Hyperbaric oxygen therapy has been used in the past to help people with traumatic brain injury, stroke and other conditions involving wounds to the brain. Now, researchers at Shamir Medical Center in Tel Aviv are studying how it could treat Long Covid.
Shai Efrati
Long COVID is not a single disease, it is a syndrome or cluster of symptoms that can arise from exposure to SARS-CoV-2, a virus that affects an unusually large number of different tissue types. That's because the ACE2 receptor it uses to enter cells is common throughout the body, and inflammation from the immune response fighting that infection can damage surrounding tissue.
One of the most widely shared groups of symptoms is fatigue and what has come to be called “brain fog,” a difficulty focusing and an amorphous feeling of slowed mental functioning and capacity. Researchers have tied these COVID-related symptoms to tissue damage in specific sections of the brain and actual shrinkage in its size.
When Shai Efrati, medical director of the Sagol Center for Hyperbaric Medicine and Research in Tel Aviv, first looked at functional magnetic resonance images (fMRIs) of patients with what is now called long COVID, he saw “micro infarcts along the brain.” It reminded him of similar lesions in other conditions he had treated with hyperbaric oxygen therapy (HBOT). “Once we saw that, we said, this is the type of wound we can treat. It doesn't matter if the primary cause is mechanical injury like TBI [traumatic brain injury] or stroke … we know how to oxidize them.”Efrati came to HBOT almost by accident. The physician had seen how it had helped heal diabetic ulcers and improved the lives of other patients, but he was busy with his own research. Then the director of his Tel Aviv hospital threatened to shut down the small HBOT chamber unless Efrati took on administrative responsibility for it. He reluctantly agreed, a decision that shifted the entire focus of his research.
“The main difference between wounds in the leg and wounds in the brain is that one is something we can see, it's tangible, and the wound in the brain is hidden,” says Efrati. With fMRIs, he can measure how a limited supply of oxygen in blood is shuttled around to fuel activity in various parts of the brain. Years of research have mapped how specific areas of the brain control activity ranging from thinking to moving. An fMRI captures the brain area as it’s activated by supplies of oxygen; lack of activity after the same stimuli suggests damage has occurred in that tissue. Suddenly, what was hidden became visible to researchers using fMRI. It helped to make a diagnosis and measure response to treatment.
HBOT is not a single thing but rather a tool, a process or approach with variations depending on the condition being treated. It aims to increase the amount of oxygen that gets to damaged tissue and speed up healing. Regular air is about 21 percent oxygen. But inside the HBOT chamber the atmospheric pressure can be increased to up to three times normal pressure at sea level and the patient breathes pure oxygen through a mask; blood becomes saturated with much higher levels of oxygen. This can defuse through the damaged capillaries of a wound and promote healing.
The trial
Efrati’s clinical trials started in December 2020, barely a year after SARS-CoV-2 had first appeared in Israel. Patients who’d experienced cognitive issues after having COVID received 40 sessions in the chamber over a period of 60 days. In each session, they spent 90 minutes breathing through a mask at two atmospheres of pressure. While inside, they performed mental exercises to train the brain. The only difference between the two groups of patients was that one breathed pure oxygen while the other group breathed normal air. No one knew who was receiving which level of oxygen.
The results were striking. Before and after fMRIs showed significant repair of damaged tissue in the brain and functional cognition tests improved substantially among those who received pure oxygen. Importantly, 80 percent of patients said they felt back to “normal,” but Efrati says they didn't include patient evaluation in the paper because there was no baseline data to show how they functioned before COVID. After the study was completed, the placebo group was offered a new round of treatments using 100 percent oxygen, and the team saw similar results.
Scans show improved blood flow in a patient suffering from Long Covid.
Sagol Center for Hyperbaric Medicine
Efrati's use of HBOT is part of an emerging geroscience approach to diseases associated with aging. These researchers see systems dysfunctions that are common to several diseases, such as inflammation, which has been shown to play a role in micro infarcts, heart disease and Alzheimer’s disease. Preliminary research suggests that HBOT can retard some underlying mechanisms of aging, which might address several medical conditions. However, the drug approval process is set up to regulate individual disease, not conditions as broad as aging, and so they concentrate on treating the low hanging fruit: disorders where effective treatments currently are limited and success might be demonstrated.
The key to HBOT's effectiveness is something called the hyperoxic-hypoxic paradox where a body does not react to an increase in available oxygen, only to a decrease, regardless of the starting point. That danger signal has a powerful effect on gene expression, resulting in changes in metabolism, and the proliferation of stem cells. That occurs with each cycle of 20 minutes of pure oxygen followed by 5 minutes of regular air circulating through the masks, while the chamber remains pressurized. The high levels of oxygen in the blood provide the fuel necessary for tissue regeneration.
The hyperbaric chamber that Efrati has built can hold a dozen patients and attending medical staff. Think of it as a pressurized airplane cabin, only with much more space than even in first class. In the U.S., people think of HBOT as “a sack of air or some tube that you can buy on Amazon” or find at a health spa. “That is total bullshit,” Efrati says. “It has to be a medical class center where a physician can lose their license if they are not operating it properly.”
