This work was supported by research grants from the Ministry of Education, Culture, Sports, Science and Technology, Japan (25462136).

NOTE: All the surgical procedures performed on animals should be carried out in accordance with the Guide for the Care and Use of Laboratory Animals (www.nap.edu/catalog/5140.html) or other appropriate ethical guidelines. Protocols should be approved by the animal welfare committee at the appropriate institution before proceeding.
1. Preparation of animals
<ol>
	<li>Purchase male Japanese white rabbits (or rabbits with equivalent body size) weighing 2.7&#8211;3.0 kg.</li>
	<li>Acclimate the ...

<ol>
	<li>Causes of death, 2000-2016, Global Health Estimates (GHE). World Health Organization (WHO) Available from: <a target="_blank" href="https://www.who.int/healthinfo/global_burden_disease/estimates/en/">https://www.who.int/healthinfo/global_burden_disease/estimates/en/</a> (2019)</li><li>Benjamin, E. J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Heart+Disease+and+Stroke+Statistics-2019+Update:+A+Report+From+the+American+Heart+Association.">Heart Disease and Stroke Statistics-2019 Update: A Report From the American Heart Association.</a> Circulation. 139 (10), 56 (2019).</li><li>Norgren, L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Inter-Society+Consensus+for+the+Management+of+Peripheral+Arterial+Disease+(TASC+II).">Inter-Society Consensus for the Management of Peripheral Arterial Disease (TASC II).</a> Journal of Vascular Surgery. 45, 5-67 (2007).</li><li>Caliskan, E., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Saphenous+vein+grafts+in+contemporary+coronary+artery+bypass+graft+surgery.">Saphenous vein grafts in contemporary coronary artery bypass graft surgery.</a> Nature Reviews: Cardiology. , (2020).</li><li>Goldman, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Long-term+patency+of+saphenous+vein+and+left+internal+mammary+artery+grafts+after+coronary+artery+bypass+surgery:+results+from+a+Department+of+Veterans+Affairs+Cooperative+Study.">Long-term patency of saphenous vein and left internal mammary artery grafts after coronary artery bypass surgery: results from a Department of Veterans Affairs Cooperative Study.</a> Journal of the American College of Cardiology. 44 (11), 2149-2156 (2004).</li><li>Muto, A., Model, L., Ziegler, K., Eghbalieh, S. D., Dardik, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mechanisms+of+vein+graft+adaptation+to+the+arterial+circulation:+insights+into+the+neointimal+algorithm+and+management+strategies.">Mechanisms of vein graft adaptation to the arterial circulation: insights into the neointimal algorithm and management strategies.</a> Circulation Journal. 74 (8), 1501-1512 (2010).</li><li>Motwani, J. G., Topol, E. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Aortocoronary+saphenous+vein+graft+disease:+pathogenesis,+predisposition,+and+prevention.">Aortocoronary saphenous vein graft disease: pathogenesis, predisposition, and prevention.</a> Circulation. 97 (9), 916-931 (1998).</li><li>Schachner, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Pharmacologic+inhibition+of+vein+graft+neointimal+hyperplasia.">Pharmacologic inhibition of vein graft neointimal hyperplasia.</a> Journal of Thoracic and Cardiovascular Surgery. 131 (5), 1065-1072 (2006).</li><li>Kulik, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Secondary+prevention+after+coronary+artery+graft+surgery:+a+scientific+statement+from+the+American+Heart+Association.">Secondary prevention after coronary artery graft surgery: a scientific statement from the American Heart Association.</a> Circulation. 131 (10), 927-964 (2015).</li><li>Gerhard-Herman, M. D., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=2016+AHA/ACC+Guideline+on+the+Management+of+Patients+With+Lower+Extremity+Peripheral+Artery+Disease:+Executive+Summary:+A+Report+of+the+American+College+of+Cardiology/American+Heart+Association+Task+Force+on+Clinical+Practice+Guidelines.">2016 AHA/ACC Guideline on the Management of Patients With Lower Extremity Peripheral Artery Disease: Executive Summary: A Report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines.</a> Circulation. 135 (12), 686-725 (2017).</li><li>Aboyans, V., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=2017+ESC+Guidelines+on+the+Diagnosis+and+Treatment+of+Peripheral+Arterial+Diseases,+in+collaboration+with+the+European+Society+for+Vascular+Surgery+(ESVS):+Document+covering+atherosclerotic+disease+of+extracranial+carotid+and+vertebral,+mesenteric,+renal,+upper+and+lower+extremity+arteries+Endorsed+by:+the+European+Stroke+Organization+(ESO)+The+Task+Force+for+the+Diagnosis+and+Treatment+of+Peripheral+Arterial+Diseases+of+the+European+Society+of+Cardiology+(ESC)+and+of+the+European+Society+for+Vascular+Surgery+(ESVS).">2017 ESC Guidelines on the Diagnosis and Treatment of Peripheral Arterial Diseases, in collaboration with the European Society for Vascular Surgery (ESVS): Document covering atherosclerotic disease of extracranial carotid and vertebral, mesenteric, renal, upper and lower extremity arteries Endorsed by: the European Stroke Organization (ESO) The Task Force for the Diagnosis and Treatment of Peripheral Arterial Diseases of the European Society of Cardiology (ESC) and of the European Society for Vascular Surgery (ESVS).