Abstract 20455: Comparing the Efficacy of Contractile and Pre-Contractile Cardiomyocytes in Restoring the Function of the Injured Myocardium
BACKGROUND: Cell therapy has shown to promote the repair of injured cardiac muscle post-myocardial infarction (MI). However, transplantation of human embryonic stem cell (hESC)-derived cardiomyocytes (hCMs) has not demonstrated consistent functional restoration of the injured myocardium. This may be explained by their reduced plasticity and engraftment potential due to their developmentally differentiated state.
HYPOTHESIS: Pre-contractile hCMs (pre-hCMs) will provide significant and sustained restoration of the injured myocardium compared to the contractile hCMs.
METHODS & RESULTS: H7 hESCs were differentiated through small molecule manipulation of the Wnt signaling pathway in cardiac development. Cells were cultured for 2 days with 6 uM CHIR99021, a Wnt activator, followed by another 2 days with 5 uM IWR-1, a Wnt inhibitor. Spontaneous contractility was typically observed around 10 days after initial exposure. For the purpose of analysis, hCMs were harvested at day 35 and pre-hCMs were harvested at day 8. Flow cytometry revealed that 76.8 ± 16.2% of CMs expressed cardiac troponin T whereas less than 5% of pre-hCMs expressed this same protein (p < 0.05). RT-PCR was also performed to determine the genetic profile of these populations. Relative to the undifferentiated hESCs, both groups displayed significant down-regulation of pluripotency genes, but compared to hCMs, pre-hCMs were found to have higher levels of mesodermal and early cardiac genes and lower levels of late cardiac genes. SCID mice with permanent LAD ligation had hCMs, pre-hCMs, or PBS injected into the peri-infarct zone and underwent MRI to record changes in EF. Baseline EF was 44.1 ± 3.8% but 2 weeks after surgery the pre-hCM mice were up to 47.5 ± 1.1%* while the hCM mice had dropped to 28.9% and the PBS mice had fallen even further to 16.1 ± 8.1%. This trend was maintained at week 4: pre-hCM 45.0%*, hCM 29.9 ± 4.3%, and PBS 6.2%. [* p < 0.05 vs. hCM and PBS]
CONCLUSIONS: We demonstrate that the mesodermal/early cardiac developmental state of pre-hCMs compared to hCMs provides sustained and significant improvement in LVEF. While the exact mechanism is not known, the non-contractile cells may enhance their engraftment by the ability to align their orientation with the existing myocardium.
Author Disclosures: R. Thakker: None. A. Tachibana: None. Y. Matsuura: None. M. Wang: None. E. Rulifson: None. P. Yang: None.
- © 2014 by American Heart Association, Inc.