Gene therapy restores olfactory sense in mice

September 3rd, 2012 - 2:20 pm ICT by IANS  

Washington, Sep 3 (IANS) Scientists have restored olfactory sense in mice through gene therapy for the very first time - potentially opening the way for people to regain their sense of smell lost since birth or owing to disease.

The breakthrough in curing congenital anosmia, the medical term for life-long inability to detect odours, may also aid research on other conditions that stem from problems with the cilia. Those tiny hair-shaped structures on the surfaces of cells throughout the body are involved in many diseases, from the kidneys to the eyes.

Researchers from the University of Michigan Medical School caution that it will take time for their work to affect human treatment, and that it will be most important for people who have lost their sense of smell due to a genetic disorder, rather than those who lose it due to aging, head trauma, or chronic sinus problems, the journal Nature Medicine reported.

“Using gene therapy in a mouse model of cilia dysfunction, we were able to rescue and restore olfactory function, or sense of smell,” said senior author Jeffrey Martens, associate professor of pharmacology at Michigan.

“Essentially, we induced the neurons that transmit the sense of smell to re-grow the cilia they’d lost.”

The mice in the study all had a severe genetic defect that affected a protein called IFT88, causing a lack of cilia throughout their bodies. Such mice are prone to poor feeding and to early death as a result. In humans, the same genetic defect is fatal, according to a university statement.

Researchers were able to insert normal IFT88 genes into the cells of the mice by giving them a common cold virus loaded with the normal DNA sequence, and allowing the virus to infect them and insert the DNA into the mouse’s own cells.

They then monitored cilia growth, feeding habits, and well as signals within and between the nerve cells, called neurons, that are involved in the sense of smell.

Only 14 days after the three-day treatment, the mice had a 60 percent increase in their body weight, an indication they were likely eating more.

Cell-level indicators showed that neurons (nerve cells) involved in smelling were firing correctly when the mice were exposed to amyl acetate, a strong-smelling chemical also called banana oil.

“At the molecular level, function that had been absent was restored,” added Martens.

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