The skin's pigment cells can be formed from completely different cells than has hitherto been thought, a new study from the Swedish medical university Karolinska Institutet shows. The results, which are published in the journal Cell, also mean the discovery of a new kind of stem cell.
The body's pigment gives essential protection against UV radiation. It is made up of a substance called melanin, which is produced by pigment cells in the skin called melanocytes. According to the established theory of body pigmentation, these melanocytes bud off from the spinal cord at an early foetal stage and then migrate to the skin where they remain for the rest of their lives.
Scientists at Karolinska Institutet in Stockholm have now shown that most melanocytes actually appear later on in foetal development from an immature cell type that exists in the skin's nerve fibres. These cells, called Schwann cell precursors (SCPs), can also be found in adults. In addition to this, the scientists have demonstrated how neuronal damage in adults can excite the maturation of melanocytes to form hyperpigmentation around the affected nerves.
"Our findings can provide new knowledge of how changes in skin pigmentation occur, not least of the links that have been observed between neurological disease and changes in pigmentation," says Professor Patrik Ernfors, who led the study.
Their results also shed new light on SCP cells, which were previously seen as an immature form of supportive cells the nervous system. The researchers describe how a change in cell signalling can make the SCP cells in the skin develop into pigment cells instead, and argue that SCP cells are really a kind of stem cell.
"This can help science to understand the development of diseases such as melanoma," says Professor Ernfors. "We've always believed that it develops from melanocytes, but maybe it actually originates in the SCP cells."
Publication: 'Schwann Cell Precursors from Nerve Innervation is a Cellular Origin of Melanocytes in Skin', Igor Adameyko, Francois Lallemend, Jorge B Aquino, Piotr Topilko, Jorge A Pereira, Thomas Müller, Nicolas Fritz, Anna Beljajeva, Makoto Mochii, Isabel Liste, Dmitry Usoskin, Ueli Suter, Carmen Birchmeier and Patrik Ernfors, Cell, 16 October 2009.
For further information, please contact:
Professor Patrik Ernfors
Department of Medical Biochemistry and Biophysics
Tel: +46(0)8-524 876 59
Mobile: +46(0)70 3297659
Press Officer Katarina Sternudd
Tel: +46(0)8-524 838 95
Karolinska Institutet is one of the leading medical universities in Europe. Through research and education, Karolinska Institutet contributes to improving human health. Each year, the Nobel Assembly at Karolinska Institutet awards the Nobel Prize in Physiology or Medicine. For more information, visit ki.se