03 September 2012

If you lose your sense of smell, gene therapy will help

Gene therapy restored the ability of mice to sense odors – scientists

RIA NewsGene therapy has restored the sense of smell to mice suffering from a genetically determined loss of sense of smell, which will allow using this technique to treat people who are unable to smell from birth, scientists say in an article published in the journal Nature Medicine (McIntyre et al., Gene therapy rescues cilia defects and restores olfactory function in a mammalian ciliopathy model; short The retelling can be read in the press release of NIDCD NIH-Funded Researchers Restore Sense of Smell in Mice Using Genetic Technique – VM).

"The results of this work may become the first available treatment for people suffering from anosmia (loss of sense of smell). In addition, this technique can also be used to treat other diseases associated with disorders of the cilia (sensitive flagella on the surface of neurons), which can be deadly to the body," said James Battey, director of the National Institute of Deafness and Other Communication Disorders (NIDCD) in Bethesda (USA), the sponsor of the study.

A group of physicians led by Jeffrey Martens from the University of Michigan in Ann Arbor (USA) studied genetic defects associated with congenital forms of anosmia.

As scientists explain, most of these disorders occur due to the appearance of ciliopathies - disorders in the work of sensitive hairs–cilia on the surface of olfactory neurons. These hairs "catch" molecules of volatile substances and nerve cells transmit a signal about the presence of a particular smell to the olfactory center of the brain. Mutations in the genes involved in the "assembly" of cilia lead to disturbances in their work or even to their death, which deprives olfactory neurons of the ability to read odors.

Martens and his colleagues turned their attention to the IFT88 gene, a breakdown in which leads to serious disturbances in the work of cilia in the olfactory epithelium and some other parts of the body. Scientists have grown a population of mice in which this gene was damaged, and tried to replace it with gene therapy.

To do this, doctors created a special retrovirus that inserted a new copy of IFT88 into neurons and removed the damaged DNA fragment. During the experiment, scientists applied a solution with retrovirus particles to the olfactory epithelium of mice for three days and monitored changes in their reaction to amyl acetate, a solvent with a specific smell of varnish.

According to scientists, after ten days, the mice began to smell the solvent no worse than their relatives who do not suffer from congenital defects of smell. In addition, the acquisition of a sense of smell had a beneficial effect on the health of rodents – their weight increased by 60% and approached the normal indicators for mice. As the researchers note, mice with anosmia are not able to smell food, and therefore they have no appetite.

The authors of the article plan to start experiments on volunteers in the near future, when they complete a full cycle of tests on rodents and other animals. In addition, similar therapy can also be used to treat other diseases, in particular, polycystic kidney disease, retinal degradation and other ailments associated with impaired cilia.

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