Exact relevance of bone marrow cells in the healing process after myocardial infarction:: Analysis with a murine model of bone marrow cell transplantation

BACKGROUND: Cellular cardiomyoplasty has created new possibilities in cardiac regeneration. Several cell types can be used in the procedure, such as skeletal myoblasts and bone marrow cells. Recent publications have suggested that bone marrow cells may be excellent candidates due to their pluripotency, but their actual role in cardiac regeneration is unknown. OBJECTIVE: To evaluate the exact physiological role of bone marrow cells in the healing process after myocardial infarction. METHODS: A mouse bone marrow cell transplantation model was used in which transplanted cells were easily detectable by immunohistochemistry. Chimeric mice were subjected to myocardial infarction by ligation of the left descending coronary artery. After one month, the mice were sacrificed and the scars were analyzed. RESULTS: Transplanted bone marrow cells were detected in the scars and these cells seemed able to transdifferentiate into endothelial cells, but no transdifferentiation into cardiomyocytes occurred. This mechanism of regeneration was dismissed because only 2% of the vessels in the scars were positive for transplanted cells. CONCLUSIONS: Bone marrow cells might be involved in myocardial healing, but this physiological mechanism is insufficient to allow correct regeneration.