Saturday, February 6, 2016

Genomic editing of viable human embryos using CRISPR/Cas9 could yield customized human embryonic stem cells, but ethical issues remain

The Human Fertility and Embryology Authority (HFEA) of the United Kingdom last week authorized a team led by Dr. Kathy Niakan at the Francis Crick Institute in London to edit the cells in viable human embryos, using the powerful CRISPR/Cas9 technology, in order to investigate the causes of miscarriage.  This is a controversial decision, since this is the first time that “germline” genomic editing has been approved by any government.

There are strict rules accompanying the HFEA’s permission to pursue this research:  the modified embryos cannot be implanted in a womb, and they must be destroyed after two weeks.

However, two weeks is long enough for the fertilized egg to develop into a blastocyst, the outer part of which, in the traditional course of events, will become the placenta and the inner part of which will become the embryo.  The inner cell mass can, alternatively, be re-purposed as human “embryonic stem cells,” (hESCs) by removing them from the blastocyst, a process that renders the blastocyst incapable of producing a fetus or a child.

Using CRISPR/Cas9 techniques to edit the genetic code of the first cells in the fertilized egg means that it would be possible to create human embryonic stem cells with specific and customized characteristics that are designed to treat a range of medical conditions or for further experimental purposes.

The upside of this process is the derivation of hESCs capable of treating disease or for further research.  The downsides include the inconvenience and discomfort for the women whose eggs are harvested, the expense of the process, and the ethical objections to the instrumental use of viable human embryos, which some critics consider to be the taking of a human life.

The ability to create customized embryonic stem cells through CRISPR/Cas9 genomic editing has not gone unnoticed by the scientists affiliated with the California Institute for Regenerative Medicine (CIRM), which met on February 4th to discuss the issue of CRISPR/Cas9 gene modification in human embryos, as reported yesterday by Etopia News.

According to Kevin McCormack, Sr. Director of Public Communications and Patient Advocate Outreach at CIRM, at this meeting “the researchers did talk about cells harvested from blastocysts.”

CIRM identifies itself, on its website and generally, as “California’s Stem Cell Agency,” which makes sense, since it was created, through Proposition 71, the “California Stem Cell Research and Cures Initiative,” as an institution dedicated to pursuing breakthroughs in science that would enable the use of stem cells for a variety of therapeutic and research purposes.

The kind of germline genomic editing now authorized by the HFEA means that customized stem cells can probably now be created by using CRISPR/Cas9 to modify the first cells of the fertilized egg, letting the cell mass develop into a blastocyst and then harvesting the inner cells, which would then become human embryonic stem cells, possibly capable of treating a range of human diseases.

All this could be done within the two-week period authorized for experimentation on the embryo by the U.K.’s HFEA, or during a similar period as specified by CIRM.

The key ethical (and semantic) question then becomes “Does the rule established by the HFEA that the embryo must be “destroyed” after two weeks allow for the harvesting of the embryonic stem cells, a process that “destroys” the blastocyst, as required under the HFEA’s rules?”

Federal law prohibits the use of federal funds for human embryonic stem cell research.  This is why California created CIRM in the first place.  Current law in the U.S. neither authorizes nor prohibits CRISPR/Cas9 genomic editing of embryos, as long as federal funds are not used for the research.  CIRM was set up to investigate the use of human stem cells to treat disease.  CRISPR/Cas9, discovered and developed after CIRM’s establishment, now gives scientists a powerful new tool capable of creating customized hESCs.

Will California, under the leadership of CIRM, pioneer this new process, or will ethical objections block its development?  Such objections were raised during and after the campaign to pass Proposition 71 itself.  

Does CIRM have the authority to authorize such CRISPR/Cas9 research on viable human embryos in California?  Will it award grants to the state’s scientists to conduct this kind of research and the treatments derived from it?

Keep reading Etopia News to follow this issue as it evolves and find out.

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