Autologous cardiomyotissue implantation promotes myocardial regeneration, decreases infarct size, and improves left ventricular function.

BACKGROUND: Cell therapy for myocardial infarction (MI) may be limited by poor cell survival and lack of transdifferentiation. We report a novel technique of implanting whole autologous myocardial tissue from preserved myocardial regions into infarcted regions. METHODS AND
RESULTS: Fourteen rats were used to optimize cardiomyotissue size with peritoneal wall implantation (300 μm identified as optimal size). Thirty-nine pigs were used to investigate cardiomyotissue implantation in MI induced by left anterior descending balloon occlusion (10 animals died; male-to-female transplantation for tracking with in situ hybridization for Y chromosome, n=4 [2 donors and 2 MI animals]; acute MI implantation cohort at 1 hour, n=13; and healed MI implantation at 2 weeks, n=12). Assessment included echocardiography, magnetic resonance imaging, hemodynamics, triphenyltetrazolium chloride staining, and histological and molecular analyses. Tracking studies demonstrated viable implants with donor cells interspersed in the adjacent myocardium with gap junctions and desmosomes. In the acute MI cohort, treated animals compared with controls had improved perfusion by magnetic resonance imaging (1.2±0.01 versus 0.86±0.05; P<0.01), decreased MI size (magnetic resonance imaging: left ventricle, 2.2±0.5% versus 5.4±1.5%, P=0.04; triphenyltetrazolium chloride: anterior wall, 10.3±4.6% versus 28.9±5.8%, P<0.03), and improved contractility (dP/dt, 1235±215 versus 817±817; P<0.05). In the healed MI cohort, treated animals had less decline in ejection fraction between 2 and 4 week assessment (-3±4% versus -13±-4%; P<0.05), less decline in ±dP/dt, and smaller MI (triphenyltetrazolium chloride, 21±11% versus 3±8%; P=0.006) than control animals. Infarcts in the treated animals contained more mdr-1(+) cells and fewer c-kit(+) cells with a trend for decreased expression of matrix metalloproteinase-2 and increased expression of tissue inhibitor of metalloproteinase-2.
CONCLUSION: Autologous cardiomyotissue implanted in an MI area remains viable, exhibits electromechanical coupling, decreases infarct size, and improves left ventricular function.