PHCbi-Panasonic eBook - 9

Cell Therapy Today * New Developments in Immunotherapy * Benefits of Oxygen Control in the Cell Culture Incubator

Numerous
studies have
demonstrated that
embryos cultured
at elevated O2
concentration
levels are impacted
negatively during
their development,
whereas culturing
with low oxygen
(5%) levels results
in improved
embryo quality.

oxygen levels, it is likely that physiological
oxygen (~5%) and hypoxic (~0.1% to 2.5%)
studies will increase in the future.

HIFs in Embryology
Researchers in the field of in vitro fertilization
(IVF) have already realized the benefits of physiological oxygen and pioneered its use in their
cultures.
Physiological oxygen is a stimulus for the
expression of certain factors that play a role in
embryogenesis. With the strict conditional nature
of embryo development and host implantation for fertilization, IVF researchers demand
an optimized in vitro environment for embryo
cultivation.
Numerous studies have demonstrated that
embryos cultured at elevated O2 concentration
levels are impacted negatively during their development, whereas culturing with low oxygen (5%)
levels results in improved embryo quality.
Studies have also shown that 5% O2 (or physiological oxygen) yields higher quality embryos,

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implantation and better pregnancy success than
20% O2 (atmospheric oxygen) culturing.13

HIF is one of several factors important for the
success of embryo development. During embryogenesis and organogenesis, there are many
hypoxic microenvironments that form; HIF is
expressed to adapt to these situations.
In one study, HIF-deficient embryos, a similar
phenotype as those that might be cultured at
atmospheric oxygen levels, had defects in blood
vessel formation and neural-fold closure.14 These
results support the role that HIF plays in angiogenesis and cell proliferation.
Another study demonstrated the role of HIF
in the proper formation of a placental architecture and its subsequent vascularization.
Other studies have characterized the increased
expression of HIF proteins during placental
development.
Taking these studies into account suggests

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