Developmental
biologist could grow the human embryos in the lab up to 9 days till now, but
according to a recent paper published in Nature and Nature cell biology they have grown
human embryos in the lab up to 13 days’ post fertilization.
The technique
has already made it possible for the scientist to visualize features never seen
before in human embryos or to know the reasons behind early pregnancy loss.
The authors
reported that it was fascinating to watch as the human embryos derived from IVF
self-organized themselves in the absence of maternal tissue in a petri dish eventually
differentiating into founding cell lineage of the fetus and its supporting
tissue.
This is the
first glimpse of beginning of human life at a time when it usually implants
itself into the endometrium making it impossible to visualize.
An improved
culture medium of gel matrix with higher level of oxygen seems to be the key
towards this advancement.
Marta
Shahbazi, a researcher at Britain's University of Cambridge who was part of the
research teams quoted "Embryo development is an extremely complex process
and while our system may not be able to fully reproduce every aspect of this
process, it has allowed us to reveal a remarkable self-organizing capacity ...
that was previously unknown."
The recent achievement
has wider implications for scientists and fertility industry around the world. Martin
Pera, a stem-cell researcher at the University of Melbourne in Australia said “Studying
embryos in vitro could help researchers who are trying to grow stem
cells into embryo-like structures to judge the accuracy of
their work.”
About 50% of
embryos that are implanted in the mother’s womb do not go far in pregnancy and
studies of embryos in vitro could give a new insight into the process.
Norbert
Gleicher, head of the Center for Human Reproduction, an IVF clinic in New York
City said “The implantation process is a big black box for us clinicians.”
This work
could also help the scientists and researchers to understand the role of signaling
molecules from extraembryonic tissues for the developing embryo. This in turn
could lead to a better understanding of how to induce a human stem cell to grow
into cell lines that have therapeutic potential.
The researchers
terminated the experiment at 13 days because raising embryos past 14 days or
primitive streak formation raises many ethical and policy issues. At least 12 countries including U.K. prohibit
the scientists to work past the 14 days’ limit. This is also the latest time when an embryo
can split into monozygotic twins, and it is also the beginning of an individual
existence.
George
Daley, a stem-cell researcher at Children’s Hospital Boston in Massachusetts
said “Their achievements in the lab may be grounds for re-examining the limit.”
Other researchers also agreed that this work raises questions around the 14 days’
limit because if scientist succeed in growing stem cells into embryo-like
structures, then will the 14 days’ limit also apply to them?
At the same
time longer and improved culture does provide important information about human
biology, and improves success rates in ARTs. But, it does raise the question
that when it comes to human embryos, where should we put the limit.
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