Freeze-preservation of enzymatically prepared tumor cell suspensions and their use in tumor transplantation.

Methods currently in use for preparation of cell suspensions for tissue culture are useful for tumor transplantation work and permit quantitative assays of factors affecting transplantation. Enzymatic digestion yields higher numbers of viable cells than the commonly used mechanical method of squeezing cells through metal meshes. Cell suspensions prepared by enzymatic digestion can be stored at low temperatures for prolonged periods of time without changing their transplantability. Tumors re quiring only small inoculum sizes for transplantation can be successfully freezepreserved by virtually any method of tissue freezing currently in use. The less "viru lent" tumors studied require protection by adequate suspension media with added