Abstract 11094: Cardiac Endothelial Progenitor Cells Isolated from Human Atrial Appendages Demonstrate Biological and Functional Properties Typical of Endothelial Cells
Background: The number of circulating endothelial progenitor cells (EPCs) typically positive for CD34/KDR has been reported to be inversely related to cardiovascular mortality. However, it is unknown whether the heart itself contains EPCs which have migrated from blood or whether EPCs are resident to cardiac tissue. Recently, two types of cardiac stem cells (CSCs) have been isolated from adult heart, termed “myogenic CSCs” (mCSCs) & “vasculogenic CSCs” (vCSCs) based on their markers and capacities for cardiac lineage differentiation. Existing data suggest that vCSCs are different from EPCs in terms of endothelial cell (EC)-specific markers and differentiation potential. We hypothesized that within the heart reside endogenous cardiac EPCs (termed cEPCs) possessing properties typical of ECs, and therefore, differing intrinsically from vCSCs.
Methods: Human CSCs were isolated from right atrial appendage specimens (n=15). The isolated cells underwent c-kit magnetic activated cell sorting (MACS), followed by MACS for CD31 from passages 1 to 3. At every other passage up to passage 10, the cells were collected for various analyses including immunostaining, flow cytometry, and functional assays for ECs. Dexamethasone & EC medium were used for in vitro cardiac differentiation, which was evaluated with immunostaining & RT-PCR.
Results: Specific antibody staining demonstrated that tissue sections and freshly-isolated cells from right atrial appendages contained <1% c-kit+ cells among the total nuclei counted. Following MACS for c-kit and CD31, we found that the c-kit+/CD31+ cell population (cEPCs) showed typical morphology of ECs. This population was positive for KDR (>90%), vWF (60%), VE-cadherin (>80%), CD34 (10%), GATA4/Nkx2.5 (20-40%), but negative for CD45, CD133, and Lin (0%). These cells also exhibited the capacity to form capillary structures & to uptake Dil-AC-LDL dye, both unique properties of EPCs. After differentiation, almost all of cEPC became mature ECs.
Conclusion: To our knowledge, this is the first report of the existence of a resident CSC population (cEPCs) identified by c-kit+/CD31+ selection. These cells demonstrate the biological and functional properties typical for ECs and similar to circulating EPCs but different from vCSCs.
- © 2011 by American Heart Association, Inc.