The ISSCR Issues Statement on Human Germ Line Genome Modification

The International Society for Stem Cell Research has released a statement calling for a moratorium on attempts to apply nuclear genome editing of the human germ line in clinical practice

Sunday, 22 March 2015

In a statement released on Thursday, the International Society for Stem Cell Research called for a moratorium on attempts at clinical application of nuclear genome editing of the human germ line to enable more extensive scientific analysis of the potential risks of genome editing and broader public discussion of the societal and ethical implications.

Technologies used to introduce changes into the DNA sequence of cells have advanced rapidly, making genome editing increasingly simple. Genome editing is feasible, not just in the somatic cells of an adult organism, but also in early embryos, as well as the gametes (sperm and egg) that carry the inheritable, germ line DNA. Research involving germ line nuclear genome editing has been performed to date in many organisms, including mice and monkeys, and applications to human embryos are possible.

The ISSCR statement raises significant ethical, societal and safety considerations related to the application of nuclear genome editing to the human germ line in clinical practice. Current genome editing technologies carry risks of unintended genome damage, in addition to unknown consequences. Moreover, consensus is lacking on what, if any, therapeutic applications of germ line genome modification might be permissible.

The statement calls for a moratorium on attempts to apply nuclear genome editing of the human germ line in clinical practice, as scientists currently lack an adequate understanding of the safety and potential long term risks of germ line genome modification. Moreover, the ISSCR asserts that a deeper and more rigorous deliberation on the ethical, legal and societal implications of any attempts at modifying the human germ line is essential if its clinical practice is ever to be sanctioned.

In calling for the above moratorium, the ISSCR is not taking a position on the clinical testing of mitochondrial replacement therapy, a form of germ line modification that entails replacing the mitochondria (found outside the nucleus) in the eggs of women at risk of transmitting certain devastating diseases to their children.

Source: International Society for Stem Cell Research

Contact: Michelle Quivey

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Mitochondrial Donation: How Many Women Could Benefit?

Two and a Half Thousand Women Could Benefit from Mitochondrial Donation in the UK

Thursday, 29 January 2015

Almost 2,500 women of child-bearing age in the UK are at risk of transmitting mitochondrial disease to their children, according to the most recent estimates published today in the New England Journal of Medicine.

The research offers the most recent evidence yet of how many families could potentially be helped by new IVF techniques to prevent mitochondrial disease, which would be permitted by new regulations on which a vote in parliament is imminent.

Mitochondrial diseases are caused by inherited mutations in the DNA contained in mitochondria - tiny structures present in every cell that generate energy. Mitochondrial diseases can be devastating and particularly affect tissues that have high energy demands - brain, muscle (including heart), liver and kidney.

New IVF-based techniques have been developed which have the potential to prevent the transmission of serious mitochondrial disease. Known as 'mitochondrial donation' the techniques involve removing faulty mitochondria inherited from the mother and replacing them with the healthy mitochondria of another woman. The nuclear DNA, containing 99.9% of genetic material from the mother and father, remains unchanged.

Researchers at the Wellcome Trust Centre for Mitochondrial Research at Newcastle University, which will be the first to offer mitochondrial donation if parliament agrees to new regulations of the Human Fertilisation and Embryology Act (1990), have now calculated how many women have disease-causing mutations in their mitochondrial DNA in order to estimate how many could potentially benefit. The new regulations only allow for mitochondrial donation to prevent mitochondrial disease and set no precedent for genetic manipulation of nuclear DNA.

They calculate that 2,473 women in the UK, and 12,423 women in the US, aged between 15 and 44 years, are at risk of passing on potentially lethal mitochondrial DNA disease to their children. This equates to an average of 152 births per year in the UK, and 778 births per year in the US.

The estimates were made by identifying the number of women in North East England who are at risk of passing on mitochondrial disease to their children and extrapolating the figure to the rest of the UK, based on the relative number of women of child-bearing age in the North East compared to the UK as a whole. A similar method was used for the US figures. The study did not account for variance due to ethnicity or potentially different fertility rates in different parts of the UK.

Researchers also assessed the fertility of women with mitochondrial DNA mutations. To do this they compared fertility data from their patients' to data about the general population, obtained from the UK Office for National Statistics. They found that mitochondrial mutation has no statistically significant effect on fertility rate.

Dr Gráinne Gorman from the Wellcome Trust Centre for Mitochondrial Research at Newcastle University, and joint first author of the paper, said:

"Our estimate of how many women could benefit from mitochondrial donation is based on our data from North East England, where we have very detailed insight into how many women are affected. We are confident that there are a similar number of women across the UK at risk of passing on mitochondrial disease to their children."

Professor Doug Turnbull, Director of the Wellcome Trust Centre for Mitochondrial Research at Newcastle University, and an author of the paper, said:

"Our findings have considerable implications for all countries that are considering allowing mitochondrial donation techniques. In the UK we are waiting for parliament to decide whether to support these regulations. This would allow women who carry these mutations greater reproductive choice. "

Source: Wellcome Trust 

Contact: Clare Ryan 

Reference:

Mitochondrial Donation: How many women could benefit? 

Gráinne S. Gorman, John P. Grady, Yi Ng, Andrew M. Schaefer, Richard J. McNally, Patrick F. Chinnery, Patrick Yu Wai Man, Mary Herbert, Robert W. Taylor, Robert McFarland, and Doug M. Turnbull

New England Journal of Medicine, January 28, 2015 DOI: 10.1056/NEJMc1500960

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Three Parents and a Baby

Scientists advise caution with regard to artificial insemination method

Wednesday, 18 June 2014

Already a few dysfunctional mitochondria (in

yellow on top of the picture) could cause a

disease by overgrowing functional ones (in blue).

Credit: Illustration: Iain Johnston. 

Mitochondria are cell organelles located within animal and human cells. They produce energy for the organism, possess their own genetic material - mitochondrial DNA (mtDNA) - and are transmitted exclusively by the mother. Depending on their activity and tasks, different numbers of mitochondria are present in a cell - usually a few hundred to a thousand per body cell.

Inherited mitochondrial disorders or so-called mitochondropathies occur in about one of 10,000 humans throughout the world. Diseases such as diabetes, stroke, cardiac defects, epilepsy, or muscle weakness may originate from mitochondrial defects. Inherited mitochondrial disorders have been incurable so far. Therefore, efforts are now being made to enable women with this disease to bear healthy children by means of nuclear transfer.

Mitochondria multiply at different rates

Jörg Burgstaller, a scientist and member of Gottfried Brem's research group at the Vetmeduni Vienna, has been working for several years on the genetics of mitochondria. It was known before that different types of mitochondria within a cell can proliferate at different rates. However, it was not known whether this is a singular phenomenon or if these cases occur more frequently.

Burgstaller investigated this in four newly bred mouse models which carried different mixtures of mitochondria whose DNA were related to each other to a differing extent.

This meant no health problem for the mice since all mtDNAs are were fully functional.

The outcome was: the more distantly two types of mitochondria within an egg cell were related, the more frequently a growth advantage was noted in favour of one of the two types of mitochondria. When two different mtDNAs were equally common in cells of an organ at the time of birth, one type was completely lost after a while. One mitochondria variant had thus achieved a growth advantage compared to the other variant and superseded the latter. This effect was almost non-existent in genetically very similar mitochondria within the cells; the ratio between the two types of mitochondria was not altered in that case.

The effect is of significance in reproduction medicine

Burgstaller's results may have effects on the planned introduction of the so called "Three-Parent Baby" in Great Britain. Experts take the cell nucleus of one human egg cell whose mitochondria have a defect and place it in an egg cell with "healthy" mitochondria. The baby resulting from this procedure has three parents, namely the mother whose cell nucleus is used, the mother whose mitochondria are involved, and the father whose sperm inseminated the egg cell.

However, this method raises the following problem: in every nuclear transfer, a small number of defective mitochondria are transferred into the healthy egg cell.

"So far it was believed that this minimal 'contamination' is of no consequence for the baby. However, our data show that the effect may have dramatic consequences on the health of the offspring. If the mitochondria of both mothers are genetically very different, it may have the same effects seen in the mouse model," says Burgstaller who developed the theory together with co-author Joanna Poulton, Professor of Mitochondrial Genetics at the John Radcliffe Hospital in Oxford.

"One mitochondrial type may be able to assert itself against the other. If the assertive one happens to carry the defective mtDNA, the benefit of the therapy would be jeopardized."

