Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Human clone not miracle cure

28.11.2001


Cloned human embryos: did genes kick in?
© SPL


Rewiring the egg: mechanism remains murky.

From a scientific viewpoint, the cloning of human embryos may be more of a step than a leap, say sceptics. If the signals that turn adult cells into embryonic ones can be found, the creation of cloned embryos for tissue repair may become redundant.

Researchers at Advanced Cell Technology (ACT) in Worcester, Massachusetts, now report that they have created cloned human embryos. They aimed to make blastocysts, hollow balls of cells from which embryonic stem cells can be isolated and used to grow immunologically matched tissues to replace diseased ones.



Other researchers question whether ACT’s short-lived embryos, which did not become blastocysts, are a success. "A critical stage of development is the kicking in of genes," explains Harry Griffin of the Roslin Institute in Edinburgh, which cloned Dolly the sheep. "They didn’t get over this threshold."

The ACT team transferred nuclei from adult skin and ovarian cells into human eggs that had been stripped of their own chromosomes. Of 19 eggs, 11 appeared to undergo early stages of embryo development by forming a ’pronucleus’, a structure which forms in eggs fertilised with sperm. Two went on to divide into 4 cells and one into 6 cells1.

Embryonic genes in the nucleus only get switched on at, or after, this stage, explains embryologist Richard Gardner of the University of Oxford, UK. Before this, embryos are instructed by molecules in the mother’s egg cell. It is unclear whether ACT’s early embryos would progress any further, says Gardner.

Damage to genes incurred during manipulation of the nucleus can halt further development, explains John Gurdon, who studies embryos at the University of Cambridge, UK. The success rate for all cloning attempts so far "is very low indeed", says Gurdon.

Many researchers are trying to uncover the underlying mechanism by which adult nuclei, which have stopped dividing, are ’reprogrammed’ - made to switch off adult genes and switch on embryonic ones. With most work being done in mice, sheep and cows, "There’s almost nothing known in humans", says Gurdon.

If such signals can be identified, they might be used directly on adult human cells, points out Griffin, to turn them into the tissue of choice. "Maybe we can miss out the first stage and reprogramme directly," he says.

This would alleviate the need for human eggs in the cloning procedure altogether. It would also avoid the risks of genetic defects in cloned tissues, which have been reported in some cloned animals.

ACT are already working on alternatives to human cloning. In the same paper they describe a technique in which they stimulated human eggs - before the stage at which they halve their number of chromosomes - to divide and form embryos without fertilization by sperm. Using a chemical that triggers ions to enter the cell, they activated 22 eggs, of which 6 went some way towards forming blastocysts.

References

  1. Cibelli, J.B. et al. Somatic cell nuclear transfer in humans: pronuclear and early embryonic development. The Journal of Regenerative Medicine, 2, 25 - 31, (2001).


HELEN PEARSON | © Nature News Service
Further information:
http://www.nature.com/nsu/011129/011129-9.html

More articles from Life Sciences:

nachricht Cancer diagnosis: no more needles?
25.05.2018 | Christian-Albrechts-Universität zu Kiel

nachricht Less is more? Gene switch for healthy aging found
25.05.2018 | Leibniz-Institut für Alternsforschung - Fritz-Lipmann-Institut e.V. (FLI)

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Powerful IT security for the car of the future – research alliance develops new approaches

The more electronics steer, accelerate and brake cars, the more important it is to protect them against cyber-attacks. That is why 15 partners from industry and academia will work together over the next three years on new approaches to IT security in self-driving cars. The joint project goes by the name Security For Connected, Autonomous Cars (SecForCARs) and has funding of €7.2 million from the German Federal Ministry of Education and Research. Infineon is leading the project.

Vehicles already offer diverse communication interfaces and more and more automated functions, such as distance and lane-keeping assist systems. At the same...

Im Focus: Molecular switch will facilitate the development of pioneering electro-optical devices

A research team led by physicists at the Technical University of Munich (TUM) has developed molecular nanoswitches that can be toggled between two structurally different states using an applied voltage. They can serve as the basis for a pioneering class of devices that could replace silicon-based components with organic molecules.

The development of new electronic technologies drives the incessant reduction of functional component sizes. In the context of an international collaborative...

Im Focus: LZH showcases laser material processing of tomorrow at the LASYS 2018

At the LASYS 2018, from June 5th to 7th, the Laser Zentrum Hannover e.V. (LZH) will be showcasing processes for the laser material processing of tomorrow in hall 4 at stand 4E75. With blown bomb shells the LZH will present first results of a research project on civil security.

At this year's LASYS, the LZH will exhibit light-based processes such as cutting, welding, ablation and structuring as well as additive manufacturing for...

Im Focus: Self-illuminating pixels for a new display generation

There are videos on the internet that can make one marvel at technology. For example, a smartphone is casually bent around the arm or a thin-film display is rolled in all directions and with almost every diameter. From the user's point of view, this looks fantastic. From a professional point of view, however, the question arises: Is that already possible?

At Display Week 2018, scientists from the Fraunhofer Institute for Applied Polymer Research IAP will be demonstrating today’s technological possibilities and...

Im Focus: Explanation for puzzling quantum oscillations has been found

So-called quantum many-body scars allow quantum systems to stay out of equilibrium much longer, explaining experiment | Study published in Nature Physics

Recently, researchers from Harvard and MIT succeeded in trapping a record 53 atoms and individually controlling their quantum state, realizing what is called a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

In focus: Climate adapted plants

25.05.2018 | Event News

Save the date: Forum European Neuroscience – 07-11 July 2018 in Berlin, Germany

02.05.2018 | Event News

Invitation to the upcoming "Current Topics in Bioinformatics: Big Data in Genomics and Medicine"

13.04.2018 | Event News

 
Latest News

In focus: Climate adapted plants

25.05.2018 | Event News

Flow probes from the 3D printer

25.05.2018 | Machine Engineering

Less is more? Gene switch for healthy aging found

25.05.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>