The fact that a rat forelimb has been grown in the lab from living cells offers hope that someday in the future amputees will be able to get fully functional biolimbs that will essentially eliminate their handicaps and allow them to lead even better lives. Growing a rat forelimb might go down in the history books as the first step towards achieving that goal of creating fully functional biological replacement limbs.
Harald Ott of Massachusetts General Hospital in Boston grew the limb, he says that they’re focusing on the forearm and hand so that it can be used as a model system and proof of principle. “But the techniques would apply equally to legs, arms and other extremities,” he adds.
Artificial limb replacements that amputees now get look fine cosmetically but they don’t function as well as real limbs, work is being done on bionic limbs that offer much better functionality but they tend to look unnatural. In some cases hand transplants have also proven to be successful however the recipient is then required to take immunosuppressive drugs throughout their life so as to prevent the body from rejecting the hand.
Biolimbs would not face most of these obstacles because they will have cells from the recipient thus eliminating the need for immunosuppression, in theory the biolimb should also look and behave as a natural limb would.
The technique that has been used to built the rat forelimb is called “decel/recel,” it has been used previously to make lungs, hearts and kidneys in the lab. In the first step detergents treat the organs from dead donors to completely strip off the soft tissue. What’s left behind is the “scaffold” of the organ that’s made from inert protein collagen. The second step involves recellularization of the flesh by proverbially filling the scaffold with relevant cells from the recipient. It’s off to the bioreactor then where the new tissue grows and colonises the scaffold.
Since the donor’s soft tissue doesn’t remain the new organ isn’t recognized as foreign by the recipient’s body which doesn’t reject it. What about the limb’s muscles though? The team used electrical pulses in the rat forelimb it created and discovered that the paw could clench and unclench. They also attached the biolimbs to anaesthetised healthy rats and saw that blood from the recipient rat did circulate in the new limb. They didn’t test muscle movement or rejection.
The team has now started experiments using human myoblasts in rates as opposed to mice ones, it’s going to be a slow and steady road, they expect it to be a decade before biolimbs are created that are deemed fit enough for human testing.
Filed in .. Source: newscientist