Assessment of Macrophage Depletion on Acute Cardiac Allograft Rejection by MRI

Danielle F. Eytan¹, T Kevin Hitchens¹, Qing Ye¹, Yijen L. Wu¹, Chien Ho¹

Abundant macrophage infiltration is observed in cardiac allograft rejection, yet their contribution to the rejection process and the tissue damage that results remains unclear. Here we investigated the role these cells play in our rat model of acute cardiac rejection by selectively depleting circulating macrophages using liposomal-clodronate. We used T2*-weighted imaging to detect immune-cell infiltration at sites of rejection by monitoring the accumulation of iron oxide-labeled cells, and cardiac cine-tagging to detect regional myocardial function loss. Our results indicate that macrophages contribute to tissue damage during acute rejection, and that their depletion may attenuate the damaging effects of rejection in rat cardiac allografts.