</a> European Heart Journal. 39 (9), 763-816 (2018).</li><li>Neumann, F. J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=2018+ESC/EACTS+Guidelines+on+myocardial+revascularization.">2018 ESC/EACTS Guidelines on myocardial revascularization.</a> European Heart Journal. 40 (2), 87-165 (2019).</li><li>Alexander, J. H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Efficacy+and+safety+of+edifoligide,+an+E2F+transcription+factor+decoy,+for+prevention+of+vein+graft+failure+following+coronary+artery+bypass+graft+surgery:+PREVENT+IV:+a+randomized+controlled+trial.">Efficacy and safety of edifoligide, an E2F transcription factor decoy, for prevention of vein graft failure following coronary artery bypass graft surgery: PREVENT IV: a randomized controlled trial.</a> Journal of the American Medical Association. 294 (19), 2446-2454 (2005).</li><li>Carrel, A., Guthrie, C. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Uniterminal+and+biterminal+venous+transplantations.">Uniterminal and biterminal venous transplantations.</a> Surgery, Gynecology and Obstetrics. 2 (3), 266-286 (1906).</li><li>Nabatoff, R. A., Touroff, A. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+maximal-size+vein+graft+feasible+in+the+replacement+of+experimental+aortic+defects,+long+term+observations+concerning+the+function+and+ultimate+fate+of+the+graft.">The maximal-size vein graft feasible in the replacement of experimental aortic defects, long term observations concerning the function and ultimate fate of the graft.</a> Bulletin of the New York Academy of Medicine. 28 (9), 616 (1952).</li><li>Kanar, E. A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Experimental+vascular+grafts.+I.+The+effects+of+dicetyl+phosphate+on+venous+autografts+implanted+in+the+thoracic+aorta+of+growing+pigs:+a+preliminary+report.">Experimental vascular grafts. I. The effects of dicetyl phosphate on venous autografts implanted in the thoracic aorta of growing pigs: a preliminary report.</a> Annals of Surgery. 138 (1), 73-81 (1953).</li><li>Jones, T. I., Dale, W. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Study+of+peripheral+autogenous+vein+grafts.">Study of peripheral autogenous vein grafts.</a> AMA Archives of Surgery. 76 (2), 294-306 (1958).</li><li>Stehbens, W. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Experimental+production+of+aneurysms+by+microvascular+surgery+in+rabbits.">Experimental production of aneurysms by microvascular surgery in rabbits.</a> Vascular Surgery. 7 (3), 165-175 (1973).</li><li>Bannister, C. M., Mundy, L. A., Mundy, J. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fate+of+small+diameter+cervical+veins+grafted+into+the+common+carotid+arteries+of+growing+rabbits.">Fate of small diameter cervical veins grafted into the common carotid arteries of growing rabbits.</a> Journal of Neurosurgery. 46 (1), 72-77 (1977).</li><li>Bergmann, M., Walther, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ultrastructural+changes+of+venous+autologous+bypass+grafts+in+rabbits:+correlation+of+patency+and+development.">Ultrastructural changes of venous autologous bypass grafts in rabbits: correlation of patency and development.</a> Basic Research in Cardiology. 77 (6), 682-694 (1982).</li><li>Murday, A. J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Intimal+hyperplasia+in+arterial+autogenous+vein+grafts:+a+new+animal+model.">Intimal hyperplasia in arterial autogenous vein grafts: a new animal model.</a> Cardiovascular Research. 17 (8), 446-451 (1983).</li><li>Quist, W. C., LoGerfo, F. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Prevention+of+smooth+muscle+cell+phenotypic+modulation+in+vein+grafts:+a+histomorphometric.">Prevention of smooth muscle cell phenotypic modulation in vein grafts: a histomorphometric.</a> Journal of Vascular Surgery. 16 (2), 225-231 (1992).</li><li>Davies, M. G., Dalen, H., Svendsen, E., Hagan, P. O. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Influence+of+perioperative+catheter+injury+on+the+long-term+vein+graft+function+and+morphology.">Influence of perioperative catheter injury on the long-term vein graft function and morphology.</a> Journal of Surgical Research. 66 (2), 109-114 (1996).</li><li>Davies, M. G., Dalen, H., Svendsen, E., Hagan, P. O. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Balloon+catheter+injury+and+vein+graft+morphology+and+function.">Balloon catheter injury and vein graft morphology and function.</a> Annals of Vascular Surgery. 10 (5), 429-442 (1996).</li><li>Jiang, Z., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+novel+vein+grat+model:+adaptation+to+differential+flow+environments.">A novel vein grat model: adaptation to differential flow environments.