Accelerated tissue regeneration is a technology achieved by the Visitors. Used for both Human and Visitor to heal cuts, bruises or other forms of incisions into the skin.
Device
At the Visitor Healing Centers, they have a device which emits a blue light which instantaneously heals cuts, bruises in a matter of seconds. However, it takes V Doctors to go over the cut or bruises a few times for the skin to completely heal.
Injection
For Sleeper Agents, they instead have to depend on a clear liquid which when applied heals the skin, but is much slower than the device.
Ryan Nichols who had a cut in his skin in Pilot, needed to be given a clear liquid where it healed but was much slower.