Name: in vivo gene transfer to the rabbit common carotid artery endothelium
Uploaded: 2018-05-06T13:00:00.000+00:00
Duration: 10 min 18 s
Description: Watch this Scientific Journal Video about In Vivo Gene Transfer to the Rabbit Common Carotid Artery Endothelium at JoVE.com

We thank AdVec, Inc. for permission to use HDAd reagents, Julia Feyk for administrative assistance, and the Department of Comparative Medicine veterinary services for surgical advice and support. This work was supported by HL114541 and the John L. Locke, Jr. Charitable Trust.

The authors have nothing to disclose.

Certain aspects of surgical technique merit particular attention. Full exposure and mobilization of the common carotid artery via careful dissection will facilitate gene transfer and arteriotomy repair. However, during the dissection, direct manipulation of the carotid artery should be minimized&#160;to prevent vasospasm. In addition, any bleeding adjacent to the artery should be stopped by applying light pressure with gauze and extravasated blood should be cleaned up immediately by rinsing the area with normal saline. I...

The goal of this method is to introduce a transgene into the endothelium of rabbit common carotid arteries. Introduction of the transgene allows the assessment of the biological role of the transgene product both in normal arteries and in rabbit models of human arterial disease. Overexpression of the transgene in disease models can reveal whether the transgene (and its protein product) show promise as therapeutic agents1,2,3,4. Inclusion of cis-acting regulatory elements in the transgene expression cassette enables assessment of the activity of these elements in arterial endothelium in vivo5,6. Knowledge of the activity of specific cis-acting regulatory elements can be used to design more-active expression cassettes and to probe mechanisms of gene regulation in large artery endothelium in vivo7.
Rabbits are a valuable model for various aspects of human vascular physiology and disease. Rabbits share many vascular features with humans. For example, baseline hematological values, hemostatic regulation, and vascular longitudinal tension are similar between rabbits and humans8. Rabbit models of vascular diseases replicate key features of many human diseases including: aneurysms (similar geometric and flow characteristics)9, vasospasm (similar response to endovascular treatment)10,11, and atherosclerosis (intimal plaques with similar features including a core rich in lipid, macrophages, and smooth muscle cells in a fibrous cap)12,13. Accordingly, rabbit models have been developed for many vascular diseases such as thrombosis, vasospasm, aneurysm, diabetes, vascular graft stenosis, and atherosclerosis8,13,14,15,16.
For researchers choosing among animal models of vascular physiology and disease, the rabbit has several advantages. Compared to rodents, the larger vessels of rabbits allow easier surgical manipulation, use of endovascular devices, and a larger amount of tissue for quantitative measurements. Rabbits are much closer phylogenetically to primates than are rodents17, and the greater genetic diversity of outbred rabbits better approximates the genetic variability of humans. Genetic diversity is particularly important for preclinical studies, which-by their nature-aim to develop therapies that can be applied to the genetically diverse human population. As with many if not all other model species, rabbit genes are easily cloned or synthesized because the rabbit genome has been sequenced with high coverage (7.48x) [http://rohsdb.cmb.usc.edu/GBshape/cgi-bin/hgGateway?db=oryCun2]. Compared to other large animal models (such as dogs, pigs, or sheep), rabbits are relatively inexpensive to purchase and house and they are easier to breed and handle. Specific vascular disease models in rabbits each have their own advantages and shortcomings as models of human disease that are beyond the scope of this manuscript8,12,18. An investigator should review these advantages and shortcomings to determine if the rabbit is the best model for answering a specific experimental question.
Introduction of deoxyribonucleic acid (DNA) regulatory sequences into endothelial cells in vivo enables investigation of the activity of these sequences in a complex physiologic environment. In vitro studies in transfected endothelial cells can be useful for the initial assessment of DNA regulatory sequences; however, expression levels in tissue culture models are sometimes not reproduced when the studies are repeated in vivo5,19,20. In vitro systems can also be useful for exploring basic pathways of protein signaling and endothelial physiology as well as communication between cultured vascular cells; however, more-complex pathways or regulatory networks that are influenced by complex populations of neighboring vascular cells or the immune system are best studied in an in vivo system6,20. The method described herein provides a platform for exploring regulation of transgene expression in the endothelium within the context of an intact vessel, with or without disease. The in vivo system also permits investigation of physiological and pathological cellular crosstalk and identification of contributions of the immune system to regulation of gene expression6.
Germ-line transgenesis (especially in mice) is an alternative approach for directing transgene expression to endothelial cells. This approach can provide life-long transgene expression, with endothelial targeting mediated by specific promoter or regulatory regions21,22. However, the generation of transgenic mice is time-consuming and expensive, several transgenic lines must be often tested to ensure targeting of the transgene to the desired cell type and achievement of adequate transgene expression levels, and experimental results in murine systems can be strain-dependent. Murine transgenic models with endothelial-targeted transgenes have many advantages: there is no need to perform surgery on every experimental animal in order to achieve transgenesis, experimental mice can be bred with numerous other available transgenic mice in order to test genetic and phenotypic interactions, and there is a wide selection of antibodies that react with murine proteins, facilitating characterization of phenotypes. However, targeting of transgenes to the endothelium via the germ line typically results in transgene expression throughout the vasculature,22 making it difficult to determine the site at which the transgene product is acting. This is especially true when the transgene product is secreted, because a transgene product secreted by endothelial cells throughout the vasculature could have biological activity at any number of sites within an animal. Although the method described in this manuscript requires technical expertise and specialized facilities, it can be less time consuming and less expensive than developing an endothelial-specific transgenic mouse line. It allows for the assessment of the function of a protein selectively in endothelial cells of a segment of large artery, and it permits use of the contralateral common carotid as a paired control (eliminating systemic factors that can vary among experimental animals-for example, blood pressure or cholesterol levels-as uncontrolled variables).
Gene therapy is a promising approach for the treatment of vascular diseases, particularly chronic diseases, because a single application can provide sustained or possibly life-long expression of a therapeutic gene23. The therapeutic promise of gene therapy has been explored in animal models of somatic gene transfer, often targeting the liver24,25, which is a relatively easy target because many blood-borne viral vectors are hepatotropic. However, to have an effect on vascular disease, gene therapy targeted to the liver must achieve systemic overexpression of proteins. This typically requires large doses of vector, which can be toxic or even fatal26. Moreover, increased systemic levels of a protein raise the risk of off-target side effects, which could complicate or even obscure interpretation of experimental results. Local gene therapy targeting vascular endothelium as described in this manuscript could avoid systemic side effects because the infused vector is not widely disseminated beyond the transduced arterial segment, and local vascular effects can be achieved without changes in systemic plasma levels of protein.27 In addition, a far lower amount of vector is needed to transduce an arterial segment than is needed to achieve robust hepatic transduction. Transgene expression from the liver has been reported to decline over time, probably due to cell turnover, requiring repeated dosing if high-level transgene expression is to be maintained.28 In contrast, the low turnover rate of the endothelium provides stable expression for at least 48 weeks in chow-fed rabbits and for at least 24 weeks in atherosclerotic lesions of cholesterol-fed rabbits.1,27
To determine if this method of gene transfer to rabbit common carotid endothelium is appropriate, the advantages and disadvantages (Table 1) should be considered in the context of the specific research goals. Advantages of this method include: outbred rabbits are better representative of human genetic diversity than are inbred mice (important for preclinical work); rabbits provide larger vessels for easier manipulation and more tissue for analysis; the method can achieve endothelium-targeted transgene expression far more quickly than does germ-line endothelial targeting in transgenic mice; vector dose can be easily adjusted to model variable levels of transgene expression; processes specific to large-artery endothelium can be investigated; and local vascular transgenesis allows the opposite carotid in the same animal to be used as a control, eliminating systemic factors as uncontrolled variables. Disadvantages include: special facilities and expertise are required; fewer genetically modified backgrounds on which to experiment are available in rabbits than in mice; and there is a less extensive selection of antibodies to rabbit versus mouse proteins (for immunodetection of transgene protein and other antigens that may be important in interpreting experimental results).

