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CRISPR and human embryo


CRISPR and human embryo

Larry H. Bernstein, MD, FCAP, Curator

LPBI

 

 

Chinese team genetically modifies human embryo, using CRISPR gene-editing technique

http://www.kurzweilai.net/chinese-team-genetically-modifies-human-embryo-using-crispr-gene-editing-technique

http://www.kurzweilai.net/images/human-3PN-zygote.jpg

Photos showing injection of a human 3PN zygote (left) and development to 8 to 16-cell stage in vitro (right). Scale bar = 100 μm. (credit: Xiangjin Kang et al./Journal of Assisted Reproduction and Genetics)

Chinese researchers have genetically modified a human embryo using CRISPR/Cas9, the gene editing technique, using embryos that carried an extra set of chromosomes (so they were not viable) — hoping to learn more about the possibility of producing human babies that would be immune to HIV.

The Chinese team reports in the Journal of Assisted Reproduction and Genetics that they obtained 213 fertilized eggs from a fertility clinic, which had been deemed unsuitable for in vitro therapy.* They used the eggs to study a mutation that causes damage to an immune cell gene called CCR5 (this type of cell, when damaged naturally, has been found to lead to HIV resistance).

Aside from a previous study in China last year that involved editing human embryo genes (see Researchers in China have created genetically modified human embryos), most of the world has decided to hold off doing this controversial research. “We believe that any attempt to generate genetically modified humans through the modification of early embryos needs to be strictly prohibited until we can resolve both ethical and scientific issues,” the researchers say in their paper.

Failed experiment

The team reports that just 4 out of 26 of the embryos that were edited were modified successfully — some still contained genes that had not been modified, and others had resulted in unexpected gene mutations.

“This paper doesn’t look like it offers much more than anecdotal evidence that it works in human embryos, which we already knew,” George Daley, a stem-cell biologist at Children’s Hospital Boston, told Nature. “It’s certainly a long way from realizing the intended potential” — a human embryo with all its copies of CCR5 inactivated.

“It just emphasizes that there are still a lot of technical difficulties to doing precision editing in human embryo cells,” Xiao-Jiang Li, a neuroscientist at Emory University, also said in the Nature article . He thinks that researchers should work out these kinks in non-human primates, for example, before continuing to modify the genomes of human embryos using techniques such as CRISPR.

* The women who had donated the eggs all gave permission for the embryos to be used for genetic research, on condition that the embryos would not be allowed to mature into a human being (all of the embryos were destroyed after three days).


Abstract of Introducing precise genetic modifications into human 3PN embryos by CRISPR/Cas-mediated genome editing

Purpose

As a powerful technology for genome engineering, the CRISPR/Cas system has been successfully applied to modify the genomes of various species. The purpose of this study was to evaluate the technology and establish principles for the introduction of precise genetic modifications in early human embryos.

Methods

3PN zygotes were injected with Cas9 messenger RNA (mRNA) (100 ng/μl) and guide RNA (gRNA) (50 ng/μl). For oligo-injections, donor oligo-1 (99 bp) or oligo-2 (99 bp) (100 ng/μl) or dsDonor (1 kb) was mixed with Cas9 mRNA (100 ng/μl) and gRNA (50 ng/μl) and injected into the embryos.

Results

By co-injecting Cas9 mRNA, gRNAs, and donor DNA, we successfully introduced the naturally occurring CCR5Δ32 allele into early human 3PN embryos. In the embryos containing the engineeredCCR5Δ32 allele, however, the other alleles at the same locus could not be fully controlled because they either remained wild type or contained indel mutations.

Conclusions

This work has implications for the development of therapeutic treatments of genetic disorders, and it demonstrates that significant technical issues remain to be addressed. We advocate preventing any application of genome editing on the human germline until after a rigorous and thorough evaluation and discussion are undertaken by the global research and ethics communities.

 

Comments

1

This is some of the most interesting, important and cutting edge research on the planet IMO.

I am all for ethical research in this field. The research AS described in this report does not cross the unethical line IMO.

