Modello murino di dall'arteria femorale Wire Injury con impianto di una Perivascolare Drug Delivery Patch
Summary
We describe a surgical technique that produces wire injury in the femoral artery of mice to induce neointimal hyperplasia to serve as a model testing system for the perivascular delivery of therapeutic compounds for the inhibition of restenosis.
Abstract
Percutaneous interventions including balloon angioplasty and stenting have been used to restore blood flow in vessels with occlusive vascular disease. While these therapies lead to the rapid restoration of blood flow, these technologies remain limited by restenosis in the case of bare metal stents and angioplasty, or reduced healing and possibly enhanced risk of thrombosis in the case of drug eluting stents. A key pathophysiological mechanism in the formation of restenosis is intimal hyperplasia caused by the activation of vascular smooth muscle cells and inflammation due to arterial stretch and injury. Surgeries that induce arterial injury in genetically modified mice are useful for the mechanistic study of the vascular response to injury but are often technically challenging to perform in mouse models due to the their small size and lack of appropriate sized devices. We describe two approaches for a surgical technique that induces endothelial denudation and arterial stretch in the femoral artery of mice to produce robust neointimal hyperplasia. The first approach creates an arteriotomy in the muscular branch of the femoral artery to obtain vascular access. Following wire injury this arterial branch is ligated to close the arteriotomy. A second approach creates an arteriotomy in the main femoral artery that is later closed through localized cautery. This method allows for vascular access through a larger vessel and, consequently, provides a less technically demanding procedure that can be used in smaller mice. Following either method of arterial injury, a degradable drug delivery patch can be placed over or around the injured artery to deliver therapeutic agents.
Introduction
Arterial injury and inflammation caused by angioplasty and stent implantation can induce neointimal hyperplasia that contributes to the thickening of the arterial wall, a process known as restenosis.1,2 The formation of restenosis is major mode of failure for interventions such as angioplasty and stenting with bare metal stents.3 Due to recent concerns with the inhibition of vascular healing in arteries treated with drug eluting stents, there is also a need to find compounds that can inhibit restenosis while maintaining vascular healing and re-endothelialization.4-7 In addition, while stents have had success in the coronary vasculature, percutaneous interventions of all types in the peripheral arteries continue to fail at a higher rate due to restenosis.8-10 Mouse models of surgical interventions allow the use of powerful genetic manipulations that can provide mechanistic insight into the mechanisms underlying the failure of clinical therapies and can provide an initial test bed for compounds to inhibit intimal hyperplasia.
Here, we describe a mouse model of vascular injury that allows the testing of therapeutic compounds to inhibit neointimal hyperplasia and assess whether their effects on re-endothelialization following endothelial denudation. A key challenge in executing vascular injury in mice is the technical skill needed to obtain vascular access and to restore flow to the injured artery following the wire injury. For this reason, simple arterial ligation models have been used to study neointimal hyperplasia in mice that do not require endovascular manipulations but are easier to implement.11 However, this type of surgical model differs substantially from the mechanical and biological aspects of a percutaneous intervention, lacking key aspects including arterial wall stretch, endothelial denudation and luminal blood flow following injury.
We present two methods for obtaining and closing vascular access for wire injury of the femoral artery in mice. The first technique is the conventional method described by several groups previously and uses vascular access through a side branch of the femoral artery.12-14 This method requires older, larger mice and more surgical skill to implement the endoluminal access through the smaller artery. It also requires the ligation of the muscular branch of the femoral artery following the procedure. The second method we describe uses an arteriotomy in the branch point of the main and side branch and thereby allows for a larger access to the artery for performing wire injury. In this method, the arteriotomy is closed using controlled local cauterization that leaves both branches with blood flow following the procedure. The conventional method is applicable to mice of at least 20 weeks of age while the alternative method can be used in mice of at least 15 weeks of age. In both methods, the wire creates arterial stretch and abrasion leading to injury and endothelial denudation. Following either procedure a perivascular drug delivery patch can be implanted that allows the delivery of compounds to alter the response to injury. The use of the drug delivery patch allows mice to be used as a test bed for new compounds to inhibit restenosis through perivascular therapies.15,16
Protocol
Representative Results
Discussion
We have presented a method for performing vascular injury in mice and delivery therapeutic compounds to the injured region through a perivascular cuff. The ligation method for femoral and carotid arteries has been described in conventional methods papers and characterized extensively11-14,19-23 and we present an alternative method for achieving the same vascular injury that is less technically demanding procedure that can often be used in younger mice. One of the chief advantages of the using a mouse wire inju…
Disclosures
The authors have nothing to disclose.