<table><tbody><tr><td>&lt;strong&gt;Disposables&lt;/strong&gt;</td><td></td><td></td><td></td></tr><tr><td>3mL syringe with 24G needle</td><td>Becton Dickinson</td><td>309571</td><td>2x for gene transfer surgery; 3x for harvest surgery</td></tr><tr><td>1mL syringe with 27G needle</td><td>Becton Dickinson</td><td>309623</td><td>6x for gene transfer surgery; 1x for harvest surgery</td></tr><tr><td>20mL syringe, luer lock</td><td>Nipro Medical Corp</td><td>JD+20L</td><td></td></tr><tr><td>Catheters, 24G x 3/4&quot;</td><td>Terumo Medical Products</td><td>SROX2419V</td><td></td></tr><tr><td>19G needle</td><td>Becton Dickinson</td><td>305187</td><td>Gene transfer surgery only</td></tr><tr><td>21G needle</td><td>Becton Dickinson</td><td>305165</td><td>For 20 mL syringe of saline</td></tr><tr><td>Gauze 4&quot; x 4&quot;</td><td>Dynarex</td><td>3242</td><td>~10-15 per surgery</td></tr><tr><td>3-0 silk suture</td><td>Covidien Ltd.</td><td>S-244</td><td></td></tr><tr><td>5-0 silk suture</td><td>Covidien Ltd.</td><td>S-182</td><td>Gene transfer surgery only</td></tr><tr><td>7-0 polypropylene suture</td><td>CP Medical</td><td>8648P</td><td>Gene transfer surgery only</td></tr><tr><td>5-0 polyglycolic acid suture</td><td>CP Medical</td><td>421A</td><td>Gene transfer surgery only</td></tr><tr><td>3-0 polyglycolic acid suture</td><td>CP Medical</td><td>398A</td><td>Gene transfer surgery only</td></tr><tr><td>Alcohol swabs</td><td>Covidien Ltd.</td><td>6818</td><td>For placement of I.V. line</td></tr><tr><td>Catheter plug</td><td>Vetoquinol</td><td>411498</td><td>Gene transfer surgery only</td></tr><tr><td>Ketamine HCl, 100 mg/mL</td><td>Vedco Inc.</td><td>05098916106</td><td></td></tr><tr><td>Xylazine, 100 mg/mL</td><td>Akorn Inc.</td><td>4821</td><td></td></tr><tr><td>Lidocaine HCl, 2%</td><td>Pfizer</td><td>00409427702</td><td></td></tr><tr><td>Bupivacaine HCl, 0.5%</td><td>Pfizer</td><td>00409161050</td><td></td></tr><tr><td>Beuthanasia D-Special</td><td>Intervet Inc.</td><td>NDC 00061047305</td><td>Harvest surgery only</td></tr><tr><td>Buprenorphine HCl, 0.3 mg/mL&amp;nbsp;</td><td>Patterson Veterinary</td><td>12496075705</td><td>Gene transfer surgery only</td></tr><tr><td>Saline IV bag, 0.9% sodium chloride</td><td>Baxter</td><td>2B1309</td><td>2x for gene transfer surgery; can use vial of sterile saline in place of one</td></tr><tr><td>Heparin&amp;nbsp; (5000 U/mL)</td><td>APP Pharmaceuticals</td><td>NDC 63323-047-10</td><td>Gene transfer surgery only</td></tr><tr><td>Fentanyl patch, 25 mcg/hr&amp;nbsp;</td><td>Apotex Corp.</td><td>NDC 60505-7006-2</td><td>Gene transfer surgery only</td></tr><tr><td>Isoflurane</td><td>Multiple vendors</td><td>Catalog number not available</td><td></td></tr><tr><td>Gene transfer vector</td><td></td><td></td><td>Dilute 350 &amp;micro;L per artery; 2 x 10&lt;sup&gt;11&lt;/sup&gt; vp/mL for adenovirus; gene transfer surgery only</td></tr><tr><td>&lt;strong&gt;Surgical Instruments&lt;/strong&gt;</td><td></td><td></td><td></td></tr><tr><td>Metzenbaum needle holder 7&quot; straight</td><td>Roboz</td><td>RS-7900</td><td>Gene transfer surgery only</td></tr><tr><td>Operating scissors 6.5&quot; straight