</a> American Journal of Physiology Heart and Circulatory Physiology. 286 (1), 240-245 (2004).</li><li>Ohnaka, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effect+of+microRNA-145+to+prevent+vein+graft+disease+in+rabbits+by+regulation+of+smooth+muscle+cell+phenotype.">Effect of microRNA-145 to prevent vein graft disease in rabbits by regulation of smooth muscle cell phenotype.</a> Journal of Thoracic and Cardiovascular Surgery. 148 (2), 676-682 (2014).</li><li>Nishio, H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=MicroRNA-145-loaded+poly(lactic-co-glycolic+acid)+nanoparticles+attenuate+venous+intimal+hyperplasia+in+a+rabbit+model.">MicroRNA-145-loaded poly(lactic-co-glycolic acid) nanoparticles attenuate venous intimal hyperplasia in a rabbit model.</a> Journal of Thoracic and Cardiovascular Surgery. 157 (6), 2242-2251 (2019).</li><li>Ohno, N., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Accelerated+reendothelialization+with+suppressed+thrombogenic+property+and+neointimal+hyperplasia+of+rabbit+jugular+vein+grafts+by+adenovirus-mediated+gene+transfer+of+C-type+natriuretic+peptide.">Accelerated reendothelialization with suppressed thrombogenic property and neointimal hyperplasia of rabbit jugular vein grafts by adenovirus-mediated gene transfer of C-type natriuretic peptide.</a> Circulation. 105 (14), 1623-1626 (2002).</li><li>Osgood, M. J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Surgical+vein+graft+preparation+promotes+cellular+dysfunction,+oxydative+stress,+and+intimal+hyperplasia+in+human+saphenous+vein.">Surgical vein graft preparation promotes cellular dysfunction, oxydative stress, and intimal hyperplasia in human saphenous vein.</a> Journal of Vascular Surgery. 60 (1), 202-211 (2014).</li><li>Shintani, T., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Intraoperative+transfection+of+vein+grafts+with+the+NFkappaB+decoy+in+a+canine+aortocoronary+bypass+model:+a+strategy+to+attenuate+intimal+hyperplasia.">Intraoperative transfection of vein grafts with the NFkappaB decoy in a canine aortocoronary bypass model: a strategy to attenuate intimal hyperplasia.</a> Annals of Thoracic Surgery. 74 (4), 1132-1137 (2002).</li><li>Petrofski, J. A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Gene+delivery+to+aortocoronary+saphenous+vein+grafts+in+a+large+animal+model+of+intimal+hyperplasia.">Gene delivery to aortocoronary saphenous vein grafts in a large animal model of intimal hyperplasia.</a> Journal of Thoracic and Cardiovascular Surgery. 127 (1), 27-33 (2004).</li><li>Steger, C. M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Neointimal+hyperplasia+in+a+porcine+model+of+vein+graft+disease:+comparison+between+organ+culture+and+coronary+artery+bypass+grafting.">Neointimal hyperplasia in a porcine model of vein graft disease: comparison between organ culture and coronary artery bypass grafting.</a> European Surgery. 43 (3), 174-180 (2011).</li><li>Thim, T., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Oversized+vein+grafts+develop+advanced+atherosclerosis+in+hypercholesterolemic+minipigs.">Oversized vein grafts develop advanced atherosclerosis in hypercholesterolemic minipigs.</a> BMC Cardiovascular Disorders. 12 (24), (2012).</li><li>Zou, Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mouse+model+of+venous+bypass+graft+arteriosclerosis.">Mouse model of venous bypass graft arteriosclerosis.</a> American Journal of Pathology. 153 (4), 1301-1310 (1998).</li><li>de Vries, M. R., Simons, K. H., Jukema, J. W., Braun, J., Quax, P. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Vein+graft+failure:+from+pathophysiology+to+clinical+outcomes.">Vein graft failure: from pathophysiology to clinical outcomes.</a> Nature Reviews Cardiology. 13 (8), 451-470 (2016).</li><li>Dietrich, H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rapid+development+of+vein+graft+atheroma+in+ApoE-deficient+mice.">Rapid development of vein graft atheroma in ApoE-deficient mice.</a> American Journal of Pathology. 157 (2), 659-669 (2000).</li><li>Kumar, A., Lindner, V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Remodeling+with+neointima+formation+in+the+mouse+carotid+artery+after+cessation+of+blood+flow.">Remodeling with neointima formation in the mouse carotid artery after cessation of blood flow.</a> Arteriosclerosis, Thrombosis, and Vascular Biology. 17 (10), 2238-2244 (1997).</li><li>Lindner, V., Fingerie, J., Reidy, M. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mouse+model+of+arterial+injury.">Mouse model of arterial injury.</a> Circulation Research. 73 (5), 792-796 (1993).</li><li>Moroi, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Interaction+of+genetic+deficiency+of+endothelial+nitric+oxide,+gender,+and+pregnancy+in+vascular+response+to+injury+in+mice.">Interaction of genetic deficiency of endothelial nitric oxide, gender, and pregnancy in vascular response to injury in mice.</a> Journal of Clinical Investigation. 101 (6), 1225-1232 (1998).</li></ol>

