April 30 : A recent study by researchers at Johns Hopkins Medical Institutions has identified a backup supply of stem cells that can mend the harshest damage to the nerves in charge for our sense of smell.

According to scientists, these cells laze about and do nothing under normal conditions, but when the adjoining cells die, the stem cells spring into action.

A report on the discovery will appear online next week in Nature Neuroscience.

“These stem cells act like the Army Reserves of our nose supporting a class of active-duty stem cells that help repair normal wear and tear. They don’t come in until things are really bad,” explains lead author Randall Reed, Ph.D., a professor of neuroscience at Johns Hopkins.

Olfactory cells, which are the only nerve cells in the body to run directly from the brain to the outside world, are under continuous attack from harsh chemicals that one may happen to grasp a hint of by accident, risking damage or death.

To decipher how the olfactory system looks after severely injured nerve cells, Reed’s team exposed mouse olfactory nerves to a cloud of toxic methyl-bromide gas, which not only kills olfactory nerve cells but also adjacent, non-nerve cells in the nasal passage.

Three weeks after chemical exposure, the researchers inspected nasal cells to make out which, if any, had grown back.

They found that the recently grown cells, both nerve and non-nerve, grew from HBCs, a population of cells not previously known for repair abilities.

“We were stunned because HBCs normally don’t grow much or do anything. And the most surprising thing is that HBCs can grow into both nerves and non-nerve cells; they do so by generating the other active type of nasal stem cell,” says Reed.

After the chemical exposure tests, the team then went back and looked at nerve repair under less destructive circumstances where only the olfactory nerve cells are killed.

In this condition, the HBCs did nothing to fix the dented cells; rather, they allowed the earlier known stem cells to do all the repair work.

“The ability to smell is crucial for eating, mating and survival, and it’s important that the olfactory system be fully operational all the time,” explains Reed. “The HBCs act as a fail-safe to ensure continued function of the sense of smell.”

The unearthing of these two dissimilar types of stem cells in one neural tissue is a first, says Reed, who is concerned to see if other types of nerves in the body have parallel repair mechanisms in play. (ANI)