Biological properties of HeLa cells serially cultivated in hypertonic medium and their susceptibility to enteroviruses. I. Biological characteristics of HeLa cells serially cultivated in hypertonic growth medium

Abstract

It has been reported that virus reproduction was inhibited when osmotic pressure decreased in maintenance medium (Eaton and Scala, 1956; Tolskaya et al., 1966), while no literature concerning hypertonic effect has appeared as yet, because no cells resistant to high osmotic pressure are available.This paper presents an attempt made to produce a HeLa cell line that would be cultivated in hypertonic medium for a long time in order to examine hypertonic maintenance medium effect for on virus reproduction.1) HeLa cells cultivated by the conventional method were suspended in a hypertonic growth medium containing twice as much NaCl as the normal medium does. Then, most of the cells (97-98%) were destroyed. The cells that survived, however, retained the multiplying potential. While repeated medium changes were continued, they started to grow in the hypertonic growth medium a few days later. After several serial cultivations the cells manifested constant growth in the hypertonic medium.2) These HeLa cells were designated as HeLa-O200 cells (since their osmotic pressure was 200%). They were more bulky than, and about 3 times as heavy as, conventionally cultivated HeLa cells. They contained almost the same concentration of NaCl as the latter cells.3) HeLa O200 cells lost the propagating capacity when subcultures were carried out over 30 to 60 times in the high osmotic medium. They ceased growing when they formed a monolayer. When they hypertonic medium was replaced by an isotonic medium, the cells increased again in number.4) When HeLa-O200 cells were cultivated in the isotonic medium over two generations, they lost not only their resistance to high osmotic pressure but also their morphological and propagating characteristics. They did not appear to be the newly established cell line which had been selected for the first hypertonic cultivation.