Effect of hypertonicity on survival of unprotected human cultured cells following freezing and thawing

An investigation was carried out on the post-thaw survival of unprotected human heteroploid EUE cells, either maintained in isotonic medium (0.137 M NaCl) or adapted to hypertonicity (0.356 M NaCl) and frozen in medium with an increased concentration of NaCl. A fivefold increase in the survival fraction of the adapted cells in comparison with the unadapted ones was observed when cells were frozen in isotonic medium. When cells were frozen in hypertonic medium (0.356 M NaCl), the two cell types exhibit comparable survival values. The results are discussed, with special attention to cell defense mechanisms against freezing injury.