The overall goal of the current study is to present the techniques of induction of myocardial infarction (MI) and post-myocardial infarction heart failure (post-MI HF) in closed-chest, adult Göttingen minipigs and the characterization of post-MI HF model in Göttingen minipigs as compared to Landrace pigs.
The development of heart failure is the most powerful predictor of long-term mortality in patients surviving acute myocardial infarction (MI). There is an unmet clinical need for prevention and therapy of post-myocardial infarction heart failure (post-MI HF). Clinically relevant pig models of post-MI HF are prerequisites for final proof-of-concept studies before entering into clinical trials in drug and medical device development.
Here we aimed to characterize a closed-chest porcine model of post-MI HF in adult Göttingen minipigs with long-term follow-up including serial cardiac magnetic resonance imaging (CMRI) and to compare it with the commonly used Landrace pig model.
MI was induced by intraluminal balloon occlusion of the left anterior descending coronary artery for 120 min in Göttingen minipigs and for 90 min in Landrace pigs, followed by reperfusion. CMRI was performed to assess cardiac morphology and function at baseline in both breeds and at 3 and 6 months in Göttingen minipigs and at 2 months in Landrace pigs, respectively.
Scar sizes were comparable in the two breeds, but MI resulted in a significant decrease of left ventricular ejection fraction (LVEF) only in Göttingen minipigs, while Landrace pigs did not show a reduction of LVEF. Right ventricular (RV) ejection fraction increased in both breeds despite the negligible RV scar sizes. In contrast to the significant increase of left ventricular end-diastolic (LVED) mass in Landrace pigs at 2 months, Göttingen minipigs showed a slight increase in LVED mass only at 6 months.
In summary, this is the first characterization of post-MI HF in Göttingen minipigs in comparison to Landrace pigs, showing that the Göttingen minipig model reflects post-MI HF parameters comparable to the human pathology. We conclude that the Göttingen minipig model is superior to the Landrace pig model to study the development of post-MI HF.
Despite the decreasing mortality of acute myocardial infarction (MI), the incidence of post-myocardial infarction heart failure (post-MI HF) has not changed over time1. Heart failure (HF) is one of the most powerful predictors of death in MI patients2. To date, reperfusion therapy is the only available treatment option to limit myocardial infarct size and to reduce the risk of a subsequent HF3,4,5. HF and other complications may occur as a consequence of reperfusion injury; therefore, there is still an unmet need for the development of cardioprotective therapies beyond timely reperfusion6,7,8. Numerous cardioprotective therapies effective even in large animal models have been described, but only remote ischemic conditioning (RIC) seemed to improve clinical outcomes of post-MI HF in a small clinical trial9. However, this encouraging result on the efficacy of RIC was questioned in a single-blind, randomized controlled trial (CONDI-2/ERIC-PPCI) performed at 33 centers across Europe in STEMI patients, where RIC failed to improve clinical outcomes10. Potential reasons for the failed translation of the preclinical data might be the use of suboptimal post-MI HF animal models with low clinical relevance11.
Cardiovascular (patho)morphology and (patho)physiology of the pig models resemble human conditions; thus, it is widely used and accepted in translational cardiovascular research12,13,14. Pig breeds used in cardiovascular research belong to the very diverse domestic pig (Sus scrofa domestica) species that includes swine that vary in size, appearance, and genetic background15,16. Although post-MI HF has been researched in pigs extensively, no study was published with the aim of characterizing and comparing the effect of MI on the outcome of post-MI HF in Landrace pigs and Göttingen minipigs. The intensive growth rate of Landrace pigs may affect the cardiac morphofunctional outcomes; however, Göttingen minipigs with restricted growth patterns may overcome these concerns and can serve as a feasible model for long-term follow up in the assessment of post-MI HF. Moreover, a guideline on the relevance of rigor and reproducibility in preclinical studies on cardioprotection recommends the use of cardiac magnetic resonance imaging (CMRI) as a clinically relevant model for measurement of ventricular function in pigs12.
