Last year, we published Lou Hawthorne’s account of therapeutic plasma exchange, which is premised on a two-decade old experiment called “heterochronic parabiosis,” where the vasculature of old mice were surgically connected to those of young ones. Those experiments showed tantalizing results, with the young blood having profound, age-reversing revitalization effects on the old mice. A group of researchers at the Chinese Academy of Sciences in Beijing have now done a new study of heterochronic parabiosis in mice, this time analyzing RNA transcripts in single cells across aged tissues and organs. They found that one key player in this rejuvenation appears to be the hematopoietic stem cells in those tissues. They were “one of the most responsive cell types to young blood exposure,” they write. Cell Stem Cell

Despite how much we associate vitamin D with soaking up UVB sun rays, the major source of this essential nutrient for humans is, in fact, food—especially sources like salmon, liver, red meat, egg yolks, and fortified cow’s milk. But far too many people get nowhere near enough in their diets, which is why vitamin D deficiency is a major global health problem, affecting a billion people worldwide and contributing to cancer, depression, dementia, and lowered immune function—not to mention worse COVID-19 outcomes. Now researchers at the John Innes Center in Norwich, United Kingdom, have used CRISPR to genetically engineer a tomato plant to accumulate a vitamin D precursor called 7-DHC. Tomato varieties based on this approach could address vitamin D deficiency, the researchers write, “which is of particular relevance to those adopting plant-rich, vegetarian, or vegan diets.” Nature Plants

Doctors at Massachusetts General Hospital have discovered a new source of easily harvested neural stem cells in mouse and human fat tissues, which could help advance regenerative medicine therapies for the treatment of Parkinson’s disease and stroke. The lack of an accessible source of neural stem cells in a person’s own body hinders potential stem cell therapies for nervous system disorders, while this new source found within the fat pads of adult humans and mice offers “unprecedented accessibility,” the doctors write. Science Translational Medicine

Growing new replacement tendons in the laboratory to use as tissue grafts for people with sports injuries is technically feasible but practically impossible. We can culture the right “fibroblast” cells in bioreactors easily enough, but growing them into tendon-like tissues that properly mimic the real thing requires the cells to be precisely stretched and pulled exactly as if they were in your body. Every tendon in the body sees different stresses, and even the same two tendons in two different people can vary according to their physique and athleticism. It’s a precision problem: You just can’t stuff enough mechanical actuators into a growth vessel to get anywhere close to the real thing. But new research shows that if you can’t get the robots into the bioreactor, maybe you can get the bioreactors into the robots. Researchers at the University of Oxford modified an existing humanoid robotic shoulder with a soft, flexible chamber for cultured cells, and in a proof-of-concept experiment they showed promising results growing cells in them. Communications Engineering

IndieBio, the pioneering synthetic biology accelerator from the SOSV venture capital group, and the nonprofit Genome Project-write (GP-write) announced this week the launch of a new fund to support the development of genome synthesis companies. Called the GP-write Startup Team, the project aims to provide a small amount of funding and a lot of advice and support for a new crop of startups aiming to do large-scale genome editing and synthesis. Their RFP announcement invites startups working on new genome-scale design software, DNA synthesis tools, precision genome editing, or chromosomal and organism engineering to apply for investments of up to $500,000. Proposals due July 1. Here’s the announcement.

Human mitochondria, which we inherit from our mothers, are the buzzing heart of metabolism and energetics within our cells. These tiny organelles are so important that their dysfunction is tied to 150 different diseases. Even so, the functions of many mitochondrial proteins are not well understood, and the genetic basis for about 40 percent of all mitochondrial disorders is still a mystery to medicine. But hope for unraveling some of those diseases should come from a new “functional compendium” of human mitochondrial proteins published this week by scientists at Washington University School of Medicine in St. Louis and the University of Wisconsin-Madison. Nature

Of all the ways experts predict global warming will affect human health in this century, one we have not heard a lot about is sleep. Warmer nights mean more disrupted sleep, which can potentially reduce cognitive performance, diminish work productivity, compromise immunity, and contribute to cardiovascular and mental health problems. Now researchers at the University of Copenhagen, Denmark, have quantified how global warming could affect sleep quality in the next few decades by comparing daily meteorological data in 68 countries to 10 billion minute-by-minute sleep measurements generated by the wristband tracker data of 47,628 people in those countries. The data confirms what scientists suspect: that warmer nighttime temperatures interfere with sleep—and not equally. “The elderly, residents of lower-income countries, females, and those already living in hotter climates [will be] disproportionately impacted,” the researchers write. One Earth