Limbs in the Lab

Scientists bioengineer rat arms and hands from scaffolds stripped of their cellular material.

Jun 8, 2015
Amanda B. Keener

BERNARD JANK, M.D., OTT LABORATORY, MASSACHUSETTS GENERAL HOSPITAL CENTER FOR REGENERATIVE MEDICINE

As an alternative to prosthetics, some scientists are interested in bioengineering replacement limbs using tissues or cells from limb recipients. Last month (May 22), researchers at Harvard Medical School and Massachusetts General Hospital reported a technique in Biomaterials that took a step toward this goal by essentially regrowing rat forearms and hands from a biological scaffold.

To do this, the scientists “decellularized” the limbs by treating them with detergents, leaving behind cell-free collagen scaffolds of blood vessels, tendons, and muscle. They supplied the limbs with nutrients and oxygen through an artificial circulatory system as they “recellularized” the scaffolds by delivering several lineages of cells, such as muscle progenitors, to repopulate the limb tissues. At the end of the recellularization process, which took several weeks, the limbs’ muscle fibers were able to respond to electrical stimuli.

The team also coated the limbs with skin grafts before reattaching some to anesthetized rats to test whether they could circulate blood from live recipients. Although the limbs circulated blood, it’s unclear whether their muscles are functional. The procedure still needs to be extended to introduce cells that can rebuild bone, cartilage, and nerves. “The composite nature of our limbs makes building a functional biological replacement particularly challenging,” study coauthor Harold Ott of Harvard Medical School said in a statement.

“It’s a very exciting development, but the challenge will be to create a functioning limb,” Daniel Weiss of the University of Vermont College of Medicine who was not involved in the work told New Scientist.