blunt/blunt</td><td>Roboz</td><td>RS-6828</td><td></td></tr><tr><td>Needle holder /w suture scissors</td><td>Miltex</td><td>8-14-IMC</td><td>Gene transfer surgery only</td></tr><tr><td>Castroviejo scissors</td><td>Roboz</td><td>RS-5658</td><td></td></tr><tr><td>Castroviejo needle holder, 5.75&quot; straight with lock</td><td>Roboz</td><td>RS-6412</td><td>Gene transfer surgery only</td></tr><tr><td>Stevens scissors 4.25&quot; curved blunt/blunt</td><td>Roboz</td><td>RS-5943</td><td></td></tr><tr><td>Alm retractor 4&quot; 4X4 5mm blunt prongs</td><td>Roboz</td><td>RS-6514</td><td>2x</td></tr><tr><td>Backhaus towel clamp 3.5&quot;</td><td>Roboz</td><td></td><td>4x</td></tr><tr><td>Micro clip setting forceps 4.75&quot;</td><td>Roboz</td><td>RS-6496</td><td>Gene transfer surgery only</td></tr><tr><td>Micro vascular clips, 11 mm</td><td>Roboz</td><td></td><td>2x for gene transfer surgery only</td></tr><tr><td>Surg-I-Loop</td><td>Scanlan International</td><td>1001-81M</td><td>5 cm length</td></tr><tr><td>Bonaccolto forceps, 4&amp;rdquo; (10 cm) long longitudinal serrations, cross serrated tip, 1.2mm tip width</td><td>Roboz</td><td>RS-5210</td><td></td></tr><tr><td>Dumont #3 forceps Inox tip size .17 X .10mm</td><td>Roboz</td><td>RS-5042</td><td></td></tr><tr><td>Graefe forceps, 4&amp;rdquo; (10 cm) long serrated straight, 0.8mm tip</td><td>Roboz</td><td>RS-5280</td><td></td></tr><tr><td>Halstead mosquito forceps,&amp;nbsp; 5&quot; straight, 1.3mm tips</td><td>Roboz</td><td>RS-7110</td><td>2x</td></tr><tr><td>Halstead mosquito forceps,&amp;nbsp; 5&quot; curved, 1.3mm tips</td><td>Roboz</td><td>RS-7111</td><td></td></tr><tr><td>Jacobson mosquito forceps 5&quot; curved extra delicate, 0.9 mm tips</td><td>Roboz</td><td>RS-7117</td><td></td></tr><tr><td>Kantrowitz forceps, 7.25&quot; 90 degree delicate, 1.7 mm tips</td><td>Roboz</td><td>RS-7305</td><td></td></tr><tr><td>Tissue forceps 5&quot;, 1X2 teeth, 2 mm tip width</td><td>Roboz</td><td>RS-8162</td><td></td></tr><tr><td>Allis-Baby forceps, 12 cm, 4x5 teeth, 3 mm tip width</td><td>Fine Science Tools</td><td>11092-12</td><td>2x</td></tr><tr><td>Adson forceps, 12 cm, serrated, straight</td><td>Fine Science Tools</td><td>11006-12</td><td></td></tr><tr><td>Veterinary electrosurgery handpiece and electrode</td><td>MACAN Manufacturing</td><td>HPAC-1; R-F11</td><td></td></tr><tr><td>&lt;strong&gt;Surgical Suite Equipment&lt;/strong&gt;</td><td></td><td></td><td></td></tr><tr><td>Circulating warm water blanket and pump</td><td>Multiple vendors</td><td>Catalog number not available</td><td></td></tr><tr><td>Forced air warming unit</td><td>3M</td><td>Bair Hugger Model 505</td><td>Gene transfer surgery only</td></tr><tr><td>IV infusion pump</td><td>Heska</td><td>Vet IV 2.2</td><td>Gene transfer surgery only</td></tr><tr><td>Isoflurane vaporizer and scavenger</td><td>Multiple vendors</td><td>Catalog number not available</td><td></td></tr><tr><td>Veterinary multi-parameter monitor</td><td>Surgivet</td><td>Surgivet Advisor</td><td></td></tr><tr><td>Veterinary electrosurgery unit</td><td>MACAN Manufacturing</td><td>MV-9</td><td></td></tr><tr><td>Surgical microscope</td><td>D.F. Vasconcellos</td><td>M900</td><td>Needs ~16x magnification</td></tr></tbody></table>

