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

Background: Cell transplantation improves heart function after myocardial infarction. This study investigated the survival of implanted cells in normal and infarcted myocardium. Methods: Male 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. Results: In vitro, the accuracy of polymerase chain reaction measurement was excellent in cultured cells (r(2) = 0.996) and the myocardium (r(2) = 0.786). In vivo, 1 hour after 2 X 10(6) cell implantation, live cell numbers decreased to 1.0 +/- 0.2 X 10(6) and 1.1 +/- 0.3 X 10(6), and dead cell numbers decreased to 0.9 +/- 0.2 X 10(6) and 0.8 +/- 0.2 X 10(6) 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 X 10(6) and 0.27 +/- 0.07 X 10(6) in normal myocardium and 0.29 +/- 0.08 X 10(6) and 0.18 +/- 0.05 X 10(6) in infarcted myocardium. Conclusions: One 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.