The Effect of Freezing I N Vitro on Some Transplantable Mammalian Tumors and on Normal Rat Skin'

Isolated observations of the effect of freezing on various animal cells are encountered in the literature. Bacteria resist freezing to a remarkable degree, though Haines has shown that freezing of bacteria in aqueous suspension results in the death of approximately 80 per cent of the living organisms (1). Swift has been able to demonstrate that bacteria may be desiccated in the frozen state, after which their cultural, biochemical, and immunological characteristics are unaltered ( 2 ) . Unicellular microorganisms resist cold in different degree. Turner noted that the treponemata of yaws and syphilis retain their normal motility and virulence for rabbits after exposure to 78" C. for four months ( 3 ) . Trypanasoma gambiense withstood freezing in liquid air for twenty minutes, but not for forty minutes (4). Vegetative forms of amoebae were killed by exposure to 5" C. for five minutes in vitro ( S ) , while malarial schizonts survived for a longer period at the same temperature ( 6 ) . Encysted Trichinella spiralis failed to produce infection after exposure to 33.9" C. and viability was reduced at 27.6" C. ( 7 ) . Chick embryo heart is killed by exposure to the temperature of solid carbon dioxide (-74" C.) for less than one minute but survives -20" C. for five minutes (8). Various observers have reported that specific mammalian tissues frozen in vitro are killed by exposure to moderately low temperatures. Lake established 7 " C. as the critical point for rabbit tissue (9). Gaylord reported that mouse embryo epithelium failed to grow on subcutaneous transplantation after exposure to the temperature of liquid air (180" C.) (4). Simonin subjected pieces of mouse, rat, and beef embryos to cold. At 15" C . the cells were killed after a short period of exposure, although they grew in vitro after five days at 5" C. " as long as the tissues did not congeal " (lo), This investigator concluded that mammalian tissues are not equally sensitive to cold, heart, lung and intestine being the most resistant. Salvin-Moore exposed transplantable mouse sarcoma. and carcinoma to the temperature of liquid air for twenty to thirty minutes. The tumors grew on transplantation ( 11, 12). Both of these investigators froze the cells en masse. Auler obtained different results with saline emulsions. The Ehrlich mouse carcinoma grew after being frozen Chick embryos develop after exposure to -5" C. for ten days.