Inner ear hair cells are crucial to the vestibular system that ensures balance 

We are born with 30,000 of these cells but they die over time and don't regrow 

35% of Americans over 40 have vestibular dysfunctions, causing imbalance, vertigo and falls that prove deadly for elderly people 

Stanford University scientist tweaked mice to regenerate inner ear hair cells, restoring their balance 

Humans have very similar balance systems, suggesting the same alteration could improve balance for millions of older Americans