Photoacoustic Tracing of Postinfarction Myocardial Scarring by Collagen Hybridization

Myocardial infarction (MI) leads to fibrotic scarring, which impairs cardiac function and necessitates accurate assessment for prognosis and therapy evaluation. Unfortunately, current imaging modalities lack direct specificity for fibrosis. Here, we report a photoacoustic (PA) imaging strategy based on an indocyanine green-loaded albumin nanoparticle (ICG-AN-CHP) modified with a collagen-hybridizing peptide (CHP) that targets denatured collagen, a key molecular feature of post-MI scars. In a murine MI model, the probe exhibited high specificity for scar tissue, with an excellent spatial correlation to the histological gold standard, Masson's trichrome staining. In vivo PA imaging allowed noninvasive quantification of scar size, which strongly correlated with functional impairment of the hearts and could detect occult fibrosis even in mice with preserved ejection fraction. PA imaging with ICG-AN-CHP also enabled longitudinal monitoring of antifibrotic treatment responses in individuals, offering a promising direct sensor for prognostic assessment and therapy development in myocardial fibrosis.