http://motherboard.vice.com/blog/scientists-perfect-mouse-re-cloning-to-the-25th-generation
the cite is:
Sayaka Wakayama, Takashi Kohda, Haruko Obokata, Mikiko Tokoro, Chong Li, Yukari Terashita, Eiji Mizutani, Van Thuan Nguyen, Satoshi Kishigami, Fumitoshi Ishino and Teruhiko Wakayama “Successful serial cloning in the mouse over multiple generations.” Cell Stem Cell, 2013, doi:org/10.1016/j.stem.2013.01.005
Abstract
Previous studies of serial cloning in animals showed
a decrease in efficiency over repeated iterations
and a failure in all species after a few generations.
This limitation led to the suggestion that repeated
recloning might be inherently impossible because of
the accumulation of lethal genetic or epigenetic
abnormalities. However, we have now succeeded in
carrying out repeated recloning in themouse through
a somatic cell nuclear transfer method that includes
a histone deacetylase inhibitor. The cloning efficiency
didnotdecreaseover 25 generations, and, todate,we
have obtained more than 500 viable offspring from
a single original donor mouse. The reprogramming
efficiency also did not increase over repeated rounds
of nuclear transfer, and we did not see the accumula-
tion of reprogramming errors or clone-specific abnor-
malities. Therefore, our results show that repeated
iterative recloning is possible and suggest that, with
adequately efficient techniques, it may be possible
to reclone animals indefinitely.