The solution to the "Three-Parent Baby"-problem

Burgstaller and his colleagues suggest the following solution to the problem: the mtDNA of both mothers, i.e. the donor of the nucleus and the donor of the mitochondria, should be analysed in advance and aligned to each other. So called "matching haplotypes" could prevent the dangerous effect. In the future the effect may even be utilized in a targeted manner to suppress defective mtDNA.

Source: University of Veterinary Medicine – Vienna 

Contact: Joerg Burgstaller

Reference:

mtDNA Segregation in Heteroplasmic Tissues Is Common In Vivo and Modulated by Haplotype Differences and Developmental Stage

Joerg Patrick Burgstaller, Iain G. Johnston, Nick S. Jones, Jana Albrechtová, Thomas Kolbe, Claus Vogl, Andreas Futschik, Corina Mayrhofer, Dieter Klein, Sonja Sabitzer, Mirjam Blattner, Christian Gülly, Joanna Poulton, Thomas Rülicke, Jaroslav Piálek, Ralf Steinborn and Gottfried Brem

Cell Reports. DOI:10.1016/j.celrep.2014.05.020 

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Call for Public Debates on Future Uses of Stem Cells

Science is running ahead of public debate and guidelines to grapple with use of stem cell-derived eggs and sperm Thursday, 02 July 2009 More than 40 scientists, bioethicists, lawyers and science journal editors are calling on their colleagues, policy makers and the public to begin developing guidelines for the research and reproductive use of stem cell-derived eggs and sperm, even though such use may be a decade or more away. "Science has always moved faster than social debate or society's ability to grapple with these issues," says Debra Mathews, Ph.D., lead author of a paper published in the July issue of Cell Stem Cell and assistant director of science programs at the Johns Hopkins Berman Institute of Bioethics. The paper calls for all parties to begin engaging in open discussion and debates, and describes the need for informed social policy well in advance of the eventual use of eggs and sperm derived from pluripotent stem cells. Mathews said stem cell researchers need to be better prepared to address public questions about uses of so-called pluripotent stem cell-derived gametes – regardless of how realistic or soon those uses may be. Such uses would potentially include reproductive uses such as the creation of sperm and eggs for in vitro fertilization, embryo selection based on genetic profile, and the creation of embryos from the tissues of foetuses, children and the deceased. The issues are too complex, and the stakes are too high, the authors suggest, for the public to be caught unaware by some new capability for using stem cell-derived gametes, and the research already is moving rapidly toward generation of sperm and eggs capable of making human embryos and potentially children. "Because derived-gamete research will require the creation and destruction of human embryos, this line of research will be morally objectionable to those who imbue human embryos with full moral status, and those objections must be addressed," the authors state. In their paper, the Johns Hopkins-led team described an analysis of the current state of pluripotent stem cell science and suggested a framework for the debates that need to take place. There was consensus by the authors that policymakers should not restrict scientific inquiry solely because ethical or moral disagreement exists about the use of these cells. Instead, they offered recommendations for guidelines that would be the focus of social debate. Among them were that restrictions should be specific to those aspects of the technology that are deemed morally unacceptable in a given nation or state, and that specific consent should be required of tissue donors whose cells will be used to derive gametes for use in reproduction. This approach would rule out using for reproduction any tissue from foetuses, minors and the deceased. Consent, they said, need not be required in situations involving laboratory studies that produce no embryos. The authors emphasized that significant oversight rules must be in place before any reproductive uses of gametes even begins, and early attempts to use gametes for these purposes should take place only as part of clinical research that follows the highest ethical standards. Assuming that reproductive use of stem cell-derived gametes does occur, the health of women carrying the resulting foetuses, and of children born to them, should be monitored rigorously and tracked in long-term studies. Pluripotent stem cell-derived gamete research brings together several of today's most contentious ethical issues, including the use of embryonic stem cells, the increasing ability to identify and understand risks associated with particular parts of the human genome, advanced reproductive technologies to treat infertility and interest in "human enhancement." Mathews noted that pluripotent stem cell-derived gamete research already is producing significant advances in basic understanding of how eggs and sperm develop from germ cells, infertility, genetic diseases and some cancers. Mathews said the most difficult scientific issue the study team faced was predicting how long it would take to get from a human stem cell to a set of gametes capable of successful test-tube fertilization, and how long, if ever, it would be until such gametes are used in clinical care. The group believes it will take at least a decade to develop derived human gametes and that clinical applications likely will not be available for several years beyond that. Whatever the time frame, she said determining whether pluripotent stem cell-derived gametes can function reliably and normally is critical for both non-reproductive and reproductive purposes. Scientists and the public also must prepare, Mathews noted, for the potential production of large numbers of human gametes that facilitate multigenerational laboratory studies of human genetics and disease. "Although many welcome the prospects for disease prevention and health promotion that such research should facilitate, many others will find the treatment of human embryos in such blatantly manipulative ways to be ethically unacceptable," the authors said in their paper. Reference: Pluripotent Stem Cell-Derived Gametes: Truth and (Potential) Consequences Debra J.H. Mathews, Peter J. Donovan, John Harris, Robin Lovell-Badge, Julian Savulescu and Ruth Faden Cell Stem Cell, Volume 5, Issue 1, 11-14, 2 July 2009, doi:10.1016/j.stem.2009.06.005 ......... ZenMaster

