The establishment of new, continuously growing cell line of human origin takes between 4-8 months, depending on the availability of the tissue of interest, cell type and the degree of characterization. Moreover, isolation of individual clones from a mass culture takes about 2 months. The establishment of new, continuously growing cell line of human origin takes between 4-8 months, depending on the availability of the tissue of interest, cell type and the degree of characterization. Moreover, isolation of individual clones from a mass culture takes about 2 months.