Injection of bone marrow mesenchymal stem cells in the borderline area of infarcted myocardium: Heart status and cell distribution

Objective: This study aimed to test the distribution of intramyocardially injected cells in variations in heart status in a porcine model of myocardial infarction. Methods: Bone marrow-derived mesenchymal stem cells were obtained from male swine and labeled with iron oxide during culture. One week after creation of a myocardial infarction in female swine, the survivors were randomly divided into 4 groups. Cardiopulmonary bypass was set up to arrest the heart, and then labeled cells (1 X 10(8)) were intramyocardially injected into the border zone of the infarcted zone in group 1 (n = 6). The same volume of cells was grafted into the beating heart in group 2 (n = 6). In groups 3 and 4, saline was injected in either the arresting or beating heart. Three days later, cell distribution was assessed by T2* change with magnetic resonance imaging and sex-determining region on Y-chromosome (SRY) with quantitative polymerase chain reaction. Results: The cells were identified in the heart, spleen, lung, and liver. Most injected cells were localized in the myocardium in groups 1 and 2; however, the amount of cells was much higher in group 1 (T2* change: 22.3 +/- 2.2 vs 17 +/- 0.84; SRY gene: 0.15 +/- 0.062 vs 0.072 +/- 0.003). Conclusions: Even after intramyocardial injection, many cells migrated to extracardiac organs, especially to the spleen. Our results indicated that injection in the arresting heart could favor retaining more cells in the myocardium. Thus, it was an optimal approach to deliver mesenchymal stem cells during open chest surgery.