To analyze the scientific interest on post-MI HF in pigs we performed literature search on PubMed using the following search string: "(pig OR swine OR porcine OR sus-scrofa OR minipig OR mini-pig OR miniature-pig OR miniature-swine) AND (infarct* OR ischem* OR ischaem* OR reperfus*) AND (heart OR cardi* OR myocard*) AND (LAD OR left-anterior* OR LCX OR left-circumflex OR RCA) AND (heart-failure OR lvef OR ejection-fraction OR infarct-size OR infarction-size)" and found that pig models of cardiac ischemia/reperfusion are frequently used to study MI and post-MI HF, but only 17% (71 out of 425 articles) of studies involved minipigs and 7% (30 out of 425 articles) used Göttingen minipigs. Only about 1% (5 out of 425) of studies used Göttingen minipigs and clinically relevant protocols with long-term follow-up (1-9 months of reperfusion) and CMRI to analyze cardiac function. The small number of clinically relevant studies highlights the translational gap between basic research and clinical trials. Therefore, a comprehensive characterization of the closed-chest post-MI HF models in Göttingen minipigs and Landrace pigs with repeated assessment of left and right ventricular function and anatomy using CMRI during long-term follow up is required. Here we aimed to focus on the technical feasibility and clinical relevance of two post-MI HF models to describe standardized and reproducible experimental protocols for post-MI HF studies that may be used to assess cardioprotective drug and/or medical device therapies.
The present study is the first one in the literature to characterize a clinically relevant model of post-MI HF using adult Göttingen minipigs and to compare morphological and cardiac left and right ventricular functional parameters with that of the adolescent Landrace pigs.
13 healthy and sexually mature female Göttingen minipigs (age between 12 and 14 months) and 10 healthy and sexually immature female Landrace pigs (age between 2 and 3 months) were housed in pig stalls conforming to the size recommendations of the most recent Guide for the Care and Use of Laboratory Animals DHEW and EU Guidelines 63/2010. Animals were not spayed. The temperature of the animal rooms was controlled, and animals were kept at a 12-hour light/dark cycle and vermin-free. Ad libitum feeding leads to overt weight gain in both Göttingen minipigs and Landrace pigs, therefore, pigs from both the breeds were fed with a restricted diet regimen. Göttingen minipigs were put on restricted diet as early as they arrived to the animal facility and for the whole study duration. Special Diet Services pig chow 180-220 g/meal/animal was given twice daily according to "Taking good care of Ellegaard Göttingen Minipigs" guideline (revision date: 13 March, 2013) in the first 2 days. Between day 3 and 12 animals were fed 50% Special Diet Services pig chow and 50% maintenance minipig diet. From day 14 until the end of the study animals were fed a maintenance minipig diet. Landrace pigs received pregnant sow chow, 1.5% of body weight given two times a day according to PIC Wean to Finish Manual 2008 and 2013. All the animals received food individually dispensed and food intake was monitored to avoid competition for chow. Animals with feeding difficulties were fed individually aided by tending personnel. All animals received tap water ad libitum. The experimental protocol of post-MI HF in Göttingen minipigs and in Landrace pigs is shown in Figure 1.
Figure 1. Experimental protocol for post-myocardial infarction-induced heart failure in Landrace pigs and Göttingen minipigs. CMRI – cardiac magnetic resonance imaging. Please click here to view a larger version of this figure.
1. Baseline CMRI
2. Premedication, vascular access and coronary artery occlusion
3. Intracoronary drug administration
4. Wound closure and post-operative care
5. Post-MI CMRI and its evaluation
6. Statistics
Mortality
Out of 13 Göttingen minipigs subjected to myocardial infarction, two animals died (15.4% mortality), one during the ischemic period due to irreversible VT and one owing to asystole in reperfusion. In Göttingen minipigs, one animal was successfully resuscitated during cardiac ischemia. The mortality rate was 0% in Landrace pigs, ten out of ten animals survived, two of them required resuscitation due to VF in the ischemic period. Mortality did not differ significantly between the two breeds.
Myocardial scar sizes were comparable between the two breeds
To measure the extent of cardiac scar as a consequence of MI, CMRI was performed. Scar sizes and BARI scores were comparable between the two breeds measured at the 2nd month of follow-up in Landrace pigs, and at the 3rd and 6th month in Göttingen minipigs (Figure 2E,F). No differences were observed when scar sizes were related to the BARI scores in Landrace pigs at 2 months (0.55 ± 0.1) and in Göttingen minipigs at 3 months and 6 months respectively (0.75 ± 0.12 and 0.57 ± 0.08). The scars were localized in the anterior, anteroseptal, septal, anteroapical and apical segments of the heart in both breeds. The lateral wall was affected only in Göttingen minipigs. Right ventricular infarction was negligible, affected only one animal out of eleven surviving Göttingen minipigs and one out of ten Landrace pigs (2.11 ± 2.11 vs. 0.97 ± 0.97).
