Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

World first: scientists succeed in cloning human embryos from eggs matured in the lab

20.06.2005


Scientists in Belgium have discovered how to clone human embryos from eggs that have been matured in the laboratory. Their discovery should make it easier for scientists to create embryonic stem cell lines from cloned embryos and develop them to provide eggs and sperm for infertile couples, the 21st annual conference of the European Society of Human Reproduction and Embryology heard today (Monday 20 June).



Until now, scientists investigating human cloning for therapeutic purposes have been limited to using mature eggs (oocytes) that have reached the metaphase II stage (MII) at which ovulation and fertilisation occurs in humans. However, there are few human MII oocytes available for research because almost all that are retrieved from women seeking fertility treatment are used to treat the patient. Immature oocytes are not used routinely for treatment at present, and so any that are retrieved can be donated for research. These immature oocytes are arrested in the prophase I stage, before meiotic division is complete, when the enlarged nucleus is called the germinal vesicle (GV).

Bjorn Heindryckx, a PhD student at the Infertility Centre at Ghent University Hospital, Belgium, and his colleagues, matured GV oocytes in culture in the laboratory for 44 hours, after which time 85% of the GV oocytes had developed into MII oocytes. From each of these, they removed the nuclear apparatus, which contained the chromosomes that held all the genetic information. Using conventional ICSI techniques, they injected into the empty oocytes the nuclei taken from somatic cumulus1 cells (i.e. non-germ cells) of another person – a process known as non-autologous nuclear transfer. After time for nuclear re-programming the oocytes were artificially activated by incubation in a medium containing calcium ionophore, which enabled the injected nucleus to prepare for the first embryonic division.


Mr Heindryckx said: “Eighteen out of the 25 in vitro matured MII oocytes survived this nuclear transfer. Of these, 11 showed the formation of one pronucleus. In normal fertilisation the formation of male and female pronuclei is an important stage just before the maternal and paternal chromosomes start to pair up in preparation for the first cell division. In the case of these oocytes they had undergone a pseudo-fertilisation because the pronuclei were derived from whole foreign nuclei, each one with a complete set of homologous [matching] chromosomes, instead of from sperm and eggs which carry only one set of chromosomes each.”

Five oocytes divided to the two-cell stage, and of these, three continued to divide to the six- to ten-cell stage. One embryo continued to develop to the compacted stage, when the individual cells started to flatten and increase their contact with one another.

Mr Heindryckx said: “To our knowledge, this is the first report describing the development of cloned human embryos using in vitro matured oocytes and non-autologous transfer via a conventional method of nuclear transfer.

“Our final goal is to use human therapeutic cloning for infertility treatment by creating artificial eggs and sperm for patients who are infertile because of absence or premature loss of eggs or sperm. We would do this by isolating embryonic stem cell lines from cloned early embryos and driving these embryonic stem cells to develop into eggs and sperm in the laboratory.”

However, Mr Heindryckx warned that there was a long way to go and many problems to overcome before he and his colleagues could reach their goal.

“None of these early embryos developed to the blastocyst stage, and failure to do so could reveal some problems in gene activation, especially in cloned embryos. So, first we have to understand how to get cloned blastocysts of good quality from in vitro matured oocytes. This will be difficult because it is well known that embryonic development is compromised when in vitro matured oocytes are used, and in cloning technology the oocytes undergo intensive micromanipulation, which makes it even harder to develop good quality blastocysts. Once we have achieved this, the next step will be the isolation of the Inner Cell Mass (ICM) from which we can obtain embryonic stem cells.

“The availability of human oocytes is a major obstacle at the moment for research into therapeutic cloning. Therefore, we consider this research is important because it makes best use of more easily available biological material – in this case, immature oocytes.”

Emma Mason | alfa
Further information:
http://www.eshre.com

More articles from Life Sciences:

nachricht Designed proteins to treat muscular dystrophy
29.06.2017 | Universität Basel

nachricht Funding of Collaborative Research Center developing nanomaterials for cancer immunotherapy extended
28.06.2017 | Johannes Gutenberg-Universität Mainz

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Can we see monkeys from space? Emerging technologies to map biodiversity

An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.

Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...

Im Focus: Climate satellite: Tracking methane with robust laser technology

Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.

Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...

Im Focus: How protons move through a fuel cell

Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.

As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...

Im Focus: A unique data centre for cosmological simulations

Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.

With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...

Im Focus: Scientists develop molecular thermometer for contactless measurement using infrared light

Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine

Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Plants are networkers

19.06.2017 | Event News

Digital Survival Training for Executives

13.06.2017 | Event News

Global Learning Council Summit 2017

13.06.2017 | Event News

 
Latest News

High conductive foils enabling large area lighting

29.06.2017 | Power and Electrical Engineering

Designed proteins to treat muscular dystrophy

29.06.2017 | Life Sciences

Climate Fluctuations & Non-equilibrium Statistical Mechanics: An Interdisciplinary Dialog

29.06.2017 | Seminars Workshops

VideoLinks
B2B-VideoLinks
More VideoLinks >>>