Calcium-Sensing Receptor-Mediated Osteogenic and Early-Stage Neurogenic Differentiation in Umbilical Cord Matrix Mesenchymal Stem Cells from a Large Animal Model

Background: Umbilical cord matrix mesenchymal stem cells (UCM-MSCs) present a wide range of potential therapeutical applications. The extracellular calcium-sensing receptor (CaSR) regulates physiological and pathological processes. We investigated, in a large animal model, the involvement of CaSR in triggering osteogenic and neurogenic differentiation of two size-sieved UCM-MSC lines, by using AMG641, a novel potent research calcimimetic acting as CaSR agonist. Methodology/Principal Findings: Large (.8mm in diameter) and small (,8mm) equine UCM-MSC lines were cultured in medium with high calcium (Ca2+) concentration ([Ca2+]o; 2.87 mM) and dose-response effects of AMG641 (0.01 to 3mM) on cell proliferation were evaluated. Both cell lines were then cultured in osteogenic or neurogenic differentiation medium containing: 1) low [Ca2+]o (0.37 mM); 2) high [Ca 2+]o (2.87 mM); 3) AMG641 (0.05, 0.1 or 1 mM) with high [Ca 2+]o and 4) the CaSR antagonist NPS2390 (10 mM for 30 min) followed by incubation with AMG641 in high [Ca2+]o. Expression of osteogenic or neurogenic differentiation biomarkers was compared among groups. In both cell lines, AMG641 dose-dependently increased cell proliferation (up to P,0.001). Osteogenic molecular markers expression was differentially regulated by AMG641, with stimulatory (OPN up-regulation) in large or inhibitory (RUNX2 and OPN down-regulation) effect