Abstract 260: Cardiosphere Derived Cells Generated from the Human Atria Exhibit Superior Potency Compared to the Left Ventricle
Currently, allogeneic cardiosphere-derived cells (CDCs) are being tested in a phase I/II clinical trial. Our manufacturing process utilizes the atria and other regions of the heart to build a master cell bank, but leaves the left ventricle (LV) intact thus eliminating a potential source to build our clinical stocks. In an effort to increase CDC yield per heart, we compared CDCs generated from the atria to the left ventricle (LV). To investigate this hypothesis we characterized CDCs by flow cytometry, growth kinetics and in vivo potency. The surface marker profiles for atrial CDCs and LV CDCs were very similar. Of the 17 markers used to characterize CDCs (c-kit, MDR-1, Sca-1, Abcg2, CD133, CD31, CD34, CD45, CD105, CD29, CD44, CD73, CD166, CD140b, CD90, DDR2 and α-SMA) only one demonstrated substantial differential expression in LV versus atria. PDGFR-β (CD140b) was upregulated in CDCs derived from the LV compared to the atria. Consistent with this finding, GEO2R analysis of DNA microarray data revealed increased PDGFR-β and PDGF-B expression in normal human LV tissue compared to atrial tissue. We have also observed that CDC expression of PDGFR-β negatively correlates with in vivo potency (R=0.899) suggesting that the high expression of this marker in CDCs derived from the LV may limit its regenerative performance. Indeed when calculated growth rates were compared, tissue samples from the atria yielded 4 to 6-fold more CDCs compared to the LV (atria=26±10 versus LV=5±5 Million CDCs/g/day). Also, CDCs derived from the atria and LV led to differential improvements in ejection fraction (EF) over three weeks. CDCs from the atria significantly outperformed the control group (atrial CDCs=Δ+12.6±10.8%, control=Δ-15.3±13.6%), while CDCs from the LV showed minimal treatment effects and failed to meet our minimal potency requirement (LV CDCs=Δ+0.0±6.2%). In conclusion, LV CDCs display limited potential for clinical use. This observation provides a unique opportunity to explore the mechanisms that govern functional potency and assist in understanding the basic processes involved in CDC mediated repair.
- © 2013 by American Heart Association, Inc.