In Part 1, it was stated that Tsunade has miotic regeneration. She uses chakra to force her cells to divide and repair any damage she takes. HOWEVER, Shizune states there is a finite amount of times a person can have their cells regenerate and repair. It's why everytime the yin seal on Tsuna's head disappears, she begins to show her true age; wrinkled and old. At the expense of accelerated healing in combat, Tsunade is burning up her body and potentially shaving years off her life.
Compare Tsuna's regeneration to say Wolverine's (X-Men) regenertation. Wolverine has a healing factor that repairs any illness, inhibitor (alcohol, anesthesia) and damage he sustains and keeps him in his physical prime longer. Tsunade uses chakra to force her body to do the exact same thing, but at the expense of her own body.
From the way Madara described Hashirama's healing, it would seem his is similar to Wolverine's and not Tsuna's.