. When group-dependent differences in mRNA expression levels were found for a particular gene, immunostainings were conducted. Strikingly, responses to the endothelium-dependent vasodilator, bradykinin, were markedly impaired in retinal arterioles of LPS-treated pigs, but no differences were seen between ciliary arteries of LPS- and sham-treated animals. ROS levels were increased in retinal arterioles but not in ciliary arteries of LPS-treated pigs. Messenger RNA levels for HIF-1α, VEGF-A and NOX2 were markedly increased in retinal arterioles of LPS-treated pigs, whereas ciliary arteries had only negligible mRNA level changes. Pronounced immunoreactivity for HIF-1α, VEGF-A and NOX2 was seen in the endothelium of retinal arterioles from LPS-treated pigs. Histologically, massive edema was seen especially in the retinal nerve fiber layer of pigs treated with LPS. Our study provides the first evidence that ARDS induced by intratracheal LPS application evokes endothelial dysfunction in porcine retinal arterioles together with retinal edema, indicative of vascular leakage. In contrast, ciliary arteries appear to be resistant to intratracheal LPS application.

Effects of granulocyte colony‑stimulating factor on rabbit carotid and porcine heart models of chronic obliterative arterial disease.

Previous studies suggest that granulocyte colony-stimulating factor (G-CSF) can promote bone marrow derived progenitor cells to mediate cardiovascular repair, potentially reversing mechanical dysfunction in chronic ischaemic heart disease and post myocardial infarction. Two models were used in the present study both using a surgical ameroid constrictor to induce arterial stenosis. The first model used the carotid artery of rabbits. They were divided into high fat diet (inducing atherosclerosis) or normal fat diet (control) groups. Each was subdivided into surgical exposure group without constrictor, ameroid constrictor receiving normal saline or receiving G-CSF 15 µg/kg/day. Endothelial markers of endothelial nitric oxide synthase and endothelin 1 were increased by the use of ameroid constrictor in both atherosclerotic and non-atherosclerotic mice, however were not further altered by G-CSF. Scanning electron microscopy indicated that ameroid constrictor application altered endothelial morphology from an oval shape to a round shape and this was more prominent in the atherosclerotic compared with the non-atherosclerotic group. G-CSF injection increased the number of endothelial cells in all groups. The second model used the left coronary artery of pigs. They were equally divided into following groups, receiving normal saline (control), G-CSF 2.5 µg/kg/day (low dose), 5 µg/kg/day (medium dose) and 10 µg/kg/day (high dose) for 5 days. G-CSF at a low or high dose worsened intimal hyperplasia however at a medium dose improved it. In conclusion, G-CSF had no effect in a rabbit carotid artery model of atherosclerosis. Its effects on the porcine heart were dose-dependent; arterial disease worsened at a low or high dose, but improved at a medium dose.

Delivery of Cell-Specific Aptamers to the Arterial Wall with an Occlusion Perfusion Catheter

Current strategies to prevent restenosis following endovascular treatment include the local delivery of anti-proliferative agents to inhibit vascular smooth muscle cell (VSMC) proliferation and migration. These agents, not specific to VSMCs, are deposited on the luminal surface and therefore target endothelial cells and delay vascular healing. Cell-targeted therapies, (e.g., RNA aptamers), can potentially overcome these safety concerns by specifically binding to VSMC and inhibiting proliferation and migration. The purpose of this study was to therefore demonstrate the ability of a perfusion catheter to deliver cell-specific RNA aptamer inhibitors directly to the vessel wall. RNA aptamers specific to VSMCs were developed using an in vitro cell-based systematic evolution of ligand by exponential enrichment selection process. Two aptamers (Apt01 and Apt14) were evaluated ex vivo using harvested pig arteries in a pulsatile flow bioreactor. Local drug delivery of the aptamers into the medial wall was accomplished using a novel perfusion catheter. We demonstrated the feasibility to deliver aptamer-based drugs directly to the medial layer of an artery using a perfusion catheter. Such cell-specific targeted therapeutic drugs provide a potentially safer and more effective treatment option for patients with vascular disease.

Urapidil, but not dihydropyridine calcium channel inhibitors, preserves the hypoxic pulmonary vasoconstriction: an experimental study in pig arteries.

Hypoxic pulmonary vasoconstriction (HPV) is a protective mechanism maintaining blood oxygenation by redirecting blood flow from poorly ventilated to well-ventilated areas in the lung. Such a beneficial effect is blunted by antihypertensive treatment with dihydropyridine calcium channel inhibitors. The aim of the present study was to evaluate the effect of urapidil, an antihypertensive agent acting as an α1 adrenergic antagonist and a partial 5-HT1A agonist, on HPV in porcine proximal and distal pulmonary artery rings, and to characterize underlying mechanisms. Rings from proximal and distal porcine pulmonary artery were suspended in organ chambers and aerated with a 95% O2 + 5% CO2 gas mixture. HPV was induced by changing the gas to a 95% N2 + 5% CO2 mixture following a low level of pre-contraction with U46619. Hypoxia induced a contractile response in both proximal and distal pulmonary artery rings. This effect is observed in the presence of a functional endothelium and is inhibited by a soluble guanylyl cyclase inhibitor (ODQ), a NO scavenger (carboxy-PTIO), and by catalase in proximal pulmonary artery rings. The endothelium-dependent HPV is prevented by nicardipine and clevidipine but remained unaffected by urapidil in both proximal and distal pulmonary artery rings. These findings indicate that urapidil, in contrast to nicardipine and clevidipine, preserves the hypoxia-triggered vasoconstriction in isolated pulmonary arteries. They further indicate the involvement of the NO-guanylyl cyclase pathway and H2 O2 in HPV. Further research is warranted to determine the potential clinical relevance of the preserved hypoxia-induced pulmonary vasoconstriction by urapidil.