Establishment of an outgrowth culture system to study growth regulation of normal human epithelium.

To study the growth regulation of epithelial cells as a sheet, I developed an outgrowth culture system for normal human ectocervical epithelial (NHCE) cells, whereby outgrowths from tissue explants increase their radius in a constant rate over time. Cinematographic observation revealed that throughout the outgrowths the cells coordinately migrate and proliferate. To date, all 59 specimens examined have shown similar growth characteristics, with explant size not causing any difference in the growth rate; 10(8) cells/specimen can easily be obtained in 3 wk. Cell densities of outgrowths also remain constant. Moreover, there is no fibroblast contamination, and removal of explants does not affect growth rate. Therefore, pure epithelial outgrowth in uniform growth condition can be prepared for further experiments. The results demonstrate that the outgrowth culture system is an attractive model for analysis of growth control mechanisms in normal human epithelium in vitro.