Increase in left ventricular mass was more pronounced in Landrace pigs during follow-up
The cardiac growth rate was measured by CMRI. LVED mass in Göttingen minipigs increased only moderately (8%) at 6 months (Figure 3A). In contrast, in Landrace pigs, LVED mass increased by almost 100% at 2 months (Figure 3B).
Left ventricular ejection fraction decreased only in Göttingen minipigs
LVEF, as the most widely used parameter of left ventricular systolic function, was measured by CMRI. MI resulted in a significant decrease in LVEF in minipigs at 3 months and 6 months (Figure 4A). In Landrace pigs, LVEF did not change after 2 months (Figure 4B).
Post-infarction LVESV and LVEDV increased significantly in both breeds (Table 1). LVESV increased by 69% and 80% in Göttingen minipigs after 3 and 6 months, respectively, and by 80% in Landrace pigs after 2 months. LVEDV showed a 28% increase after 3 months and a 42% increase after 6 months in Göttingen minipigs and an 82% increase in Landrace pigs after 2 months. LVSV of Landrace pigs increased by 85% in 2 months and LVSV of Göttingen minipigs did not increase significantly even at 6 months.
Left atrial volume indexed to body surface area increased only in Göttingen minipigs, but both the breeds developed pulmonary oedema following myocardial infarction
In order to further examine signs of HF, we performed measurement of the left atrial volume indexed to body surface area (LAVi). LAVi increased by 34% in Göttingen minipigs after 6 months (Figure 5A) and did not change significantly in Landrace pigs after 2 months (Figure 5B). Representative images show the tracing of the left atria (Figure 5C-D). Moreover, the presence or absence of pulmonary oedema was assessed by CMRI on the localizer images (Figure 5E). Pulmonary oedema was observed in both breeds as a result of cardiac decompensation. Ten out of eleven Göttingen minipigs and nine out of ten Landrace pigs showed obvious signs of pulmonary oedema.
Increase in body weight was more pronounced in Landrace pigs during follow-up
In Göttingen minipigs body weight gain was only 8% after 3 months and 30% after 6 months (Figure 6A), whereas increased heart weight was accompanied by a nearly 100% increase in body weight in Landrace pigs at 2 months (Figure 6B).
Trends in cardiac functional parameters differ between Göttingen minipigs and Landrace pigs
Coronary artery occlusion led to an almost significant decrease in mean arterial pressure (MAP) in Göttingen minipigs (57.9 ± 3.98 mmHg vs. 49.89 ± 1.24 mmHg) and decreased significantly in Landrace pigs (65.4 ± 5.97 mmHg vs. 45.47 ± 4.79* mmHg) in the early reperfusion phase as compared to the baseline (pre-infarction) values.
CI is a reliable indicator of cardiac performance, which relates left ventricular CO to BSA. In Göttingen minipigs, CI did not change at the measured time points (Figure 7A), whereas in Landrace pigs a tendency to increase was detected in cardiac index (Figure 7B).
HR of Göttingen minipigs increased significantly at 3 (20%) and 6 months (22%) after MI compared to baseline values (Table 2).
In contrast, the HR of Landrace pigs did not change significantly during the follow-up period. In Göttingen minipigs CO showed a significant 32% increase only at 6 months of follow-up, whereas CO was increased by 76% in Landrace pigs after 2 months due to a significant increase in LVSV (Table 2). BSA increased significantly in both breeds at the measured time points (Table 2). BSA increased by 4% and 19% in Göttingen minipigs after 3 and 6 months, respectively, and by 54% in Landrace pigs after 2 months.
Increase in right ventricular morphofunctional parameters were observed in both Göttingen minipigs and Landrace pigs
MI affected not only left ventricular function, but it also resulted in a significant increase of RVEF in both breeds (Figure 8) measured by CMRI, despite the negligible right ventricular scar size. RVED mass increased in Landrace pigs only (Table 3).
RVESV did not change during follow up in any of the breeds. RVEDV increased significantly by 37% only in Landrace pigs (Table 3). While RVSV in Göttingen minipigs increased significantly by 23% only after 6 months, in Landrace pigs a significant 80% increase in RVSV was observed at 2 months.
