Oh for god’s sake. New Scientist reports:

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 T?ɬ