Hubel A, Cravalho E G, Nunner B, Körber C
Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge 02139.
Cryobiology. 1992 Apr;29(2):183-98. doi: 10.1016/0011-2240(92)90019-x.
Reduction of temperature during freezing brings about two complex and interrelated phenomena: (1) crystal nucleation and subsequent growth processes and (2) change in biophysical properties of a biological system. The purpose of this investigation is to relate the morphology of the solid phase with the survival of a cell. To this end, B-lymphoblasts were exposed to directional solidification in phosphate-buffered saline + 0.05 M dimethyl sulfoxide. Directional solidification is a freezing technique which allows the morphology of the interface to be varied without varying the chemical history that a cell would experience during a constant cooling rate protocol. Results indicated that, for the range of experimental conditions tested, a maximum survival of approximately 78% could be achieved using a temperature gradient of 25(10)3 K/m and an interface velocity of 23(10)-6 m/s (cooling rate: 35 K/min). Survival dropped off sharply for freezing at faster cooling rates with little or no variation in survival for different crystal growth conditions. Survival at slower cooling rates decreased with decreasing cooling rate. It was observed, however, that the presence of secondary branches in the ice phase correlated with lower survival for a given cooling rate. These results indicated that not only is the redistribution of solute during freezing a potential source of damage during freezing but ice/cell interactions are also. Thus, the cooling rate alone may not be adequate to describe the freezing process.
（1）晶核形成及随后的生长过程，以及（2）生物系统生物物理性质的变化。本研究的目的是将固相的形态与细胞的存活联系起来。为此，将B淋巴细胞暴露于含有0.05 M二甲基亚砜的磷酸盐缓冲盐水中进行定向凝固。定向凝固是一种冷冻技术，它能在不改变细胞在恒定冷却速率方案中所经历的化学历程的情况下改变界面的形态。结果表明，在所测试的实验条件范围内，使用25×10³ K/m的温度梯度和23×10⁻⁶ m/s的界面速度（冷却速率：35 K/min）可实现约78%的最大存活率。在更快的冷却速率下冷冻时，存活率急剧下降，而在不同晶体生长条件下存活率几乎没有变化。在较慢的冷却速率下，存活率随冷却速率的降低而降低。然而，观察到在给定冷却速率下，冰相中二次分支的存在与较低的存活率相关。这些结果表明，冷冻过程中溶质的重新分布不仅是冷冻期间潜在的损伤来源，冰/细胞相互作用也是如此。因此，仅冷却速率可能不足以描述冷冻过程。
