The term 'line' is used when a culture has undergone an intentional experimental process to establish a more uniform and stable population of cells (see 'establishing cell line'). This will require one or more passages, but may involve additional selection processes. Through such passaging and/or selection processes, the resulting 'line' attains some level of genetic stability and compositional homogeneity which is typically absent in primary cultures. Because of their relative homogeneity, ‘lines’ are capable of being characterized and stably propagated over a period of time. A new *type* of cell line can be established not only through the passaging/selection of a primary culture, but also through experimental modifications of existing lines (e.g. immortalization, stable genetic modifications, drug selection for a resistant subset, etc.). The definition provided here establishes the 'scale' of cell populations that qualify as cell lines - specifically those with a shared propagation history in culture. In this way, the 'cell line' class demarcates populations that represent what researchers actually use in the practice of science - e.g. as inputs to culturing, experimentation, and sharing. The definition is such that cell lines will exhibit important attributes. For example, they will have a relatively homogenous cell type composition as they have experienced similar selective pressures due to their continuous co-propagation. In addition, these populations can also be characterized by a passage number, again owing to their common passaging history.  As defined here, 'cell line' can refer to a population of cells in active culture, applied experimentally, or stored in a quiescent state for future use.

In the spring of 2013, a working group comprised of domain experts and representatives from CLO, OBI, CL, and ReO worked to establish a consensus model and definitions of cultured cells across these efforts. This included a careful characterization of how the term 'cell line' should be defined and applied. Notes about this work and its outcomes can be found on the CLO wiki here: http://code.google.com/p/clo-ontology/wiki/Cell_Lines

cell line

He, Tong-Chuan, et al., Identification of c-MYC as a target of the APC pathway. Science 281.5382 (1998): 1509-1512.: "To evaluate the transcriptional effects of APC, we studied a human colorectal cancer cell line (HT29-APC) containing a zinc-inducible APC gene and a control cell line (HT29–β-Gal) containing an analogous inducible lacZ gene". Note that common usage in the literature is often of the form "a human colorectal cancer cell line", as seen above. But such references to studies in "a line" refer to the fact that discrete populations of cells that are input into culturing or experiments, not an entire lineage of cells. It is these discrete populations that we refer to as 'cell lines'.

http://purl.obolibrary.org/obo/obi.owl, http://purl.obolibrary.org/obo/clo.owl

MB, SS, JZ, MAH, BP, CS, YH

• establishing cell line
• cell line cell culturing

• cell line cell culturing