Scientists at Massachusetts General Hospital were recently able to grow a fully functional forelimb in a laboratory for the first time ever. While it was only a rat's forearm that scientists managed to grow, this breakthrough could lead to human limbs being developed in the future.
The research team described using an experimental approach previously used to build bio-artificial organs to engineer rat forelimbs with functioning vascular and muscle tissue. They also provided evidence that this same approach could be applied to the limbs of primates.
Functional testing of the isolated limbs showed that electrical stimulation of muscle fibers caused them to contract with a strength 80% of what would be seen in newborn animals. The vascular systems of bio-engineered forelimbs transplanted into recipient animals quickly filled with blood which continued to circulate, and electrical stimulation of muscles within transplanted grafts flexed the wrists and digital joints of the animals' paws. The researchers also successfully de-cellularized baboon forearms to confirm the feasibility of using this approach on the scale that would be required for human patients.