We sought to establish a swine model of heart failure induced by left circumflex artery blockage and rapid pacing to test the effect and safety of intramyocardial administration of stem cells for cell-based therapies.
Although advances have been achieved in the treatment of heart failure (HF) following myocardial infarction (MI), HF following MI remains one of the major causes of mortality and morbidity around the world. Cell-based therapies for cardiac repair and improvement of left ventricular function after MI have attracted considerable attention. Accordingly, the safety and efficacy of these cell transplantations should be tested in a preclinical large animal model of HF prior to clinical use. Pigs are widely used for cardiovascular disease research due to their similarity to humans in terms of heart size and coronary anatomy. Therefore, we sought to present an effective protocol for the establishment of a porcine chronic HF model using closed-chest coronary balloon occlusion of the left circumflex artery (LCX), followed by rapid ventricular pacing induced with pacemaker implantation. Eight weeks later, the stem cells were administered by intramyocardial injection in the peri-infarct area. Then the infarct size, cell survival, and left ventricular function (including echocardiography, hemodynamic parameters, and electrophysiology) were evaluated. This study helps establish a stable preclinical large animal HF model for stem cell treatment.
Cardiovascular diseases, coronary artery disease (CAD) in particular, remain the major cause of morbidity and mortality in Hong Kong and worldwide1. In Hong Kong, a 26% increase from 2012 to 2017 of the number of CAD patients treated under the Hospital Authority was projected2. Among all CADs, acute myocardial infarction (MI) is a leading cause of death and subsequent complications, such as heart failure (HF). These contribute to significant medical, social, and financial burdens. In patients with MI, thrombolytic therapy or primary percutaneous coronary intervention (PCI) is an effective therapy in preserving life, but these therapies can only reduce cardiomyocyte (CM) loss during MI. The treatments available are unable to replenish the permanent loss of CMs, which leads to cardiac fibrosis, myocardial remodeling, cardiac arrhythmia, and eventually heart failure. The mortality rate at 1-year post-MI is around 7% with more than 20% patients developing HF3. In end-stage HF patients, heart transplantation is the only available effective therapy, but it is limited by a shortage of available organs. Novel therapies are necessary to reverse the development of post-MI HF. As a result, cell-based therapy is considered an attractive approach to repair the impaired CMs and ameliorate left ventricular (LV) function in HF following MI. Our previous studies found stem cell transplantation to be beneficial for heart function improvement after direct intramyocardial transplantation in small animal models of MI4,5. Standardized preclinical large animal HF protocols are thus needed to further test the efficacy and safety of stem cell transplantation before clinical use.
Recent decades have witnessed the widespread use of pigs in cardiovascular research for stem cell therapy. HF pigs are a promising model of translational research due to their similarity to humans in terms of cardiac size, weight, rhythm, function, and coronary artery anatomy. Moreover, porcine HF models can mimic post-MI HF patients in terms of CM metabolism, electrophysiological properties, and neuroendocrine changes under ischemic conditions6. The protocol presented here uses such a standardized pig HF model, employing a closed-chest coronary balloon occlusion of the left circumflex artery (LCX) followed by rapid pacing induced by pacemaker implantation. The study also optimizes the route of intramyocardial administration of stem cells for the treatment of post-MI HF. The purpose is to produce a porcine animal model of chronic myocardial infarction that can be used to develop treatments that are clinically relevant for patients with severe CAD.
Standard animal models are of paramount importance to understand the pathophysiology and mechanisms of diseases and test novel therapeutics. Our protocol establishes a porcine model of HF induced by left circumflex artery blockage and rapid pacing. Eight weeks after the induction of MI, the animals developed significant impairment of LVEF, LVEDD, LVESD, +dP/dt, and ESPVR. This protocol also tests the administration method of stem cell therapy for heart regeneration by intramyocardial injection. The infarct size, and card…
The authors have nothing to disclose.
The authors acknowledge Alfreda and Kung Tak Chung for their excellent technical support during the animal experiments.
Amiodarone | Mylan | – | – |
Anaesthetic machines and respirator | Drager | Fabius plus XL | – |
Angiocath | Becton Dickinson | 381147 | – |
Anti-human nuclear antigen | abcam | ab19118 | – |
Axio Plus image capturing system | Zeiss | Axioskop 2 PLUS | Axioskop 2 plus |
AxioVision Rel. 4.5 software | Zeiss | – | – |
Baytril | Bayer | – | enrofloxacin |
Betadine | Mundipharma | – | – |
CardioLab Electrophysiology Recording Systems | GE Healthcare | G220f | – |
Culture media | MesenCult | 05420 | – |
Cyclosporine | Novartis | – | – |
Defibrillator | GE Healthcare | CardioServ | – |
Dorminal | TEVA | – | – |
Echocardiographic system | GE Vingmed | Vivid i | – |
EchoPac software | GE Vingmed | – | – |
Electrophysiological catheter | Cordis Corp | – | – |
Embozene Microsphere | Boston Scientific | 17020-S1 | 700 μm |
Endotracheal tube | Vet Care | VCPET70PCW | Size 7 |
Ethanol | VWR chemicals | 20821.33 | – |
Formalin | Sigma | HT501320 | 10% |
IVC balloon Dilatation Catheter | Boston Scientific | 3917112041 | Mustang |
JR4 guiding catheter | Cordis Corp | 67208200 | 6F |
Lidocaine | Quala | – | – |
Mersilk | Ethicon | W584 | 2-0 |
Metoprolol succinate | Wockhardt | – | – |
Microtome | Leica | RM2125RT | – |
Mobile C arm fluoroscopy equipment | GE Healthcare | OEC 9900 Elite | – |
Pacemaker | St Jude Medical | PM1272 | Assurity MRI pacemaker |
Pacemaker generator | St Jude Medical | Merlln model 3330 | – |
Pressure-volume catheter | CD Leycom | CA-71103-PL | 7F |
Pressure–volume signal processor | CD Leycom | SIGMA-M | – |
Programmable Stimulator | Medtronic Inc | 5328 | – |
PTCA Dilatation balloon Catheter | Boston Scientific | H7493919120250 | MAVERICK over the wire |
Ramipril | TEVA | – | – |
Sheath introducer | Cordis Corp | 504608X | 8F, 9F, 12F |
Steroid | Versus Arthritis | – | – |
Temgesic | Nindivior | – | buprenorphine |
Venous indwelling needle | TERUMO | SR+OX2225C | 22G |
Vicryl | Ethicon | VCP320H | 2-0 |
Xylazine | Alfasan International B.V. | – | – |
Zoletil | Virbac New Zealand Limited | – | tiletamine+zolezepam |