Acetoacetate is a more efficient energy-yielding substrate for human mesenchymal stem cells than glucose and generates fewer reactive oxygen species.
Acetoacetate is a more efficient energy-yielding substrate for human mesenchymal stem cells than glucose and generates fewer reactive oxygen species.
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DOI：
10.1016/j.biocel.2017.05.007
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发表时间：
2017-07
期刊：
影响因子：
--
通讯作者：
Carr C
中科院分区：
文献类型：
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作者：
Board M;Lopez C;van den Bos C;Callaghan R;Clarke K;Carr C
人类间充质干细胞的能量产生途径葡萄糖通过糖酵解和氧化途径消耗。丙酮酸、乙酰乙酸和谷氨酰胺被hMSC氧化。外源底物以实线框显示，途径中间体以虚线框显示，产物以虚线框显示。显示外源底物进入途径的途径的箭头被加权以表示利用率（不按比例）。人类间充质干细胞氧化乙酰乙酸比葡萄糖快35倍。与葡萄糖相比，乙酰乙酸的氧化使ROS产生减少45倍。乙酰乙酸加丙酮酸是ATP生产的最佳底物组合。在20%氧气中培养hMSC可将能量代谢上调2倍。干细胞已被假定证明依赖于无氧能量产生，适合于其体内缺氧环境。然而，我们发现，人类间充质干细胞（hMSCs）有一个活跃的氧化代谢与一系列的底物。培养的hMSCs通过底物氧化比糖酵解产生更多的ATP。强烈的底物偏好显示与酮体，乙酰乙酸，被氧化的速度高达35倍的葡萄糖。在乙酰乙酸氧化过程中，ROS的生成比葡萄糖低45倍，底物偏好可能是一种适应，以减少氧化应激。UCP2抑制剂京尼平使乙酰乙酸或葡萄糖的ROS产生增加2倍，表明UCP2在抑制ROS产生中的作用。添加丙酮酸刺激乙酰乙酸氧化和这种组合增加ATP的生产27倍，与单独的葡萄糖相比，这对生长培养基的组成有影响。培养过程中的氧分压影响hMSCs的代谢。在第2代和第5代之间，糖酵解和底物氧化的速率对于常氧（20%O2）培养的hMSCs增加至少2倍，但对于低氧（5%O2）培养的hMSCs没有增加，尽管生长速率下降并且没有可检测到的分化迹象。用3-羟基丁酸盐培养细胞可抑制这些途径的速率增加。这些发现对干细胞治疗有影响，这必然涉及细胞的体外培养，因为低传代次数常氧培养的干细胞显示代谢适应性，而干细胞样状态没有可检测的变化。
Energy yielding pathways of human mesenchymal stem cells Glucose is consumed by both the glycolytic and the oxidative pathways. Pyruvate, acetoacetate and glutamine are oxidised by hMSCs. Exogenous substrates are shown in boxes with solid lines, pathway intermediates in boxes with dashed lines and products in boxes with dotted lines. Arrows showing routes of entry of exogenous substrates into pathways are weighted to represent rates of utilisation (not to scale). Human mesenchymal stem cells oxidise acetoacetate 35 times faster than glucose. Oxidation of acetoacetate reduces ROS-production 45-fold compared with glucose. Acetoacetate plus pyruvate is the optimal substrate combination for ATP-production. Culture of hMSCs in 20% oxygen upregulates energy metabolism 2-fold. Stem cells have been assumed to demonstrate a reliance on anaerobic energy generation, suited to their hypoxic in vivo environment. However, we found that human mesenchymal stem cells (hMSCs) have an active oxidative metabolism with a range of substrates. More ATP was consistently produced from substrate oxidation than glycolysis by cultured hMSCs. Strong substrate preferences were shown with the ketone body, acetoacetate, being oxidised at up to 35 times the rate of glucose. ROS-generation was 45-fold lower during acetoacetate oxidation compared with glucose and substrate preference may be an adaptation to reduce oxidative stress. The UCP2 inhibitor, genipin, increased ROS production with either acetoacetate or glucose by 2-fold, indicating a role for UCP2 in suppressing ROS production. Addition of pyruvate stimulated acetoacetate oxidation and this combination increased ATP production 27-fold, compared with glucose alone, which has implications for growth medium composition. Oxygen tension during culture affected metabolism by hMSCs. Between passages 2 and 5, rates of both glycolysis and substrate-oxidation increased at least 2-fold for normoxic (20% O2)- but not hypoxic (5% O2)-cultured hMSCs, despite declining growth rates and no detectable signs of differentiation. Culture of the cells with 3-hydroxybutyrate abolished the increased rates of these pathways. These findings have implications for stem cell therapy, which necessarily involves in vitro culture of cells, since low passage number normoxic cultured stem cells show metabolic adaptations without detectable changes in stem-like status.