Author + information
- Ivan Cokic,
- Avinash Kali,
- Richard Tang,
- Hsin-Jung Yang,
- Andreas Kumar,
- Frank S. Prato,
- Joseph Francis,
- Eduardo Marban and
- Rohan Dharmakumar
Background: Reperfusion hemorrhage following acute myocardial infarction (AMI) leads to abnormal accumulation of iron deposits (IDs) within the infarcted territory. Given that these IDs drive a prolonged recruitment of macrophages into scar tissue, we investigated the physicochemical characteristics of IDs and the polarization status of newly recruited macrophages in the chronic MI (CMI).
Methods: Dogs (n=9) were subjected to 3 hrs of LAD occlusion followed by reperfusion and imaged with T2* and LGE CMR on day 7 post-MI (Fig 1). Animals were re-imaged on week 8 post-MI and then sacrificed. Explanted hearts underwent histological, transmission electron microscopy (TEM) and energy-dispersive X-ray spectroscopy analyses.
Results: IDs in CMI were found within macrophages as aggregates of nanocrystals (∼2.5 nm diameter) in the ferric state (Fig 2). Histological evaluation of CMI revealed extensive co-localization of PID (Perls’ stain) with newly recruited macrophages (MAC387 marker), CD163 (marker of iron-specific macrophage activation), as well as the proinflammatory cytokines (TNF-α, IL-1β) within the CMI (Fig 3).
Conclusions: Reperfusion hemorrhage evolves into crystallized iron deposition in CMI and promotes macrophage polarization preferentially to a M1 phenotype. Since M1 macrophages are known to impart deleterious effects on the heart, therapeutic strategies to combat post-hemorrhagic AMI adverse remodeling should take into account the chronic iron-driven inflammatory process.
Poster Hall, Hall C
Friday, March 17, 2017, 10:00 a.m.-10:45 a.m.
Session Title: Non Invasive Imaging: MR Characterization and Function
Abstract Category: 29. Non Invasive Imaging: MR
Presentation Number: 1118-214
- 2017 American College of Cardiology Foundation