Scientists have restored the sense of smell in mice through gene therapy for the first time -- a hopeful sign for people who can’t smell anything from birth or lose it due to disease. The achievement in curing congenital anosmia -- the medical term for lifelong inability to detect odors -- may also aid research on other conditions that also 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.
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. The 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 involved in smelling were firing correctly when the mice were exposed to amyl acetate, a strong-smelling chemical also called banana oil.