The authors have nothing to disclose.

The present protocol is designed to provide an experimental platform to test various molecular or genetic interventions for VSMCs to control the phenotype from the proliferative to the contractile state and subsequently attenuate the progression of venous intimal hyperplasia in vivo. Using this model, we successfully prepared intimal hyperplasia at 2 weeks after surgery (Figure 1A) and indicated the therapeutic potential of microRNA-145 to control the VSMC phenotype26...

The number of patients experiencing ischemic diseases due to atherosclerosis is increasing worldwide1. Despite the current advances in medical and surgical therapies for cardiovascular diseases, ischemic heart diseases, such as myocardial infarction, remain a major cause of morbidity and mortality2. Furthermore, peripheral arterial diseases characterized by reduced blood flow to the limbs induces critical limb ischemia, wherein approximately 40% of the patients lose their legs within 6 months of diagnosis, and the mortality rate is up to 20%3.
Revascularization surgeries, such as coronary artery bypass grafting (CABG) and bypass surgery for peripheral arteries, are major therapeutic options for ischemic diseases. The purpose of these surgeries is to provide a new blood pathway to provide sufficient blood flow toward the distal site of the stenotic or occluded lesions of the atherosclerotic arteries. Although in situ arterial grafts, such as internal thoracic arteries for CABG, are preferred as the bypass grafts because of the expected longer patency, vein grafts, such as autologous saphenous veins, are commonly used because of the higher accessibility and availability4. The weak point of the vein grafts is the poor patency rate compared to that of artery grafts5 due to accelerated intimal hyperplasia when subjected to arterial pressure, which leads to vein graft disease6.
Vein graft disease develops through the following three steps: 1) thrombosis; 2) intimal hyperplasia; and 3) atherosclerosis7. In order to address vein graft disease, a lot of basic research has been conducted8. Thus far, no pharmacological strategy other than antiplatelet and lipid-lowering therapies are recommended for secondary prevention after coronary or peripheral revascularization surgeries in recent guidelines9,10,11,12. Thus, to overcome vein graft disease, especially intimal hyperplasia, the establishment of a relevant experimental platform for further studies is required.
Intimal hyperplasia is an adaptive phenomenon that occurs in response to the change in the surroundings, where vascular smooth muscle cells (VSMCs) proliferate, accumulate, and generate extracellular matrix in the intima. Consequently, it presents a foundation for graft atheroma7. In the hyperplastic intima, VSMCs bear proliferation, and production rather than contraction, termed &#8220;phenotypic change&#8221;8. It is a key research target to control the phenotype of the VSMCs of the vein grafts to prevent vein graft disease, and numerous basic studies have been conducted on this topic8. However, a randomized controlled clinical study that aimed to achieve pharmacological control of the VSMC phenotype showed limited results13. Further, there are no standardized therapies to prevent intimal hyperplasia. More basic research, including animal model studies, is necessary.
To promote research in this field, it is crucial to establish an animal model that recapitulates vein grafts under arterial blood pressure, allowing a long-term, postoperative observation. Carrel et al. established a canine model of implantation of the external jugular vein into the carotid artery14. Therafter, a variety of vein grafts have been employed to investigate the physiological and pathological effects of alterations in arterial blood pressure, including the inferior vena cava engrafted into the thoracic or the abdominal aorta, or the saphenous vein engrafted into the femoral artery15,16,17. These models were built in larger animals, such as pigs or dogs, that are suitable for mimicking a vein graft disease in a clinical case. However, the establishment of an animal model that can be prepared without special surgical techniques and at a lower cost would be ideal for researchers trying to develop a new therapeutic strategy for attenuating intimal hyperplasia through VSMC phenotype control in vivo. Initially, the interposition of the jugular vein into the carotid artery in a rabbit was introduced in the field of neurosurgery18,19. Thereafter, it was applied to research on intimal hyperplasia20,21. The initial model consists of venous interposition alone, thus saving time. Moreover, a subsequent study demonstrated that the preparation of a vein graft also affected the intimal hyperplasia22. Davies et al. evaluated the effect of balloon catheter injury on the intimal hyperplasia in a rabbit venous interposition model23,24. Although balloon catheter injury in addition to vein interposition was more relevant to a clinical setting, a more reproducible model was also desired. Thus, Jiang et al. examined the impact of differential flow environments on intimal hyperplasia and established a distal branch ligation procedure as a reproducible model25. However, they employed a cuff technique at the time of vein graft interposition that seems different from hand-sewn anastomosis in the clinical setting. In the present protocol, we report a reproducible, clinically relevant, and broadly available procedure for the preparation of a rabbit venous interposition model to assess intimal hyperplasia under arterial blood pressure.