Figure 2. Estimation of the myocardium at risk based on the BARI (Bypass Angioplasty Revascularization Investigation Myocardial Jeopardy Index) score (A-D). The total value of the infarct-related artery is divided by the sum of the 3 total values of each coronary artery, the right coronary artery (RCA), the left circumflex coronary artery (LCX), and the left anterior descending coronary artery (LAD). Left ventricular scar sizes in Göttingen minipigs and Landrace pigs measured by cardiac magnetic resonance imaging (E). Scar size is shown as a ratio of mass of infarction to the mass of left ventricle at end of diastole (LVED). BARI scores in Göttingen minipigs and Landrace pigs measured before coronary occlusion (F). Please click here to view a larger version of this figure.
Figure 3. Left ventricular end-diastolic (LVED) mass (g) of Göttingen minipigs (A) and Landrace pigs (B) measured by cardiac magnetic resonance imaging. *p<0.05 vs. corresponding baseline (repeated measures one-way ANOVA followed by Fisher's LSD test in Göttingen minipigs; paired t-test in Landrace pigs). Please click here to view a larger version of this figure.
Figure 4. Left ventricular (LV) ejection fraction (%) of Göttingen minipigs (A) and Landrace pigs (B) measured by cardiac magnetic resonance imaging. *p<0.05 vs. corresponding baseline (repeated measures one-way ANOVA followed by Fisher's LSD test in Göttingen minipigs; paired t-test in Landrace pigs). Please click here to view a larger version of this figure.
Measured parameter | Göttingen minipigs | Landrace pigs | |||
Baseline | 3 months | 6 months | Baseline | 2 months | |
LVESV [ml] | 25.77 ± 1.73 | 43.65 ± 4.53* | 46.28 ± 4.35* | 54.59 ± 2.00 | 98.26 ± 8.60* |
LVEDV [ml] | 55.49 ± 3.14 | 71.08 ± 5.25* | 78.81 ± 5.46* | 93.99 ± 3.85 | 171.20 ± 11.50* |
LVSV [ml] | 29.71 ± 1.65 | 27.44 ± 1.97 | 32.52 ± 2.37 | 39.40 ± 3.05 | 72.94 ± 3.99* |
Table 1. Left ventricular end-systolic volume (LVESV), left ventricular end-diastolic volume (LVEDV), and left ventricular stroke volume (LVSV) at the measured time points in Landrace pigs and Göttingen minipigs. *p<0.05 vs. corresponding baseline (repeated measures one-way ANOVA followed by Fisher's LSD test in Göttingen minipigs; paired t-test in Landrace pigs).
Figure 5. Left atrial volume indexed to body surface area (LAVi) in mL/m2 in Göttingen minipigs (A) and Landrace pigs (B) measured by cardiac magnetic resonance imaging. Representative images of left atrial volumes, tracings were made on the two- (C) and four chamber (D) cine images. The white arrows show the presence of pulmonary oedema on the representative localizer image (E). *p<0.05 vs. corresponding baseline (paired t-test in Göttingen minipigs and Landrace pigs). Please click here to view a larger version of this figure.
Figure 6. Body weight (kg) of Göttingen minipigs (A) and Landrace pigs (B). *p<0.05 vs. corresponding baseline (repeated measures one-way ANOVA followed by Fisher's LSD test in Göttingen minipigs; paired t-test in Landrace pigs). Please click here to view a larger version of this figure.
Figure 7. Left ventricular (LV) cardiac indices (L/min/m2) of Göttingen minipigs (A) and Landrace pigs (B). Please click here to view a larger version of this figure.
Measured parameter | Göttingen minipigs | Landrace pigs | |||
Baseline | 3 months | 6 months | Baseline | 2 months | |
HR [1/min] | 79.64 ± 4.03 | 95.55 ± 5.34* | 97.00 ± 4.46* | 93.44 ± 2.73 | 88.00 ± 2.52 |
CO [L/min] | 2.37 ± 0.16 | 2.58 ± 0.20 | 3.12 ± 0.24* | 3.65 ± 0.25 | 6.41 ± 0.39* |
BSA [m2] | 0.70 ± 0.01 | 0.73 ± 0.01* | 0.83 ± 0.03* | 0.70 ± 0.01 | 1.08 ± 0.03* |
Table 2. Heart rate (HR), cardiac output (CO), and body surface area (BSA) of Göttingen minipigs and Landrace pigs. *p<0.05 vs. corresponding baseline (repeated measures one-way ANOVA followed by Fisher's LSD test in Göttingen minipigs; paired t-test in Landrace pigs).