If we let Nature take its course without any Human or external intervention, I suspect that in millions of years, Humans would evolve into a species that is extremely long lived, with throughout exceptional health and intellect.

Clearly, this choice would be unrealistic in many obvious ways.

The Natural choice is to embrace our Natural ability/duty to safely, ethically, yet expediently, improve the longevity, health and intellect of our Human species.

 

2

It’s not simply based in a desire to have super-children – remember that the PRC did everything in it’s power to crush the traditional clan system in China.

Rather, it’s based on fundamentally different values when it comes to what it means to be a human. In China, traditional religious notions mingle with Atheist practicality to produce a culture which thinks it can judge people as superior or inferior. The west shared this point of view until very recently, relatively.

The revulsion against the Nazis was motivated by a disgust towards the unnatural and the synthetic – hypocritically, despite having eugenics programs of their own which continued after the fall of Nazi Germany, the rest of the world used Germany as a sacrifice to Gaia. To make matters even muddier, Operation Paperclip assured that the USA was infected by the German elite.

Just like the Nazis, the Chinese are motivated by lofty ideals of the perfect human. The world at large doesn’t condemn or punish them for their political repression, their work camps, or their censorship. Germany didn’t apologize to gays until 2001, and it still hasn’t apologized to trade unionists. Instead the world condemns the Nazis and Chinese for trying to make a perfect person.

This has nothing to do with human rights or dignity, and everything to do with social conservatism and a ‘nature is best; god gave you cancer’ mentality. Our biology determines the reality we experience, and how we can interact with that reality. Sentimentalism demands that we all feel the same – or else there is no empathy, as in the modern west.

All this ‘ethical debate’ amounts to is a way to prevent individuals from pursuing their own biological destinies. To muddy the waters, and tie together human rights and state contorol – as if you can’t have one without the other.

Western humanism is being left in the dust – in a few decades, the average westerner isn’t going to be in the running for anything but a Darwin Award. Regulation will have driven everyone with any ambition or imagination further east and west – to China and the pacific ocean. Note seasteading.

 

SJ Williams

“The team reports that just 4 out of 26 of the embryos that were edited were modified successfully — some still contained genes that had not been modified, and others had resulted in unexpected gene mutations.

“This paper doesn’t look like it offers much more than anecdotal evidence that it works in human embryos, which we already knew,” George Daley, a stem-cell biologist at Children’s Hospital Boston, told Nature. ”

Now a company in Iowa, Exemplar Genetics can reproducibly inject and create cloned mammal embryos with Somatic Cell Nuclear Transfer and have been doing it for a while.

Lots of Crispr talks at last AACR also

 

AACR 2016: CRISPR as a Screening Tool for Drug Targets

AACR 2016 CRISPR in Drug Discovery Symposium Recap [AACR]

  • NEW ORLEANS—Once again the quality of research presented at the annual American Association for Cancer Research (AACR) meeting transcends excellence. Researchers from around the globe have descended on the city of New Orleans to exchange ideas that they all hope will lead them down the path toward the next impactful cancer therapeutic. There is certainly no shortage of innovative presentations that vary in topics from cancer epigenetics to the latest molecular diagnostic techniques that are poised to reshape clinical medicine.

    Yet, genome editing still continues to lead the pack as one of the most exciting revolutions in cancer research over the past several decades. In particular, the CRISPR/Cas9 system has been associated with an extraordinary number of research publications since its initial use as a genome engineering tool in 2012. Now, genome editing using the CRISPR/Cas9 nuclease is empowering real genetic analyses within human cell cultures. Because this technique can be used to inactivate a set of genes completely or regulate their expression, it becomes feasible to identify the molecular mechanisms that control a particular pathway, especially as it relates to disease states, such as cancer.

    Researchers are continually looking for new ways to apply CRISPR technology, and identifying synthetic lethal mutations of oncogenic targets holds enormous potential for the development of novel drug targets. Moreover, identifying genes that mediate the sensitivity of cancer cells to existing drugs may also provide valuable insight into possible drug resistance mechanisms.

