On the suitability of organotypic cultures of fetal rat lung type II cells for biochemical studies concerning development.

When organotypic cultures of fetal rat lung epithelial cells are initiated with undifferentiated cells, the cells differentiate into type II cells (Douglas, W.H.J., McAteer, J. A., Smith, J.R. and Braunschweiger, W.R. (1979) Int. Rev. Cytol., Suppl. 10, 45-65). This conclusion was based only on morphologic studies. The present study was undertaken to investigate whether such maturation in culture could also be demonstrated biochemically. In organotypic cultures initiated with epithelial cells from fetal rat lungs at 17-days gestation, the amount of phospholipids increased for at least 10 days. However, no change took place in the percentage of phosphatidylglycerol nor in the ratio of disaturated to total phosphatidylcholine. In cultures initiated with cells obtained at day 17 of gestation the specific activity of cholinephosphate cytidylyltransferase reached a maximum after approximately 3 days, followed by a decrease. A similar profile was obtained, however, if the culture was started at day 20 of gestation. This indicates that the activity profiles obtained in the organotypic cultures reflect changes caused by the culture conditions rather than changes caused by maturation. From these investigations it is concluded that biochemical studies on type II cell development using organotypic cultures as model should be interpreted with caution.