Abstract 15186: Human Cardiac Stem Cells Cultured with Low Density Provides Higher Therapeutic Potential in Rat Acute Infarction Model
[Background] Human cardiac stem cells have cariomyogenic potential and to be possible candidate for cardiac regeneration therapy. However, though cell-cell contact may play a pivotal role to induce cardiac differentiation, cell density for maintaining the therapeutic potential of the stem cells has not been fully examined. We hypothesized that low density culture maintain the undifferentiated state and enhance therapeutic effect of the cells.
[Methods and Results] C-Kit positivity and doubling time were examined in different initial cell densities; 340, 1400 or 5500 cells/cm2 with 5 days/passage. Real time PCR was performed to check cell-cycle regulating genes and differentiation markers expressed in each condition. To assess the differentiation potential, several markers were analyzed by real time PCR after inducing differentiation with dexamethasone. Therapeutic potential was examined by implantation of these cells into rat acute myocardial infarction model. We detected higher C-Kit positivity and faster doubling time in the 340 cells/cm2 [340 vs. 1400 vs. 5500; C-Kit positivity, 33 ± 2 vs. 22 ± 1 vs. 6 ± 3 (%), P < 0.01; Doubling time, 26 ± 1 vs. 30 ± 2 vs. 41 ± 3 (hours), P < 0.01]. The real time PCR revealed that the cells with 340 and 1400 cells/cm2 express lower levels of p21, p53, Tie2 and alpha Smooth muscle actin compared with 5500 cells/cm2 (Figure 1). After inducing differentiation, the cells with 340 cells/cm2 expressed higher levels of the cardiomyocyte markers (cardiac troponin T and α Sarcomeric actin) and vascular markers (Tie2 and PDGFRB) compared with 5500 cells/cm2 (Figure 2). Echocardiography revealed that implantation of the cells with 340 cells/cm2 attenuates cardiac remodeling more strongly compared with the 5500 cells/cm2 at 3 weeks after implantation [340 vs. 5500; LVEF, 80 ± 1 vs. 60 ± 3 (%), P < 0.01].
[Conclusion] The low density culture improves the differentiation potential of the human cardiac stem cells and the therapeutic effect in heart failure.
- © 2011 by American Heart Association, Inc.