Echocardiographic and Histological Examination of Cardiac Morphology in the Mouse
Summary
Echocardiographic examination is frequently used in mice. Expensive high-resolution ultrasound devices have been developed for this purpose. This protocol describes an affordable echocardiographic procedure combined with histological morphometric analyses to determine cardiac morphology.
Abstract
An increasing number of genetically modified mouse models has become available in recent years. Moreover, the number of pharmacological studies performed in mice is high. Phenotypic characterization of these mouse models also requires the examination of cardiac function and morphology. Echocardiography and magnetic resonance imaging (MRI) are commonly used approaches to characterize cardiac function and morphology in mice. Echocardiographic and MRI equipment specialized for use in small rodents is expensive and requires a dedicated space. This protocol describes cardiac measurements in mice using a clinical echocardiographic system with a 15 MHz human vascular probe. Measurements are performed on anesthetized adult mice. At least three image sequences are recorded and analyzed for each animal in M-mode in the parasternal short-axis view. Afterwards, cardiac histological examination is performed, and cardiomyocyte diameters are determined on hematoxylin-eosin- or wheat germ agglutinin (WGA)-stained paraffin sections. Vessel density is determined morphometrically after Pecam-1 immunostaining. The protocol has been applied successfully to pharmacological studies and different genetic animal models under baseline conditions, as well as after experimental myocardial infarction by the permanent ligation of the left anterior descending coronary artery (LAD). In our experience, echocardiographic investigation is limited to anesthetized animals and is feasible in adult mice weighing at least 25 g.
Introduction
A large variety of genetically modified mouse models are available, and the number of pharmacological studies in mice is high1,2. Echocardiography and MRI are commonly used approaches for the phenotypic characterization of cardiac function and morphology in these mouse models3. The aim of the presented protocol is to analyze cardiac function and morphology in adult mice. It combines echocardiographic, histological, and immunohistochemical measurements. Echocardiographic examination is widely used in mice4,5,6,7,8,9,10,11,12. Pachon et al.11 identified 205 studies published in Circulation, Circulation Research, American Journal of Physiology – Heart and Circulatory Physiology, and Cardiovascular Research between 2012 and 2015 that used echocardiographic examination in animals.
Echocardiography is used to identify cardiac phenotypes in genetically modified mice5,6,13,14,15,16,17,18,19,20,21,22, as well as to analyze cardiac function in chronic overload-induced hypertrophy, myocardial ischemia, and cardiomyopathy models in mice (reviewed in12). Improved echocardiography equipment allows for the the standard measure of left-ventricular (LV) systolic and diastolic dimensions, tissue Doppler imaging, myocardial contrast echography, and the assessment of LV regional function and coronary reserve12. Ideally, echocardiographic examination should be performed in conscious mice to avoid the negative effects of anesthesia on contractile function, autonomic reflex control, and heart rate11. Nevertheless, this approach is limited by the requirement to train the animals; difficulties in keeping the body temperature stable; movement artifacts; stress; very high cardiac frequencies; and the requirement for at least two investigators to perform the experiment, especially if a large number of animals are under investigation. Interestingly, a recent study reported no differences in echocardiographic parameters in trained and untrained animals19. We perform echocardiographic measurements in anesthetized mice. Different anesthesia protocols will be discussed below.
Although standard resolution echocardiography (>10 MHz) is sufficient to measure LV systolic and diastolic dimensions and cardiac function in adult mice, the method is limited in its description of underlying structural phenomena. Thus, we combine the in vivo measurements with histological and immunohistological analyses to measure, for example, cardiomyocyte diameter and vessel density. Other histological and immunohistological investigations, such as the determination of proliferation, examination of apoptosis, infarct size measurements, determination of fibrosis, and specific marker expression, can also be performed on the same type of processed tissue but are not the subject of this protocol. The combination of in vivo echocardiographic examination with histological analyses provides additional insights into underlying structural alterations. In an additional step, we can complete these measurements with molecular and ultra-structural investigations. Histological analyses not only complete the echocardiographic examination but also become indispensible when the resolution of echocardiography is not sufficient. This is especially the case in models of genetically modified mice that are embryonic lethal23,24.
