February News in brief

MEDICINE

February

BIOTECH

Switching blood types - a step towards creating universal donor organs?

Biohybrid fish powered by human cardiac muscle cells swims for 100 days

Each individual has a particular blood type, which corresponds to the type of antigen presented on the surface of red blood cells. For example, type A blood contains A antigens (AAg) and anti-B antibodies, while type O lack antigens but has both anti-A and anti-B antibodies. Before patients undergo organ transplantation, doctors must ensure the ABO blood groups of the donor and patient are compatible. This is because our immune systems are not infallible - if the body detects foreign antigens from an incompatible blood type, hyperacute rejection could be launched, bearing deleterious consequences for the organ recipient. Given the lack of antigens in type O organs, an immune response will not be provoked, heralding type O as the “ universal donor” . Dr Marcelo Cypel and his team at the University of Toronto, Canada performed a proof-ofconcept study into switching a type A organ into a type O, effectively making it a universal donor. They treated lungs with sugar-digesting-enzymes which removed nearly all A-Ag. Fluids were then supplied to the lungs in preparation for the transplantation via ex-vivo lung perfusion, where they tested the tolerance of the treated lungs. To simulate an incompatible transplant, type O blood containing high amounts of anti-A antibodies was added to the fluid. Minimal antibody response was recorded, suggesting a low chance of antibody-mediated injuries if done in vivo. How long the lack of antigens will be maintained is not clear, and the team has plans to test the novel technique further in mice. With wait times for type O patients averaging twice as long as type A patients, “ switching” blood types to create type O organs has massive implications for eliminating the “bloodmatching barrier” and allows doctors to “ prioiritise patients by medical urgency, saving more lives and wasting less organs” , says Dr Cypel.

Vanessa Yip

ECOLOGY

The first fully autonomous biohybrid fish from human stem-cell derived cardiac muscle cells. Credit: Michael Rosnach, Keel Yong Lee, Sung-Jin Park, Kevin Kit Parker

Harvard University researchers, in collaboration with colleagues from Emory University, have developed the first fully autonomous biohybrid fish from human cardiac muscle cells, in pursuit of building an artificial heart. The biohybrid fish is engineered with two cardiac muscle cells, one of each side of the tail fin. Whenever one of the muscles contracts, it opens a protein channel which can trigger the muscles on the opposite side to contract. The fish is also equipped with a pacemaker to coordinate the frequency and rhythm of the contractions. As a result, this closed-loop system recreates the muscle contractions of a pumping heart, highlighting the role of feedback mechanisms in the heart muscular pump. The good news was that the fish could swim around for more than 100 days, which hinted that the researchers could build a long-lasting muscular pump from human stem-cell derived cardiac muscle cells, which was part of their aim to replace a child's malformed heart. Noelle Lee

A new method to eradicate invasive species

Over the recent centuries, invasive species have posed a threat to fragile ecosystems all over the world and people have come up with all sorts of methods to rid that areas of them. However, recently chefs and conservationists alike have agreed on a method to eradicate invasive species: by eating them. This new food movement is called invasivorism in which invasive species are incorporated into everyday and gourmet dishes. This method has already been adapted in many places around the world, for example in the Caribbean Sea where restaurants serve the invasive lionfish, or in the where UK restaurants serve grey squirrel. However, though at face value it sounds amazing, there’s one important thing that everyone should keep in mind: eating invasive species should be to reduce or eradicate the species and it is not intended to create a market for that creature. Ludmila Neil

MEDICINE

Third person is cured of H.I.V. using novel stem cell technology

Budding HIV virions

Using a stem cell transplant from an umbilical cord, a woman suffering from leukaemia and HIV (whose identity remains disclosed) has become the third person to be cured of HIV, a virus that targets the immune system, thus increasing susceptibility to cancers and infections. Two other men had been previously cured of HIV, but this case is substantially more ground-breaking: being a woman of mixed race is "really important scientifically" said Dr Steven Deeks, an AIDS expert at the University of California, San Francisco who was not involved in the work. HIV infection is thought to progress differently in women compared to men, but while women account for more than half of HIV cases in the world, they make up only 11 percent of participants in cure trials.

Previously, the two men cured received bone marrow transplants, which brought about adverse side effects. From the donor cells attacking the recipient's own body, to extreme hearing or weight loss, one patient almost died following his transplant. The woman, who received a slightly different treatment, did not experience such side effects. She received cord blood to treat her leukaemia from a partially matched donor (despite not being of a similar race), where the donor's cord blood cells contained a mutation that blocked HIV entry into cells. Due to an engraftment period of 6 weeks, she was given additional blood stem cells from a firstdegree relative to provide a temporary immune defence. After numerous blood tests 14 months later, the patient showed no signs of HIV in blood tests. Though reasons as to why umbilical cord stem cells are more effective than those taken from bone marrow are unclear, a possibility is that they are more capable of adapting to a new environment, said Dr Koen Van Besien, director of the transplant service at Weill Cornell. “These are newborns, they are more adaptable, ” . Regardless, the successes of the cord transplant provides promise that umbilical stem cells could pave the way to further breakthroughs in the future.

only 11% of participants trialsare women

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Lily Pfaffenzeller

NUCLEAR PHYSICS

Nuclear Fusion Breakthrough

The UK-based Joint European Torus (JET) laboratory (nuclear fusion reactor) beat the record for the most amount of energy extracted from squeezing two atoms of hydrogen together at unprecedented temperatures and pressure. Nuclear fusion is a type of energy source that if created on Earth would essentially be a mini star contained within a nuclear reactor from which scientists could extract large quantities of energy mirroring the magnitude of the sun's processing power (known as fusion power). This experiment which lasted five seconds produced 59 megajoules of energy! That is enough energy to boil 60 kettles full of water at once, or 14kg of TNT going off!

A new combination of materials and isotopes used resulted in the record-breaking plasma shots: instead of graphite, metals such as tungsten and beryllium were used in the walls of the JET to act as a sponge for the hydrogen isotopes used to create plasma. A mixture of hydrogen isotopes were used this time too in contrast to the typical choice of sole deuterium, as a combination of deuterium and tritium ensured fusion could occur at much lower temperatures. Unlike its cousin nuclear fission (in which hydrogen atoms are split, rather than fused), the ever-persistent issue of radioactive waste isn't produced through fusion, in addition to the low carbon supply the process advantageously demands. Though JET was only able to maintain the plasma for 5 seconds, this record solidifies the potential of better power that could be wielded from nuclear fusion, bringing us one step closer to reality.

JET interior with superimposed plasma (Image: UKAEA)

Ludmila Neil

CONSERVATION

Poland’s Steel Wall Border Threatens Species

Poland is in the process of building a five metre tall steel wall along the Poland-Belarus border which spans 186 kilometres in an attempt to counter the entry of migrants from Belarus. The wall will demolish one of the largest wildlife corridors in the world. Currently there is a three-metre tall razor-wire fence which has already killed or entrapped many animals including bison and moose. As the steel wall begins to grow, more environmental effects will be observed, especially since the border will separate the oldest lowland forest in all of Europe into two. Ludmila Neil