Scientists Grow Rat Forearm in a Lab

Posted on June 4, 2015

Scientists at Massachusetts General Hospital (MGH) have grown a rat forelimb in a lab. The scientists call it the first steps towards development of bioartificial replacement limbs suitable for transplantation. The researchers used technology to strip living cells from the forearm of a deceased rat and then transplanted new progenitor cells into the forearm.

To strip living cells from the donor forearm a special detergent solution is used. This removes the unwanted cells yet preserves the primary vasculature and nerve matrix. The scientists grew populations of muscle and vascular cells in a culture while the donor forearm was being cleared of cellular debris. Here is a video of the rat tissue decellularization process:

The research team then cultured the forelimb matrix in a bioreactor. The arm inside the bioreactor is pictured below. Vascular cells were injected into the main artery of the forearm to regenerate veins and arteries. Muscle progenitors were injected directly into the matrix sheaths for each muscle. Electrical stimulation was applied to the potential limb graft after five days to promote muscle formation. The grafts were removed from the bioreactor after a two week period.

The scientists say the limbs quickly filled with blood with circulated when they were transplanted onto recipient animals. Electrical stimulation of muscles within the transplanted grafts caused the wrists and digital joints of the recipient rats to flex.

Wired reports that the researchers plan to try a similar procedure using a baboon limb next. The researchers have already successfully decellularized baboon forearms.

Harald Ott, MD, of the MGH Department of Surgery and the Center for Regenerative Medicine, says in a statement, "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. Additional next steps will be replicating our success in muscle regeneration with human cells and expanding that to other tissue types, such as bone, cartilage and connective tissue."

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