For the first time, it was possible to grow a live limb in a laboratory, which looks so natural that it seems to have been amputated, writes New Scientist.
Will surgeons soon have custom-made limbs transplanted in biotechnology centers instead of hands collected from corpses? After such procedures, recipients would not need to take immunosuppressants (drugs that reduce immunity to prevent transplant rejection).
Scientists more and more boldly implement the boldest ideas of authors of science fiction novels and films. One of them is Harald Otto from Massachusetts General Hospital in Boston (USA), who grew a rat’s forearm using living cells. “He tested a technique that could be used to grow an entire arm and a lower limb,” he says.
Daniel Weiss of the University Vermont College of Medicine in Burlington (US), who grows lungs, has no doubt that science fiction is entering laboratories. “It’s a great achievement, although the main goal is to get a hand that is functional,” he says.
Harald Otto used a method that was already used to cultivate the heart muscle, lungs and kidneys. It consists in the fact that an organ is collected from a donor, in this case an animal, from which all soft tissues are removed with the use of chemicals. The only thing that remains is its “skeleton” made mainly of collagen, which is the scaffolding for many organs and tissues.
The rat forearm was first cleaned of all soft tissues forming blood vessels, muscles, tendons and bones. Then the researchers placed its collagen structure in a bioreactor with an appropriate nutrient solution. Then they started to recreate them using different types of live cells from another rodent.
Scientists placed epithelial cells in the right fragments of the forearm to regenerate blood vessels. They were also connected to an artificial circulation with the use of a fluid enriched with appropriate substances. They used myoblasts to restore the muscles, which, by reproducing in the porous structure of collagens, formed the muscle tissue. Then they covered it with skin that has been grown in a laboratory for many years and transplanted mainly to patients with extensive burns.
Otto claims that the paw obtained in this way may be functional, because the muscles are active. To confirm this, the researchers stimulated them with electrical stimuli, and the rat’s paw tightened and relaxed accordingly. The researchers also checked whether blood could circulate in the grown paw. They attached it to the healthy paw of a rat that had previously been anesthetized and its blood began to circulate around the new paw.
However, it is not a fully functional forearm, as it does not contain all the bones and cartilage. Neither are there any nerve fibers, but they do not need to be recreated in the bioreactor. The cadaver hand transplants that have been carried out so far have shown that the donor nerves are gradually growing into them. Only then, usually after a few months, you can try to move it and feel in it.
For a hand grown in a laboratory, you will not need to use immunosuppressants after the transplant, as it will be reconstituted from cells obtained earlier from the donor.
When will it be possible to grow a human hand? The herald Otto has already begun trying to obtain the hand of primates in a similar way. He cleaned it of the animal’s soft tissues and replaced them with human myoblasts into the porous structure of collagen. There is still a lot of work ahead of us, it will be at least a decade before we are able to transplant it – admits the specialist.
One of the most famous specialists in regenerative medicine, Steve Badylak of the University of Pittsburgh, Pennsylvania, believes that the greatest challenge will be getting blood vessels working properly. The smallest ones must pass blood well and must not clot.
Oskar Aszmann from the Medical University of Vienna points out that thousands of nerve fibers must grow into the limb grown in a bioreactor after transplantation in order to be able to use it. However, until recently, growing a hand in a laboratory seemed to be only the domain of science fiction.