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Genetically Modified Human Embryo Stirs Controversy

Scientists create first GM human embryo 
Tuesday, 13 May 2008 

Researchers at Cornell University in New York have made a breakthrough in genetics by creating the first genetically modified (GM) human embryo. The GM embryo was produced to study how early cells in the embryo develop, but the scientists destroyed it just after five days. Led by Nikica Zaninovic, researchers at Cornell University used a virus to add a gene, a green fluorescent protein, to an embryo left over from assisted reproduction. It is believed to be the first documented genetic modification of a human embryo. 

Zaninovic's achievement was announced at the American Society for Reproductive Medicine annual meeting in 2007, but was only publicized recently when the United Kingdom's reproductive technology regulators reviewed the research. One of the authors of the study said to AP that the work was focused on stem cells. He noted that the researchers used an abnormal embryo that could never have developed into a baby anyway. 

"None of us wants to make designer babies," said Dr. Zev Rosenwaks, director of the Center for Reproductive Medicine and Infertility at New York-Presbyterian/Weill Cornell Medical Center. Dr. Rosenwaks said the research had been approved by a review board at his medical center and been privately financed, so it did not violate federal restrictions on research involving human embryos. 

 Doctors already put foreign genes into people as part of gene therapy to treat diseases. But those genetic changes generally cannot be passed on to future generations because they are made to only certain types of cells in the body, like blood cells or muscle cells. Genetic changes made to an embryo would theoretically be heritable if the embryo became a baby. So far, this has been a no-go area for scientists and medical professionals. 

 The breakthrough has brought with it major concerns. The British regulator, the Human Fertilisation and Embryology Authority (HFEA), has even cautioned that such controversial experiments may lead to "large ethical and public interest issues". However, the HFEA has said that it is preparing for scientists to apply for licences to create GM embryos. 

A paper, published by the authority, states: “The bill has taken away all inhibitions on genetically altering human embryos for research. The Science and Clinical Advances Group [of the HFEA] thought there were large ethical and public interest issues and that these should be referred for debate.” 

 The House of Commons in Britain is about to consider legislation permitting this and other controversial reproductive technologies, such as the creation of chimeras – human-animal hybrid embryos. The first voting on this Bill took place yesterday in the British Parliament. There the MPs voted to allow, with a great majority, the plan to update the human embryology laws to continue to their next Parliamentary stage. The research raises a number of difficult ethical questions. 

Though adding a fluorescent protein was merely a proof-of-principle step, modified embryos could be used to research human diseases. Scientists say embryos wouldn't be allowed to develop for more than a few weeks, much less implanted in a woman and brought to term. If the embryos were allowed to develop, genetic modifications – which would be permanent and passed to future generations – might prevent disease. 

Modifications might also be used for other reasons – physical appearance, intellectual prowess and personality changes – though the necessary science remains hypothetical at this point. Developing such techniques would necessarily involve at this stage trial-and-error and risk-taking with human life.

Let's have that debate:
What do you think CellNEWS readers? 

• Should genetically modified human embryos be used in research, or reproduction? Both? Neither? 
• What would be the advantages or disadvantages? 
• Would it OK to produce ‘designer babies’ in the future, when the technique is perfected? 

