Abstract 906: Neural Crest-Derived Stem Cells in the Heart Proliferate and Differentiate into Cardiomyocytes After Myocardial Infarction
[Introduction]: A recent study suggests that neural crest-derived cells still exist as multipotent stem cells in various organs of adult tissues. We recently reported that neural crest-derived stem cells in the heart are capable of differentiation into neurons, glia, smooth muscle cells, and cardiomyocytes in vitro and in vivo, and that they might exist as cardiac tissue-specific stem cells (J Cell Biol. 170:1135, 2005). However, the role of neural crest-derived stem cells in injury repair or regeneration following tissue damage remains unknown. This cell linage analysis study investigated whether or not neural crest-derived stem cells migrate to the damaged area, proliferate, and differentiate into cardiomyocytes following myocardial infarction.
Neural crest-derived cells were marked with enhanced GFP by generating double transgenic mice using P0-CRE recombinase-transgenic (Tg) mice crossed with CAG-CAT-EGFP Tg mice carrying the enhanced green fluorescent protein (EGFP) gene downstream of chicken α-actin promoter and “stuffer” fragment flanked by two loxP sites.
Myocardial infarction was generated by ligation of the left anterior descending coronary artery in 10-week-old double-Tg mice, and immunofluorescent staining against actinin, GATA4, nestin, and p75 nerve growth factor receptor (NGFR) was examined at 4 weeks.
In the control heart, fluorescent microscopy revealed that EGFP+ cells were observed at the intramuscular and subepicardial layers of both ventricles and atrium, and were particularly concentrated in the interventricular septum. These cells were nestin and p75NGFR positive and some were GATA4 positive. A few cells were EGFP+actinin+ cardiomyocytes.
In the infarcted heart, EGFP+ cells were apparently increased in number, suggesting that they were proliferating or migrated to the infarct area. Some EGFP+ cells clearly demonstrated actinin+ cardiomyocytes. These cardiomyocytes were concentrated and formed a cluster at the ischemic border zone area.
[Conclusion]: These findings strongly suggest that neural crest-derived stem cells remain in the heart as stem cells, proliferate or migrate into the ischemic area, and can differentiate into cardiomyocytes following myocardial infarction.