Adult stem cells are crucial for physiological tissue renewal and regeneration following injury. Current models assume the existence of a single quiescent (resting) population of stem cells residing in a single niche of a given tissue.
The Linheng Li Lab and others have previously reported that primitive blood-forming stem cells can be further separated into quiescent (reserved) and active (primed) sub-populations. Emerging evidence indicates that quiescent and active stem cell sub-populations also co-exist in several tissues — including hair follicle, intestine, bone marrow, and potentially in the neural system — in separate yet adjacent microenvironments. In the review, Dr. Li proposes that quiescent and active stem cell populations have separate but cooperative functional roles.
"Both quiescent and active stem cells co-exist in separate 'zones' in the same tissue," explained Dr. Li. "Active stem cells are the 'primed' sub-population that account for the generation of corresponding tissues, whereas quiescent stem cells function as a 'back-up' or 'reserved' sub-population, which can be activated in response to the loss of active stem cells or to tissue damage."
The new model would explain how the balance can be regulated between stem cell maintenance and simultaneous support of rapid tissue regeneration, not only at the individual cell level but also at the stem cell population level. The advantage of maintaining 'zoned' sub-populations of stem cells is to increase longevity of stem cells within organisms that have long life spans and large bodies.
The existence of two sub-populations of adult stem cells offers another advantage in the rapidly regenerating tissues in mammals by reducing the risk for mutations that cause tumors.
Intriguingly, cancers may utilize this same mechanism to maintain co-existing active-quiescent pools of stem cell sub-populations that support fast tumor growth (by active stem cells) while preserving the root of malignancy (by quiescent stem cells). This may explain the basis of drug resistance to cancer treatment.
"If this hypothesis is true, the critical question will be how to target quiescent drug-resistant cancer stem cells," said Dr. Li. "We will test this model in cancers in an effort to determine how to activate quiescent (drug-resistant) cancer stem cells for further targeting."
Dr. Li also is a Professor in the Department of Pathology & Laboratory Medicine at The University of Kansas School of Medicine. Learn more about his work at www.stowers.org/labs/LiLab.asp.
Dr. Clevers is also a Professor of Molecular Genetics at the Hubrecht Institute and was the first to report the existence of active stem cells in intestine. Learn more about his work at www.hubrecht.eu/research/clevers.
The Stowers Institute for Medical Research is a non-profit, basic biomedical research organization dedicated to improving human health by studying the fundamental processes of life. Jim Stowers, founder of American Century Investments, and his wife Virginia opened the Institute in 2000. Since then, the Institute has spent over a half billion dollars in pursuit of its mission. Currently the Institute is home to nearly 500 researchers and support personnel; over 20 independent research programs; and more than a dozen technology development and core facilities.
Susan Weigel | EurekAlert!
Rainbow colors reveal cell history: Uncovering β-cell heterogeneity
22.09.2017 | DFG-Forschungszentrum für Regenerative Therapien TU Dresden
The pyrenoid is a carbon-fixing liquid droplet
22.09.2017 | Max-Planck-Institut für Biochemie
Plants and algae use the enzyme Rubisco to fix carbon dioxide, removing it from the atmosphere and converting it into biomass. Algae have figured out a way to increase the efficiency of carbon fixation. They gather most of their Rubisco into a ball-shaped microcompartment called the pyrenoid, which they flood with a high local concentration of carbon dioxide. A team of scientists at Princeton University, the Carnegie Institution for Science, Stanford University and the Max Plank Institute of Biochemistry have unravelled the mysteries of how the pyrenoid is assembled. These insights can help to engineer crops that remove more carbon dioxide from the atmosphere while producing more food.
A warming planet
Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.
The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...
Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...
Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!
When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...
For the first time, physicists have successfully imaged spiral magnetic ordering in a multiferroic material. These materials are considered highly promising candidates for future data storage media. The researchers were able to prove their findings using unique quantum sensors that were developed at Basel University and that can analyze electromagnetic fields on the nanometer scale. The results – obtained by scientists from the University of Basel’s Department of Physics, the Swiss Nanoscience Institute, the University of Montpellier and several laboratories from University Paris-Saclay – were recently published in the journal Nature.
Multiferroics are materials that simultaneously react to electric and magnetic fields. These two properties are rarely found together, and their combined...
19.09.2017 | Event News
12.09.2017 | Event News
06.09.2017 | Event News
22.09.2017 | Life Sciences
22.09.2017 | Medical Engineering
22.09.2017 | Physics and Astronomy