Abstract 12105: Targeted Delivery of Therapeutic Agents After Myocardial Infarction

Introduction: Current therapies for heart failure (HF) after myocardial infarction (MI) only slow the progression of LV remodeling and have little capacity to regenerate cardiac muscle lost to MI. To expedite targeted delivery of regenerative therapies post-MI, we hypothesized that suitable targets could be identified by biopanning the heart with a phage display library in a mouse model of MI. Methods: A phage display library was biopanned in vivo to identify peptides specific for the infarct/border zone 4 days post-MI. Fluorescence molecular tomography (FMT) followed by tissue immunofluorescence was performed to interrogate the specificity of phage groups and individual clones with targeted phage at VT680 and neg control phage at VT750. The VT680 fluorophore on the targeted phage clones was then used to identify the cellular targets of those clones by counter-staining with antibodies against cell types of interest. Results: We identified phage clones specific for endothelium, cardiomyocytes, inflammatory fibroblasts and c-Kit+ cells present in the border zone post-MI. Liposomes conjugated with different cell type specific peptides had different accumulation rates in the post-infarct heart as visualized by FMT imaging (Fig. 1a). Immunofluorescence analysis demonstrated cell-type specific association of the targeted liposomes with cells expressing c-Kit, CD31 and Hrnr (Figs. 1b&c). We have also been successful in remote loading of anti-apoptotic and immune suppresive drugs into these liposomes and are currently studying their effect in mice after MI. Conclusions: Peptides identified by this screen enable the targeting of different cell types present in the border zone with different drugs. Identifying the molecular binding partners for these peptides may yield insight into the various events/pathways that evolve after a myocardial infarction.