in vivo gene transfer to the rabbit common carotid artery endothelium

The goal of this method is to introduce a transgene into the endothelium of isolated segments of both rabbit common carotid arteries. The method achieves focal endothelial-selective transgenesis, thereby allowing an investigator to determine the biological roles of endothelial-expressed transgenes and to quantify the in vivo transcriptional activity of DNA sequences in large artery endothelial cells. The method uses surgical isolation of rabbit common carotid arteries and an arteriotomy to deliver a transgene-expressing viral vector into the arterial lumen. A short incubation period of the vector in the lumen, with subsequent aspiration of the lumen contents, is sufficient to achieve efficient and durable expression of the transgene in the endothelium, with no detectable transduction or expression outside of the isolated arterial segment. The method allows assessment of the biological activities of transgene products both in normal arteries and in models of human vascular disease, while avoiding systemic effects that could be caused either by targeting gene delivery to other sites (e.g. the liver) or by the alternative approach of delivering genetic constructs to the endothelium by germ line transgenesis. Application of the method is limited by the need for a skilled surgeon and anesthetist, a well-equipped operating room, the costs of purchasing and housing rabbits, and the need for expertise in gene-transfer vector construction and use. Results obtained with this method include: transgene-related alterations in arterial structure, cellularity, extracellular matrix, or vasomotor function; increases or reductions in arterial inflammation; alterations in vascular cell apoptosis; and progression, retardation, or regression of diseases such as intimal hyperplasia or atherosclerosis. The method also allows measurement of the ability of native and synthetic DNA regulatory sequences to alter transgene expression in endothelial cells, providing results that include: levels of transgene mRNA, levels of transgene protein, and levels of transgene enzymatic activity.

To implement this method with confidence, preliminary experiments are necessary to establish that the operator achieves efficient and reproducible gene transfer, with transgene expression primarily in luminal endothelial cells. In our experience, this is most easily assessed using a vector that expresses &#946;-galactosidase. 5-bromo-4-chloro-3-indolyl-&#946;-D-galactopyranoside (X-gal) staining of common carotid segments removed 3 days after vector infusion, as well as measurement of &#9...

Watch this Scientific Journal Video about In Vivo Gene Transfer to the Rabbit Common Carotid Artery Endothelium at JoVE.com

In Vivo Gene Transfer to the Rabbit Common Carotid Artery Endothelium

This method is to introduce a transgene into the endothelium of rabbit carotid arteries. Introduction of the transgene allows the assessment of the biological role of the transgene product either in normal arteries or disease models. The method is also useful for measuring activity of DNA regulatory sequences.

In Vivo Gene Transfer to the Rabbit Common Carotid Artery Endothelium

The goal of this method is to introduce a transgene into the endothelium of isolated segments of both rabbit common carotid arteries. The method achieves ...

in-vivo-gene-transfer-to-the-rabbit-common-carotid-artery-endothelium

Research

JoVE Journal

Medicine

9.0K Views.  University of Washington. This method is to introduce a transgene into the endothelium of rabbit carotid arteries. Introduction of the transgene allows the assessment of the biological role of the transgene product either in normal arteries or disease models. The method is also useful for measuring activity of DNA regulatory sequences.