Protocol
Representative Results
Discussion
Different methods have been developed to evaluate cardiac structure and function in mice, including echocardiography, contrast-enhanced MRI, micro CT, and PET scan. Due to its cost-effectiveness and simplicity, echocardiography is the most widely used technique for functional analysis in mice11. In general, because of the small size of the heart and the high frequency of the heart rate in mice, transducers with a frequency >10 MHz should be used, although successful measurements have been repo…
Declarações
The authors have nothing to disclose.
Acknowledgements
The work was supported by the French Government (National Research Agency, ANR) through the "Investments for the Future" LABEX SIGNALIFE program (reference ANR-11-LABX-0028-01) and by grants to K. D. W. from the Association pour la Recherche sur le Cancer, Fondation de France, and Plan Cancer Inserm. D. B. and A. V. received fellowships from the Fondation pour la Recherche Médicale and from the City of Nice, respectively. The echocardiograph and the transducer were kindly provided by Philips. We thank A. Borderie, S. Destree, M. Cutajar-Bossert, A. Landouar, A. Martres, A. Biancardini, and S. M. Wagner for their skilled technical assistance.
Materials
| Wheat germ agglutinin (WGA) conjugated tetramethylrhodamine | Life Technologies, Molecular Probes | W849 | |
| Biotinylated Goat Anti-Rabbit IgG Antibody | Vectorlabs | BA-1000 | |
| Avidin/Biotin Blocking Kit | Vectorlabs | SP-2001 | |
| VECTASTAIN Elite ABC HRP Kit (Peroxidase, Standard) | Vectorlabs | PK-6100 | |
| VECTASHIELD Antifade Mounting Medium with DAPI | Vectorlabs | H-1200 | |
| SIGMAFAST 3,3'-Diaminobenzidine tablets | Sigma | D4168 | |
| Hydrogen peroxide solution | Sigma | H1009 | |
| Anti-Pecam-1 (CD31) antibody | Abcam | ab28364 | |
| Ultrasound transmission gel, Gel Aquasonic 100 | Parker | ||
| Linear ultrasound probe, L15-7io | Philips Healthcare | ||
| Echocardiograph, IE33 xMATRIX | Philips Healthcare | ||
| Microscope, Leica DMi8 | Leica | ||
| Fluorescence Filterset DAPI | Leica | 11525304 | |
| Filterset TxR | Leica | 11525310 | |
| Digital Camera, SPOT RT3 Color Slider | Spot Imaging | ||
| Imaging Software, SPOT 5.2 Advanced and Basic Software | Spot Imaging | ||
| Imaging Computer | Dell | ||
| Fine Scissors | Fine Science Tools | 14028-10 | |
| Large Scissors | Fine Science Tools | 14501-14 | |
| Scalpel blades | Fine Science Tools | 10023-00 | |
| Graefe Forceps | Fine Science Tools | 11650-10 | |
| Rodent shaver | Harvard Apparatus | 34-0243 | |
| cassettes for paraffin embedding | Sakura | 4155F | |
| neutral buffered Formalin | Sakura | 8727 | |
| Xylene | Sakura | 8733 | |
| Paraffine TEK III | Sakura | 4511 | |
| automated embedding apparatus, Tissue-Tek VIP | Sakura | 6032 | |
| paraffin-embedding station Tissue-Tek TEC 5 | Sakura | 5229 | |
| microtome blades,Accu-Edge S35 | Sakura | 4685 | |
| microscopy slides, Tissue-Tek | Sakura | 9533 | |
| cover slips, Tissue-Tek | Sakura | 9582 | |
| Mounting medium Tissue-Tek | Sakura | 1408 | |
| slide boxes | Sakura | 3958 | |
| eosine solution | Sakura | 8703 | |
| hematoxyline solution | Sakura | 8711 | |
| microtome, RM2125RT | Leica | 720-1880 (VWR) | |
| water bath, Leica HI1210 | Leica | 720-0113(VWR) | |
| Ethanol | VWR | ACRO444220050 | |
| 15 ml tubes | VWR | 734-0451 | |
| staining glass dish | VWR | MARI4220004 | |
| staining jars | VWR | MARI4200005 | |
| Incubator | Binder | 9010-0012 | |
| DAB and urea hydrogen peroxide tablets, SIGMAFAST 3,3′-Diaminobenzidine tablets | Sigma | D4293 | |
| PBS (10X) | Thermo Fisher Scientific | 70011044 |
Referências
- Ormandy, E. H., Dale, J., Griffin, G. Genetic engineering of animals: ethical issues, including welfare concerns. Can Vet J. 52 (5), 544-550 (2011).
