Redefining cooling rate in terms of ice front velocity and thermal gradient: first evidence of relevance to freezing injury of lymphocytes.

摘要: Abstract A freezing process and the resulting injury or survival of biological cells is commonly characterized in terms cooling rate, B . Under certain circumstances, rate can be expressed as = G · v , where denotes thermal gradient at ice-liquid interface its velocity, respectively. To determine influence on morphology cell survival, a stage was designed. Flat capillaries could pushed with constant velocity from warm to cold heat reservoir. With this setup both parameters, are independently adjustable directional solidification observed dynamically light microscope. Human lymphocytes phosphate-buffered saline 10 vol% dimethyl sulfoxide were used test material. Viability assessed by membrane integrity fluorescein diacetate ethidium bromide. All cooled down final temperature −196 °C then rapidly thawed. The results obtained technique show that viability determined after thawing may vary considerably depending imposed values gradient, ice front In addition, data seem suggest that, first, maximum which reached governed and, second, for given achieved establishing small gradients high velocities (about 30 ° K/cm 500 (μm/sec, respectively, range tested).