Supercritical Fluid-Assisted Fabrication of Pd Nanoparticles/Graphene Using a Choline Chloride-Oxalic Acid Deep Eutectic Solvent for Enhancing the Electrochemical Oxidation of Glycerol.

A green method for synthesizing Pd nanoparticles/graphene composites from a choline chloride-oxalic acid deep eutectic solvent (DES) without a reducing agent or a surfactant is reported. Deep eutectic solvents are usually composed of halide salts and hydrogen-bond donors, and many are biocompatible and biodegradable. The merits of deep eutectic solvents include that they serve as reducing agents and dispersants, and Pd nanoparticles are tightly anchored to graphene. The size and dispersion of Pd particles are improved when supercritical carbon dioxide (scCO2) is used because it has gaslike diffusivity and near-zero surface tension, which results in excellent wettability between the scCO2 and the carbon surface. The prepared sc-Pd NPs/GR/SPCE shows excellent activity toward glycerol oxidation compared to composites not fabricated by scCO2 processes. This study demonstrates the potential of using this scCO2-assisted protocol combined with deep eutectic solvents to further construct nanoparticles/graphene composites.

Adipose-Derived Mesenchymal Stem Cells Ameliorate Lipid Metabolic Disturbance in Mice.

UNLABELLED: : Adipose-derived mesenchymal stem cells (AD-MSCs) have been shown to ameliorate hyperglycemia in diabetic animals and individuals. However, little is known about whether AD-MSCs affect lipid metabolism. Here we have demonstrated for the first time that AD-MSC infusion can significantly suppress the increase in body weight and remarkably improve dyslipidemia in db/db obese mice and diet-induced obesity mice. Induction of white fat tissue "browning" and activation of adenosine monophosphate-activated protein kinase and its downstream hormone-sensitive lipase in adipose tissue contribute to the antiobesity and lipid-lowering effects. Thus, AD-MSC infusion holds great therapeutic potential for dyslipidemia and associated cardiovascular diseases. SIGNIFICANCE: Mesenchymal stem cells (MSCs) are considered one of the most promising types of stem cells for translational application because of their rich tissue sources, multilineage differentiation capacity, and easy amplification in vitro and unique immunobiological properties. This study demonstrated that adipose-derived MSCs (AD-MSCs) infusion can significantly suppress the increase in body weight and remarkably improve dyslipidemia in obese mice. Induction of white fat tissue "browning" and activation of adenosine monophosphate-activated protein kinase and its downstream hormone-sensitive lipase in adipose tissue were demonstrated to contribute to the antiobesity and lipid-lowering effects. Thus, AD-MSC infusion holds great therapeutic potential for dyslipidemia.

Short-term memory of danger signals or environmental stimuli in mesenchymal stem cells: implications for therapeutic potential.

Mesenchymal stem/stromal cells (MSCs) possess some characteristics of immune cells, including a pro-inflammatory phenotype, an immunosuppressive phenotype, antibacterial properties and the expression of Toll-like receptor proteins. Here we show that, similar to immune cells, MSCs retain information from danger signals or environmental stimuli for a period of time. When treated with the pro-inflammatory factors lipopolysaccharide (LPS) or tumor necrosis factor-α (TNF-α), MSCs display increased expression of IL-6, IL-8 and MCP-1. Following re-plating and several rounds of cell division in the absence of stimulating factors, the expression of IL-6, IL-8 and MCP-1 remained higher than in untreated cells for over 7 days. A spike in cytokine secretion occurred when cells were exposed to a second round of stimulation. We primed MSCs with LPS and LPS-primed MSCs had better therapeutic efficacy at promoting skin flap survival in a diabetic rat model than did unprimed MSCs. Finally, we found that several microRNAs, including miR146a, miR150 and miR155, along with the modification of DNA by 5-hydroxymethylcytosine (5hmC), mediate the MSC response to LPS and TNF-α stimulation. Collectively, our data suggest that MSCs have a short-term memory of environmental signals, which may impact their therapeutic potential.

Effect of serum choice on replicative senescence in mesenchymal stromal cells.

BACKGROUND AIMS: Multipotent mesenchymal stromal cells (MSCs) are promising candidates for innovative cell therapeutic applications. Before their use, however, they usually need to be expanded in vitro with serum-supplemented media. MSCs can undergo replicative senescence during in vitro expansion, but it is not yet clear how serum supplements influence this process. METHODS: In the present study, we compared how media supplemented with fetal bovine serum (FBS) or calf serum (CS) affected morphology, proliferation, differentiation, senescence and other functional characteristics of human umbilical cord-derived MSCs (UC-MSCs). RESULTS: UC-MSCs cultured in both FBS- and CS-containing media were able to differentiate along osteogenic and adipogenic lineages but ultimately reached proliferation arrest. However, senescence-associated characteristics, such as ß-galactosidase activity, reactive oxygen species levels, proliferation rate and gene expression, demonstrate that UC-MSCs grown with FBS have better proliferation potential and differentiation capacity. In contrast, UC-MSCs grown with CS have a higher proportion of apoptotic cells and senescent characteristics. Possible mechanisms for the observed phenotypes include changes in gene expression (Bax, p16, p21 and p53) and cytokine production (interleukin-6 and interleukin-8). CONCLUSIONS: This study demonstrates that FBS-supplemented media provides a better microenvironment for the expansion of UC-MSCs in vitro than CS-supplemented media. This work provides insight into MSCs generation practices for use in basic research and clinical therapies.

Secreted galectin-3 as a possible biomarker for the immunomodulatory potential of human umbilical cord mesenchymal stromal cells.

BACKGROUND AIMS: Human umbilical cord-derived mesenchymal stromal cells (UC-MSCs) possess broad and potent immunomodulatory activities and have shown great potential in anti-inflammatory therapies. However, a biomarker that can be used to assess quickly and efficiently the immunomodulatory function of UC-MSCs has not been identified. Several studies have revealed that galectin-3 (Gal-3), a member of the human galectin family, is involved in the immunosuppressive function of MSCs. METHODS: Gal-3 gene expression in UC-MSCs was analyzed using quantitative reverse transcriptase polymerase chain reaction and Western blotting. Blocking of Gal-3 expression in UC-MSCs with small interfering RNA was employed to analyze whether the immunosuppressive function of UC-MSCs was affected. RESULTS: We found that UC-MSCs expressed Gal-3 both on the cell surface and in secreted form, and the expression levels of Gal-3 did not show significant variation after cell passaging. We further showed that Gal-3 expression correlated with the immunosuppressive function of UC-MSCs because knock-down of Gal-3 expression with small interfering RNA significantly abrogated the inhibitory effects of UC-MSCs on mitogen-stimulated and alloantigen-stimulated proliferation of human peripheral blood mononuclear cells; meanwhile, the inhibitory effect of UC-MSCs was reversed by adding back recombinant Gal-3 to the co-culture systems. The inhibitory activities of human UC-MSCs were not reduced even when they were separated from human peripheral blood mononuclear cells in a transwell co-culture system, indicating that the soluble form of Gal-3 was the major effector. CONCLUSIONS: The Gal-3 protein secreted by UC-MSCs shows good correlation with immunosuppressive potential and may serve as a possible biomarker for the potency test of UC-MSCs.