The effects of freezing storage, and thawing upon the transplantability of mouse leukemic cells.

The need for a dependable method for the stor age and preservation of viable tumor tissues has long been of concern to investigators in experimen tal oncology. This problem is of particular interest in the study of mouse leukemia, where the main tenance of any given line of leukemia depends upon continuous serial transfer through successive generations of inbred mice of known genetic con stitution—a procedure that is costly in time and materials. In attempts to solve this problem, low temperatures for the preservation of cells have been employed with varying and conflicting re ports of success. Commonly, these differences can be attributed to the inherent complexity of any of the variety of methods available for the prepara tion and preservation of cells. Thus, of particular concern and interest are the procedures for the preparation of tissues prior to freezing, the ingredi ents and temperature of the cooling bath, the meth od and time allotted for freezing and storage, and the method and time required for thawing frozen material in preparation for its injection into sus ceptible animals. Each of these factors has been shown, at one time or another, to be of importance. A recognition of the many deficiencies in exist ing methods and information led to the present series of investigative studies on the effects of freezing and thawing upon the transplantability of