NEUROSCIENCE
Transplanted neurons integrate into brain circuits When neurons die, they cannot be repaired—but perhaps they can be replaced. The idea of transplanting cells into injured brains has shown promise in the clinic. For example, some of the symptoms of Parkinson’s disease patients were alleviated after they received transplants of fetal brain cells to peripheral regions of the brain. But researchers did not know whether transplanted neurons can truly be integrated into preexisting circuits and participate in neural pathways. Now, a team led Mark Hübener of the Max Planck Institute of Neurobiology and Magdalena Götz of the Institute of Stem Cell Research at Munich’s Helmholtz Center have shown that embryonic neurons transplanted into the injured visual cortex of adult mice establish connections with other Embryonic neurons (red) cells in the brain such that their transplanted into the brains of neurological responses “become adult mice connect with host indistinguishable from those of neurons (black) to rebuild neural host neurons” (Nature 2016, DOI: circuits lost in an injury. 10.1038/nature20113). If the work in mice holds true in humans, this finding could lay a path toward healing brain injuries. An important next step is identifying chemical guidance cues that allow foreign cells to pass as native.—SARAH EVERTS
CREDIT: SOFIA GRADE (BRAIN IMAGE); MOL. PHARMACEUTICS (SCHEME); SCIENCE (ENDOPLASMIC RETICULUM)
Superresolution microscopy shows that the peripheral endoplasmic reticulum is an array of small tubes. This image was acquired by a method called grazing incidence structured illumination microscopy.
Craig Blackstone of NIH (Science 2016, DOI: 10.1126/ science.aaf3928). To probe the ER in multiple types of cells, the team used four superresolution optical microscopy methods, which provide images at a resolution that exceeds conventional microscopy limits, as well as focused ion beam scanning electron microscopy. With these methods, the researchers observed that the peripheral ER is actually made of a dense matrix of tubes instead of flat membrane sheets. They acquired images fast enough to observe the tiny tubes undergoing rapid movement and interconversion between tight and loose arrays. The tube organization may allow the ER to rapidly change its conformation as necessary to perform its many functions, the researchers speculate.—CELIA ARNAUD
DRUG DELIVERY
▸ Injectable, lightactivated gel releases insulin Patients with type 1 diabetes rely on daily insulin injections to help regulate their blood glucose. Now, researchers have devised a potentially less invasive way to deliver the drug: an insulin-carrying gel that can be placed under the skin and activated by light to release the hormone when needed (Mol. Pharmaceutics 2016, DOI: 10.1021/
N O N H Polymer bead
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acs.molpharmaceut.6b00633). To make the material, Simon H. Friedman of the University of Missouri, Kansas City, and colleagues linked human insulin molecules to a commercially available gel—a copolymer made of polystyrene and polyethylene glycol—using a linker molecule containing a light-sensitive chemical bond. When exposed to 365-nm-wavelength light, this bond breaks, Insulin (blue) is releasing the linked to a polymer insulin. To test bead (green) via a the material, molecule containing a the researchers
light-sensitive bond. Shining ultraviolet light on the material cleaves the bond, releasing the insulin. O
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injected 10-µm-diameter beads of the gel under the skin of diabetic rats and attached a coin-sized light-emitting device over the area. The researchers switched on the light for two minutes, then monitored the animals’ blood glucose and insulin levels. Insulin release began a few minutes after light exposure, peaked at 25 minutes, and then plateaued. The researchers found that blood glucose levels dropped in response to insulin and that they could reactivate the gel 65 minutes later to release a second dose of the hormone.—JYOTI
MADHUSOODANAN, special to C&EN
Bond cleaved by light O O O Insulin OH NO2
UV light
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O Insulin
OH
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OCTOBER 31, 2016 | CEN.ACS.ORG | C&EN
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