Advanced Cell Technology, Inc. or “ACT” (OTCBB:ACTC)
reported that a range of therapeutic cell types obtained from induced
pluripotent stem (iPS) cells exhibit abnormal expansion and early
cellular aging. The research, which appears online (published-ahead-of-
print) in the journal STEM CELLS by ACT and its collaborators at
Stem International (SCRMI), Harvard Medical School, and the University
of Illinois, compares a variety of replacement cell types derived from
human iPS cells with their embryonic stem (ES) cell counterparts. The
findings support the use of ACT’s single blastomere-derived human
embryonic stem cell lines which do not display early aging.
“Before clinical application, it will be necessary to determine the
cause and extent of such abnormalities, and whether they also occur in
stem cells generated using different reprogramming methods”
The research shows that human iPS cells can generate blood, vascular and
retinal cells with characteristics similar to those derived from ES
cells, but with a dramatic decreased efficiency. However, in distinct
contrast to the ES cell derivatives, major differences were observed in
cells derived from iPS cells, including significantly increased cell
death (apoptosis), severely limited growth and expansion capability, as
well as a substantially decreased capacity to generate blood
progenitors. After further differentiation into red blood cells, over a
thousand-fold difference in expansion capability was observed in iPS
cells versus ES cell progenitors. Although vascular cells derived from
iPS cells were capable of forming capillary-like structures, the cells
also demonstrated early cell aging (senescence). Similarly, retinal
cells derived from iPS cells also displayed early signs of aging.
“Before clinical application, it will be necessary to determine the
cause and extent of such abnormalities, and whether they also occur in
stem cells generated using different reprogramming methods” said Robert
Lanza, M.D., Chief Scientific Officer at ACT, and senior author of the
study. “Fortunately, we think the problem may be related to the use of
viruses. Preliminary results suggest that these abnormalities are
significantly reduced using stem cells generated using proteins (without
the use of viruses or genetic manipulation). Although there is
excitement that iPS cells can serve as an embryo-free source of stem
cells, it would premature to abandon research using embryonic stem cells
until we fully understand what’s causing these problems.”