<table>
	<tbody>
		<tr>
			<td>10% Povidone-iodine solution</td>
			<td>Nakakita</td>
			<td>872612</td>
			<td>Surgical expendables</td>
		</tr>
		<tr>
			<td>2-0 VICRYL Plus</td>
			<td>Johnson and Johnson</td>
			<td>VCP316H</td>
			<td>Surgical expendables</td>
		</tr>
		<tr>
			<td>4-0 Silk suture</td>
			<td>Alfresa pharma</td>
			<td>GA04SB</td>
			<td>Surgical expendables</td>
		</tr>
		<tr>
			<td>8-0 polypropylene suture</td>
			<td>Ethicon</td>
			<td>8741H</td>
			<td>Surgical expendables</td>
		</tr>
		<tr>
			<td>Cefazorin sodium</td>
			<td>Nichi-Iko Pharmaceutical</td>
			<td>6132401D3196</td>
			<td>Antibiotics</td>
		</tr>
		<tr>
			<td>Fogarty Catheter (2Fr)</td>
			<td>Edwards Lifesciences LLC</td>
			<td>E-060-2F</td>
			<td>Surgical expendables</td>
		</tr>
		<tr>
			<td>Heparin</td>
			<td>Nipro</td>
			<td>873334</td>
			<td>Anticoagulant</td>
		</tr>
		<tr>
			<td>Intravenous catheter (20G)</td>
			<td>Terumo</td>
			<td>SR-OT2051C</td>
			<td>Surgical expendables</td>
		</tr>
		<tr>
			<td>Isoflurane</td>
			<td>Fujifilm</td>
			<td>095-06573</td>
			<td>Anesthesia</td>
		</tr>
		<tr>
			<td>Lidocaine hydrochloride</td>
			<td>MP Biomedicals</td>
			<td>193917</td>
			<td>Anesthesia</td>
		</tr>
		<tr>
			<td>Pentobarbital sodium</td>
			<td>Tokyo Chemical Industry</td>
			<td>P0776</td>
			<td>Anesthesia</td>
		</tr>
	</tbody>
</table>

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.

Figure 1A shows a representative image of successful intimal hyperplasia at 2 weeks after venous interposition surgery (upper panel). The lower panel shows the therapeutic effects of microRNA-145-loaded poly(lactic-co-glycolic acid) nanoparticles that attenuated the intimal hyperplasia (lower panel). Figure 1B shows the comparison of intimal hyperplasia between the control group using phosphate buffered saline control (PBS), control microRNA (Cont-miR), and micr...