Figure 8. Right ventricular (RV) ejection fractions (%) of Göttingen minipigs (A), and Landrace pigs (B). *p<0.05 vs. corresponding baseline (repeated measures one-way ANOVA followed by Fisher's LSD test in Göttingen minipigs; paired t-test in Landrace pigs). Please click here to view a larger version of this figure.
Measured parameter | Göttingen minipigs | Landrace pigs | |||
Baseline | 3 months | 6 months | Baseline | 2 months | |
RVED mass [g] | 8.64 ± 0.68 | 8.98 ± 0.76 | 7.94 ± 0.77 | 16.49 ± 0.90 | 23.61 ± 1.40* |
RVESV [ml] | 18.27 ± 1.47 | 16.91 ± 1.80 | 14.57 ± 1.02 | 43.59 ± 3.68 | 42.65 ± 2.37 |
RVEDV [ml] | 44.16 ± 2.61 | 42.14 ± 2.83 | 46.27 ± 3.45 | 83.03 ± 3.42 | 113.72 ± 5.12* |
RVSV [ml] | 25.82 ± 1.72 | 25.25 ± 1.67 | 31.71 ± 2.99* | 39.44 ± 3.52 | 71.06 ± 3.38* |
Table 3. Right ventricular end-diastolic (RVED) mass, right ventricular end-systolic volume (RVESV), right ventricular end-diastolic volume (RVEDV), and right ventricular stroke volume (RVSV) in Göttingen minipigs and Landrace pigs. *p<0.05 vs. corresponding baseline (repeated measures one-way ANOVA followed by Fisher's LSD test in Göttingen minipigs; paired t-test in Landrace pigs).
Here we described a detailed protocol highlighting the critical steps of a technique of induction of acute MI and the evaluation of post-MI HF in a closed-chest model of adult Göttingen minipigs. We also described the method of intracoronary drug administration, BARI scoring, and reported left and right ventricular cardiac morpho-functional changes in a translational post-MI HF model. This is the first characterization of post-MI HF in Göttingen minipigs in comparison to Landrace pigs, showing that the Göttingen minipig model reflects post-MI HF parameters comparable to humans. We conclude that the Göttingen minipig model is superior to the Landrace pig to follow-up the development of post-MI HF. Clinically relevant pig models of post-MI HF are prerequisites for final proof-of-concept studies before entering into clinical trials in most of the cardiovascular drug and medical device development projects6,7,12. Indeed, pig models resemble humans in anatomy, physiology, and biochemical properties in particular in the field of MI research as they develop trans-mural infarctions due to the lack of collateral perfusion14. Therefore, pig models can serve as models for the analysis of cardioprotective therapies and their mechanisms24,25,26,27,28,29.
Here we have found that despite the equal scar sizes, mortality rates, and BARI scores in the two breeds, left ventricular dysfunction characterized by decreased LVEF was observed only in Göttingen minipigs. Here we observed a 15.4% acute mortality in Göttingen minipigs and no mortality in the follow-up period, the latter is comparable to that in clinical studies. Indeed, a patient-level meta-analysis of 10 randomized clinical trials found that the Kaplan-Meier estimated 1-year rate of all-cause mortality was as low as 2.2% following myocardial infarction30. Scar sizes reported here are comparable to those in clinical trials. In clinical trials performed by Lonborg et al and Stone et al in patients surviving ST-elevation myocardial infarction the median scar sizes, measured as % of left ventricular myocardial mass were 9.5% and 17.9% respectively30,31. Moreover, scar sizes in the present study accord with those reported in previous publications in Göttingen minipigs (12-25%)32,33,34,35,36,37 and in Landrace pigs (14-18%)38,39,40. The present finding on baseline LVEF in Landrace swine is according to data reported by others in large swine13,41,42. These values in large swine are smaller as compared to healthy human LVEF reference ranges (58-61%)43 and baseline (pre-infarction) values in Göttingen minipigs (55-73%)33,44,45. Nevertheless, it is worth noting that only the post-infarction data or delta changes of LVEF are reported in most publications46,47,48,49,50. In accordance with the present results, previous studies of either post-MI HF induced by 45 to 90 min LAD occlusion followed by reperfusion or by permanent LAD occlusion have demonstrated either no reduction or modest reduction of LVEF in Landrace or Yorkshire swine after 4-6 weeks follow up as compared to baseline (pre-infarction) LVEF51,52,53. However, Schuleri et al. compared morphofunctional parameters between Göttingen minipigs and Yorkshire swine and found that both breeds showed a decrease of LVEF 8 weeks after induction of MI by 120 to 150 min LAD occlusion-reperfusion; however, baseline LVEF values in Yorkshire swine were not reported54. In other experiments in female Dalland Landrace pigs post-MI adverse remodeling was induced by 90 min LAD occlusion, however, LVEF was not reported after 4 weeks of follow-up55. In contrast to our findings, in a study by de Jong et al., LVEF markedly decreased in Landrace pigs subjected to open chest LAD occlusion and followed by a 12-week follow-up56. This difference can be attributed to substantially longer ischemic period (150 min), which resulted in larger infarct size (23.4 ± 2.1% of LV). Elsewhere, 120-min closed-chest occlusion of left circumflex (LCX) coronary artery in German Landrace pigs led to a significant reduction in LVEF after eight weeks of reperfusion, suggesting that the different location of MI may also affect global left ventricular function57. Our present findings are consistent with others showing significant reduction in LVEF in post-MI HF in Göttingen minipigs after long-term follow up33,44,45.
