Homestead mailing list

[tvoivozhd <tvoivozd AT infionline.net>]

ScientificAmerican.com      
January 31, 2005
      
Scientists Switch Stem Cells into Neurons
      
Scientists have long been studying the process of how mammalian stem 
cells differentiate to form specific types of brain cells. Researchers 
are now reporting another small step toward understanding what 
conditions are necessary for spinal motor neurons to form: they have 
coaxed human embryonic stem cells to differentiate into one critical 
component of the nervous system.

Su-Chun Zhang of the University of Wisconsin-Madison and his colleagues 
exposed human embryonic stem cells to a variety of growth factors and 
hormones in sequence in order to encourage them to change into motor 
neurons. "You need to teach the [embryonic stem cells] to change step by 
step, where each step has different conditions and a strict window of 
time," Zhang explains. "Otherwise, it just won't work." The embryonic 
stems cells first became neural stem cells then changed into the 
beginnings of motor neurons before finally differentiating into spinal 
motor neuron cells, the cell type that, in the human body, transmits 
messages from the brain to the spinal cord. The newly generated motor 
neurons exhibited electrical activity, the signature action of neurons, 
and survived in culture for more than three months.

The team next plans to test the cells' ability to communicate with other 
cell types after they are transplanted into developing chickens. Tests 
on humans, however, remain years in the future, Zhang cautions. But the 
findings could still prove useful for people: Zhang posits that motor 
neuron modeling systems in the laboratory could be used as proxies to 
screen potential new drugs. The results were published online today by 
the journal Nature Biotechnology. --Sarah Graham
      
© 1996-2005 Scientific American, Inc.
      
8:47 AM 2/7/2005