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

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 ...

Our protocol provides an easy, cost-effective, reproducible and clinical relevant model for researchers in the field of venous intimal hyperplasia. Our protocol is economically, clinically, and technically balanced. Therefore, it is highly recommended for researchers who want to apply their in vitro outcomes to an in vivo setting.We believe that our protocol can be applied to a larger animal model for the development of new treatment strategies in ischemic heart and lower extremity diseases. Our protocol is mainly relevant to the field of cardiovascular surgery. However, it may also be used to address degenerative changes in arteriovenous fistulas in patients with end stage renal disease.After local anesthetic, and prophylactic antibiotic analgesic administration, disinfect the surgical site with 10%povidone-iodine. And make a 50 to 60 millimeter incision with a surgical scalpel in the cervical region of the anesthetized male Japanese white rabbit. Bluntly dissect the subcutaneous tissues and fascia to expose a 20 to 30 millimeter segment of the jugular vein.And use 4-0 silk sutures to ligate all of the branches of the exposed vein. Place a 2-0 silk suture around the internal and external jugular veins and make a one millimeter incision in the venous wall of the distal side of the vein. Insert a 2-French balloon catheter from the cut toward the proximal side of the vein.And ligate the 2-0 silk suture at the distal sites of the jugular veins. Inflate the balloon with 200 microliters of air. And use the balloon to denude the intima of the vein three times for endothelial exfoliation.After the third passage, ligate the proximal end of the vein and cut the vein at the distal site. Then insert a 20 gauge intravenous catheter into the harvested vein from the distal to the proximal direction, and cut the vein at the proximal site. To interpose the carotid artery with the harvest jugular vein, expose a 20 to 30 millimeter segment of the ipsilateral carotid artery.And separate the artery carefully from the nearby vein and nerve. Ligate all the branches of the exposed vein with 4-0 silk suture. And intravenously administer 200 International Units per kilogram of heparin sodium.Clamp the proximal and distal ends of the artery with surgical rubber clamps. And cut the artery between the clamps. Inject normal saline into the incised carotid artery proximally and distally to distend the artery.And place the harvest vein near the artery to anastomose the vessel in a reversed end-to-end fashion. To anastomose the proximal end of the vein to the distal end of the artery, place two anchor stitches of 8-0 polypropylene at the site and the opposite site. Add stitches the upper side of the anastomosis line between the anchor stitches.Flip the artery and the vein graft upside down. And add stitches on the remaining part of the anastomosis line. Next, remove the intravenous catheter from the vein and clamp the vein graft proximally.Declamp the carotid artery distally. And observe whether the vein graft expands gradually. Using 8-0 polypropylene interrupted sutures, anastomose the distal end of the vein to the proximal end of the artery.And declamp the artery to check for bleeding from the anastomosis sites. Finally, ligate the internal carotid artery with a 4-0 silk suture to simulate a poor runoff condition and to facilitate intimal hyperplasia. Then clean the wound with saline.Close the incision with 3-0 polyglactin 910 in layers. And allow the rabbit to fully recover with monitoring before returning the animal to its home cage. In this representative image, a successful intimal hyperplasia at 2 weeks after venous interposition surgery can be observed.Here, the therapeutic effects of microRNA-145 loaded poly(lactic-co-glycolic acid)nanoparticles on the intimal hyperplasia morphology can be observed. Indeed, treatment with microRNAs loaded with poly(lactic-co-glycolic acid)nanoparticles results in a significant attenuation of intimal hyperplasia. In addition, immunostaining for Ki-67, a cell proliferative marker, reveals fewer Ki-67-positive cells within the microRNA-145 treated group indicating a phenotype change in the vascular smooth muscle cells from the immature proliferative state to the mature contractile state.The main goal of our protocol is to achieve patency of the implanted graft. It is also important to confirm that the graft expands after declamping the carotid artery.

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5.5K Views.  Kyoto University. Our protocol provides an easy, cost-effective, reproducible and clinical relevant model for researchers in the field of venous intimal hyperplasia. Our protocol is economically, clinically, and technically balanced. Therefore, it is highly recommended for researchers who want to apply their in vitro outcomes to an in vivo setting.We believe that our protocol can be applied to a larger animal model for the development of new treatment strategies in ischemic heart and lower extremity dis...

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