The reduction of LVEF in Göttingen minipigs following MI is consistent with clinical data showing cardiac dysfunction as a consequence of ventricular remodeling in patients after AMI58. In conclusion, Göttingen minipigs better mimic the human conditions, since pre-infarction LVEF, scar size, post-infarction LVEF, and mortality are all comparable to these parameters found in humans.
Here we observed an 8% increase in LVED mass after six months in Göttingen minipigs and a markedly higher (97%) increase in LVED masses in Landrace pigs after two months. Similar data were reported by Schuleri et al. in Yorkshire pigs, where a 40% increase in heart weight was observed after two months. In contrast, in other experiments of closed-chest post-MI HF in Göttingen minipigs no significant changes in left ventricular masses were observed33,44. Therefore, differences between the two breeds regarding LVEF can be attributed to an intensive cardiac growth rate in Landrace pigs and thus altered cardiac remodeling.
In clinical settings, besides the LVEF, left ventricular volume provides valuable insight into long-term prognosis and mortality rate in post-MI patients59. LVESV is the primary determinant of both early and late mortality in patients after AMI60,61. Here we have shown that ventricular volume assessed by CMRI increased significantly in both breeds. Post-MI remodeling induced a more pronounced increase in LVESV than in LVEDV in Göttingen minipigs, while both LVESV and LVEDV were increased by a similar rate in Landrace pigs. Consequently, left ventricular ejection fraction (LVEF) was significantly decreased at 3 and 6 months only in Göttingen minipigs but not in Landrace pigs after 2 months. These results must be interpreted with caution in Landrace pigs, where increased LVESV, LVEDV, and LVSV (calculated as the difference between the LVESV and LVEDV) are more likely related to an intensive increase in cardiac mass. Increased LVESV and LVEDV are consistent with clinical data of patients with post-MI HF62,63,64. Moreover, adverse left ventricular remodeling was defined as an increase of 15% or more in the LVEDV in clinical studies65,66 and we found here a 28% increase after 3 months and a 42% increase after 6 months in LVEDV in Göttingen minipigs showing a clinically relevant adverse remodeling. In addition, here we have shown that LAVi increased only in Göttingen minipigs, but not in Landrace pigs. Increase of left atrial volume is an additional key structural alteration in the context of HF and is an independent predictor of death and HF hospitalization in patients surviving MI67.
Right ventricular function is rarely studied in post-MI HF models. Here we have found that right ventricular ejection fraction increased in both breeds. Although RV was practically not involved in myocardial necrosis, RVEF increased significantly in both breeds indicating RV volume overload and hence left ventricular dysfunction. Similarly, a clinical study enrolling 2008 patients with chronic systolic HF showed that 733 patients (37%) belonged to normal right ventricular function category with RVEF≥40%68.
In conclusion, we have shown here that the adult Göttingen minipig model with long-term follow-up mimics functional and morphological parameters of post-MI HF comparable to humans. Our present data also show that Landrace pigs are not suitable for the evaluation of post-MI HF mainly due to consequences of the rapid increase in body and heart weight that does not allow long-term follow-up and interferes with post-MI HF pathology. Landrace pigs might be suitable to assess the consequences of acute myocardial infarction. The present comprehensive characterization of the closed-chest infarction models in Landrace and Göttingen minipigs will be useful for choosing the optimal large animal models to study post-MI HF and developing novel therapies against this pathology.
