Behavior of in vitro grown normal human mucosal epithelial cells and tumorigenic rat cells inoculated into nude mice

The present study describes the behavior of in vitro grown normal human oral mucosal epithelial cells and that of a tumorigenic epithelial cell line following subcutaneous inoculation into nude mice. A successful recovery of viable human epithelial cell inocula was seen in 25-90% of mice and there was no improvement in recovery rates after addition of fibroblasts. These inocula resulted in cyst formation lined by a 2-6 cell layer unkeratinized squamous epithelium without rete ridges. There was no increase in recovery rate or size of cysts when coinoculated with fibroblasts. The tumorigenic cell inocula were successfully recovered in all cases. Tumors established from these inocula had a low grade of differentiation and were without signs of metastasis. Inocula of tumorigenic cells showed an increased size after addition of fibroblasts to the inocula. The model may be useful in studies of interactions between inoculations of heterologous normal and pathologic cells as well as in studies of differentiation of carcinogen-treated epithelial cells.