Cloned human embryos: did genes kick in?
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.
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.
HELEN PEARSON | © Nature News Service
Decoding the genome's cryptic language
27.02.2017 | University of California - San Diego
New risk factors for anxiety disorders
24.02.2017 | Julius-Maximilians-Universität Würzburg
On January 15, 2009, Chesley B. Sullenberger was celebrated world-wide: after the two engines had failed due to bird strike, he and his flight crew succeeded after a glide flight with an Airbus A320 in ditching on the Hudson River. All 155 people on board were saved.
On January 15, 2009, Chesley B. Sullenberger was celebrated world-wide: after the two engines had failed due to bird strike, he and his flight crew succeeded...
In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport
Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...
The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.
The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...
Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...
13.02.2017 | Event News
10.02.2017 | Event News
09.02.2017 | Event News
27.02.2017 | Materials Sciences
27.02.2017 | Interdisciplinary Research
27.02.2017 | Life Sciences