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
BigH1 -- The key histone for male fertility
14.12.2017 | Institute for Research in Biomedicine (IRB Barcelona)
Guardians of the Gate
14.12.2017 | Max-Planck-Institut für Biochemie
MPQ scientists achieve long storage times for photonic quantum bits which break the lower bound for direct teleportation in a global quantum network.
Concerning the development of quantum memories for the realization of global quantum networks, scientists of the Quantum Dynamics Division led by Professor...
Researchers have developed a water cloaking concept based on electromagnetic forces that could eliminate an object's wake, greatly reducing its drag while...
Tiny pores at a cell's entryway act as miniature bouncers, letting in some electrically charged atoms--ions--but blocking others. Operating as exquisitely sensitive filters, these "ion channels" play a critical role in biological functions such as muscle contraction and the firing of brain cells.
To rapidly transport the right ions through the cell membrane, the tiny channels rely on a complex interplay between the ions and surrounding molecules,...
The miniaturization of the current technology of storage media is hindered by fundamental limits of quantum mechanics. A new approach consists in using so-called spin-crossover molecules as the smallest possible storage unit. Similar to normal hard drives, these special molecules can save information via their magnetic state. A research team from Kiel University has now managed to successfully place a new class of spin-crossover molecules onto a surface and to improve the molecule’s storage capacity. The storage density of conventional hard drives could therefore theoretically be increased by more than one hundred fold. The study has been published in the scientific journal Nano Letters.
Over the past few years, the building blocks of storage media have gotten ever smaller. But further miniaturization of the current technology is hindered by...
With innovative experiments, researchers at the Helmholtz-Zentrums Geesthacht and the Technical University Hamburg unravel why tiny metallic structures are extremely strong
Light-weight and simultaneously strong – porous metallic nanomaterials promise interesting applications as, for instance, for future aeroplanes with enhanced...
11.12.2017 | Event News
08.12.2017 | Event News
07.12.2017 | Event News
14.12.2017 | Health and Medicine
14.12.2017 | Physics and Astronomy
14.12.2017 | Life Sciences