Cell fusion is quite simply the process in which multiple cells are fused together to form a single cell. Cells of the same type, cells of different types from the same species of organism, and even those from different species can be fused together.
Cell fusion may occur in nature during the formation of skeletal muscle or as a result of viral infection. For instance, the HIV virus infects T-helper lymphocytes, causing them to display surface proteins, which cause other T-helper lymphocytes to bind to the infected cell. With the cells bound together, their cell membranes re-organizes leaving a single, non-functional synctium.
Cell Fusion in vitro
There are also methods for inducing cell fusion in vitro. Cells can be fused by chemical and electrical perturbations; however, artificial methods rely on perturbations of the cells' outer membrane, while they are in close contact to induce fusion. Chemicals, such as polyethylene glycol (PEG), create perturbations by an osmotic pressure, which causes cells to shrink as water diffuses across their outer membrane. When the PEG is removed from the cell environment, neighbouring cells will swell back to full size, and if cells are in close contact, they may reorganize their membranes into one single cell, which contains the contents of both of the original cells.
Electrical fields can induce perturbations in the membrane structure by changing the stability of the membrane structure. One way in which this occurs is through the build-up of charge across the membrane. This can create a substantial voltage across the membrane, which may result in localized breakdown of the membrane through a process called electroporation.
Cell fusion is currently being studied for a number of reasons relevant to both health and medicine. Hybridomas are cells produced from the fusion of an antibody-producing cell with a cancer cell. The resultant cell has the immortality of a cancer cell and retains the ability to produce antibodies. The formation of hybridomas can preserve cells which produce antibodies against dangerous pathogens.
Another important application of cell fusion is for the study of the way in which stem cells or embryonic germ cells can reprogram somatic cells - the differentiated cells within your body. This reprogramming can be observed in hybrid cells of these types.
- Alison M. Skelley, Oktay Kirak, Heikyung Suh, Rudolf Jaenisch, and Joel Voldman. "Microfluidic control of cell pairing and fusion". Nature Methods (2009), Vol. 6(2), pp. 147-152.