Collectively, these results highlight the potential of pharmacological intervention against LPA signaling for blunting senescence-associated loss of function characteristic of human MSCs. Introduction Stem/progenitor cells are the subject of intense investigation for cell-based therapies . all panels, the data are presented as the means standard error (values compared to controls were indicated.(TIF) pone.0032185.s001.tif (221K) GUID:?4E032FD7-709C-4BBA-A652-7104D8E3B318 Abstract Marrow stromal cells (MSCs) isolated from mesenchymal tissues can propagate to some extent and differentiate into various tissue lineages to be used for cell-based therapies. Cellular senescence, which occurs readily in continual MSC culture, leads to loss of these characteristic properties, representing one of the major limitations to achieving the potential of MSCs. In this study, we investigated the effect of lysophosphatidic acid (LPA), a ubiquitous metabolite in membrane phospholipid synthesis, on the senescence program of human MSCs. We show that MSCs preferentially express the LPA receptor subtype 1, and an abrogation of the receptor engagement with the antagonistic compound Ki16425 attenuates senescence RETF-4NA induction in continually propagated human MSCs. This anti-aging effect of Ki16425 results in extended rounds of cellular proliferation, increased clonogenic potential, and retained plasticity for osteogenic and adipogenic RETF-4NA differentiation. Expressions of p16Ink4a, Rb, p53, and p21Cip1, which have been associated with cellular senescence, were all reduced in human MSCs by the pharmacological inhibition of LPA signaling. Disruption of this signaling pathway was accompanied by morphological changes such as cell thinning and elongation as well as actin filament deformation through decreased phosphorylation of focal adhesion kinase. Prevention of LPA receptor engagement also promoted ubiquitination-mediated c-Myc elimination in MSCs, and consequently the entry into a quiescent state, G0 phase, of the cell cycle. Collectively, these results highlight the potential of pharmacological intervention against LPA signaling for blunting senescence-associated loss of function characteristic of human MSCs. Introduction Stem/progenitor cells are the subject of intense investigation for cell-based therapies . In particular, marrow stromal cells (MSCs, also referred to as mesenchymal stem cells), which can be isolated from most mesenchymal tissues (e.g., bone marrow, fat, and blood vessels), not only represent multilineage potential for differentiating into several skeletal cell types such as osteoblasts and adipocytes but also have the capacity to secrete soluble factors that can improve repair of multiple organs such as bone, brain, heart, lung, and pancreas and modulate the immune system , , , , , , . MSCs divide rapidly in culture and thus are potentially attractive for use in developing new therapeutic approaches , , . However, MSCs in culture are readily observed to senesce after 25 population doublings, a process in which they propagate slowly, decrease their clonogenicity, and lose their potential to differentiate , , , , . The propensity for a decrease in the MSC’s potential prevents extensive rounds of expansion for obtaining clinically significant cell numbers and demands modification of culture conditions to alleviate their senescence , . Lysophosphatidic acid (LPA) is an extracellular signaling molecule that is ubiquitously produced from membrane phospholipids through phospholipase A2 (PLA2)-mediated pathways , . To date, five subtypes of rhodopsin-like receptors with seven-transmembrane alpha helices, LPA1-LPA5, have been reported to bind LPA and activate G proteins, thereby inducing various biological effects on diverse cellular and organ systems , . In MSCs, some evidence has demonstrated the expression of LPA1-LPA4 receptors that are likely implicated in protecting against stress-induced apoptosis and regulating migration and differentiation , , , , , . Here, we set out to determine whether the biological activity of LPA toward human MSCs was also associated with the phenotypic changes that MSCs entering into a state of senescence undergo Rabbit Polyclonal to RPL26L RETF-4NA during continuous propagation. Based on RETF-4NA our finding that human MSCs preferentially express the LPA1 receptor subtype, we used a synthesized isoxazole derivative named Ki16425, 3-(4-[4-([1-(2-chlorophenyl)ethoxy]carbonyl amino)-3-methyl-5-isoxazolyl] benzylsulfanyl) propanoic acid, that antagonizes LPA binding, particularly to LPA1 and LPA3 (rank order of antagonizing affinity of Ki16425, LPA1LPA3?LPA2) . Treatment of human MSCs with Ki16425 promoted quiescence in the G0-phase of the cell cycle and thus enabled cells to.