The week’s most astounding developments from the neobiological frontier.

January 28, 2022

Frog legs regrown in regeneration breakthrough

The challenge of regenerating a lost leg or arm is not simply a matter of getting the severed stump to regrow—it’s one of patterning. You can induce growth, but how do you get the cells to fall into the right places and morph into a new, functional knuckle, vein, toe, or flesh? Now a research team at Tufts and Harvard has shown this can be achieved by attaching to a severed limb a silk-gel sack they termed a “wearable bioreactor” filled with five regenerative growth factors. In a carefully controlled experiment, they showed that 24-hour exposure to the drug-filled sack was enough to kickstart tissue regeneration in adult Xenopus laevis—the African claw-toed frog, which do not regenerate limbs as adults. But over 18 months, the wearable bioreactor induced severed stumps to regrow, repattern, and reemerge as viable, functionally restored hind limbs. Science Advances

How many lives could a little exercise save?

If most adults over 40 engaged in just 10 more minutes of moderate-to-vigorous physical activity daily, more than 111,000 deaths could be prevented in the United States every year, according to researchers at the National Cancer Institute, a component of the U.S. National Institutes of Health. The study involved 4,840 people between the ages of 40–84 who wore accelerometers for one week. By estimating and comparing their daily activity, the researchers found that 10-, 20-, and 30-minute increases of moderate-to-vigorous exercise were associated with 6.9 percent, 13 percent, and 16.9 percent fewer deaths each year respectively. This means if Americans added 10 minutes of exercise per day, an estimated 111,174 deaths could be prevented; 209,459 deaths could be prevented with 20 additional minutes and 272,297 deaths could be prevented with 30 additional minutes. JAMA Internal Medicine

An eye exam for the heart

Ophthalmologists do way more than flip lenses, project letters on the wall, and trial-and-error their way to your new prescription. They also provide vital health screening by testing for diseases like glaucoma and diabetic retinopathy, often detecting them before symptoms appear. A new study from the University of Leeds in the United Kingdom suggests that they could also detect people who are at risk of a heart attack by imaging their retinas, the veiny tissue at the back of the eye. They trained an AI on a combination of retinal and cardiac scans from 5,000 people in order to gauge heart conditions from eye scans obtained using routine and widely available ophthalmology equipment, and they showed that their AI could predict a person’s 12-month risk of a heart attack with an accuracy of 70–80 percent. Nature Machine Intelligence

A graphical representation of the idea of using a scan of the eye to get a window into heart health. University of Leeds

Structures could help design non-hallucinogenic psychedelics

As we reported last month, the proponents of psychedelic therapy are divided into two distinct camps with competing visions of the future: one where once purely recreational drugs like mushrooms, acid, or ecstasy would be used in a communal, guided, and spiritually uplifting setting—the other where the drugs would be chemically modified to be bereft of any ability to induce hallucinations. The non-trippers are gaining ground this week with a new study from the Chinese Academy of Sciences, which describes six new high-resolution molecular structures of the human serotonin 2A receptor in the brain, a target of psilocybin and LSD. The structures reveal new details of how this crucial brain receptor works and should accelerate the design of non-hallucinogenic psychedelic analogs, the authors write. Science

Fully robotic laparoscopic surgery on pigs

It may seem like yesterday self-driving cars were just a pipe dream, but sometimes the pace of scientific and technological innovation actually does keep up with imagination. For more than 20 years, surgeons have been able to control mechanical arms and instruments in robot-assisted surgeries, and some examples of fully automated robotic systems exist for procedures involving rigid bony structures. But operating on soft tissue is much more difficult because the low visibility inside those tissues requires adaptive control. Now a study from Johns Hopkins University suggests that it may be within reach. Researchers tested a fully autonomous robot for consistency and accuracy while performing routine laparoscopic surgeries for intestinal anastomosis on pigs, finding the robotic system actually outperformed expert surgeons. Nature Robotics

Blocking genes regenerates mouse liver

Researchers at the University of Texas Southwestern Medical Center in Dallas have used a CRISPR screen to parse 165 molecules, called chromatin regulatory proteins, in mice with damaged livers, looking for any that might possibly be involved in repairing the organ. They identified two genes, called BAZ2A and BAZ2B, that were not previously known to be involved in tissue regeneration but appear to suppress it in the mice. They showed that blocking the action of these genes helped to regenerate the tissue—an observation that provides a path forward to designing experimental new drugs that could enhance tissue repair in people who suffer from cirrhosis, inflammatory bowel disease, or acute organ trauma. Cell Stem Cell

Atlas of the human brain vasculature

An adult human brain “transcriptome” atlas of blood vessels was reported today by a team of surgeons and biologists at the University of California, San Francisco. It catalogs all the genetic RNA transcripts within 181,388 cells taken from resected tissue donated by five people undergoing surgery for severe epilepsy. The map has important implications for neuroscience and clinical medicine, the authors write, helping us better understand and treat cerebrovascular diseases like stroke. As a proof-of-concept, they used the resource to investigate brain arteriovenous malformations, a leading cause of stroke in young people, and identified some of the pathological cellular and gene expression changes involved in the malformations. Science