Abstract 1838: Neural Crest Stem Cells Supply Intrinsic Cardiac Adrenergic Cells and Contribute to Reinnervation after Myocardial Infarction in Mice

Abstract

Cardiac nerve sprouting and heterogeneous reinnervation after myocardial infarction (MI) lead to arrhythmogenesis and sudden cardiac death. Despite its importance, little is known about the contribution of the intrinsic cardiac nervous system on reinnervation. We previously reported that neural crest stem cells (NCSC) reside in the heart, and can differentiate into neuron, glia, smooth muscle cells, and cardiomyocytes. The present study scrutinized the developmental origin of intrinsic cardiac adrenergic (ICA) cells, and investigated whether NCSC supply ICA and contribute to reinnervation after MI. (1) We analyzed two distinct double transgenic mice, encoding protein 0-Cre/Floxed-EGFP (P0-EGFP) and dopamine β -hydroxylase-Cre/Floxed-EGFP (DBH-EGFP), to map neural crest-derived cell fate and catecholaminergic cell fate, respectively. ICA cells, demarcated with tyrosine hydroxylase (TH, catecholaminergic marker)-immunopositive cells within ventricles, co-expressed EGFP in both P0-EGFP and DBH-EGFP mice. Most ICA cells were nucleated and round-shaped, although 5% of the cells extended nerve fibers. (2) NCSC were marked with EGFP in P0-EGFP mice, expressed nestin, musashi-1 and p75 nerve growth factor (NGF) receptor, and showed sphere formation. They frequently resided in the outflow tract, but also existed in all parts of the heart. (3) ICA cell number and TH mRNA expression within ventricles were increased in transgenic mice overexpressing NGF in the heart. (4) P0-EGFP mice were subjected to MI by coronary artery occlusion. EGFP-positive cells were markedly increased after MI, and more so in the border zone area than in the non-infarcted area. (5) Similarly, DBH-EGFP subjected to MI revealed an increase in EGFP-positive cells at the border zone area, and some of them extended neurites among the sprouting nerves. (6) TH and EGFP mRNA were increased in DBH-EGFP ventricles, concomitant with cardiac NGF upregulation. These findings demonstrated that ICA cells were derived from neural crest cells, and dependent on NGF synthesized in the heart. NCSC were mobilized to the infarcted myocardium, differentiated into TH-positive nerves, and contributed to reinnervation after MI.