1. An isolated population of human induced pluripotent stem (iPS) cells, said population comprising human pluripotent cells that comprise Epstein-Barr virus (EBV)-based reprogramming vectors comprising a replication origin and one or more expression cassettes encoding iPS reprogramming factors comprising at least Sox-2, Oct-4, wherein said cells, or one or more of said expression cassettes, comprise a nucleotide sequence encoding a trans-acting factor that binds to the replication origin to replicate an extra-chromosomal template, the cell population comprising the genome of a selected adult human individual and essentially free of chromosomally integrated retroviral elemants.