Cells and Iron Oxide Nanoparticles on the Move

T he treatment of myocardial infarction (MI) has focused heavily on early reperfusion of the infarct-related artery.However, the inflammatory processes in the infarct that occur shortly after MI and govern wound healing in the heart have not been targeted therapeutically.Perhaps this has resulted from our inability to visualize these processes.In contrast to coronary angiography, which has clearly depicted stenotic arteries for decades and initiated the era of percutaneous coronary interventions, imaging inflammation in the heart of patients with MI has been difficult.In this issue of Circulation: Cardiovascular Imaging, Alam et al 1 describe important progress to overcome this hurdle.Their article reports the first human study in which an iron oxide nanoparticle (ferumoxytol, AMAG Pharmaceuticals, Lexington, MA) was used to image leukocytes in the infarcted tissue by T2* weighted magnetic resonance imaging (MRI).Building on previous preclinical data in mice with MI, 2 and the use of ferumoxtran in patients with inflammatory disease, 3-5 the authors imaged 16 patients within the first week after MI, 10 of whom received intravenous ferumoxytol.R2* values tripled in the infarct and doubled in the remote zone 24 to 48 hours after ferumoxytol administration.Because all patients in this small pilot study survived the subacute infarct period, corroborating histologic data on the tissue uptake of ferumoxytol were not available.