Crowe J H, Oliver A E, Hoekstra F A, Crowe L M
Section of Molecular and Cellular Biology, University of California, Davis 95616, USA.
Cryobiology. 1997 Aug;35(1):20-30. doi: 10.1006/cryo.1997.2020.
R. P. Goodrich and co-workers (1989, U.S. Patent 4,874,690; 1992, Proc. Natl. Acad. Sci. USA 89,967-971) have reported that red blood cells can be preserved in the dry state by addition of mixtures of hydroxyethyl starch (HES) and glucose. More recently, Spieles and co-workers (1996, Cryo-Lett. 17, 43-52) found that HES alone is insufficient to preserve the dry cells and concluded on this basis that the studies of Goodrich et al. were incorrect. In the present paper we revisit that suggestion, using liposomes as a model to study effects of HES and glucose on membrane stability. In previous studies we and others have established that liposomes can be stabilized in the dry state if they are dried in the presence of disaccharides. Monosaccharides have not been effective. Measurements of effects of glucose on phase transitions in the dry lipids and vibrational frequency of the phosphate headgroup suggest that glucose shows an interaction with dry egg phosphatidylcholine similar to that seen with disaccharides. Nevertheless, glucose does not inhibit fusion in liposomes during drying, and it does not prevent leakage. Hydroxyethyl starch, which has a very high glass transition (Tg), inhibits fusion in the dry liposomes, but it does not depress the liquid crystalline to gel phase transition temperature (Tm) in the dry phospholipids, does not cause a shift in the phosphate vibration indicative of hydrogen bonding of the sugar to the phosphate, and does not stop leakage of trapped carboxyfluorescein. However, if glucose is added to the HES-containing samples, the liposomes are stabilized, so long as the samples are maintained below the Tg of the mixture. If they are heated above that Tg they fuse and leak their contents. We conclude that both glass formation and depression of Tm in the dry lipids are required. The role of glass formation in stabilization during drying of liposomes appears to be inhibition of fusion.
R.P.古德里奇及其同事（1989年，美国专利4,874,690；1992年，《美国国家科学院院刊》89,967 - 971）报道，通过添加羟乙基淀粉（HES）和葡萄糖的混合物，红细胞可以在干燥状态下保存。最近，施皮尔斯及其同事（1996年，《低温生物学通讯》17, 43 - 52）发现仅HES不足以保存干燥的细胞，并据此得出结论，认为古德里奇等人的研究是错误的。在本论文中，我们重新审视这一观点，使用脂质体作为模型来研究HES和葡萄糖对膜稳定性的影响。在先前的研究中，我们和其他人已经确定，如果脂质体在二糖存在下干燥，它们可以在干燥状态下稳定。单糖则没有效果。对葡萄糖对干燥脂质中相变的影响以及磷酸头部基团振动频率的测量表明，葡萄糖与干燥的卵磷脂之间的相互作用类似于二糖所表现出的相互作用。然而，葡萄糖在干燥过程中不会抑制脂质体的融合，也不能防止渗漏。羟乙基淀粉具有非常高的玻璃化转变温度（Tg），它能抑制干燥脂质体的融合，但不会降低干燥磷脂中液晶到凝胶相转变温度（Tm），不会导致表明糖与磷酸之间氢键形成的磷酸振动发生位移，也不能阻止被困羧基荧光素的渗漏。但是，如果将葡萄糖添加到含HES的样品中，只要样品保持在混合物的Tg以下，脂质体就会稳定。如果将它们加热到高于该Tg，它们就会融合并泄漏其内容物。我们得出结论，干燥脂质中玻璃的形成和Tm的降低都是必需的。玻璃形成在脂质体干燥过程中的稳定作用似乎是抑制融合。
