Rat Limb Grown in the Lab

Future amputees could one day have a natural transplant option that doesn't require immunosuppressive therapies.

In a first step toward engineering replacement limbs in the lab, scientists have grown a rat leg from living cells.

Although the advance may not immediately help the 1.5 million people in the United States alone who have lost a limb, it could give future amputees a natural transplant option that doesn't require immunosuppressive therapies.

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The rat limb was grown by a team from the Massachusetts General Hospital in Boston. They used a technique called "decellularization," which basically strips the cellular materials from a limb of a dead rat, while leaving behind the nerve and blood vessel structures.

This step is important because in the past, scientists working in the field of tissue engineering have been unable to construct a basic framework to hold together all of the biological components that make up a leg or arm, such as the bone, cartilage, nerves, blood vessels and muscles.

Using the stripped leg as a framework, the researchers injected vascular cells into the limb's main artery to regenerate veins and arteries. According to the press release, "Muscle progenitors were injected directly into the matrix sheaths that define the position of each muscle."

The leg was left to culture in a bioreactor for five days. After that, the researchers applied electrical stimulation to promote muscle formation.

After two weeks, the scientists removed the leg from the bioreactor to analyze it.

Tests confirmed the presence of vascular cells along blood vessel walls and muscle cells growing in fibrous structures.

When electrically stimulated, the muscle fibers contracted with a strength 80 percent of what would be seen in newborn animals. What's more, the blood vessels filled with blood.

"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, MD, of the MGH Department of Surgery and the Center for Regenerative Medicine and senior author of the research paper, which appeared in this week's journal Biomaterial.

via Motherboard

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