A RIKEN-led team of molecular biologists has determined why human embryonic stem cells (ESCs) and induced pluripotent stem (iPS) cells undergo apoptosis, or programmed cell death, when separated from each other. The finding should allow more efficient culturing of human stem cells, making them easier to maintain, more flexible to handle, and generally improving their survival.
At present, human ESCs, unlike those derived from mice, must be cultured in clumps, which makes them difficult to manipulate. When they lose contact with neighboring cells, human ESCs immediately go into apoptosis.
The research team, led by Yoshiki Sasai from the RIKEN Center for Developmental Biology in Kobe, and including members from Kyoto University, showed that this apoptotic response could be countered by application of an inhibitor of the enzyme ROCK (Rho-dependent protein kinase). Now, using a combination of live-cell imaging and laboratory analysis, the team has elucidated the onset and progress of dissociation-induced apoptosis1.
They found that within a few hours of separation, human ESCs began blebbing—a process whereby the membrane spontaneously bulges in finger-like projections causing the cells to jiggle around. Blebbing occurs when the membrane breaks away from the internal cytoskeleton, and can vary in its duration and severity. In this case, blebbing lasted for hours and inevitably ended with the cell bursting. The researchers dubbed it the death dance, and traced its onset to hyperactivation of myosin, a contractile protein associated with cell movement.
By studying the levels of ROCK after dissociation, as well as the regulation of its activity by the compounds with which it interacts, Sasai and colleagues determined that myosin hyperactivation—hence the blebbing and apoptosis—is caused directly by ROCK. It can be suppressed by the myosin inhibitor, blebbistatin. Further, the whole process is triggered by loss of intercellular contact, and regulated by a compound known as Abr.
The molecular mechanism that the researchers have unraveled should be susceptible to manipulation, potentially allowing human ESCs to be separated and handled without risking their certain death. Interestingly, they found that the difference in susceptibility to apoptosis of dissociated human and mouse ESCs had nothing to do with species, but could be attributed to the stage of development from which the parent stem cells were derived.
“We are now planning further work to understand the detailed mechanism of Abr activation,” says Sasai. “Another question we wish to study is why cells die upon myosin hyperactivation.”
The corresponding author for this highlight is based at the Laboratory for Organogenesis and Neurogenesis, RIKEN Center for Developmental Biology
1. Ohgushi, M., Matsumura, M., Eiraku, M., Murakami, K., Aramaki, T., Nishiyama, A., Muguruma, K., Nakano, T., Suga, H., Ueno, M., et al. Molecular pathway and cell state responsible for dissociation-induced apoptosis in human pluripotent stem cells. Cell Stem Cell 7, 225–239 (2010).
gro-pr | Research asia research news
Warming ponds could accelerate climate change
21.02.2017 | University of Exeter
An alternative to opioids? Compound from marine snail is potent pain reliever
21.02.2017 | University of Utah
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...
Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".
Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...
13.02.2017 | Event News
10.02.2017 | Event News
09.02.2017 | Event News
21.02.2017 | Earth Sciences
21.02.2017 | Medical Engineering
21.02.2017 | Trade Fair News