Stoll Christoph, Holovati Jelena L, Acker Jason P, Wolkers Willem F
Institute of Multiphase Processes, Leibniz Universität Hannover, Hannover, Germany.
Mol Membr Biol. 2011 Oct-Nov;28(7-8):454-61. doi: 10.3109/09687688.2011.622304. Epub 2011 Sep 28.
Previous studies have shown that certain saturated lipids protect red blood cells (RBCs) during hypothermic storage but provide little protection during freezing or freeze-drying, whereas various unsaturated lipids destabilize RBCs during hypothermic storage but protect during freezing and freeze-drying. The protective effect of liposomes has been attributed to membrane modifications. We have previously shown that cholesterol exchange and lipid transfer between liposomes composed of saturated lipids and RBCs critically depends on the length of the lipid acyl chains. In this study the effect of unsaturated lipids with differences in their number of unsaturated bonds (18:0/18:1, 18:1/18:1, 18:2/18:2) on RBC membrane properties has been studied. RBCs were incubated in the presence of liposomes and both the liposomal and RBC fraction were analyzed by Fourier transform infrared spectroscopy (FTIR) after incubation. The liposomes caused an increase in RBC membrane conformational disorder at suprazero temperatures. The fluidizing effect of the liposomes on the RBC membranes, however, was found to be similar for the different lipids irrespective of their unsaturation level. The gel to liquid crystalline phase transition temperature of the liposomes increased after incubation with RBCs. RBC membrane fluidity increased linearly during the first 8 hours of incubation in the presence of liposomes. The increase in RBC membrane fluidity was found to be temperature dependent and displayed Arrhenius behaviour between 20 and 40°C, with an activation energy of 88 kJ mol⁻¹. Taken together, liposomes composed of unsaturated lipids increase RBC membrane conformational disorder, which could explain their cryoprotective action.
先前的研究表明，某些饱和脂质在低温储存期间可保护红细胞（RBC），但在冷冻或冻干过程中保护作用甚微；而各种不饱和脂质在低温储存期间会使红细胞不稳定，但在冷冻和冻干过程中具有保护作用。脂质体的保护作用归因于膜修饰。我们先前已表明，由饱和脂质组成的脂质体与红细胞之间的胆固醇交换和脂质转移严重取决于脂质酰基链的长度。在本研究中，研究了具有不同不饱和键数量（18:0/18:1、18:1/18:1、18:2/18:2）的不饱和脂质对红细胞膜特性的影响。将红细胞与脂质体一起孵育，孵育后通过傅里叶变换红外光谱（FTIR）分析脂质体和红细胞部分。脂质体在零上温度下导致红细胞膜构象无序增加。然而，发现脂质体对红细胞膜的流化作用对于不同脂质而言是相似的，与它们的不饱和水平无关。与红细胞孵育后，脂质体的凝胶到液晶相转变温度升高。在脂质体存在下孵育的最初8小时内，红细胞膜流动性呈线性增加。发现红细胞膜流动性的增加与温度有关，并且在20至40°C之间表现出阿伦尼乌斯行为，活化能为88 kJ mol⁻¹。综上所述，由不饱和脂质组成的脂质体增加了红细胞膜构象无序，这可以解释它们的冷冻保护作用。