Shai Efrati
Alexander Charney, a research psychiatrist at the Icahn School of Medicine at Mount Sinai in New York City, calls Efrati’s study thoughtful and well designed. But it demands a lot from patients with its intense number of sessions. Those types of regimens have proven difficult to roll out to large numbers of patients. Still, the results are intriguing enough to merit additional trials.
John J. Miller, a physician and editor in chief of Psychiatric Times, has seen “many physicians that use hyperbaric oxygen for various brain disorders such as TBI.” He is intrigued by Efrati's work and believes the approach “has great potential to help patients with long COVID whose symptoms are related to brain tissue changes.”
Efrati believes so much in the power of the hyperoxic-hypoxic paradox to heal a variety of tissue injuries that he is leading the medical advisory board at Aviv Clinic, an international network of clinics that are delivering HBOT treatments based on research conducted in Israel. His goal is to silence doubters by quickly opening about 50 such clinics worldwide, based on the model of standalone dialysis clinics in the United States. Sagol Center is treating 300 patients per day, and clinics have opened in Florida and Dubai. There are plans to open another in Manhattan.
Silkworm silk is fragile, which limits its uses, but a few extra genes can help.
Adobe Stock
Today, biomimetics is everywhere. Shark-inspired swimming trunks, gecko-inspired adhesives, and lotus-inspired water-repellents are all taken from observing the natural world. After millions of years of evolution, nature has quite a few tricks up its sleeve. They are tricks we can learn from. And now, thanks to some spider DNA and clever genetic engineering, we have another one to add to the list.
The elusive spider silk
We’ve known for a long time that spider silk is remarkable, in ways that synthetic fibers can’t emulate. Nylon is incredibly strong (it can support a lot of force), and Kevlar is incredibly tough (it can absorb a lot of force). But neither is both strong and tough. In all artificial polymeric fibers, strength and toughness are mutually exclusive, and so we pick the material best for the job and make do.
Spider silk, a natural polymeric fiber, breaks this rule. It is somehow both strong and tough. No surprise, then, that spider silk is a source of much study.The problem, though, is that spiders are incredibly hard to cultivate — let alone farm. If you put them together, they will attack and kill each other until only one or a few survive. If you put 100 spiders in an enclosed space, they will go about an aggressive, arachnocidal Hunger Games. You need to give each its own space and boundaries, and a spider hotel is hard and costly. Silkworms, on the other hand, are peaceful and productive. They’ll hang around all day to make the silk that has been used in textiles for centuries. But silkworm silk is fragile. It has very limited use.
The elusive – and lucrative – trick, then, would be to genetically engineer a silkworm to produce spider-quality silk. So far, efforts have been fruitless. That is, until now.
We can have silkworms creating silk six times as tough as Kevlar and ten times as strong as nylon.
Spider-silkworms
Junpeng Mi and his colleagues working at Donghua University, China, used CRISPR gene-editing technology to recode the silk-creating properties of a silkworm. First, they took genes from Araneus ventricosus, an East Asian orb-weaving spider known for its strong silk. Then they placed these complex genes – genes that involve more than 100 amino acids – into silkworm egg cells. (This description fails to capture how time-consuming, technical, and laborious this was; it’s a procedure that requires hundreds of thousands of microinjections.)
This had all been done before, and this had failed before. Where Mi and his team succeeded was using a concept called “localization.” Localization involves narrowing in on a very specific location in a genome. For this experiment, the team from Donghua University developed a “minimal basic structure model” of silkworm silk, which guided the genetic modifications. They wanted to make sure they had the exactly right transgenic spider silk proteins. Mi said that combining localization with this basic structure model “represents a significant departure from previous research.” And, judging only from the results, he might be right. Their “fibers exhibited impressive tensile strength (1,299 MPa) and toughness (319 MJ/m3), surpassing Kevlar’s toughness 6-fold.”
A world of super-materials
Mi’s research represents the bursting of a barrier. It opens up hugely important avenues for future biomimetic materials. As Mi puts it, “This groundbreaking achievement effectively resolves the scientific, technical, and engineering challenges that have hindered the commercialization of spider silk, positioning it as a viable alternative to commercially synthesized fibers like nylon and contributing to the advancement of ecological civilization.”
Around 60 percent of our clothing is made from synthetic fibers like nylon, polyester, and acrylic. These plastics are useful, but often bad for the environment. They shed into our waterways and sometimes damage wildlife. The production of these fibers is a source of greenhouse gas emissions. Now, we have a “sustainable, eco-friendly high-strength and ultra-tough alternative.” We can have silkworms creating silk six times as tough as Kevlar and ten times as strong as nylon.
We shouldn’t get carried away. This isn’t going to transform the textiles industry overnight. Gene-edited silkworms are still only going to produce a comparatively small amount of silk – even if farmed in the millions. But, as Mi himself concedes, this is only the beginning. If Mi’s localization and structure-model techniques are as remarkable as they seem, then this opens up the door to a great many supermaterials.
Nature continues to inspire. We had the bird, the gecko, and the shark. Now we have the spider-silkworm. What new secrets will we unravel in the future? And in what exciting ways will it change the world?
This article originally appeared on Freethink, home of the brightest minds and biggest ideas of all time.
