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Stem Cells International
Volume 2017 (2017), Article ID 9605432, 14 pages
https://doi.org/10.1155/2017/9605432
Research Article

Comparative Analysis of Spontaneous and Stimulus-Evoked Calcium Transients in Proliferating and Differentiating Human Midbrain-Derived Stem Cells

1Department of Cardiovascular and Renal Research, University of Southern Denmark, J.B.Winsløws Vej 21, 5000 Odense C, Denmark
2Department of Neurobiology Research, Institute of Molecular Medicine, University of Southern Denmark, J.B.Winsløws Vej 21, 5000 Odense C, Denmark
3Department of Molecular Biology and Center of Molecular Biology Severo Ochoa, UAM-CSIC, Campus Cantoblanco, 28049 Madrid, Spain

Correspondence should be addressed to Morten Meyer

Received 30 June 2017; Accepted 10 September 2017; Published 22 October 2017

Academic Editor: Luca Vanella

Copyright © 2017 Torben Johansen et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Spontaneous cytosolic calcium transients and oscillations have been reported in various tissues of nonhuman and human origin but not in human midbrain-derived stem cells. Using confocal microfluorimetry, we studied spontaneous calcium transients and calcium-regulating mechanisms in a human ventral mesencephalic stem cell line undergoing proliferation and neuronal differentiation. Spontaneous calcium transients were detected in a large fraction of both proliferating (>50%) and differentiating (>55%) cells. We provide evidence for the existence of intracellular calcium stores that respond to muscarinic activation of the cells, having sensitivity for ryanodine and thapsigargin possibly reflecting IP3 receptor activity and the presence of ryanodine receptors and calcium ATPase pumps. The observed calcium transient activity potentially supports the existence of a sodium-calcium antiporter and the existence of calcium influx induced by depletion of calcium stores. We conclude that the cells have developed the most important mechanisms governing cytosolic calcium homeostasis. This is the first comparative report of spontaneous calcium transients in proliferating and differentiating human midbrain-derived stem cells that provides evidence for the mechanisms that are likely to be involved. We propose that the observed spontaneous calcium transients may contribute to mechanisms involved in cell proliferation, phenotypic differentiation, and general cell maturation.