Navigation Links
Scientists succeed in cloning human embryos from eggs matured in the lab

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."


Source:European Society for Human Reproduction and Embryology

Related biology news :

1. Scientists ID molecular switch in liver that triggers harmful effects of saturated and trans fats
2. Scientists Replicate Hepatitis C Virus in Laboratory
3. Scientists detect probable genetic cause of some Parkinsons disease cases
4. Scientists find missing enzyme for tuberculosis iron scavenging pathway
5. Scientists seek answers on what activates deadly anthrax spores
6. Yale Scientists Find MicroRNA Regulates Ras Cancer Gene
7. Scientists collaborate to assess health of global environment
8. Scientists decipher genome of fungus that can cause life-threatening infections
9. Scientists discover the cellular roots of graying hair
10. Scientists rid stem cell culture of key animal cells
11. Scientists develop new color-coded test for protein folding
Post Your Comments:

(Date:11/18/2015)... , November 18, 2015 ... published a new market report titled  Gesture Recognition Market ... Forecast, 2015 - 2021. According to the report, the global gesture ... is anticipated to reach US$29.1 bn by 2021, at ... North America dominated the global ...
(Date:11/17/2015)... 17, 2015 Paris ... --> Paris , qui s,est ... DERMALOG, le leader de l,innovation biométrique, a inventé le ... et empreintes sur la même surface de balayage. Jusqu,ici, ... l,autre pour les empreintes digitales. Désormais, un seul scanner ...
(Date:11/17/2015)... , Nov. 17, 2015 Pressure BioSciences, Inc. ... the development and sale of broadly enabling, pressure cycling ... sciences industry, today announced it has received gross proceeds ... million Private Placement (the "Offering"), increasing the total amount ... or more additional closings are expected in the near ...
Breaking Biology News(10 mins):
(Date:11/30/2015)... Partnership includes an MPP ... the u niversity , s Solid Drug Nanoparticle ... cale - up through cost ... , where licensees based anywhere in the world will have the right to ... Africa , where licensees based anywhere in the world will have the ...
(Date:11/30/2015)... , Nov. 30, 2015 Harvard Apparatus ... a biotechnology company developing bioengineered organ implants for ... notification from The NASDAQ Stock Market that it ... requirements. The letter noted that as a result ... stock having exceeded $1.00 per share for more ...
(Date:11/30/2015)... 2015 Spherix Incorporated (Nasdaq: SPEX ... fostering and monetization of intellectual property, today provided ... designed to create shareholder value. ... "Based on published reports, the total addressable market ... and Spherix will seek to secure fair and ...
(Date:11/30/2015)... , Nov. 30, 2015  Champions Oncology, Inc. (CSBR), ... services to personalize the development and use of oncology ... Executive Officer, will be presenting at the LD MICRO ... Pacific Standard Time (PST).  The conference, held at the ... Angeles, CA , will feature 200 small/micro-cap companies ...
Breaking Biology Technology: