Functional expression of the extracellular calcium sensing receptor (CaSR) in equine umbilical cord matrix size-sieved stem cells

Background

The present study investigates the effects of high external calciumconcentration ([Ca²⁺]_o) and thecalcimimetic NPS R-467, a known calcium-sensing receptor (CaSR) agonist, ongrowth/proliferation of two equine size-sieved umbilical cord matrixmesenchymal stem cell (eUCM-MSC) lines. The involvement of CaSR on observedcell response was analyzed at both the mRNA and protein level.

Methodology/Principal Findings

A large (>8 µm in diameter) and a small (<8 µm) cell linewere cultured in medium containing: 1) low[Ca²⁺]_o (0.37 mM); 2) high[Ca²⁺]_o (2.87 mM); 3) NPS R-467 (3µM) in presence of high [Ca²⁺]_oand 4) the CaSR antagonist NPS 2390 (10 µM for 30 min.) followed byincubation in presence of NPS R-467 in medium with high[Ca²⁺]_o. Growth/proliferation rateswere compared between groups. In large cells, the addition of NPS R-467significantly increased cell growth whereas increasing[Ca²⁺]_o was not effective in thiscell line. In small cells, both higher[Ca²⁺]_o and NPS R-467 increasedcell growth. In both cell lines, preincubation with the CaSR antagonist NPS2390 significantly inhibited the agonistic effect of NPS R-467. In both celllines, increased [Ca²⁺]_o and/or NPSR-467 reduced doubling time values.Treatment with NPS R-467 down-regulatedCaSR mRNA expression in both cell lines. In large cells, NPS R-467 reducedCaSR labeling in the cytosol and increased it at cortical level.

Conclusions/Significance

In conclusion, calcium and the calcimimetic NPS R-467 reduce CaSR mRNAexpression and stimulate cell growth/proliferation in eUCM-MSC. Their use ascomponents of media for eUCM-MSC culture could be beneficial to obtainenough cells for down-stream purposes.