Bovine liver cells in long-term cultivation and their specific properties; albumin production and glycogen storage

The liver cells obtained from a calf have been cultured continuously for 257 days in total at present (May 31, 1967). The primary culture was maintained in rotatory culture for about 2 months with gradual and continuous cell proliferation. The two original strains, LD-BS20 and LD-CS20, have been maintained in static culture since 4th subcultivation. Three substrains, LD-BS10, YLE-BS20 and LD-CS10, were derived from the original strains. Two kinds of appropriate media, in which the cells could be subcultured with trypsin without severe damages and maintained with some characteristic functions of liver cells, were reported. The one consisted of 20 per cent bovine serum, 0.4 per cent lactalbumin hydrolysate and saline D, and the other was added with 0.08 per cent yeast extract to the above mentioned medium. Calf serum examined was not so effective as bovine serum for cell proliferation. Morphologically, the cultured cells resembled parenchymal liver cells quite well. The cells spread wide with abundant pale staining cytoplasm and their large nuclei, oval or round, generally contained one to several nucleoli. The cells as well as the nuclei varied considerably in size, some being two to four times larger than others. Binuclear, trinuclear or polynuclear cells were also observed. No silver impregnated fiber was detected among the epithelial cells. Two attempts to characterize cell types in culture were made. First, the presence of glycogen was tested with PAS reaction and saliva digestion procedure. Secondly, the albumin formation in cultured liver cells was examined with the fluorescent antibody technique. The fact that both albumin and glycogen were observed in the cells suggests strongly that there is a possibility of the continuous cultivation of liver cells by the present method, and by these procedures it seems possible to identify functionally the cultured cells with the parenchymal liver cells.