Calcium‐dependent potassium channels control proliferation of cardiac progenitor cells and bone marrow‐derived mesenchymal stem cells

Abstract

Endogenous c-Kit cardiac progenitor cells (eCPCs) and bone marrow (BM)-derived mesenchymal stem cells (MSCs) are being developed for cardiac regenerative therapy, but a better understanding of their physiology is needed. Here, we addressed the unknown functional role of ion channels in freshly isolated eCPCs and expanded BM-MSCs using patch-clamp, microfluorometry and confocal microscopy. Isolated c-Kit eCPCs were purified from dog hearts by immunomagnetic selection. Ion currents were barely detectable in freshly isolated c-Kit eCPCs with buffering of intracellular calcium (Ca ). Under conditions allowing free intracellular Ca , freshly isolated c-Kit eCPCs and ex vivo proliferated BM-MSCs showed prominent voltage-independent conductances that were sensitive to intermediate-conductance K -channel (KCa3.1 current, I ) blockers and corresponding gene (KCNN4)-expression knockdown. Depletion of Ca induced membrane-potential (V ) depolarization, while store-operated Ca entry (SOCE) hyperpolarized V in both cell types. The hyperpolarizing SOCE effect was substantially reduced by I or SOCE blockade (TRAM-34, 2-APB), and I blockade (TRAM-34) or KCNN4-knockdown decreased the Ca entry resulting from SOCE. I suppression reduced c-Kit eCPC and BM-MSC proliferation, while significantly altering the profile of cyclin expression. I was reduced in c-Kit eCPCs isolated from dogs with congestive heart failure (CHF), along with corresponding KCNN4 mRNA. Under perforated-patch conditions to maintain physiological [Ca ] , c-Kit eCPCs from CHF dogs had less negative resting membrane potentials (-58 ± 7 mV) versus c-Kit eCPCs from control dogs (-73 ± 3 mV, P < 0.05), along with slower proliferation. Our study suggests that Ca -induced increases in I are necessary to optimize membrane potential during the Ca entry that activates progenitor cell proliferation, and that alterations in KCa3.1 may have pathophysiological and therapeutic significance in regenerative medicine.

A critical role of the KCa3.1 channel in mechanical stretch‐induced proliferation of rat bone marrow‐derived mesenchymal stem cells

“…K Ca 3.1 channel, also known as KCNN4, IK Ca and SK4, is an intermediate‐conductance member of the Ca 2+ ‐activated K + channel family and is widely expressed in both excitable and non‐excitable cells, where it plays an important role in various cell functions . Interestingly, there is increasing evidence to support the K Ca 3.1 channel is engaged in MSC proliferation . Previous studies showed that the expression of the K Ca 3.1 channel in human umbilical vein endothelium cells was up‐regulated by fluid flow‐induced shear stress, or its channel activity in vascular smooth muscle cells was enhanced by hypotonic solution‐induced membrane stretch .…”

Cardiac progenitor cell ion currents: revealing a little more on the lesser known

“…The article by Vigneault et al . (2018) in this issue of The Journal of Physiology represents one of a few published reports assessing functional expression of ion channels in CPCs.…”

“…introduced KCa3.1 Ca 2+ ‐dependent K + channels as major contributors to optimizing canine CPC membrane potential and mediating proliferative responses. Interestingly, KCa3.1 channel‐mediated roles in CPCs were also observed in bone marrow‐derived mesenchymal stem cells (BM‐MSCs), a cell population that is widely used in clinical trials for cardiac stem cell therapy (Vigneault et al . 2018).…”

“…While Vigneault et al . report I KCa3.1 as the major ion current in freshly isolated canine CPCs (Vigneault et al . 2018), multiple ion currents have been documented in human CPCs (passages 1–3) and mouse CPCs (passages 0–2): large‐conductance Ca 2+ ‐dependent K + current (BKCa), transient outward K + current ( I to ), inwardly rectifying K + current ( I Kir ) and voltage‐gated tetrodotoxin‐sensitive Na + current ( I Na,TTX ) in human CPCs (Zhang et al .…”

“…Finally, Vigneault et al . discuss potential extension of their findings to improve therapeutic outcomes of CPC therapy in heart failure patients by targeting KCa3.1 ion channels (Vigneault et al . 2018).…”