Acknowledgements
The authors would like to acknowledge support through the American Heart Association (10SDG2630139), the Welch Foundation and through the NIH Director’s New Innovator Grant (1DP2 OD008716-01). The authors would like to thank the services provided by the ICMB (Institute of Cellular and Molecular Biology) core facility and TherapeUTex at University of Texas at Austin.
Materials
| Name | Company | Catalog Number | Comments |
| Straight spring wire, 0.15” diameter | Cook | G02426 | |
| High Temperature cautery | Bovie Medical Corp. | HIT1 | |
| High-temperature fine tip for cautery | Bovie Medical Corp. | H101 | |
| Micro-scissors | Fine Science Tools | 15000-13 | For performance of arteriotomy |
| Angled fine-tipped forceps | Fine Science Tools | 11251-35 | For blunt dissection of vascular bundle |
| Angled forceps | Roboz | RS-5069 | For clearing tissues |
| Surgical scissors | Roboz | RS-5840 | For cutting skin |
| Retractor | Fine Science Tools | 18200-10 | |
| Retractor wire | Fine Science Tools | 18200-05 | Attached to retractor |
| Base plate | Fine Science Tools | 18200-03 | For use with retractor |
| Magnetic retractor fixator | Fine Science Tools | 18200-01 | |
| Needle Holder | Roboz | RS-7822 | |
| Hemostatic forceps | Biomedical Research Instruments, Inc. | 34-1000 | |
| Dissecting microscope | Meiji Techno | EMZ-5TR | |
| Microscope light source | Meiji Techno | FT191 | |
| Warm water recirculator | Gaymar | TP-500 | For maintaining mouse body temperature |
| Reusable heating pad | Gaymar | TP-R 22G | For maintaining mouse body temperature |
| Lidocaine | Various | ||
| 4.0 Vicryl suture with half circle needle | Ethicon | J494G | For post-surgical wound closure |
| Sterile cotton-tipped applicators | Puritan | 25-806-2WC | For application of depilatory cream and absorbing fluids |
| Depilatory cream | Nair | ||
| Isoflurane | Various | ||
| Betadine | Various | ||
| 70% ethanol | Various | ||
| 6.0 braided silk suture | Teleflex Medical | 4-S | For isolation of femoral artery during surgery |
| 0.9% sodium chloride | Various | For irrigating tissues | |
| Gel eye lubricant | Various | ||
| Glass petri dish | Pyrex | 3160-60 | For femoral artery harvest |
| 10% buffered formalin | Various | For fixation of femoral artery | |
| 70% ethanol | Various | For fixation of femoral artery | |
| Bouin's fluid | Electron Microscopy Sciences | For Movat's Pentachrome staining | |
| Alcian blue, 1% | Electron Microscopy Sciences | 26385-01 | For Movat's Pentachrome staining |
| Alkaline alcohol | Electron Microscopy Sciences | 26385-02 | For Movat's Pentachrome staining |
| Orcein, 0.2% | Electron Microscopy Sciences | 26385-03 | For Movat's Pentachrome staining |
| Hematoxylin alcoholic, 5% | Electron Microscopy Sciences | 26385-04 | For Movat's Pentachrome staining |
| Ferric chloride, 10% | Electron Microscopy Sciences | 26385-05 | For Movat's Pentachrome staining |
| Lugol's Iodine | Electron Microscopy Sciences | 26385-06 | For Movat's Pentachrome staining |
| Woodstain scarlet-acid fuchsin working solution | Electron Microscopy Sciences | 26385-07 | For Movat's Pentachrome staining |
| Acetic acid, 0.5% | Electron Microscopy Sciences | Various | For Movat's Pentachrome staining |
| Phosphotungstic acid, 5% | Electron Microscopy Sciences | 26385-09 | For Movat's Pentachrome staining |
| Alcoholic saffron, 6% | Electron Microscopy Sciences | 26385-10 | For Movat's Pentachrome staining |
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