Reference: 

Genetic Modification Of Preimplantation Embryos and Embryonic Stem Cells (ESC) by Recombinant Lentiviral Vectors: Efficient and Stable Method for Creating Transgenic Embryos and ESC 

N. Zaninovic, J. Hao, J. Pareja, D. James, S. Rafii, Z. Rosenwaks. 

ASRM 2007 Annual Meeting, Poster session. 

Other Online Resources: 

HFEA 

Center for Genetics and Society 

Human Genetics Alert 

Genetics and Public Policy Center 

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ZenMaster

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Ethics of Lab Made Gametes

The Hinxton Group on Science, Ethics and Policy Challenges of Pluripotent Stem Cell-Derived Gametes Tuesday, 15 April 2008 The Hinxton Consortium, which was formed in 2004 to investigate the ethics and legality of stem cells, yesterday issued its recommendations for how research aimed at creating artificial gametes – sperm and eggs – should proceed. They warn politicians not to block scientific inquiry into subjects such as stem cells and embryo research just because there is a difference of opinion on the ethics or morality of the work. They also said that moral disagreements in society should never be used on their own to stop scientific investigation. "Societies have the authority to regulate science, and scientists have a responsibility to obey the law. However, policy-makers should refrain from interfering with scientific inquiry unless there is a substantial justification for doing so that reaches beyond disagreements based solely on divergent moral conviction. Any interference with scientific inquiry should be derived from reasonable concerns about demonstrable risks of harm to persons, societal institutions, or society as a whole," the consortium said. Scientists are working on a number of ways of making stem cells derived from embryos, or ordinary tissue such as skin, and turning them in the laboratory into mature sperm and eggs that could then be used in IVF clinics for fertility treatment. In Britain, the Human Tissues and Embryo Bill, that is currently making its way through Parliament, would allow research into human artificial gametes but further changes to the law would be needed to allow doctors to use such sperm and eggs on patients. Professor John Harris, a bioethicist at Manchester University who is part of the consortium, said that while the development of artificial sperm or eggs to treat infertile couples was still a long way off, it is important the work is not blocked from the start. "At this stage the real ethical issue is to ensure that the science can continue... Is society ready for it? We don't know that, and of course if it isn't, then it won't happen, but there is probably some considerable time in which this could be discussed," Professor Harris said. "Any tool can have applications that people can object to, from kitchen knives to anything else." The research has also prompted speculation that sperm could be produced from a woman or eggs from a man, allowing lesbian or gay couples to have children to whom both partners make an equal genetic contribution. One possible way of making sperm and eggs would be to engineer them from skin cells. Researchers, however, dismissed the prospect of male eggs and female sperm as science fiction in the new Hinxton group report. Professor Robin Lovell-Badge, of the National Institute for Medical Research in London, and a member of the group’s steering committee, said there may be insuperable barriers to the possibility of one sex making both types of gametes. “It would be very difficult to get eggs from XY cells, and even more difficult to get sperm from XX cells – my own view, indeed, is that the latter is impossible.” Human sex is determined by the inheritance patterns of the X and Y chromosomes: women have two copies of the X, while men have one X and one Y. As several genes that are critical to sperm production are carried on the Y chromosome, this will make it “difficult or even impossible” to turn female cells with two X chromosomes into sperm under any circumstances currently known to science. The production of eggs from male cells is a little less problematic, but even this is likely to be “very difficult”, the report said. Reference: Consensus Statement: Science, Ethics and Policy Challenges of Pluripotent Stem Cell-Derived Gametes The Hinxton Group ......... ZenMaster

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Three Parent Embryos Created

