Chapter 15 A Simple Device and Procedure for Successful Freezing of Cells in Liquid Nitrogen Vupor

Abstract

Cell preservation at low temperatures has become an essential practice in cell biology, particularly in laboratories working with tissue cultures. Sufficient experience has been gained in the practical technology of cryobiology to permit highly successful preservation of cell suspensions. Some of the freezing equipment that has been used for cell freezing includes sophisticated controllers. For the laboratory that only occasionally is required to freeze cells, the use of elaborate and expensive equipment would likely not be justified. Alternative approaches involve the placing of ampoules for timed periods in Dry-Ice chests or Dry-Ice-ethanol mixtures. Other freezing methods involve direct cooling in vapor or liquid nitrogen. In another approach, a mechanical freezer or liquid nitrogen is used to cool an ethanol bath containing the ampoules. While many of the various methods mentioned are reasonably effective, the recovery rate varies largely, according to the rate of initial freezing. The methods also differ in cost, sophistication and automation, amount of handling, and reproducibility of results. The cell freezer to be described has a number of attractive features that appeal to cell biologists and others working with isolated cell suspensions, especially where there is an infrequent need to freeze cells.