Transfer of green dye suggests adult stem cells and ES cells fuse.
Fused cells become nerve cells and other cell types.
Fusion may explain adult stem-cell morphing.
The hyped ability of adult stem cells to sprout replacement tissue types is being called into question. They may instead be fusing with existing cells, say two new reports, creating genetically mixed-up tissues with unknown health effects.
Recent studies have shown that adult stem cells transplanted from one tissue, such as blood, can spawn the cell types of another, such as nerves. The findings have stirred intense interest in stem cells’ medical potential to repair damaged or diseased tissues.
Fate or fusion
When certain adult stem cells are injected into mice, their descendants have been found in muscle, liver, brain and heart. Like stem cells from embryos (ES cells), adult stem cells are thought to be able to give rise to many other cell types in the body.
Some researchers remain sceptical about this, as it challenges a long-held notion that adult stem cells are committed to producing only one class of cell. "There’s something unprecedented going on," says Austin Smith of the University of Edinburgh, UK.
Smith and Naohiro Terada of the University of Florida in Gainesville, looked for an alternative explanation. They grew adult stem cells from bone marrow and brain in the same dishes as ES cells. Both types fused spontaneously into hybrid cells. These acquired the properties of ES cells and produced muscle, nerve and other cell types.
Fusion occurs rarely - only once for every 10,000-100,000 cells. But the researchers think that transplanted stem cells fusing with cells around the body could explain some of the previous results. "It is quite possible that such fusion events have been previously misinterpreted," agrees Fred Gage, who works on nerve stem cells at the Salk Insitute in La Jolla, California.
However, Smith and Terada have only demonstrated fusion under very specific culture conditions; their results may not prove relevant to other situations, Krause warns.
Cell safety checks
How stem cells produce new tissue is important. Offspring formed by fusion may carry twice the normal number of chromosomes. This could make the cells genetically abnormal, precluding their medical use. Researchers agree that more rigorous criteria are needed to establish how new cells form from stem cells, and whether they function normally.
Previous transplantation experiments have not made these checks. Generally, researchers identify new cells using a fluorescent protein carried only by the original donor cell and inherited by its offspring. If cells fuse, this marker is still carried into the resulting hybrid. Only by checking for genes from the recipient animal can fusion be ruled out.
Terada and Smith concede that some stem cells may genuinely revert to an earlier stage of development or switch fates. "I’m not saying it never occurs," says Smith. Ultimately, they hope to direct transplanted stem cells to a damaged site and turn them into the tissue that is needed. Again, the mechanism by which this occurs must first be worked out.
HELEN PEARSON | Nature News Service
Ambush in a petri dish
24.11.2017 | Friedrich-Schiller-Universität Jena
Meadows beat out shrubs when it comes to storing carbon
23.11.2017 | Norwegian University of Science and Technology
High-precision measurement of the g-factor eleven times more precise than before / Results indicate a strong similarity between protons and antiprotons
The magnetic moment of an individual proton is inconceivably small, but can still be quantified. The basis for undertaking this measurement was laid over ten...
Heat from the friction of rocks caused by tidal forces could be the “engine” for the hydrothermal activity on Saturn's moon Enceladus. This presupposes that...
The WHO reports an estimated 429,000 malaria deaths each year. The disease mostly affects tropical and subtropical regions and in particular the African continent. The Fraunhofer Institute for Silicate Research ISC teamed up with the Fraunhofer Institute for Molecular Biology and Applied Ecology IME and the Institute of Tropical Medicine at the University of Tübingen for a new test method to detect malaria parasites in blood. The idea of the research project “NanoFRET” is to develop a highly sensitive and reliable rapid diagnostic test so that patient treatment can begin as early as possible.
Malaria is caused by parasites transmitted by mosquito bite. The most dangerous form of malaria is malaria tropica. Left untreated, it is fatal in most cases....
The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.
Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...
Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.
That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...
15.11.2017 | Event News
15.11.2017 | Event News
30.10.2017 | Event News
24.11.2017 | Physics and Astronomy
24.11.2017 | Health and Medicine
24.11.2017 | Earth Sciences