Penn MCRC > Mouse Cardiovascular Physiology & Microsurgery Core

Mouse Cardiovascular Physiology & Microsurgery Core

Description

The Mouse Cardiovascular Physiology & Microsurgery Core is a component of Molecular Cardiology Research Center under the direction of Dr. Tao Wang. This core facility is dedicated to aid investigators with a central resource for creating mouse models of cardiovascular disease, which provides a unique and valuable research opportunity for translational research from animal studies to humans. We offer a wide variety of invasive surgical procedures and noninvasive ultrasound imaging techniques for comprehensive evaluation of cardiovascular phenotypes of transgenic and knockout mice that may be difficult or time-consuming for those investigators without proper expertise, experience and equipments. In addition, we offer microsurgery trainings and technique assistance for faculty, staff, fellows and students whose work requires microsurgical manipulations. Use of the core service is now available to all investigators of The University of Pennsylvania Cardiovascular Institute (CVI).

Services: Surgical Procedures and Physiological Evaluations

Services are oriented towards providing investigators with data suitable for use in grant proposals or manuscripts. While the central focus of the facility is cardiovascular research, the techniques employed are often useful to investigators in other fields.

The facility is equipped for (1) mouse microsurgery to create and study animal models; (2) ambulatory blood pressure and ECG recordings (telemetry with DSI units); (3) evaluation of cardiac function using closed chest measurement of pressure and volume via a conductance catheter for hemodynamic recording; and (4) state-of-art echocardiographic and Doppler imaging (Visual Sonic machine).

Our core currently provides the following services to the investigators of Molecular Cardiology Research Center. Investigators will be responsible for the costs incurred for their projects and prior animal protocol approval.

Murine Models of Cardiovascular Disease

Cardiac Models (myocardial infarction, heart failure and hypertrophy)

I.Myocardial infarction (MI) models: for studying the development of left ventricular dilation, remodeling and heart failure

(a) Ligation of left anterior descending (LAD) coronary artery, with or without reperfusion

Mice of bodyweight 20-35gms are anesthetized with ketamin (100mg/kg, IP). The animal is placed on artificial ventilation and a thoracotomy is performed by separating the fifth and sixth ribs to expose the heart. The pericardium is opened and the heart is exteriorized by gentle pressure on the rib cage. A 7-0 silk ligature, entering the heart on the left margin of the pulmonary cone and exiting near the insertion of the left auricular appendage is placed and tied. After tying the ligature; occlusion of the left coronary artery is determined visually by the rapid blanching, caused by lack of arterial blood flow, of the left ventricular musculature. The ends of the occluding ligature are trimmed, the heart returned to the thoracic cavity and chest and skin incision were closed by 4-0 suture, and mouse was removed from the ventilator. The sham procedure is performed in an identical manner, with the exception that the occluding ligature is not tied.

(b) Using cryo-injury to induced size-reproducible MI for left ventricle (LV) remodeling studies (mechanism and/or therapeutic intervention)

(c) Quantitative measurement of infarct size by TTC staining and area at risk by microspheres fluorescent staining

II. Aortic banding model for inducing pressure over load LV hypertrophy & heart failure in mice

Mouse was anesthetized with 1% isoflurane delivered via nose cone. A horizontal incision was made at the level of suprasternal notch. Visualization of aortic arch was gained by cut-open the proximal portion of the sternum. A 7-0 silk suture was place around the aorta between the origin of the right innominate and left common carotid artery. Transaortic constriction (TAC) was created using a 7-0 suture tied twice around the aorta and a 27-gauge needle. The needle was then gently retracted, yielding a 60-80% constriction with an outer aortic diameter of approximately 0.3 mm. The sham procedure was identical except that the aorta was not ligated.

III. Abdominal A-V shunt model of volume-overload induced heart failure

Briefly, mouse was anesthetized with pentobarbital sodium (60 mg/kg body wt), and an excision was made along the abdominal cavity and the visceral organs displaced. The descending aorta was isolated and clamped between the renal arteries to the iliac aortic bifurcation. The aorta was punctured through the adjacent wall and into the inferior vena cava with a 26-gauge needle. The needle was removed fully, and the initial aortic entry puncture point was closed with 11-0 suture. The clamps was removed after 10-20 s to insure proper drying, and the patency of the shunt was verified visually by mixing of arterial and venous blood. The entire surgical procedure took <10 min. The sham-operated control protocol was identical to AV shunt induction, except no aortic puncture was performed. This method of induction of volume-overload cardiac hypertrophy has been shown to produce an "eccentric" form of cardiac hypertrophy that is characterized by normal wall thickness, a disproportionately large increase in heart chamber volume.