- Karl, T., Pabst, R., von Hörsten, S. Behavioral phenotyping of mice in pharmacological and toxicological research. Exp Toxicol Pathol. 55 (1), 69-83 (2003).
- Phoon, C. K., Turnbull, D. H. Cardiovascular Imaging in Mice. Curr Protoc Mouse Biol. 6 (1), 15-38 (2016).
- Wagner, N., et al. Peroxisome proliferator-activated receptor beta stimulation induces rapid cardiac growth and angiogenesis via direct activation of calcineurin. Cardiovasc Res. 83 (1), 61-71 (2009).
- Wagner, K. D., Vukolic, A., Baudouy, D., Michiels, J. F., Wagner, N. Inducible Conditional Vascular-Specific Overexpression of Peroxisome Proliferator-Activated Receptor Beta/Delta Leads to Rapid Cardiac Hypertrophy. PPAR Res. 2016, 7631085 (2016).
- Ghanbarian, H., et al. Dnmt2/Trdmt1 as Mediator of RNA Polymerase II Transcriptional Activity in Cardiac Growth. PLoS One. 11 (6), e0156953 (2016).
- Meguro, T., et al. Cyclosporine attenuates pressure-overload hypertrophy in mice while enhancing susceptibility to decompensation and heart failure. Circ Res. 84 (6), 735-740 (1999).
- de Araújo, C. C., et al. Regular and moderate aerobic training before allergic asthma induction reduces lung inflammation and remodeling. Scand J Med Sci Sports. 26 (11), 1360-1372 (2016).
- Benavides-Vallve, C., et al. New strategies for echocardiographic evaluation of left ventricular function in a mouse model of long-term myocardial infarction. PLoS One. 7 (7), e41691 (2012).
- Colazzo, F., et al. Murine left atrium and left atrial appendage structure and function: echocardiographic and morphologic evaluation. PLoS One. 10 (4), e0125541 (2015).
- Pachon, R. E., Scharf, B. A., Vatner, D. E., Vatner, S. F. Best anesthetics for assessing left ventricular systolic function by echocardiography in mice. Am J Physiol Heart Circ Physiol. 308 (12), H1525-H1529 (2015).
- Gao, S., Ho, D., Vatner, D. E., Vatner, S. F. Echocardiography in Mice. Curr Protoc Mouse Biol. 1, 71-83 (2011).
- Mor-Avi, V., et al. Current and evolving echocardiographic techniques for the quantitative evaluation of cardiac mechanics: ASE/EAE consensus statement on methodology and indications endorsed by the Japanese Society of Echocardiography. J Am Soc Echocardiogr. 24 (3), 277-313 (2011).
- Collins, K. A., Korcarz, C. E., Lang, R. M. Use of echocardiography for the phenotypic assessment of genetically altered mice. Physiol Genomics. 13 (3), 227-239 (2003).
- Rottman, J. N., Ni, G., Brown, M. Echocardiographic evaluation of ventricular function in mice. Echocardiography. 24 (1), 83-89 (2007).
- Hart, C. Y., Burnett, J. C., Redfield, M. M. Effects of avertin versus xylazine-ketamine anesthesia on cardiac function in normal mice. Am J Physiol Heart Circ Physiol. 281 (5), H1938-H1945 (2001).
- Moran, C. M., Thomson, A. J., Rog-Zielinska, E., Gray, G. A. High-resolution echocardiography in the assessment of cardiac physiology and disease in preclinical models. Exp Physiol. 98 (3), 629-644 (2013).
- Fayssoil, A., Tournoux, F. Analyzing left ventricular function in mice with Doppler echocardiography. Heart Fail Rev. 18 (4), 511-516 (2013).
