Scientists have created part of the jaw¹ joint² in the lab using human adult stem cells.

科学家在实验室中利用人类成体干细胞制造出了部分下颌关节。

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The new bone was created from bone marrow stem cells

They say it is the first time a complex, anatomically-sized bone has been accurately⁴ created in this way.

It is hoped the technique could be used not only to treat disorders⁵ of the specific joint, but more widely to correct problems with other bones too.

The Columbia University study appears in Proceedings⁶ of the National Academy of Sciences.

The bone which has been created in the lab is known as the temporomandibular（颞下颌的） joint (TMJ).

Problems with the joint can be the result of birth defects（先天缺陷）, arthritis⁷（关节炎） or injury.

Although they are widespread, treatment can be difficult.

The joint has a complex structure which makes it difficult to repair by using grafts⁹（接枝，结合） from bones elsewhere in the body.

The latest study used human stem cells taken from bone marrow（骨髓）.

These were seeded into a tissue scaffold（组织支架）, formed into the precise shape of the human jaw bone by using digital images from a patient.

The cells were then cultured using a specially-designed bioreactor（生物反应器） which was able to infuse（注入） the growing tissue with exactly the level of nutrients¹⁰ found during natural bone development.

Big potential

Lead researcher Dr Gordana Vunjak-Novakovic said: "The availability of personalised bone grafts（骨移植物） engineered from the patient's own stem cells would revolutionise the way we currently treat these defects."

Dr Vunjak-Novakovic said the new technique could also be applied¹¹ to other bones in the head and neck, including skull¹² bones and cheek bones, which are similarly difficult to graft⁸.

The option to engineer anatomically pieces of human bone in this way could potentially transform the ability to carry out reconstruction¹³ work, for instance following serious injury or cancer treatment.

She said: "We thought the jawbone would be the most rigorous（严酷的，严格的） test of our technique; if you can make this, you can make any shape."

She stressed that the joint created in the lab was bone only, and did not include other tissue, such as cartilage（软骨）. However, the Columbia team is working on a new method for engineering hybrid¹⁴（混合的，杂种的） grafts including bone and cartilage.

Another major challenge for scientists will be to find a way to engineer bone with a blood supply that can be easily connected to the blood supply of the host.

Professor Anthony Hollander, a tissue engineering expert from the University of Bristol who helped produce an artificial windpipe last year, said there was still a lot of work to be done before the new bone could be used on patients.

But he said: "One of the major problems facing scientists in this field is how to engineer a piece of bone with the right dimensions - that is critical for some of these bone defects.

"This is a lovely piece of tissue engineering which has produced bone with a high degree of accuracy in terms of shape."