When the neighbor's dog leaves an unexpected surprise on your sidewalk, you might not always appreciate your sense of smell. But what if you couldn't experience the fragrance of warm laundry? Or inhale the delightfully oily bouquet of corn dogs just pulled out of the deep fryer?
For people with congenital anosmia, who cannot detect odors, the most fragrant flower and the most feculent spoor come across as the same flavorless nasal static.
But now there may be hope the the olfactorily challenged, thanks to scientists that have restored smelling function in mice that were genetically destined to have no sense of smell.
In a paper published in the journal Nature Medicine on Sunday, a team of researchers led by scientists from the University of Michigan Medical school used engineered cold viruses to deliver crucial pieces of DNA to mice with a particular genetic defect. The defect in question affects a protein called IFT88 and results in a lack of cilia - tiny cellular organs that look like hairs - throughout the mouse's body.
But 14 days after the scientists gave the mice the genetic tools to make normal IFT88, they were healthier. Neural pathways involved in the experimental mice's sense of smell were lighting up in a normal fashion when they were exposed to banana oil.
"At the molecular level, function that had been absent was restored," senior author Jeffrey Martens said in a statement. "Essentially, we induced the neurons that transmit the sense of smell to regrow the cilia they'd lost."
It will take time for the treatment to even begin to be tested in humans, and it will likely be more applicable for people that have a genetic disorder that robbed them of their sense of smell, rather than those that lose it through disease or aging.
Restoring cilia function through gene therapy could also bode well for treatments of other diseases as well. The eye disease retinitis pigmentosa and polycystic kidney disease are just one of a host of conditions that can be traced to some kind of disruption of proper cilia function.
Some might not see the feat as impressive as restoring eyesight to the blind, but to those of us with a fine appreciation for olfaction, it's a rather scent-sational acheivement.
SOURCE: McIntyre et al. "Gene therapy rescues cilia defects and restores olfactory function in a mammalian ciliopathy model." Nature Medicine published online 2 September 2012.