Direct conversion of body cells to brain cells
A stem cell breakthrough has shown that neurons can be generated directly from body cells.
Cells involved in blood vessel maintenance called pericytes have been converted into neurons by Marisa Karow and her colleagues at the Ludwig-Maximillians University in Munich.
Previous studies have shown that conversion from bodily cells to neural cells is possible by reprogramming the cell back to an earlier stage of development and then guiding it down another developmental route towards a different cell type. Converting a cell directly from one type to another without these intermediate stages is a significant step forward towards potential therapies for diseases in which neurons become damaged, such as Alzheimer's and Huntingdon's.
The Munich team used a virus to introduce two new genes into human pericytes. These encoded two proteins called Mash1 and Sox2, which influence the transcription of a number of other genes. When Mash1 and Sox2 were introduced together they caused cells to produce the protein βIII-tubulin which is a key protein in neurons. The cells became similar to neurons in shape and structure.
The transformed cells didn't just look like neurons, they acted like them too. When the team looked at the electrical activity of the transformed cells they found that 71% could perform basic electrical signalling. Although far from perfect, the cells could be recognised and have successful interactions with other ordinary neurons when grown together in a culture.
These developments advance the possibility and practicality of effective stem cell therapies for a range of neurodegenerative diseases. A way to introduce genes like Mash1 and Sox2 into the brain in a safe and convenient way needs to be found if therapies like this are to be developed.
When these barriers have been overcome, Karow and her colleagues argue in
their paper published in the journal Cell Stem Cell, stem cell therapies will be able to effectively reprogramme damaged brains.