Three Parent Embryos Created - Again! Tuesday, 05 February 2008 Ten human embryos each containing the DNA from one man and two women have been created in a project that within three years could lead to the first genetically altered babies being born in Britain. The aim is to treat mitochondrial disorders, inherited diseases that can include fatal liver failure, stroke-like episodes, mental retardation with intractable epilepsy, muscle weakness, diabetes and deafness. All cells of the body have many (typically 1000-10,000) mitochondria. Mitochondria are tiny energy-producing structures ('organelles', the cell's equivalent to organs of the body) vital to cell function. If they malfunction then organs will eventually fail. The mitochondria are transmitted to the next generation through eggs, but not via the sperm, so mitochondrial defects are only inherited from the mother. The Newcastle team would take a one-day old IVF embryo from a couple at risk of mitochondrial disease, when the DNA cargoes from the sperm and egg are still separate and sit in structures called pronuclei. Then they would remove these pronuclei and insert them into an emptied egg from a second woman, which contains healthy mitochondria. The resulting early embryo would contain DNA from the parents in the nucleus, plus the mitochondria from the egg donor. If implanted back into the mother and a girl were born in this way, the inserted mitochondria would be passed to future generations to free them of potentially deadly disorders, too. Boys would not pass on the implanted mitochondria, because sperm do not contain mitochondria. Professor Patrick Chinnery, a member of the Newcastle team, said: "We believe that from this work, and work we have done on other animals that in principle we could develop this technique and offer treatment in the foreseeable future that will give families some hope of avoiding passing these diseases to their children." This procedure has been performed successfully previously (see Three Parent Embryo’s Created, CellNEWS - Wednesday, 15 October 2003). Articles: Transplant creates embryos with three parents Telegraph - Last Updated: 12:01am GMT 05/02/2008 Three-parent embryo formed in lab BBC - Last Updated: Tuesday, 5 February 2008, 11:13 GMT Scientists create three-parent embryos Reuters - Tue Feb 5, 2008 11:17am EST ......... ZenMaster

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Changes in chromosomal constitution of preimplantation embryos suggest caution in genetic screening

Changes in chromosomal constitution of preimplantation embryos suggest caution in genetic screening June 18 2007 Embryos that are selected out as abnormal can undergo chromosomal modifications, a scientist will tell the annual conference of the European Society of Human Genetics today. Ms Tsvia Frumkin, from the Racine IVF unit, LIS Maternity Hospital, Tel Aviv Sourasky Medical Centre, Tel Aviv, Israel, will tell the conference that her team’s findings meant that the results of preimplantation genetic screening (PGS) for chromosomal abnormalities were not always reliable and should be interpreted with caution. PGS is offered to women with recurrent IVF failures as well as repeated miscarriages. It is based on the concept that the entire chromosomal constitution of an embryo can be represented by a single cell, which is removed from the embryo. If one biopsied cell is found to be abnormal, there is a 90% chance that the rest of the embryo is also abnormal or mosaic, where two or more cells with different chromosomal constitution exist in a single embryo. Ms Frumkin analysed 8 cell embryos at day 3 of development using the FISH (fluorescence in situ hybridization) technique. Two cells from each embryo were analysed, and between 5 and 9 chromosomes were investigated. The abnormal embryos were re-analysed on day 5, using the same method. “By comparing FISH results of day 5 embryos to the abnormal results of the same embryos on day 3, we could elucidate the origin of the chromosomal aberrations and follow different chromosomal modifications as they occurred during preimplantation period. The timing is significant because embryos used in IVF are normally transferred at between 3 and 5 days old”, says Ms Frumkin. “We found that embryos which were abnormal on day 3 demonstrated a high rate of mosaicism However, on day 5 some of them had undergone ‘self-correction’ into normal embryos. Others kept the same abnormalities, while some had acquired additional chromosomal abnormalities”, she says. Following the research, Ms Frumkin’s hospital has decided to offer PGS only to patients after they have undergone more than 6 previous failed IVF cycles, been checked for and found to have normal chromosomal make-up, and produced more than 6 good quality embryos. “Even in cases that fulfil these conditions, we nevertheless prefer transferring more embryos back to the uterus rather than carrying out PGS biopsies for them on day 3, assuming that natural selection will usually favour the normal embryos for implantation,” she says. “Our results can explain why PGS would not be able to increase pregnancy potential but rather can serve as a prognostic tool in a limited number of cases”, says Ms Frumkin. “It can also help us make optimal decisions about the value of switching to a different assisted reproduction technique, for example egg donation.” .........

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Sweden approves creation of ’designer babies’

Sweden approves creation of ’designer babies’ Tuesday, 29 May 2007 The Swedish National Board of Health and Welfare yesterday granted three families the right to screen embryos to create a child who can be a stem cell donor for a sibling with a deadly illness. A fourth family is under consideration. This comes after a new law on genetic screening came into effect 1st of July last year. Read all at: Sweden approves creation of ’designer babies’ CellNEWS - Tuesday, 29 May 2007 ………….. ZenMaster

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