Researchers from University of Michigan Medical School, along with the help of other universities, have published a report on Nature Medicine about gene therapy helping people restore the sense of smell.
The mice they used for the study are those with a genetic defect that results in having less amounts of microscopic hairs in their body (cilia) that they rely on for detecting chemicals in the air. Microscopic cilia are sticking out from numerous cells in their body and even simple damages on them can be severely harmful for the rat. But if losing the sense of smell for mice could bring poor feeding habits and lead to death, for humans this can be equally fatal.
To do the experiment, scientists planted the genes into cells of the mice through a common cold virus that contains many normal DNA, enabling it to infect cells easily. It was then injected into the nose of the mice for 3 consecutive days. Two weeks after they were given the 3-day treatment, researchers discovered that the mice have gained weight by 60%, lending proof that feeding habits improved. For scam prevention, they verified that the neurons of the mice are working properly when exposed to banana oil (amyl acetate).
«At the molecular level, function that had been absent was restored. The scientists say that almost all cells in the body have the ability to grow one or more cilia...When loss of smell occurs, receptors the connect odorants are restrained on the cilia, resulting the loss of cilia, and the loss of sense of smell,» said one of the researchers.
However, it will take more studies for this to be applicable to humans who have lost their ability to smell due to medical conditions (though for people who cannot smell because of old age or nose trauma, this treatment is believed to be inapplicable).
Professor Philip Beales of the University College London who was also involved in the research said, «It is a proof of concept that has shown we can get that gene back into these cells, produce the right protein, produce cilia and function as expected.