Adrenomedullin production by adult cardiac fibroblasts via NF-κB/STAT6 signaling enhances post-infarction lymphangiogenesis and cardiac repair

Myocardial infarction (MI) remains the leading cause of death worldwide. We previously found that a specific population of human fetal cardiac fibroblasts (fCFs), which express vascular cell adhesion molecule 1 (VCAM1), have cardioprotective effects after MI, inducing reparative cardiac lymphangiogenesis. This study investigated whether adult cardiac fibroblasts (aCFs), which are more feasible for autologous transplantation, differ in surface marker expression and lymphangiogenic potential compared to fCFs. Furthermore, we examined whether aCFs could be exogenously manipulated to acquire fCF-like lymphangiogenic potential and serve as a cell therapy for MI and MI-associated heart failure. In vivo MI models (rat and mouse) and in vitro coculture assays with lymphatic endothelial cells were conducted. We found that TNF-α and IL-4 stimulation induced aCFs to express VCAM1 via NF-κB and STAT6 signaling, yielding a subpopulation termed adult VCAM1⁺ cardiac fibroblasts (aVCFs). These aVCFs, distinct from myofibroblasts, expressed CD90 and improved cardiac function post-MI. Adrenomedullin (ADM) was identified as a key paracrine effector, and its knockdown attenuated the pro-lymphangiogenic and cardioprotective effects of aVCFs. Our findings demonstrate that aVCFs promote cardiac lymphangiogenesis and protect cardiac function following MI, highlighting their potential as an autologous cell therapy.