Video: In Vivo Gene Transfer to the Rabbit Common Carotid Artery Endothelium

A Model of Disturbed Flow-Induced Atherosclerosis in Mouse Carotid Artery by Partial Ligation and a Simple Method of RNA Isolation from Carotid Endothelium

Despite the well-known close association, direct evidence linking disturbed flow to atherogenesis has been lacking. We have recently used a modified version of carotid partial ligation methods [1,2] to show that it acutely induces low and oscillatory flow conditions, two key characteristics of disturbed flow, in the mouse common carotid artery. Using this model, we have provided direct evidence that disturbed flow indeed leads to rapid and robust atherosclerosis development in Apolipoprotein E knockout mouse [3]. We also developed a method of endothelial RNA preparation with high purity from the mouse carotid intima [3]. Using this mouse model and method, we found that partial ligation causes endothelial dysfunction in a week, followed by robust and rapid atheroma formation in two weeks in a hyperlipidemic mouse model along with features of complex lesion formation such as intraplaque neovascularization by four weeks. This rapid in vivo model and the endothelial RNA preparation method could be used to determine molecular mechanisms underlying flow-dependent regulation of vascular biology and diseases. Also, it could be used to test various therapeutic interventions targeting endothelial dysfunction and atherosclerosis in considerably reduced study duration.

This describes a partial carotid ligation surgery, which causes disturbed flow conditions and subsequent atherosclerosis development (in two weeks) with intraplaque neo-vascularization (in four weeks) in the mouse common carotid artery. We also describe a novel method of RNA isolation from the carotid intima, providing high purity endothelial RNA.

Despite the well-known close association, direct evidence linking disturbed flow to atherogenesis has been lacking. We have recently used a modified ...

A Strategy to Identify de Novo Mutations in Common Disorders such as Autism and Schizophrenia

There are several lines of evidence supporting the role of de novo mutations as a mechanism for common disorders, such as autism and schizophrenia. First, the de novo mutation rate in humans is relatively high, so new mutations are generated at a high frequency in the population. However, de novo mutations have not been reported in most common diseases. Mutations in genes leading to severe diseases where there is a strong negative selection against the phenotype, such as lethality in embryonic stages or reduced reproductive fitness, will not be transmitted to multiple family members, and therefore will not be detected by linkage gene mapping or association studies. The observation of very high concordance in monozygotic twins and very low concordance in dizygotic twins also strongly supports the hypothesis that a significant fraction of cases may result from new mutations. Such is the case for diseases such as autism and schizophrenia. Second, despite reduced reproductive fitness1 and extremely variable environmental factors, the incidence of some diseases is maintained worldwide at a relatively high and constant rate. This is the case for autism and schizophrenia, with an incidence of approximately 1% worldwide. Mutational load can be thought of as a balance between selection for or against a deleterious mutation and its production by de novo mutation. Lower rates of reproduction constitute a negative selection factor that should reduce the number of mutant alleles in the population, ultimately leading to decreased disease prevalence. These selective pressures tend to be of different intensity in different environments. Nonetheless, these severe mental disorders have been maintained at a constant relatively high prevalence in the worldwide population across a wide range of cultures and countries despite a strong negative selection against them2. This is not what one would predict in diseases with reduced reproductive fitness, unless there was a high new mutation rate. Finally, the effects of paternal age: there is a significantly increased risk of the disease with increasing paternal age, which could result from the age related increase in paternal de novo mutations. This is the case for autism and schizophrenia3. The male-to-female ratio of mutation rate is estimated at about 4&#x2013;6:1, presumably due to a higher number of germ-cell divisions with age in males. Therefore, one would predict that de novo mutations would more frequently come from males, particularly older males4. A high rate of new mutations may in part explain why genetic studies have so far failed to identify many genes predisposing to complexes diseases genes, such as autism and schizophrenia, and why diseases have been identified for a mere 3% of genes in the human genome. Identification for de novo mutations as a cause of a disease requires a targeted molecular approach, which includes studying parents and affected subjects. The process for determining if the genetic basis of a disease may result in part from de novo mutations and the molecular approach to establish this link will be illustrated, using autism and schizophrenia as examples.

Molecular genetic strategy for finding de novo mutations causing common disorders such as autism and schizophrenia.

There are several lines of evidence supporting the role of de novo mutations as a mechanism for common disorders, such as autism and schizophrenia. First, ...

