Alteration of growth rate and nutritional requirement of hamster brain cells transformed by adenovirus type 12 during their long-term cultivation.

HT-2 cells, one of the hamster brain cell lines transformed by adenovirus type 12 in ritro, were serially cultivated. During their long-term cultivation, the altera tion of their growth rate and nutritional requirement were examined. The growth rate of the cells gradually increased with advancing transfer generations. The bo vine serum requirement of those cells was extremely high at their early passages, but after the 50th passage, 300 of serum could support sufficient cell growth at an inoculation density of 104 Cells per nil. The comparison of growth rates of HT-2 oils of two different passages at various inoculation densities revealed increasing growth potentials during serial cultivation. Their limited growth rate in a closed gaseous system which had been reported previously remained stable all over the passage and could not be improved by various nutritional conditions. Further, growth characteristics of the cells in an open gaseous system without using a CO2 incubator suggested that they might need certain gas-circulating open condition to grow well.