Category: biotech/medical – Page 2,622
Powerful CRISPR cousin accidentally mutates RNA while editing DNA target
When researchers first reported 3 years ago that they had created base editors, a version of the powerful genome-editing tool CRISPR, excitement swirled around their distinct powers to more subtly alter DNA compared with CRISPR itself. But the weaknesses of base editors have become increasingly apparent, and a new study shows they can also accidentally mutate the strands of RNA that help build proteins or perform other key cellular tasks. Researchers say this could complicate developing safe therapies with the technology and hamper other research applications.
Human diseases from sickle cell to Tay-Sachs are caused by a single mutation to one of the four DNA bases—adenine, guanine, cytosine, and thymine—and CRISPR has often had difficulty swapping out the bad actors. That’s in part because CRISPR cuts double-stranded DNA at targeted places and then relies on finicky cell repair mechanisms to do the heavy lifting of inserting a corrected DNA sequence for a mutation. Base editors, in contrast, chemically change one DNA base into another with enzymes called deaminases, which doesn’t require a cut or help from the cell.
Base editors, which adapt key components of CRISPR to reach targeted places in the genome, have been shown to have many off-target effects on DNA. But until now, its effects on RNA, which contains three of the same bases as DNA, had escaped scrutiny. So J. Keith Joung, a pathologist and molecular biologist at the Massachusetts General Hospital in Boston, led a team that put base editors into human liver and kidney cells. Their finding: Deaminases can also alter RNA, the group reports today in.
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Boosting muscle stem cells to treat muscular dystrophy and aging muscles
Lying within our muscles are stem cells, invisible engines that drive the tissue’s growth and repair. Understanding the signal(s) that direct muscle stem cells to spring into action could uncover new ways to promote muscle growth. However, these mechanisms are poorly understood.
Now, scientists from Sanford Burnham Prebys have uncovered a molecular signaling pathway involving Stat3 and Fam3a proteins that regulates how muscle stem cells decide whether to self-renew or differentiate—an insight that could lead to muscle-boosting therapeutics for muscular dystrophies or age-related muscle decline. The study was published in Nature Communications.
“Muscle stem cells can ‘burn out’ trying to regenerate tissue during the natural aging process or due to chronic muscle disease,” says Alessandra Sacco, Ph.D., senior author of the paper and associate professor in the Development, Aging and Regeneration Program at Sanford Burnham Prebys. “We believe we have found promising drug targets that direct muscle stem cells to ‘make the right decision’ and stimulate muscle repair, potentially helping muscle tissue regeneration and maintaining tissue function in chronic conditions such as muscular dystrophy and aging.”
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Light-based, 15-second scan aims to replace painful mammograms
Up to 50% of women skip potentially life-saving mammograms often because the procedure can cause extreme discomfort and pain. Now researchers have developed a painless, light-based, non-radioactive, 15-second procedure that could revolutionize breast cancer screening and save lives.
Although early detection of breast cancer can significantly increase survival, the radioactive X-ray that requires painful squeezing of the breast to get a good picture is an event that women do not look forward to. Now Caltech researcher Lihong Wang, Ph.D., Bren Professor of Medical and Electrical Engineering, and his colleagues are using their expertise in imaging tissues with light and sound to address this problem. Their development of a revolutionary breast scanning system known as photoacoustic computed tomography (PACT) is reported in the June issue of Nature Communications.2
“The technique developed by Wang and his colleagues combines light and sound to peer noninvasively into tissues without the radioactivity of an X-ray,” explained Behrouz Shabestari, Ph.D., director of the Program in Optical Imaging at the National Institute of Biomedical Imaging and Bioengineering, which funded the study. “PACT is also superior to MRI, which is expensive and sometimes requires the injection of contrast agents, commonly gadolinium. Gadolinium cannot be used in individuals with kidney disease and has recently been shown to accumulate in the bones and brain with unknown long-term effects.”
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Don’t like blood tests? New microscope uses rainbow of light to image the flow of individual blood cells
Circa 2012
Blood tests convey vital medical information, but the sight of a needle often causes anxiety and results take time. A new device developed by a team of researchers in Israel, however, can reveal much the same information as traditional blood test in real-time, simply by shining a light through the skin. This optical instrument, no bigger than a breadbox, is able to provide high-resolution images of blood coursing through our veins without the need for harsh and short-lived fluorescent dyes.
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Organs on a Chip Experiments Will Investigate the High Rate of Infections in Astronauts
On April 25, a SpaceX Falcon 9 rocket will launch cargo to the space station and two organs-on-a-chip experiments designed by University of Pennsylvania scientists. They want to understand why so many astronauts get infections while in space. NASA has reported that 15 of the 29 Apollo astronauts had bacterial or viral infections. Between 1989 and 1999, more than 26 space shuttle astronauts had infections.
Huh and his team have created two separate experiments for this first launch. The first essentially mimics an infection inside a human airway, to see what happens to the bacteria, and the surrounding cells, in orbit. Huh’s BIOLines lab created the actual chips.
A lung chip is made of a polymer, and a permeable membrane is the platform for the human cells. For the lung-on-a-chip, one side of the membrane is coated with lung cells, to process the air, and capillary cells on the other, to provide the blood flow. The membrane is stretched and released to provide the bellows-like effect of real lungs.
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