Made in Massachusetts: World's First "Completely Functional" Artificial Animal Limb

Completely functional human limb transplants which feel and work just like real limbs could soon be reality.

A team of researchers at Massachusetts General Hospital have created a rat limb by using structural matrix of the limb obtained from another rat. The key to success is the process of cell debris removal from the donor limb to obtain the matrix. With the matrix available, researchers were able to grow muscle and circulation system to develop the limb that functioned like a real limb.

"Limbs contain muscles, bone, cartilage, blood vessels, tendons, ligaments and nerves - each of which has to be rebuilt and requires a specific supporting structure called the matrix. We have shown that we can maintain the matrix of all of these tissues in their natural relationships to each other, that we can culture the entire construct over prolonged periods of time, and that we can repopulate the vascular system and musculature," said Harald Ott the paper's senior author.

While donor limb transplants have been used for several years, to avail the limb recipients have to take immunosuppressant drugs for life with unwarranted health side-effects. The new limb developed by Ott and his team wouldn't require immune suppression as it obtains muscle and blood vessels are developed from the donor's progenitor cells which are injected into the matrix.

The process to strip the donor limb of cellular debris, also called de cellularization, has been used successfully by Ott and his team to develop whole organs including kidney, liver, heart and lungs in animal models.

Developing the nerve network is next challenge but researchers are optimistic.

"In clinical limb transplantation, nerves do grow back into the graft, enabling both motion and sensation, and we have learned that this process is largely guided by the nerve matrix within the graft. We hope in future work to show that the same will apply to bioartificial grafts," Ott said.

Researchers have also succeeded in creating an artificial baboon bio-limb to show that the process can also work for humans.