Effect of heterologous transplantation of H4-II-E rat hepatoma cells into the cheek pouch of hydrocortisone treated hamsters.

A series of transplant·explant experiments using the H 4-II-E rat hepatoma cell line and golden hamsters have been carried out. Tissue culture cells implanted into the cheek pouch of hydrocortisone treated hamsters at a concentration of 106 cells per pouch produced tumors which histologically were typical hepatomas. Cells from these tumors were placed back into tissue culture and were transferred twice more into the cheek pouch of hydrocortisone treated hamsters and tissue culture. At each stage of selection, chromosome counts, karyotypes and histological and biological characteristics were determined. Cytogenetic studies revealed that the chromosome number in both tumors and explanted cultures shifted and became more selected with each succeeding in vivo and in vitro passage. The cells from the selected cultures had a much more homogeneous karyotype than cells with the same number of chromosomes from the original H 4-II-E culture. Tumors in the third selection had less hemorrhage and necrosis than in the first and second selections and were slower growing and showed lower transptantability than the original tumors produced by implantation of the H 4·II-E cells. These results indicate that transplantation of tissue culture cells into the cheek pouch of hamsters treated with hydrocortisone results in the selection of cells wi.th a specific chromosomal constitution and altered transplantability and growth rate suggesti.ng that the chromosomal makeup may determine the biological and immunological characteristics of the cell which allow it to grow under these conditions.