Crushed optic nerve made to regrow

First they turned on a gene called BCL-2, which promotes growth and regeneration of the optic nerve in young mice. This gene is normally turned off shortly before birth. They then bred those animals with other mice carrying genetic mutations that reduce scar tissue in injured nerves.
The researchers crushed the optic nerves shortly after birth, and found that in young mice - less than 14 days old - between 40% and 70% of the injured optic nerve fibres regrew to reach their target destinations in the brain. No regrowth was seen in injured mice without the genetic modifications.