IV. Drug induced myocardial hypertrophy or hypertension by implanting osmotic pump:

(a) Using Angiotension II (0.75-1.5 mg/kg/day, Sigma-Aldrich) induces hypertension and cardiac hypertrophy

(b) Using Isoprotenol (17-30 mg/kg/day, Sigma-Aldrich) to induce cardiac hypertrophy

(c) Testing of substance (drugs, antibody, small molecules, etc) for potential human use on rodent models

V. Heterotopic heart transplantation model.

(1) Transplant studies

(2) Simulate the condition for studying left ventricular remodeling after using left ventricular assist device

Vascular Models

I. Vascular stenosis model:

(a) Carotid artery injury model: using wires or ligation

(b) Vein isograft and allograft

II. Transplant arteriosclerosis models.

(a) Carotid artery transplantation (isograft or allograft)

(b) Abdominal aorta transplantation (isograft or allograft)

III. Arteriovenous (AV) shunt (connect carotid artery to jugular vein by arteriovenous anastomosis)

IV. Mouse model of angiogenesis (Hindlimb ischemia model): The femoral artery of one hindlimb will be ligated. It can serve as a platform to evaluate therapeutic angiogenesis with gene therapy and stem cell therapy.

V. Abdominal aneurysm model

VI. Gene therapy delivery and stem cell therapy for atherosclerosis or therapeutic angiogenesis

VII. Constant pressure perfusion fixation for heart and vessels

Customized Surgeries

In addition to the models listed above, other techniques or specialized surgery may be available upon request by investigators.

Physiological Function Assessment

I. Echocardiography (2-D, M-mode, Doppler flows, or complete analysis) for evaluating cardiac structure and function

II. Ambulatory ECG or arterial blood pressure recording and data analysis with Data Science International (DSI) telemetry unit

III. Invasive hemodynamic measurements of in vivo cardiac function and analysis

Indices of left ventricular contractile performance are determined in mice under isoflurane anesthesia by introducing a 1.4 Fr. Millar catheter into the right carotid artery and gently advancing into left ventricular cavity. Pressure waves are recorded and analyzed by Chart 5 software.

(1) Basic recordings: (a) Left ventricular systolic pressure (LVSP, mmHg); (b) Left ventricular end diastolic pressure (LVEDP, mmHg); (c) Heart rate ( BPM, beats per min) (d) Positive dP/dt max-first derivative of LV pressure. This index is a measure of rate of pressure development in the left ventricle (mmHg/msec); (e) Negative dp/dtmin)-First derivative of LV pressure. This index is a measure of the rate of ventricular relaxation, or the rate of pressure decay in the LV (mmHg/msec).

(2) Left ventricular Pressure: Volume loop measurement and data analysis

Microsurgery Training and Assistance

The growing availability of well-defined genetic strains and the ability to create transgenic and knockout mice have made mouse models extremely valuable biomedical tools. However, their suitability for cardiovascular research may depend on the individual investigators ability to manipulate the mouse surgically. Many mouse models of cardiovascular disease require advanced microsurgical skills, which hitherto could not be performed without practical training.

Core Staff will work closely with researchers to assess their needs and provide the appropriate level of hands-on technical training, and scientific assistance in animal protocol preparation.

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Contact

Tao Wang, MD, Ph.D., Director
982 BRB II/III
Molecular Cardiology Research Center
Cardiovascular Institute
University of Pennsylvania
421 Curie Blvd., Philadelphia, PA 19104

Email: wangtao@mail.med.upenn.edu
Phone: 215-898-2656

Mark L. Kahn, MD, Supervisor
Email: markkahn@mail.med.upenn.edu
Phone: (215) 898-9007

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Forms

Request Forms for Physiology & Microsurgery Core services [doc]

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Useful Links

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