Gene Transfer for Ischemic Heart Failure in a Preclinical Model

Various emerging technologies are being developed for patients with heart failure. Well-established preclinical evaluations are necessary to determine their efficacy and safety.
Gene therapy using viral vectors is one of the most promising approaches for treating cardiac diseases. Viral delivery of various different genes by changing the carrier gene has immeasurable therapeutic potential.
In this video, the full process of an animal model of heart failure creation followed by gene transfer is presented using a swine model. First, myocardial infarction is created by occluding the proximal left anterior descending coronary artery. Heart remodeling results in chronic heart failure. Unique to our model is a fairly large scar which truly reflects patients with severe heart failure who require aggressive therapy for positive outcomes. After myocardial infarct creation and development of scar tissue, an intracoronary injection of virus is demonstrated with simultaneous nitroglycerine infusion. Our injection method provides simple and efficient gene transfer with enhanced gene expression. This combination of a myocardial infarct swine model with intracoronary virus delivery has proven to be a consistent and reproducible methodology, which helps not only to test the effect of individual gene, but also compare the efficacy of many genes as therapeutic candidates.

A method of gene transfer for the treatment of ischemic heart failure is described using a swine model of myocardial infarction. Our simple and reproducible method enables us to readily evaluate the efficacy of various gene transfers with a very simple and reproducible way.

Various emerging technologies are being developed for patients with heart failure. Well-established preclinical evaluations are necessary to determine ...

Vascular Gene Transfer from Metallic Stent Surfaces Using Adenoviral Vectors Tethered through Hydrolysable Cross-linkers

In-stent restenosis presents a major complication of stent-based revascularization procedures widely used to re-establish blood flow through critically narrowed segments of coronary and peripheral arteries. Endovascular stents capable of tunable release of genes with anti-restenotic activity may present an alternative strategy to presently used drug-eluting stents. In order to attain clinical translation, gene-eluting stents must exhibit predictable kinetics of stent-immobilized gene vector release and site-specific transduction of vasculature, while avoiding an excessive inflammatory response typically associated with the polymer coatings used for physical entrapment of the vector. This paper describes a detailed methodology for coatless tethering of adenoviral gene vectors to stents based on a reversible binding of the adenoviral particles to polyallylamine bisphosphonate (PABT)-modified stainless steel surface via hydrolysable cross-linkers (HC). A family of bifunctional (amine- and thiol-reactive) HC with an average t1/2 of the in-chain ester hydrolysis ranging between 5 and 50 days were used to link the vector with the stent. The vector immobilization procedure is typically carried out within 9 hr&#160;and consists of several steps: 1) incubation of the metal samples in an aqueous solution of PABT (4 hr); 2) deprotection of thiol groups installed in PABT with tris(2-carboxyethyl) phosphine (20 min); 3) expansion of thiol reactive capacity of the metal surface by reacting the samples with polyethyleneimine derivatized with pyridyldithio (PDT) groups (2 hr); 4) conversion of PDT groups to thiols with dithiothreitol (10 min); 5) modification of adenoviruses with HC (1 hr); 6) purification of modified adenoviral particles by size-exclusion column chromatography (15 min) and 7) immobilization of thiol-reactive adenoviral particles on the thiolated steel surface (1 hr). This technique has wide potential applicability beyond stents, by facilitating surface engineering of bioprosthetic devices to enhance their biocompatibility through the substrate-mediated gene delivery to the cells interfacing the implanted foreign material.

These studies report on reversible attachment of adenoviral gene vectors to coatless metal surfaces of stents and model mesh disks. Sustained release of transduction-competent viral particles contingent upon hydrolysis of cross-linkers used for vector immobilization results in a durable site-specific transgene expression in vascular cells and in stented arteries.

In-stent restenosis presents a major complication of stent-based revascularization procedures widely used to re-establish blood flow through critically ...

The Rabbit Model of Accelerated Atherosclerosis: A Methodological Perspective of the Iliac Artery Balloon Injury

Acute coronary syndrome resulting from coronary occlusion following atherosclerotic plaque development and rupture is the leading cause of death in the industrialized world. New Zealand White (NZW) rabbits are widely used as an animal model for the study of atherosclerosis. They develop spontaneous lesions when fed with atherogenic diet; however, this requires long time of 4 - 8 months. To further enhance and accelerate atherogenesis, a combination of atherogenic diet and mechanical endothelial injury is often employed. The presented procedure for inducing atherosclerotic plaques in rabbits uses a balloon catheter to disrupt the endothelium in the left iliac artery of NZW rabbits fed with atherogenic diet. Such mechanical damage caused by the balloon catheter induces a chain of inflammatory reactions initiating neointimal lipid accumulation in a time dependent fashion. Atherosclerotic plaque following balloon injury show neointimal thickening with extensive lipid infiltration, high smooth muscle cell content and presence of macrophage derived foam cells. This technique is simple, reproducible and produces plaque of controlled length within the iliac artery. The whole procedure is completed within 20 - 30 min. The procedure is safe with low mortality and also offers high success in obtaining substantial intimal lesions. The procedure of balloon catheter induced arterial injury results in atherosclerosis within two weeks. This model can be used for investigating the disease pathology, diagnostic imaging and to evaluate new therapeutic strategies.