- Schoensiegel, F., et al. High throughput echocardiography in conscious mice: training and primary screens. Ultraschall Med. 32, S124-S129 (2011).
- Yariswamy, M., et al. Cardiac-restricted Overexpression of TRAF3 Interacting Protein 2 (TRAF3IP2) Results in Spontaneous Development of Myocardial Hypertrophy, Fibrosis, and Dysfunction. J Biol Chem. 291 (37), 19425-19436 (2016).
- Jara, A., et al. Cardiac-Specific Disruption of GH Receptor Alters Glucose Homeostasis While Maintaining Normal Cardiac Performance in Adult Male Mice. Endocrinology. 157 (5), 1929-1941 (2016).
- Kerr, B. A., et al. Stability and function of adult vasculature is sustained by Akt/Jagged1 signalling axis in endothelium. Nat Commun. 7, 10960 (2016).
- Wagner, N., et al. Coronary vessel development requires activation of the TrkB neurotrophin receptor by the Wilms’ tumor transcription factor Wt1. Genes Dev. 19 (21), 2631-2642 (2005).
- Wagner, K. D., et al. The Wilms’ tumour suppressor Wt1 is a major regulator of tumour angiogenesis and progression. Nat Commun. 5, 5852 (2014).
- Yang, X. P., et al. Echocardiographic assessment of cardiac function in conscious and anesthetized mice. Am J Physiol. 277 (5 Pt 2), H1967-H1974 (1999).
- Rottman, J. N., et al. Temporal changes in ventricular function assessed echocardiographically in conscious and anesthetized mice. J Am Soc Echocardiogr. 16 (11), 1150-1157 (2003).
- Quiñones, M. A., et al. Recommendations for quantification of Doppler echocardiography: a report from the Doppler Quantification Task Force of the Nomenclature and Standards Committee of the American Society of Echocardiography. J Am Soc Echocardiogr. 15 (2), 167-184 (2002).
- van Laake, L. W., et al. Monitoring of cell therapy and assessment of cardiac function using magnetic resonance imaging in a mouse model of myocardial infarction. Nat Protoc. 2 (10), 2551-2567 (2007).
- Wagner, K. D., et al. The Wilms’ tumor suppressor Wt1 is expressed in the coronary vasculature after myocardial infarction. FASEB J. 16 (9), 1117-1119 (2002).
- Wagner, K. D., et al. RNA induction and inheritance of epigenetic cardiac hypertrophy in the mouse. Dev Cell. 14 (6), 962-969 (2008).
- Schneider, C. A., Rasband, W. S., Eliceiri, K. W. NIH Image to ImageJ: 25 years of image analysis. Nat Methods. 9 (7), 671-675 (2012).
- Ruifrok, A. C., Johnston, D. A. Quantification of histochemical staining by color deconvolution. Anal Quant Cytol Histol. 23 (4), 291-299 (2001).
- Lazzeroni, D., Rimoldi, O., Camici, P. G. From Left Ventricular Hypertrophy to Dysfunction and Failure. Circ J. 80 (3), 555-564 (2016).
- Ismail, J. A., et al. Immunohistologic labeling of murine endothelium. Cardiovasc Pathol. 12 (2), 82-90 (2003).
- Benton, R. L., Maddie, M. A., Minnillo, D. R., Hagg, T., Whittemore, S. R. Griffonia simplicifolia isolectin B4 identifies a specific subpopulation of angiogenic blood vessels following contusive spinal cord injury in the adult mouse. J Comp Neurol. 507 (1), 1031-1052 (2008).
- Ayoub, A. E., Salm, A. K. Increased morphological diversity of microglia in the activated hypothalamic supraoptic nucleus. J Neurosci. 23 (21), 7759-7766 (2003).
- Maddox, D. E., Shibata, S., Goldstein, I. J. Stimulated macrophages express a new glycoprotein receptor reactive with Griffonia simplicifolia I-B4 isolectin. Proc Natl Acad Sci U S A. 79 (1), 166-170 (1982).
- dela Paz, N. G., D’Amore, P. A. Arterial versus venous endothelial cells. Cell Tissue Res. 335 (1), 5-16 (2009).
