From the Labs: Biotechnology

A Light Switch for the Brain
A light-triggered switch to control brain cells could aid in the development of therapies for depression, Parkinson’s, epilepsy, and other neurological diseases

Sources: “Multimodal Fast Optical Interrogation of Neural Circuitry”
Feng Zhang et al.
Nature 446: 633-639

“Multiple-Color Optical Activation, Silencing, and Desynchronization of Neural Activity, with Single-Spike Temporal Resolution”
Xue Han and Edward S. Boyden
PLoS One, March 21, 2007

Results: Scientists at MIT and Stanford University have independently created a light-controlled molecular switch that can turn off electrical activity in neurons. By combining it with a similar, previously developed switch that can trigger electrical activity, neuroscientists can now use light to turn specific neural circuits on and off.

Why it matters: The new neural switch enables unprecedented control over the brain and could lead to more-effective therapies for epilepsy, ­Parkinson’s, depression, and other brain diseases. The neural switch could also serve as a research tool to help neuroscientists decipher the language of the brain–the information, encoded in the electrical activity of neurons, that forms our memories and directs our every move.

Methods: To create the new neural switch, researchers borrowed a gene from a lake-dwelling micro­örganism; the gene codes for a light-­sensitive protein that pumps chloride ions. One study showed that the ­chloride-ion pump can be genetically engineered into specific neurons in the brain or into ­muscle cells. When one of these genetically modified cells is hit with yellow light, the pump brings a negative charge into it, preventing it from firing.

Next Steps: The scientists are now using the two switches in animals genetically engineered to model epilepsy, depression, and Parkinson’s disease. The hope is to find neural cells whose activity or inactivity is responsible for symptoms characteristic of those diseases, including seizures in epilepsy. Such findings could aid in the development of drugs targeted to only those cells; one day, light-­activated implants might replace the electrodes used in treatments such as deep brain stimulation.

Universal Blood
Researchers have found a way to efficiently convert different human blood types into a neutral type that can be given to any patient

Source: “Bacterial Glycosidases for the Production of Universal Red Blood Cells”
Qiyong Liu et al.
Nature Biotechnology 25: 454-464

Results: An international team of researchers has created universal blood cells–blood that can be given to people of any blood type. The researchers developed the universal blood by using enzymes to remove the cell-surface sugars that determine whether blood is type A, B, O, or AB. These sugars can trigger immune reactions in people whose blood cells don’t share them.

Why it matters: In emergencies, doctors often have to give patients blood transfusions without knowing their blood type. So emergency medical workers must use type O, which is universally compatible but often in short supply. The new technology could make any donor’s blood universally compatible.

Methods: The researchers screened different enzymes for their ability to efficiently cleave off the complex sugars on the surfaces of red blood cells. They identified two bacterial enzymes that cleave only A- or B-type sugars, leaving other sugars on the blood cells’ surfaces intact.

Next steps: Blood processed us­ing the sugar-cleaving enzymes is currently in early phase II clinical trials in the United States. ZymeQuest, a startup based in Beverly, MA, that is commercializing the universal-blood technology, has developed a machine that uses the enzymes to process blood quickly. The company expects that if all goes well, its blood-­processing ­machines will be on the market in ­Europe in 2011 and in the United States a few years later.