Cell Fusion- Types and Significance

  • Until recently, cells were thought to be integral and discrete components of tissues, and their state was determined by cell differentiation.
  • However, under some conditions, stem cells or their progeny can fuse with cells of other types, mixing cytoplasmic and even genetic material of different (heterotypic) origins.
  • Cell fusion is an important cellular process in which several uninuclear cells (cells with a single nucleus) combine to form a multinuclear cell, known as a syncytium.
  • Syncytia are commonly found in placenta, bone, cartilage, muscle and multi-nucleated giant cells.
  • Fusion of one or more cells can occur during development as well as in mature individuals.
  • Cell fusion occurs during differentiation of muscle, bone and trophoblast cells, during embryogenesis, and during morphogenesis.
  • Cell fusion is a necessary event in the maturation of cells so that they maintain their specific functions throughout growth.
  • The fusion of heterotypic cells could be of central importance for development, repair of tissues and the pathogenesis of the disease.

Cell Fusion- Types and Significance

Types of Cell Fusion

There are two different types of cell fusion that can occur. These two types include homotypic and heterotypic cell fusion.

Homotypic cell fusion

  • It occurs between cells of the same type.
  • An example of this would be osteoclasts or myofibers being fusing together with their respective type of cells.
  • Whenever the two nuclei merge a synkaryon is produced.
  • Cell fusion normally occurs with nuclear fusion, but in the absence of nuclear fusion, the cell would be described as a binucleated heterokaryon. A heterokaryon is the melding of two or more cells into one and it may reproduce itself for several generations.
  • If two of the same type of cells fuse, but their nuclei do not fuse, then the resulting cell is called a syncytium.

Heterotypic cell fusion

  • It occurs between cells of different types, making it the exact opposite of homotypic cell fusion. The result of this fusion is also a synkaryon produced by the merging of the nuclei, and a binucleated heterokaryon in the absence of nuclear fusion.
  • An example of this would be Bone Marrow Derived Cells (BMDCs) being fused with parenchymatous organs.

Significance of Cell Fusion

  • Cell fusion can cause a change in the phenotype and/or the function of cells. Cell fusion could, therefore, explain the transdifferentiation of committed somatic cells.
  • Cell fusion can reverse or repair the injury to tissues. In this context, cell fusion facilitates the regeneration of tissues.
  • Cell fusion can promote the transmission of viruses. Fusion of cells of individuals of disparate species might explain the transmission of viruses between species and the genesis of new pathogens.
  • Cell fusion and nuclear fusion that occur in the formation of synkaryons can allow the re-sorting and recombination of chromosomal DNA. Fusion of nuclei of an immature cell, such as a stem cell, and a mature cell might generate proliferation and malignancy.


  1. Baker, J. R. The cell theory: a restatement, history and critique. Part IV. The multiplication of cells.  J. Microsc. Sci.94, 407–440 (1953).
  2. https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/cell-fusion
  3. https://www.nature.com/articles/nrm1678
  4. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3542792/
  5. https://www.cell.com/trends/cell-biology/fulltext/S0962-8924(07)00241-3
  6. http://www.wormbook.org/chapters/www_cellfusion/cellfusion.html

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