上边是英文，下边是译文：
 A 3D printing technique that produces clusters of stem cells could speed up prOGREss towards the creation of artificial organs, scientists claim.

In the more immediate future it could be used to generate biopsy-like tissue samples for drug testing.

The technique relies on an adjustable "microvalve" to build up layers of human embryonic stem cells (hESCs).

Altering the nozzle diameter precisely controls the rate at which cells are dispensed.

Lead scientist Dr Will Shu, from Heriot-Watt University in Edinburgh, said: "We found that the valve-based printing is gentle enough to maintain high stem cellviability, accurate enough to produce spheroids of uniform size, and most importantly, the printed hESCs maintained their pluripotency - the ability to differentiate into any other cell type."