Animal models of atherosclerosis are essential to understand the mechanism and to investigate newer approaches to prevent plaque development or rupture, a leading cause of death in the industrialized world. This protocol uses a combination of balloon injury and cholesterol rich diet to induce atherosclerotic plaques in rabbit iliac artery.

Acute coronary syndrome resulting from coronary occlusion following atherosclerotic plaque development and rupture is the leading cause of death in the ...

A Rabbit Model of Durable Transgene Expression in Jugular Vein to Common Carotid Artery Interposition Grafts

Vein graft bypass surgery is a common treatment for occlusive arterial disease; however, long-term success is limited by graft failure due to thrombosis, intimal hyperplasia, and atherosclerosis. The goal of this article is to demonstrate a method for placing bilateral venous interposition grafts in a rabbit, then transducing the grafts with a gene transfer vector that achieves durable transgene expression. The method allows the investigation of the biological roles of genes and their protein products in normal vein graft homeostasis. It also allows the testing of transgenes for the activities that could prevent vein graft failure, e.g., whether the expression of a transgene prevents the neointimal growth, reduces the vascular inflammation, or reduces atherosclerosis in rabbits fed with a high-fat diet. During an initial survival surgery, the segments of right and left external jugular vein are excised and placed bilaterally as reversed end-to-side common carotid artery interposition grafts. During a second survival surgery, performed 28 days later, each of the grafts is isolated from the circulation with vascular clips and the lumens are filled (via an arteriotomy) with a solution containing a helper-dependent adenoviral (HDAd) vector. After a 20-min incubation, the vector solution is aspirated, the arteriotomy is repaired, and flow is restored. The veins are harvested at time points dictated by individual experimental protocols. The 28-day delay between the graft placement and the transduction is necessary to ensure the adaptation of the vein graft to the arterial circulation. This adaptation avoids rapid loss of transgene expression that occurs in vein grafts transduced before or immediately after grafting. The method is unique in its ability to achieve durable, stable transgene expression in grafted veins. Compared to other large animal vein graft models, rabbits have advantages of low cost and easy handling. Compared to rodent vein graft models, rabbits have larger and easier-to-manipulate blood vessels that provide abundant tissue for analysis.

This method describes the placement of interposition vein grafts in rabbits, the transduction of the grafts, and the achievement of durable transgene expression. This allows the investigation of physiological and pathological roles of transgenes and their protein products in grafted veins, and testing of gene therapies for vein graft disease.

Vein graft bypass surgery is a common treatment for occlusive arterial disease; however, long-term success is limited by graft failure due to thrombosis, ...

Preclinical Model of Hind Limb Ischemia in Diabetic Rabbits

Peripheral vascular disease is a widespread clinical problem that affects millions of patients worldwide. A major consequence of peripheral vascular disease is the development of ischemia. In severe cases, patients can develop critical limb ischemia in which they experience constant pain and an increased risk of limb amputation. Current therapies for peripheral ischemia include bypass surgery or percutaneous interventions such as angioplasty with stenting or atherectomy to restore blood flow. However, these treatments often fail to the continued progression of vascular disease or restenosis or are contraindicated due to the overall poor health of the patient. A promising potential approach to treat peripheral ischemia involves the induction of therapeutic neovascularization to allow the patient to develop collateral vasculature. This newly formed network alleviates peripheral ischemia by restoring perfusion to the affected area. The most frequently employed preclinical model for peripheral ischemia utilizes the creation of hind limb ischemia in healthy rabbits through femoral artery ligation. In the past, however, there has been a strong disconnect between the success of preclinical studies and the failure of clinical trials regarding treatments for peripheral ischemia. Healthy animals typically have robust vascular regeneration in response to surgically induced ischemia, in contrast to the reduced vascularity and regeneration in patients with chronic peripheral ischemia. Here, we describe an optimized animal model for peripheral ischemia in rabbits that includes hyperlipidemia and diabetes. This model has reduced collateral formation and blood pressure recovery in comparison to a model with a higher cholesterol diet. Thus, the model may provide better correlation with human patients with compromised angiogenesis from the common co-morbidities that accompany peripheral vascular disease.

We describe a surgical procedure used to induce peripheral ischemia in rabbits with hyperlipidemia and diabetes. This surgery acts as a preclinical model for conditions experienced in peripheral artery disease in patients. Angiography is also described as a means to measure the extent of introduced ischemia and recovery of perfusion.

Peripheral vascular disease is a widespread clinical problem that affects millions of patients worldwide. A major consequence of peripheral vascular ...

