cell division, cell function, etc. For example, a hormone can be added to a liquid culture of cells,
and then a researcher can study the effects of that hormone on cell structure and/or function.
Eukaryotic Cell Lines Are a Widely Used Source of Homogeneous Cells
A cell line is a population of cells that have been derived from a single cell via many, many cell
divisions. Many cell lines that are used by researchers are immortal, which means that they will
continue to divide without becoming senescent. An immortal cell line is an experimental
advantage because researchers can continue to propagate more cells as long as they want. Some
immortal cell lines were originally derived from tumors. An example is the HeLa cell line.
Alternatively, other immortal cell lines were derived from normal tissues, but later incurred
mutations during growth in cell culture that made them immortal.
Some examples of cell lines are shown in Table 8-1. Please do not memorize this table. Cell lines
are shared among researchers. When scientists use the same cell lines in their experiments, it is
easier to directly compare each other’s results.
Embryonic Stem Cells could revolutionize medicine
Embryonic stem cells can proliferate indefinitely in culture and give rise to all cell types in the
body. Since ES cells can behave like normal cells, they could potentially be used for tissue
repair, for example to replace cardiac muscles after a heart attack or to replace dead nerve cells
in patients with Parkinson's disease. However, ES cells may also produce tumors called
teratomas or they may be rejected by the recipient's immune system.
Somatic Cell Nuclear Transplantation May Provide a Way to Generate Personalized Stem
Cells from adult tissues can be used to generate clones of genetically identical cells through a
technique called somatic cell nuclear transplantation. The nucleus of an unfertilized egg cell is
replaced by a nucleus from a somatic cell from an adult organism. Such hybrid cell can give rise
to an early embryo, which can be transferred to the uterus of a foster mother to generate a whole
new animal (reproductive cloning) or be used as a source of stem cells to treat diseases or for
tissue repair. These procedures, especially reproductive cloning, are controversial, and outlawed
in some countries.
In 2006, researchers found a way to reprogram cells from adult tissues to regain properties of
embryonic cells. These cells, known also as Induced Pluripotent Stem Cells (IPSC), could
become any cell type in an organism given the right conditions and differentiating factors and
thus could become a source of cells for therapy. Indeed, these cells were successful in
generating a cloned organism.
Hybridoma Cell Lines are factories that produce Monoclonal Antibodies.
In certain types of experiments described later in this course, different cells are made to fuse
with one another. This initially creates a heterokaryon, which is a cell with two nuclei. Later,
hybrid cells will be produced that have a single nucleus containing genetic material from both of
the original cells. If one of he parent cells was from a tumor cell line, the hybrid cell is called a
hybridoma. Hybridoma cell lines are used extensively to produce monoclonal antibodies which
recognize specific proteins.