The constraint on lifetime is cancer, and the majority cause of cancer is stem-cell copying errors, from what I have read. The whole point of the evolution of stem cells is to reduce the number of divisions, so that an organism can even survive.
Any solution that involves stem cells needs to also massively reduce errors in DNA replication, otherwise cancer would occur.
Any solution that involves stem cells needs to also massively reduce errors in DNA replication, otherwise cancer would occur.