13 September 2012

Stem cells restored hearing in gerbils

Biologists returned hearing to rodents with the help of stem cells

RIA NewsBritish biologists used stem cells to restore hearing in Mongolian gerbils suffering from damage to nerve cells inside the ear, according to an article published in the journal Nature (Chen et al., Restoration of auditory evoked responses by human ES-cell-derived otic progenitors – VM).

Over the past two decades, biologists have learned how to turn stem cells into tissues of bones, muscles, skin and nervous system. Such tissues can become "spare parts" in case of damage to the body or a medicine for a number of degenerative diseases. For example, cultures of "stem" neurons can become a means for the treatment of Alzheimer's and Parkinson's diseases. In April 2012, scientists were able to turn stem cells into hair follicles and successfully transplanted them onto the back of the head of "bald" mice.

A group of biologists led by Marcelo Rivolta from the University of Sheffield (UK) conducted experiments with stem cells, trying to turn them into "blanks" for the tissues that make up the basis of the human ear.

As scientists explain, one of the most common causes of deafness is damage to nerve cells that convert acoustic waves into electrical impulses in the cochlea of the inner ear. The cause of such disorders may be congenital genetic defects, neurodegenerative diseases or injuries.

Rivolta and his colleagues have developed a technique that makes it possible to turn human embryonic stem cells into "blanks" for ear nerve cells.

To do this, scientists tracked which genes are "turned on" and "turned off" in stem cells during the development of the mouse embryo. It turned out that genes and related proteins FGF3 and FGF10 stimulated the growth of two types of inner ear cells – small cells lining the walls of the cochlea, and long and thin "blanks" of neurons.

Guided by this information, the authors of the article grew several cultures of future neurons in a test tube and tried to use them for the treatment of deaf Mongolian gerbils (Meriones unguiculatus).

Rivolta and his colleagues acquired several rodents and injected into their left ear a small amount of the poison ouabain, which blocks the work of potassium channels in nerve cells and thereby kills neurons. Then the scientists injected stem cells into the inner ear of their wards and began to observe the development of cells.

After two or three weeks, the "blanks" of neurons migrated to the place of the dead nerve cells and successfully replaced them. The authors of the article tested their work by observing the reaction of rodents to sounds. According to biologists, the therapy restored the hearing of the gerbils – they began to respond to acoustic stimuli four weeks after the injection of cells. Two months later, the hearing sensitivity of rodents reached 50% of that typical for healthy gerbils.

Scientists believe that a successful test of stem cells on rodents allows us to hope for success among people suffering from sensorineural hearing loss. However, the therapy must pass clinical trials in order to conduct experiments on volunteers.

Portal "Eternal youth" http://vechnayamolodost.ru13.09.2012

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