A Rabbit Venous Interposition Model Mimicking Revascularization Surgery using Vein Grafts to Assess Intimal Hyperplasia under Arterial Blood Pressure

Although vein grafts have been commonly used as autologous grafts in revascularization surgeries for ischemic diseases, the long-term patency remains poor because of the acceleration of intimal hyperplasia due to the exposure to arterial blood pressure. The present protocol is designed for the establishment of experimental venous intimal hyperplasia by interposing rabbit jugular veins to the ipsilateral carotid arteries. The protocol does not require surgical procedures deep in the body trunk and the extent of the incision is limited, which is less invasive for the animals, allowing long-term observation after implantation. This simple procedure enables researchers to investigate strategies to attenuate the progression of intimal hyperplasia of the implanted vein grafts. Using this protocol, we reported the effects transduction of microRNA-145 (miR-145), which is known to control the phenotype of vascular smooth muscle cells (VSMCs) from the proliferative to the contractile state, into harvested vein grafts. We confirmed the attenuation of intimal hyperplasia of vein grafts by transducing miR-145 before implantation surgery through the phenotype change of the VSMCs. Here we report a less invasive experimental platform to investigate the strategies that can be used to attenuate intimal hyperplasia of vein grafts in revascularization surgeries.

The present protocol aims to experimentally create venous intimal hyperplasia by subjecting veins to arterial blood pressure for developing strategies to attenuate venous intimal hyperplasia following revascularization surgery using vein grafts.

Although vein grafts have been commonly used as autologous grafts in revascularization surgeries for ischemic diseases, the long-term patency remains poor ...

Implantation of Tissue-Engineered Vascular Graft in Mouse Carotid Artery via Cuff Technique

The development of small-diameter vascular grafts has been a global endeavor, with numerous research groups contributing to this field. Animal experimentation plays a pivotal role in assessing the efficacy and safety of vascular grafts, particularly in the absence of clinical applications. Compared to alternative animal models, the mouse implantation model offers several advantages, including a well-defined genetic background, a mature method for disease model construction, and a straightforward surgical procedure. Based on these advantages, the present study devised a simple cuff technique for the implantation of tissue-engineered vascular grafts in the mouse carotid artery. This technique began with the fabrication of polycaprolactone (PCL) small-diameter vascular grafts via electrostatic spinning, followed by the seeding of macrophages onto the grafts through perfusion adsorption. Subsequently,&#160;the cellularized tissue-engineered vascular grafts were transplanted into the mouse carotid artery using the cuff technique to evaluate patency and regenerative capability. After 30 days of in vivo implantation, vascular patency was found to be satisfactory, with evidence of neo-tissue regeneration and the formation of an endothelial layer within the lumen of the grafts. All data were analyzed using statistical and graphing software. This study successfully established a mouse carotid artery implantation model that can be used to explore the cellular sources of vascular regeneration and the mechanisms of action of active substances. Furthermore, it provides theoretical support for the development of novel small-diameter vascular grafts.

Here, a protocol is presented for the implantation of a tissue-engineered vascular graft into the mouse carotid artery using the cuff technique, providing a suitable animal model for investigating vascular tissue regeneration mechanisms.

The development of small-diameter vascular grafts has been a global endeavor, with numerous research groups contributing to this field. Animal ...

Bioengineering

Carotid Artery and Jugular Vein Interposition: A Technique to Induce Venous Intimal Hyperplasia in Rabbit Model

Source: Nishio, H., et al. <a href="https://www.jove.com/v/60931">A Rabbit Venous Interposition Model Mimicking Revascularization Surgery using Vein Grafts to Assess Intimal Hyperplasia under Arterial Blood Pressure</a> J. Vis. Exp. (2020).
This video demonstrates the interposition of the rabbit carotid artery with the jugular vein to induce venous intimal hyperplasia by subjecting the veins to arterial pressure. This model will help investigate molecular and genetic interventions to attenuate the progression of intimal hyperplasia after revascularization surgeries.

Source: Nishio, H., et al. A Rabbit Venous Interposition Model Mimicking Revascularization Surgery using Vein Grafts to Assess Intimal Hyperplasia under ...

In Vivo Gene Transfer to the Rabbit Common Carotid Artery Endothelium

Summary

Explore More Videos

Chapters in this video

A Model of Disturbed Flow-Induced Atherosclerosis in Mouse Carotid Artery by Partial Ligation and a Simple Method of RNA Isolation from Carotid Endothelium

A Strategy to Identify de Novo Mutations in Common Disorders such as Autism and Schizophrenia

Gene Transfer for Ischemic Heart Failure in a Preclinical Model

Vascular Gene Transfer from Metallic Stent Surfaces Using Adenoviral Vectors Tethered through Hydrolysable Cross-linkers

The Rabbit Model of Accelerated Atherosclerosis: A Methodological Perspective of the Iliac Artery Balloon Injury

A Rabbit Model of Durable Transgene Expression in Jugular Vein to Common Carotid Artery Interposition Grafts

Preclinical Model of Hind Limb Ischemia in Diabetic Rabbits

A Rabbit Venous Interposition Model Mimicking Revascularization Surgery using Vein Grafts to Assess Intimal Hyperplasia under Arterial Blood Pressure

Implantation of Tissue-Engineered Vascular Graft in Mouse Carotid Artery via Cuff Technique

Carotid Artery and Jugular Vein Interposition: A Technique to Induce Venous Intimal Hyperplasia in Rabbit Model