    In one of the major symposiums at AACR—titled CRISPR in Drug Discovery—a group of investigators presented data that showed how the genome editing technology could be employed as a screening tool for identifying or validating druggable cancer genes. Chairperson of the session and initial presenter David Sabatini, M.D., Ph.D., member of the Whitehead Institute and professor of biology at MIT, led the audience through his work on genetic screens of human cells for studying cancer. One of the primary goals of Dr. Sabatini’s work is to identify the absolutely essential genes that cancer cells need to survive.

    Dr. Sabatini discussed his laboratory’s work on developing large libraries [approximately 180,000 single guide RNAs (sgRNAs)] for CRISPR/Cas9 genetic screens, which his group used on a variety of cancer cell lines in association studies to determine which genes and pathways were most important. Interestingly, he found that pathologically similar cancer lines had very distinct molecular signatures, with only a few genes being absolutely essential among all cancer types. The Whitehead team found that the search to find genes indispensable for a single type pf cancer is often very useful for drug target identification.

    Next, Christopher Vakoc, M.D., Ph.D., associate professor at Cold Spring Harbor Laboratory (CSHL), discussed his work using CRISPR/Cas9 as a scanning and screening tool for mapping functional protein domains. Dr. Vakoc accomplished his work studying chromosome biology and using CRISPR to find essential chromatin regulators. Moreover, with the power of the CRISPR screening and scanning, Dr. Vakoc and his laboratory team are continuing to annotate methodically the functional relevance of protein domains associated with gene regulation and signal transduction for various forms of cancer.

    Specifically, Dr. Vakoc showed previously that inhibition of the transcriptional coactivator BRD4 had a positive effect on leukemia in mice. Using CRISPR technology, he has been able to reveal the precise 3D binding domains of various proteins that are essential to cancer cells, including BRD4. The CSHL team is now beginning to use this powerful genome editing tool to uncover fundamental cancer control mechanisms, as well as possible new drug targets.

    The final presentation of the CRISPR in Drug Discovery session was given by Johnathan Weissman, Ph.D., professor at the University of California, San Francisco (UCSF) School of Medicine. Dr. Weissman provided data on his work using catalytically inactive Cas9 as a CRISPR inhibition and activation tool—in other words “breaking” the DNA cutting mechanism. This afforded the UCSF team precise and fine-tuned gene expression. In essence, an inactive Cas9 enzyme is often fused to the guide RNA and recruited to the target DNA sequence. Instead of cutting the DNA strands, the fusion molecule manipulates transcription of the target DNA.

    Dr. Weissman and his team have generated a vastly improved CRISPRi/a library from almost 2700 genes that helps them define the relationship between gene expression and phenotype. Using CRISPRi/a, Dr. Weissman’s laboratory was able to modulate gene expression over approximately a 1000-fold range, which enables them to identify essential genes and regulators of complex pathways.

    Using CRISPRi/a for drug discovery allows researchers to identify drug targets rapidly and validate them. With this approach, Dr. Weismann’s lab has begun work on developing antichaperone cancer therapeutics. Chaperones, like heat shock protein 70 (HSP70), have been linked to the development of cancer drug resistance, and new therapeutics could help to resensitize the cancer cells to existing chemotherapy compounds.

    Common wisdom often points to the idea that those at the top for an extended time will falter sooner or later. There may come a day when that is true for CRISPR, although it doesn’t seem to be anytime soon, as the potential this technology possesses is just too great not to tap into or ignore.

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One Response

  1. “The team reports that just 4 out of 26 of the embryos that were edited were modified successfully — some still contained genes that had not been modified, and others had resulted in unexpected gene mutations.

    “This paper doesn’t look like it offers much more than anecdotal evidence that it works in human embryos, which we already knew,” George Daley, a stem-cell biologist at Children’s Hospital Boston, told Nature. ”

    Now a company in Iowa, Exemplar Genetics can reproducibly inject and create cloned mammal embryos with Somatic Cell Nuclear Transfer and have been doing it for a while.

    Lots of Crispr talks at last AACR also



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