Laser-guided neurons grow towards the light

Laser-guided neurons grow towards the light

Using a weak laser beam to guide nerve cells could help build artificial neural networks. These could be used for testing drugs to combat brain diseases such as Alzheimer’s and Parkinson’s.

The technique also brings the prospect of regrowing damaged nerves a step closer. It could allow surgeons to reconnect nerve fibres damaged in an accident or even to reconstruct whole networks.

Regenerating nerves in patients with a severed spinal cord, for example, is fraught with difficulties. Researchers have had some success using tubular scaffolds to guide nerve growth, but no one has restored movement in paralysed patients.

Creating artificial nerve networks on chips also means guiding nerve growth. These, “brains-on-a-chip” are useful for testing drugs and understanding brain function. To nudge the cells in the right direction, researchers etch channels onto their “circuit boards” or lay down traces of adhesive which the nerves follow. But these bully-boy tactics can damage the delicate cells. They tend to straighten and stiffen with time which can lead to ruptures at the bends.

Allen Ehrlicher and his team at the University of Leipzig in Germany favour a lighter approach instead. When they placed a nerve cell on a glass plate and shone a weak laser beam overlapping the cell’s edge, the nerves grew towards the light. By carefully steering the beam the group could persuade the neuron to grow in any direction they wanted. The cell would even make right-angle turns. “It also dramatically enhanced the growth speed of the neurons,” says Ehrlicher. The cells grew at 60 micrometres per hour – six times faster than normal, he says.

The approach resembles another device – known as optical tweezers – which moves cells around with much more powerful and focused lasers. But rather than manhandling the cells, Ehrlicher’s method manipulates the cells’ own growth processes, so it is far kinder. Even after a four-hour session under the laser, the cells were unharmed.

Quite why the cells are so obedient to their laser pointer is unclear, but Ehrlicher speculates that the laser’s electromagnetic field concentrates the molecular building blocks of the scaffold protein actin at the leading edge of the cell. As these join up to form a chain they create a bulge in the cell membrane which advances in the direction of the laser.

Eventually, the technique could help repair nerves close to the skin’s surface non-invasively. Combined with surgery, it might one day even tackle deeper nerve damage, such as to the spinal cord. But some neuroscientists are sceptical. Steve Potter, a brain expert at Caltech in Pasadena, says that regrowing nerves is “just science fiction”.

For the moment, Ehrlicher thinks the technology will be of most help in building nerve networks for testing drugs. Such networks allow you to test more subtle drug effects than is possible with single cells.

Words

artificial – искусственный, ненатуральный, не природный

prospect – обзор, обозрение; вид; проекция, ракурс; перспектива; планы на будущее

fibre – волокно; волосок; фибра; нить; волокно (о тканях организма человека)

severe – строгий, суровый; требовательный; жестокий, тяжелый (о болезни, утрате)

spinal cord – спинной мозг

fraught – полный, наполненный; преисполненный; нагруженный, наполненный

tubular scaffold – трубчатые леса, трубчатые подмости

nudge – побуждать, заставлять

etch – гравирование; травление (на металле); запечатлевать; оставлять след

circuit board – монтажная плата

adhesive – липкий, клейкий; связывающий; приверженный

bully boy – громила; террорист

stiffen – придавать жесткость; сгущать; затвердевать; усиливать; укреплять

rupture – разрыв (отношений); разрывание; прорыв; пролом

bend – сгибание; согнутое состояние

favour – расположение, приятие, благосклонность, фавор; одобрение

overlapping – работа с перекрытием, работа с совмещением

steer – править рулем, управлять (автомобилем); вести

dramatically – эффектно, ярко, заметно, впечатляюще

enhanced – расширенный, усовершенствованный

approach – приближение; подход, подъезд, подступ

resemble – походить, иметь сходство

tweezers – пинцет

move around – перемещаться, передвигаться

manhandle – тащить, передвигать вручную; грубо, жестоко обращаться; избивать

non-invasive – бесконтактный

tackle – энергично, с усердием браться; вступать в спор; пытаться найти решение

obedient – покорный, послушный, готовый подчиняться

speculate – полагать, предполагать; допускать

scaffold – поддерживать, подпирать, нести (на себе)

actin – актин

bulge – выпуклость, округлый выступ

subtle – нежный; утонченный, изысканный; действующий незаметно, медленно

Дата добавления: 2015-11-04