Skin, Umbilical Cord Cells Converted to Nerve Cells

Nerve cells, in green, converted from skin cells (Julia Ladewig/University of Bonn)

Researchers at University of Bonn, with colleagues from medical centers in Germany, have developed a process for converting human cells from skin and umbilical cords directly into usable quantities of nerve cells, bypassing previous intermediate steps. Their findings appear this week in the journal Nature Methods (paid subscription required).

Converting one type of human cell into another up to now required production of pluripotent or multi-purpose stem cells. While the process is feasible, it is also time consuming. In 2010, a team led by Oliver Brüstle, director of the Bonn Institute of Reconstructive Neurobiology, developed a technique for directly converting skin cells into induced (artificially-produced) neurons. While successful, that process was also inefficient, returning only a small percentage nerve cells from the original skin cells.

A team in Brüstle’s lab was able to improve on this method, both simplifying the process and returning a higher percentage of nerve cells from the original stock of skin cells.  Julia Ladewig, a postdoctoral researcher and lead author of the paper, based the new process on small molecules — low molecular-weight compounds — to influence the signalling pathways important for cell development.

Ladewig’s team focused on the signalling pathways and enzymes considered important for cell specialization, and found the right combination of active substances to block or inhibit the processes that impaired cell growth. The team was also able to reduce the number of transcription factors — proteins that bind to specific DNA sequences — needed to transform the cells from the original three factors to two.

Using the new methods, the Bonn team was able to return 80 percent initial yields of neurons from their original skin cells. The final yields, from continuous duplication of cells, turned out to be even higher. “We can obtain up to more than 200,000 nerve cells converted in this way from 100,000 skin cells,” says Ladewig.

The conversion process to neurons is not restricted to skin cells. The Bonn scientists also used this method with umbilical cord cells as well.

Brüstle is co-founder of a company, Life & Brain GmbH, in Bonn that commercializes his research on cell development, and related translational technologies.

Read more: University Spin-Off Begins Trial of Stem Cell ALS Treatment

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