A 3D printing technique that produces clusters of stem cells could speed up progress towards the creation of artificial organs, scientists claim.

科学家称，现在可以用3D打印技术批量制造出干细胞，这一技术将能加速实现打印人造器官的进程。

In the more immediate¹ future it could be used to generate biopsy-like tissue samples for drug testing.

The technique relies on an adjustable² "microvalve（微型阀）" to build up layers of human embryonic³ stem cells (hESCs).

Altering the nozzle（喷嘴） diameter precisely⁴ controls the rate at which cells are dispensed⁵.

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 differentiate⁶ into any other cell type."

Embryonic stem cells, which originate from early stage embryos⁷, are blank slates⁸ with the potential to become any type of tissue in the body.

The research is reported today in the journal Biofabrication.

In the long term, the new printing technique could pave the way for hESCs being incorporated into transplant-ready laboratory-made organs and tissues, said the researchers.

The 3D structures will also enable scientists to create more accurate human tissue models for drug testing.

Cloning technology can produce embryonic stem cells, or cells with ESC properties, containing a patient's own genetic⁹ programming.

Artificial tissue and organs made from such cells could be implanted into the patient from which they are derived¹⁰ without triggering a dangerous immune response.

Jason King, business development manager of stem cell biotech company Roslin Cellab, which took part in the research, said: "Normally laboratory grown cells grow in 2D but some cell types have been printed in 3D. However, up to now, human stem cell cultures have been too sensitive to manipulate in this way.

"This is a scientific development which we hope and believe will have immensely valuable long-term implications for reliable, animal-free, drug testing, and, in the longer term, to provide organs for transplant on demand, without the need for donation and without the problems of immune suppression（镇压，紧致） and potential organ rejection¹¹."