Abstract 14311: Congestive Heart Failure Upregulates Volume-Dependent Chloride Currents in c-Kit+ Endogenous Cardiac Stem Cells
Introduction: Adult hearts contain c-Kit+ endogenous cardiac stem cells (eCSCs) that are being studied for regenerative therapy. eCSCs express volume-dependent Cl- channels (ICl,vol) activated under hemodynamic stress. Here, we examined the changes in eCSC Cl- channels caused by experimental congestive heart failure (CHF).
Methods: c-Kit+ eCSCs isolated from healthy (CTL) and CHF (tachypaced) dog hearts were magnetically purified with c-Kit antibodies. Cl- channel expression in freshly isolated cells was studied with patch clamp and qPCR.
Results: Under isotonic conditions, ionic currents were barely detectable in CTL eCSCs (Fig. A). The current observed was time-independent and reversed at values close to the calculated Cl- equilibrium potential (ECl-≈ -40 mV). This current was insensitive to TEA-Cl but inhibited by the Cl- channel blocker DIDS. When cells were superfused with hypo-osmotic solution (0.7T), an outward current with unchanged reversal potential was activated, and completely inhibited by DIDS (Fig. B). CHF eCSCs had much larger DIDS-sensitive currents under isotonic conditions vs CTL (Fig. C), and were significantly smaller than CTL (membrane capacitance 4.2±2.1 pF vs 5.5±1.9 pF). Among DIDS-sensitive Cl- channels known to be expressed on plasma membranes, only Clcn3 was present in c-Kit+ eCSCs. Consistent with patch-clamp data, Clcn3 expression was greater in CHF eCSCs vs CTL (Fig. D). Inhibiting Cl- currents in vitro with DIDS (100 μM) or NPPB (50 μM) decreased eCSC proliferation by 17% (p<0.05) and 21% (p<0.05) respectively.
Conclusions: In contrast to CTL c-Kit+ eCSCs, ICl,vol is strongly activated under basal conditions in CHF. Transient activation of Cl- channels is required to initiate cell proliferation, but sustained Cl- channel activation and cell-shrinkage as seen in CHF c-Kit+ eCSCs is associated with programmed cell death. Therefore, the up-regulation of Cl- currents in CHF c-Kit+ eCSCs may have pathophysiological significance.
Author Disclosures: P. Vigneault: None. P. Naud: None. D.R. Davis: None. S. Nattel: None.
- © 2016 by American Heart Association, Inc.