What’s the News: For someone with severe peanut allergies, the tiniest trace of the nut makes their immune system go into overdrive, attacking what it perceives as an intruder so vehemently that the person can go into anaphylactic shock. Scientists may have found a way to calm that immune overreaction, a new study in rats shows, by tacking peanut proteins onto certain immune cells, effectively teaching the whole system that peanuts aren’t a threat.

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Flexibility matters.

Research teams around the world are attempting to develop new tiny synthetic particles that will enter your bloodstream to act as red blood cells, to play the part of platelets and stop the bleeding, to latch onto damaged areas and deliver drugs there, and more. And to make these lab-created particles as effective as possible, they need to stay in one’s system and not get stuck. In this week’s Proceedings of the National Academy of Sciences, Joseph DiSimone and colleagues say they have figured out a way to mimic the twistable, turnable, bendable, foldable nature of red bloods cells to make long-lasting synthetic particles, and that they’ve tested those particles on a living system, a first.

Previous studies had focused on how size, shape and surface characteristics of particles affected their movement through the bloodstream, the team wrote, but flexibility’s role is less well understood. To test it out, the researchers built artificial cells out of a gel material with “tunable elasticity” — that is, the team could control how deformable the cells were. [Los Angeles Times]

Maximizing that elasticity could allow for particles that can wiggle through tiny blood vessels:

It has long been speculated that the deformability of particles influences how long they circulate and where they are distributed in the body. Red blood cells are equipped for longevity and have an average lifespan of 120 days. As they age, they become stiffer and less capable of passing through the tiny vascular structures in the spleen, where they’re ultimately removed. [Nature]

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It may not be as miraculous as turning water into wine, or as wealth-generating as turning dirt into gold, but we still think this is a very cool trick: Researchers have transformed mature skin cells directly into mature blood cells. Crucially, this was done without reverting the cells to a flexible, “pluripotent” stage in which the cells can grow into any form.

The technique, described in Nature, could lead to lab-grown blood cells for transfusions and transplants for people with bone marrow diseases. Researchers think this new process may be safer than previous methods.

By skipping the pluripotent step, the researchers believe they have skirted the risk that the replacement cells might form dangerous tumors. [Los Angeles Times]

The research team, lead by Mickie Bhatia, coaxed the skin cells into becoming blood cells via a harmless virus that carried a gene called OCT4 into the cells–this reprogrammed the cells, turning their developmental clock back part of the way. Then the cells were incubated in a mixture of cell-stimulating proteins, called cytokines, which directed them on their new paths as either red blood cells, white blood cells, or platelets. The ability to grow a specific kind of blood cell has exciting clinical possibilities.

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For a study this week in the journal Nature Medicine, Kathleen Collins and her team have uncovered another of HIV’s dirty tricks: the virus can hide out in bone marrow cells and lie in wait for the right time to strike.

In recent years, drugs have reduced AIDS deaths sharply, but patients need to keep taking the medicines for life or the infection comes back, she said. That’s an indication that while the drugs battle the active virus, some of the disease remains hidden away to flare up once the therapy is stopped [AP]. One place the researchers already knew HIV could hide was inside resting T cells. However, Collins says, she thought T cells alone didn’t offer a complete picture of the virus’ ability to play hide-and-seek.

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Hot on the heels of the story of lab-built red blood cells that DISCOVER covered on Tuesday, a different team of scientists have announced another step forward. Bioengineer Erin Lavik announced that her team built synthetic platelets that, when given intravenously to rodents, could slow their bleeding after a cut. The study appears in Science Translational Medicine.

Your normal platelets exist in the bloodstream and use proteins to bind together and close off the bleeding when you get a cut. Lavik’s synthetic version is a nanoparticle that her team injected into the rodents intravenously. The synthetic platelets augment this process, bonding with natural blood platelets and acting as a nanostructure boosting the natural platelets’ ability to form a solid barrier that stops bleeding [Popular Science]. The rodents with synthetic platelets stopped bleeding 23 percent faster than those without.

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They may look simple, but our red blood cells are the sophisticated result of evolution. So to create new ways to study our bodies and perhaps even disperse drugs to different organs and body parts, scientists played copycat. A team of researchers announced this week that they have developed synthetic red blood cells that mimic our natural ones in both form and function. They describe their findings in the Proceedings of the National Academy of Sciences.

To make red blood cells in the lab, study leader Samir Mitragotri and colleagues started with spheres of biodegradable polymer. They then exposed the spheres to isopropanol, which collapsed them into the discoid shape characteristic of red blood cells. The researchers then layered proteins — either albumin or hemoglobin — onto the doughnut-shaped disks, cross-linked the proteins to give them extra strength and stability, and finally dissolved away the PLGA template to leave only a strong but flexible shell [The Scientist].

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