Factors influencing the survival of cell monolayers during storage at 4 degrees.

As a step towards the definition of a medium suitable for long-term storage of potential organ transplants, a study was made of the effects of various solutions on the viability of monolayers of cells stored at 4 degrees. It was found that, for these to survive for more than a few hours, an essential component of the medium was a non-toxic solute which did not cross the cell membrane at low temperatures and could therefore counterbalance the osmotic effect of the intracellular proteins. A high K+/Na+ ratio and hyperosmoticity, separately or together, were ineffective in the absence ofsuch a solute and unnecessary in its presence. The most effective non-permeating solute tested was polyethylene glycol, mol. wt. 20,000 cells stored in a 1% solution of this in phosphate buffered balanced salt solution remained viable for at least 24 hours and could subsequently be grown in culture.