snorting stem cells for neurological conditions


STEM cells show promise for treating a range of neurological conditions,
including Parkinson's, strokes and Alzheimer's, but it is tricky getting them
into the brain. Perhaps inhaling stem cells might be the answer - if mice are
anything to go by.

Other options all have their drawbacks. Drilling through the skull and injecting
the stem cells is painful and carries some risks. You can also inject them into
the bloodstream but only a fraction reach their target due to the blood-brain
barrier.

The nose, however, might be a viable alternative. In the upper reaches of the
nasal cavity lies the cribriform plate, a bony roof that separates the nose from
the brain. It is perforated with pin-size holes, which are plugged with nerve
fibres and other connective tissue. Since proteins, bacteria and viruses can
enter the brain this way, Lusine Danielyan at the University Hospital of
Tübingen in Germany, and her colleagues, wondered if stem cells would also
migrate into the brain through the cribriform plate.

To test their idea, they dripped a suspension of fluorescently labelled stem
cells into the noses of mice. The mice snorted them high into their noses, and
the cells migrated through the cribriform plate. Then they travelled either into
the olfactory bulb - the part of the brain that detects and deciphers odours -
or into the cerebrospinal fluid lining the skull, migrating across the brain.
The stem cells then moved deeper into the brain.

The mice snorted stem cells high into their noses and large numbers of them
migrated into the brain
"We found that the cells could squeeze through these holes, which are far below
their own diameter and into the brain," says Danielyan, who presented her
findings at the Strategies for Engineered Negligible Senescence meeting in
Cambridge, UK, this week.

When the researchers pre-treated the nasal membrane of the mice with an enzyme
called hyaluronidase to loosen the junctions between epithelial cells, even more
stem cells entered the brain through the nose.

Other researchers have shown that you can also deliver therapeutic proteins such
as neural growth factor into the brain in this way. If the results of this study
can be repeated in humans, snorting stem cells might be a way of getting large
numbers of cells into the brain without surgery. Repeated doses could also be
given in the form of nasal drops.


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