Mesenchymal stem cells/multipotent stromal cells (MSCs) are glycolytic and thus glucose is a limiting factor of in vitro models of MSC starvation

Abstract

BackgroundMesenchymal stem/multipotent stromal cells (MSCs) contribute to tissue repair but are challenged during wound healing when the blood supply is disrupted, thereby limiting nutrient delivery. Survival mechanisms against ‘starvation’ include autophagy, which we previously found to enhance differentiation efficiency. MSC response to models of in vitro nutrient deprivation are of great interest for improving MSC survival and therapeutic efficacy; however, the rate-limiting nutrients are unknown.MethodsMSC responses to culture nutrient and/or serum deprivations were assessed through light microscopy, cell survival, and measurements of metabolic levels. Glucose uptake was determined through conditioned media analyses over 3 days of culture. The Seahorse XF24 Flux analysis system was used to determine oxygen consumption and extracellular acidification for glycolytic metabolism. MSC autophagic response to these conditions was assessed via immunoblots for LC3-I and LC3-II, markers of autophagosome turnover.ResultsWe more closely examined limiting nutritional factors to MSC survival in vitro, finding that glucose is rapidly utilized/depleted whereas amino acids and other required nutrients were used sparingly. This finding concurred with metabolic analyses that showed a primarily glycolytic character to the MSCs at steady state. MSC autophagy, previously linked to MSC function through a unique accumulated autophagosome phenotype, also responded quickly to changes in glucose concentration, with drastic LC3-II changes within 24 h of glucose concentration shifts.ConclusionsOur results demonstrated a rapid uptake of glucose in MSC cultures that was due to a highly glycolytic phenotype for the cells; MSC starvation with serum or other nutrients appears to have a less notable effect on the cells. These findings highlight the importance of glucose and glucose metabolism on MSC function. The conditions and cellular responses outlined here may be essential in modeling MSC nutrient deprivation.Electronic supplementary materialThe online version of this article (doi:10.1186/s13287-016-0436-7) contains supplementary material, which is available to authorized users.

Survival/Adaptation of Bone Marrow-Derived Mesenchymal Stem Cells After Long-Term Starvation Through Selective Processes

“…These data together confirmed that hBM‐MSC have high resistance to genetic damage as previously demonstrated . Although it has been shown that MSC have high metabolic flexibility , when cultured in vitro they have a glycolytic phenotype being highly dependent on glycolysis and glucose metabolism for energy. Successful culture of MSC in a SF medium with “reduced” nutritional properties, with respect to a “rich” FBS‐containing medium, supports the concept of glucose as a source of energy for cell expansion.…”

Differential Effector Response of Amnion‐ and Adipose‐Derived Mesenchymal Stem Cells to Inflammation; Implications for Intradiscal Therapy

“…First, the effect of other degenerate IVD environmental stimuli including other inflammatory cytokines, oxygen tension, pH, limited nutrient supply and osmolarity, which have been shown to impact MSC effector function and viability, were not investigated . For example, studies have shown that MSC metabolism is highly dependent upon the presence of glucose, and that MSCs may be tolerant of or adapt to nutrient deprivation . Moreover, hypoxia may enhance MSC differentiation toward a IVD cell‐like phenotype .…”

Effect of metformin and celecoxib on cytotoxicity and release of GDF‐15 from human mesenchymal stem cells in high glucose condition

“…These mechanisms justify the growth inhibitory effects of metformin. On the other hand, among limiting nutritional factors to MSCs, glucose and related metabolisms are the most important factors in survival and normal function of MSCs, especially in comparison to other common nutrients such as serum, oxygen, and amino acid concentrations in culture or in implant sites . Hyperglycemic condition causes undesirable effects on proliferation and differentiation of MSCs .…”

“…On the other hand, among limiting nutritional factors to MSCs, glucose and related metabolisms are the most important factors in survival and normal function of MSCs, especially in comparison to other common nutrients such as serum, oxygen, and amino acid concentrations in culture or in implant sites. 27 Hyperglycemic condition causes undesirable effects on proliferation and differentiation of MSCs. 28 Fu and his colleagues suggested that high glucose decreases proliferation of neural stem cells by increased apoptosis and change expression of genes that are associated to cell cycle progression.…”