Quantitative analysis of survival of transplanted smooth muscle cells with real-time polymerase chain reaction

BackgroundCell transplantation improves heart function after myocardial infarction. This study investigated the survival of implanted cells in normal and infarcted myocardium.MethodsMale rat aortic smooth muscle cells were cultured. For the in vitro study, male smooth muscle cells mixed with female smooth muscle cells or male smooth muscle cells injected into a piece of female rat myocardium were used to evaluate the accuracy of quantitative real-time polymerase chain reaction to measure Y chromosomes. For the in vivo study, 2 million live or dead male smooth muscle cells were injected into normal or infarcted female myocardium. At 1 hour and 1 and 4 weeks after transplantation, hearts, lungs, and kidneys were harvested for measurement of Y chromosomes.ResultsIn vitro, the accuracy of polymerase chain reaction measurement was excellent in cultured cells (r2 = 0.996) and the myocardium (r2 = 0.786). In vivo, 1 hour after 2 × 106 cell implantation, live cell numbers decreased to 1.0 ± 0.2 × 106 and 1.1 ± 0.3 × 106, and dead cell numbers decreased to 0.9 ± 0.2 × 106 and 0.8 ± 0.2 × 106 in the normal and infarcted myocardium, respectively (P < .01 for all groups). Lungs and kidneys contained 8.5% and 1.5% of the implanted cells, but no cells were detected at 1 week. At 1 week, no dead smooth muscle cells were detected in the normal or infarcted myocardium. The numbers of live cells at 1 and 4 weeks were 0.48 ± 0.06 × 106 and 0.27 ± 0.07 × 106 in normal myocardium and 0.29 ± 0.08 × 106 and 0.18 ± 0.05 × 106 in infarcted myocardium.ConclusionsOne hour after implantation, only 50% of smooth muscle cells remained in the implanted area. Some implanted cells deposited in other tissue. Implanted cell survival progressively decreased during the 4-week study