Main Types of Cell Culture

1.Primary Cultures

Primary cultures are derived directly from excised, normal animal tissue and cultured either as an explant culture or following dissociation into a single cell suspension by enzyme digestion. Such cultures are initially heterogeneous but later become dominated by fibroblasts. The preparation of primary cultures is labor intensive and they can be maintained in vitro only for a limited period of time. During their relatively limited life span primary cells usually retain many of the differentiated characteristics of the cell in vivo.

2.Continuous Cultures

Continuous cultures are comprised of a single cell type that can be serially propagated in culture either for a limited number of cell divisions (approximately thirty) or otherwise indefinitely. Cell lines of a finite life are usually diploid and maintain some degree of differentiation. The fact that such cell lines senesce after approximately thirty cycles of division means it is essential to establish a system of Master and Working banks in order to maintain such lines for long periods.

Continuous cell lines that can be propagated indefinitely generally have this ability because they have been transformed into tumor cells. Tumor cell lines are often derived from actual clinical tumors, but transformation may also be induced using viral oncogenes or by chemical treatments. Transformed cell lines present the advantage of almost limitless availability, but the disadvantage of having retained very little of the original in vivo characteristics.

3.Culture Morphology

Morphologically cell cultures take one of two forms, growing either in suspension (as single cells or small free-floating clumps) or as a monolayer that is attached to the tissue culture flask. The form taken by a cell line reflects the tissue from which it was derived e.g. cell lines derived from blood (leukaemia, lymphoma) tend to grow in suspension whereas cells derived from solid tissue (lungs, kidney) tend to grow as monolayers. Attached cell lines can be classified as endothelial such as BAE-1 (Prod. No. 88031149-1v1), epithelial such as HeLa (Prod. No. 93021013-1v1), neuronal such as SH-SY5Y (Prod. No. 94030304-1v1) or fibroblasts such as MRC-5 (Prod. No. 84101801-1v1) and their morphology reflect the area within the tissue of origin.

The cell lines most commonly ordered from ECACC are listed in the table below (Table 1). The lines are classified by cell type.

Table 1: Commonly used cell lines of each culture type

Attached Cell Lines

Name Species and tissue of origin Morphology

MRC-5 (Prod. No. 84101801) Human lung Fibroblast

HELA (Prod. No. 93021013) Human cervix Epithelial

VERO (Prod. No. 84113001) African Green Monkey Kidney Epithelial

NIH 3T3 (Prod. No. 93061524) Mouse embryo Fibroblast

L929 (Prod. No. 85011425) Mouse connective tissue Fibroblast

CHO (Prod. No. 85050302) Chinese Hamster Ovary Fibroblast

BHK-21 (Prod. No. 85011433) Syrian Hamster Kidney Fibroblast

HEK 293 (Prod. No. 85120602) Human Kidney Epithelial

HEPG2 (Prod. No. 85011430) Human Liver Epithelial

BAE-1 (Prod. No. 88031149) Bovine aorta Endothelial

NSO (Prod. No. 85110503) Mouse myeloma Lymphoblastoid-like

U937 (Prod. No. 85011440) Human Hystiocytic Lymphoma Lymphoblastoid

Namalwa (Prod. No. 87060801) Human Lymphoma Lymphoblastoid

HL60 (Prod. No. 98070106) Human Leukaemia Lymphoblastoid-like

WEHI 231 (Prod. No. 85022107) Mouse B-cell Lymphoma Lymphoblastoid

YAC 1 (Prod. No. 86022801) Mouse Lymphoma Lymphoblastoid

U 266B1 (Prod. No. 85051003) Human Myeloma Lymphoblastoid

SH-SY5Y (Prod. No. 94030304) Human neuroblastoma Neuroblast

There are some instances when cell cultures may grow as semi-adherent cells e.g. B95-8 where there appears to be a mixed population of attached and suspension cells. For these cell lines it is essential that both cell types are subcultured to maintain the heterogeneous nature of the culture.