Limitations
The current experiment was performed only in female pigs, therefore, the potential effect of the different sexes on post-MI HF remains unknown in these models69. Signs of HF were assessed by CMRI, according to recommendations of a recent guideline on the relevance of rigor and reproducibility in preclinical studies on cardioprotection12. However, the use of more targeted angulation of CMRI imaging planes and more targeted sequence may result in better estimation of left atrial volumes, and pulmonary oedema. Although we have not measured biomarkers and histological signs of post-MI HF in this study, these models are suitable for analysis of any biomarkers since the availability of plasma and tissue samples. Due to the different susceptibility of the 2 breeds to ischemia/reperfusion injury, different durations of coronary occlusions were selected here that may although limit the comparison of the 2 models, however, by this approach we achieved similar infarct size. The follow-up time in the 2 breeds was different as in the Landrace pigs only 2 months follow up time can be achieved due to technical reasons, i.e. rapid increase in body weight that shows a major limitation of the Landrace model. A further limitation is the lack of different risk factors and comorbidities and thus the present large animal models do not completely mimic the clinical situation in terms of the presence of multiple risk factors including co-morbidities and their medications. However, currently, there are no established large animal models with multiple comorbidities for routine use. These large animal models cannot be powered for mortality analysis due to animal ethical reasons and the high cost of these studies.
The authors have nothing to disclose.
This study was funded by Quark Pharmaceuticals Inc where S.A. and E.F. are employees. This study was also supported by the National Research, Development and Innovation Office of Hungary (NKFIA; NVKP-16-1-2016-0017 National Heart Program), and by the Higher Education Institutional Excellence Program of the Ministry of Human Capacities in Hungary, within the framework of the Therapeutic Development thematic program of the Semmelweis University. GB.B. was supported by EFOP-3.6.3-VEKOP-16-2017-00009 and Gedeon Richter Plc. Scholarship. Z.G. was supported by a János Bolyai Research Scholarships of the Hungarian Academy of Sciences and by the ÚNKP-19-4 New National Excellence Program of the Ministry of Human Capacities.
Special Diet Services pig chow | SDS, Witham, England, Hungarian distributor: Akronom Kft. | ||
maintenance minipig diet | no. 9023, Altromin | ||
pregnant sow chow | Bonafarm-Bábolna Takarmány Plc | ||
ketamine hydrochloride | Richter Pharma AG | ||
xylazine | Medicus Partner | ||
atropine | Egis | ||
endotracheal tube | Portex | ||
isoflurane | Abbot | ||
anesthetic machine | Dräger Julian | ||
18 G needle | Anhul Kangda Medical Products Co. Ltd. | ||
5% glucose in Ringer solution | B Braun | ||
atracurium besylate | GSK | ||
cardiac magnetic resonance machine | Siemens Healthineers Medical GmbH | ||
acetyl salicylic acid | Bayer | ||
clopidogrel | Zentiva | ||
meloxicam (meloxidyl) | Ceva | ||
antibiotic coctail (tardomyocel) comp III. | Norbrook | ||
ear vein cannula | B Braun Melsungen AG | ||
magnesium sulfate | Wörwag Pharma GmbH | ||
povidone-iodine | Egis | ||
ECG electrodes | Leonhard Lang GmbH | ||
6F-ACT introducer | St Jude Medical | ||
heparin | TEVA | ||
arterial pressure sensor and monitoring system | GE Healthcare | ||
guidewire | PT2MS Boston Scientific | ||
5F guiding catheter | Medtronic Launcher, 5F | ||
fluoroscope, C-bow | Siemens Medical GmbH | ||
Iobitridol (Xenetix) | Guerbet | ||
balloon catheter | Boston Scientific, EMERGE, 2.5mm x 12mm | ||
heating device | 3M | ||
rectal probe | Vatner Kft | ||
pulse oxymeter | Comen medical | ||
epinephrine | Richter Gedeon Rt. | ||
lidocaine | EGIS | ||
microcatheter | Caravel ASAHI | ||
defibrillator | GE Marquette Responder 1100 | ||
perfusion pump | TSE system | ||
antiseptic coating | Friedrich Huber aeronova GmbH&Co | ||
gadobutrol | Bayer | ||
MASS 7.6 analysis software | Medis Medical Imaging Software, Leiden |