Effect of different cryopreservation regimens on Ehrlich carcinoma growth.

The freezing rate is a decisive factor in determining the purpose of using low temperatures, i.e., for cryoablation or cryobanking of tumor cells. The research aim was to determine effect of different cryopreservation regimens on Ehrlich carcinoma (EC) growth in vivo and subpopulation composition of the formed ascites. The previously cryopreserved with slow and rapid rates EC cells were cultured in peritoneal cavity (PC) of mice for 7 days. Absolute number of cells in the PC, the subpopulation composition of tumor with flow cytometry using CD44 and CD24 markers were determined. Immediately after warming, a significant redistribution of EC subpopulation composition with a decreased content of the most tumorigenic CD44high cells after both freezing regimens was found. Culturing in vivo for 7 days contributed to the restoration of EC subpopulation composition, but with some a decrease in the tumor growth intensity when slow cooling was used. Rapid cooling contributed to significant inhibition of tumor growth with a reduced number of CD44+ and increased CD24+ cells. None of the cryopreservation regimens resulted in a complete elimination of tumorigenic CD44high tumor cells. The freezing rate determines the preservation of the subpopulation composition of the EC and intensity of its growth in vivo.