Colchicine added to standard therapy further reduces fibrosis in pigs with myocardial infarction

BACKGROUND

The anti-inflammatory drug colchicine improves the outcome of patients with myocardial infarction (MI). As an intense inflammatory and fibrotic response after MI may lead to scar expansion and left ventricular (LV) remodeling, the clinical benefit of colchicine could be related to a positive effect on the infarct scar and LV remodeling.

METHODS

Pigs underwent left anterior descending artery occlusion through an angioplasty balloon for 90 min and were then randomized into two groups: standard therapy [ACE inhibitor, beta blocker, mineralocorticoid receptor antagonist (MRA), aspirin] plus colchicine (n = 14) or standard therapy alone (n = 13). The pigs were treated for 30 days and underwent two cardiac magnetic resonance (CMR) scans at 72 h and 30 days. The pigs were then sacrificed the day after the second CMR. The primary efficacy end point was the extent of fibrosis in the infarct zone (calculated on eight samples from this zone and averaged).

RESULTS

In the hearts explanted after 31 days, pigs in the colchicine group had less fibrosis in the infarct zone than the other animals [41.6% (20.4-51.0) vs. 57.4% (42.9-66.5); P = 0.022]. There was a trend toward a higher myocardial salvage index (MSI; an index of the efficacy of revascularization) in pigs on colchicine (P = 0.054). Conversely, changes in LV volumes, ejection fraction and mass did not differ between groups.

CONCLUSION

Colchicine therapy for 1 month after reperfused MI further reduces myocardial fibrosis when added to standard therapy, while it does not have additional effects on LV remodeling.

Dose-dependent improvement of cardiac function in a swine model of acute myocardial infarction after intracoronary administration of allogeneic heart-derived cells

BACKGROUND

Allogeneic cardiac-derived progenitor cells (CPC) without immunosuppression could provide an effective ancillary therapy to improve cardiac function in reperfused myocardial infarction. We set out to perform a comprehensive preclinical feasibility and safety evaluation of porcine CPC (pCPC) in the infarcted porcine model, analyzing biodistribution and mid-term efficacy, as well as safety in healthy non-infarcted swine.

METHODS

The expression profile of several pCPC isolates was compared with humans using both FACS and RT-qPCR. ELISA was used to compare the functional secretome. One week after infarction, female swine received an intracoronary (IC) infusion of vehicle (CON), 25 × 10⁶ pCPC (25 M), or 50 × 10⁶ pCPC (50 M). Animals were followed up for 10 weeks using serial cardiac magnetic resonance imaging to assess functional and structural remodeling (left ventricular ejection fraction (LVEF), systolic and diastolic volumes, and myocardial salvage index). Statistical comparisons were performed using Kruskal-Wallis and Mann-Whitney U tests. Biodistribution analysis of ¹⁸F-FDG-labeled pCPC was also performed 4 h after infarction in a different subset of animals.

RESULTS

Phenotypic and functional characterization of pCPC revealed a gene expression profile comparable to their human counterparts as well as preliminary functional equivalence. Left ventricular functional and structural remodeling showed significantly increased LVEF 10 weeks after IC administration of 50 M pCPC, associated to the recovery of left ventricular volumes that returned to pre-infarction values (LVEF at 10 weeks was 42.1 ± 10.0% in CON, 46.5 ± 7.4% in 25 M, and 50.2 ± 4.9% in 50 M, p < 0.05). Infarct remodeling was also improved following pCPC infusion with a significantly higher myocardial salvage index in both treated groups (0.35 ± 0.20 in CON; 0.61 ± 0.20, p = 0.04, in 25 M; and 0.63 ± 0.17, p = 0.01, in 50 M). Biodistribution studies demonstrated cardiac tropism 4 h after IC administration, with substantial myocardial retention of pCPC-associated tracer activity (18% of labeled cells in the heart), and no obstruction of coronary flow, indicating their suitability as a cell therapy product.

CONCLUSIONS

IC administration of allogeneic pCPC at 1 week after acute myocardial infarction is feasible, safe, and associated with marked structural and functional benefit. The robust cardiac tropism of pCPC and the paracrine effects on left ventricle post-infarction remodeling established the preclinical bases for the CAREMI clinical trial (NCT02439398).