Adult stem cells are undifferentiated or unspecialized cells found in most adult tissues. 

The three most notable advantages of adult stem cells include:

1. Ability to self-renew: Adult stem cells are capable of going through multiple cell division cycles while continuing to maintain their undifferentiated state.
2. Unlimited potency: Adult stem cells have the potential to grow into any of the more than 200 cell types in the body, which has tremendous potential for treating various diseases.
3. No immune rejection: Adult stem cells are more flexible and do not induce immune rejection, which is observed in embryonic stem cells.