This sort of stunt was first mentioned in Mawdryn Undead, quoting form the wikipedia page:
In Mawdryn Undead (1983), it is first referenced that a Time Lord could transfer his regenerative life essence to another being. In that story, the Fifth Doctor is coerced by Mawdryn to give up his future regenerations in order to cure Nyssa and Tegan Jovanka from Mawdryn 's disease.
This transfer never happens, though it's clear that it can be used for various regenerative purposes, such as curing fatal diseases.
It is not until "Let's Kill Hitler" (2011) that such a transference is shown. In that instance, River sacrifices her own regenerative power in order to save the Eleventh Doctor.... The favour is returned in "The Angels Take Manhattan" where River Song's wrist is repaired by the Doctor, who subsequently gives up a portion of his regenerative energy.
It's unclear, at this point, how much this cost the Doctor's regenerative energy, though River scolds him for his actions, perhaps showing it may have future repercussions.