In:
Circulation, Ovid Technologies (Wolters Kluwer Health), Vol. 116, No. suppl_16 ( 2007-10-16)
Abstract:
Human cardiac stem cells (hCSCs) are self-renewing, clonogenic and have the ability to differentiate into myocytes, smooth muscle and endothelial cells in vitro and in vivo. Since Ca 2+ plays a crucial role in mechanotransduction and activation of signalling pathways in mature cardiac cells, intracellular Ca 2+ cycling was studied in hCSCs to determine the function of this cation in cell division and commitment to the myocyte lineage. For this purpose, hCSCs were exposed to conditions favouring proliferation and differentiation and affecting intracellular Ca 2+ homeostasis. Moreover, hCSCs were loaded with Fluo-3 and intracellular Ca 2+ levels were monitored by 2-photon microscopy. hCSCs presented spontaneous Ca 2+ spikes mediated by Ca 2+ release from the endoplasmic reticulum (ER). ATP and histamine, which stimulate InsP 3 R-mediated ER Ca 2+ release, increased the occurrence of spikes leading to oscillations in intracellular Ca 2+ . 2-APB, an antagonist of InsP 3 R, inhibited spike formation and oscillatory events. Ryanodine, which acts on the ryanodine receptors, did not alter intracellular Ca 2+ and thapsigargin, a Ca 2+ pump blocker, prevented spontaneous and induced ER Ca 2+ release. Store operated capacitative Ca 2+ entry was evoked by increasing extracellular Ca 2+ after depletion of the ER. Ca 2+ entry was blocked by lanthanum. Additionally, patch-clamp experiments indicated the absence of the voltage-activated L-type Ca 2+ current in hCSCs. Exposure of hCSCs to IGF-1 triggered acutely Ca 2+ spikes and increased chronically their occurrence. Over a period of 24 hours, IGF-1 resulted in more than 100% increase in the proliferation of hCSCs measured by BrdU labelling. Similarly, ATP enhanced proliferation of hCSC by ~60%. Importantly, incubation with 2-APB reduced by ~50% BrdU incorporation and abolished the effect of IGF-1 and ATP on both Ca 2+ spikes and cell proliferation. In the presence of differentiating medium, the frequency of Ca 2+ spikes in active hCSCs increased significantly. Additionally, enhanced Ca 2+ cycling increased the number of hCSCs committed to the myocyte lineage, while attenuations in this phenomenon blunted hCSC differentiation. Thus, InsP 3 R-mediated Ca 2+ spikes play an obligatory role in hCSC growth and differentiation.
Type of Medium:
Online Resource
ISSN:
0009-7322
,
1524-4539
DOI:
10.1161/circ.116.suppl_16.II_203-a
Language:
English
Publisher:
Ovid Technologies (Wolters Kluwer Health)
Publication Date:
2007
detail.hit.zdb_id:
1466401-X
