Structure and Function of Organisms
Some Notes on the L8 Cells You Use in Lab
L8 is the designation given to a "cell line" derived from culture of cells from the thigh muscle of newborn rats.
If a scientist takes a piece of fresh animal tissue, dissociates the tissue into cells and attempts to culture these cells, these cultures are called "primary" cultures. Primary cultures have a finite lifetime. The cells that are cultured undergo several rounds of cell division, but then the cells cease dividing. Thus, the cells have some kind of restriction on the number of times they can divide. The reason(s) for this restriction are known to involve telomeres, a subject you can investigate using a good cell or molecular biology textbook.
As soon as scientists began to make primary cultures, they soon found there were ways the cells could be immortalized. One way was to obtain cancerous tissue from patients. Cells derived from these tissues often lack restrictions on number of divisions in culture. A second way was to isolate cells from normal tissue but to treat these cells with carcinogens. Mutations were induced in some cells that lead to their loss of growth restrictions. A third method involves continued cultured of primary cells. Spontaneous mutations in the cells often lead to a few of them losing growth restrictions. If one isolates these cells, then one obtains cells that can divide essentially forever. Cells which have lost restrictions on cell division derived in any of these 3 ways are called "cell lines". Cell lines are incredibly useful in biology/biochemistry/molecular biology. The cells can be continuously expanded. The cells can be shipped to laboratories all over the world and thus many scientists can conduct experiments using the very same cells. These cells can even be used as factories to produce proteins for biotechnology/pharmacology by introducing genes of interest into them (i.e. by "transfecting" them).
The L8 line was derived by the third method described above from a primary culture of cells isolated from the thigh of a newborn rat back in 1969. These cells are likely derived from a cell in muscle known as a "myoblast". These are single, mononucleated cells that give rise to skeletal muscle fibers. The way they do so is to proliferate, fuse with each other to give rise to the multinucleated cells, and differentiate to express contractile proteins that give these cells their ability to contract and produce movement. L8 cells retain this potential. They proliferate on the surface of the culture plastic, but as many cells are generated and they begin to crowd each other on the dish, they begin to fuse with each other to form primitive muscle fibers called "myotubes". These myotubes can contract. In fact, one of the problems we have in this lab is that when the cells become confluent they begin to contract and in the process they pull themselves off the surface of the coverslips upon which they are growing. It is also possible to cause the living cells to contract and pull themselves up by mishandling the dishes of cells before they are fixed.
If you're interested in cell lines you can explore the web page of the American Type Culture Collection at www.atcc.org. This is our source for the L8 cells. A web page describe these cells can be reached by the following:
Click on "Cell Lines". When the Word Search Menu comes up, enter "L8" into the Query box, Menu comes up, type in "L8", click "Word Search". When the cell line "CRL-1769" comes up, click on this name for the information on the L8 cell line.
The original paper describing the isolation of the cells is
Richler C. and Yaffe D. 1970. The in vitro cultivation and differentiation capacities of myogenic cell lines. Dev. Biol. 23: 1-22.
L8 has been a popular cell line for study. Use of the medline search tool available on the library web page of UT turned up more than 278 references to "L8". Despite the fact that some of these references are to other subjects which have been given the same designation, many of these are to the cell line first derived in 1969.