Molecular mechanisms underlying replicative stress and genome damage in pluripotent stem cells

Pluripotent stem cells (PSCs) in the early embryo give rise to all of
the somatic cells in the body. Maintenance of the genetic integrity of PSCs is
essential for preventing genetic defects to be passed onto multiple progeny cells,
which would be detrimental for a developing embryo. When placed under
appropriate culture conditions, PSCs retain the ability to give rise to differentiated
cells from all three embryonic germ layers, whilst acquiring the ability to self-
renew extensively and thus provide an excellent, genetically normal model
system to investigate mechanisms that control genome integrity. We and others
have previously shown that PSCs acquire non-random genetic changes upon
prolonged culture. However, the molecular mechanisms underlying their
acquisition remain poorly understood. To this end, our project will determine the
contribution of different genome damage mechanisms to the common genetic
changes we observe. We will also elucidate how extrinsic environment
(specifically, culture medium composition) enhance or diminish these damage
mechanisms. Our previous data has shown that growing cells in different culture
media and environmental conditions significantly alters their mutation rates.
Work from other groups highlighted albumin as a key component of the medium,
necessary for stabilizing small molecules and ions and scavenging free radicals
that could be harmful for macromolecules, particularly the DNA. Hence, in
collaboration with our industrial partner Albumedix, who specializes in
recombinant albumin production, we will determine the contribution of intrinsic
mechanisms and niche conditions on genome damage of PSCs.