While mechanical science has done wonders creating artificial limbs, medical science is far behind the animal world in figuring out how to regenerate a limb like salamanders do. Now these lizard-like amphibians may have finally shared their secret.
Salamanders are famous for their ability to lose a body part and replace it within days, including legs, tails, hearts, eyes, spinal cords and brain tissue. This remarkable regeneration ability does not diminish with age and the replacement part looks exactly the same as the one lost. How is this possible?
According to a study published in Stem Cell Reports this week, Dr. Max Yun at the University College London Institute of Structural and Molecular Biology and a team of researchers used red-spotted newts (Notophthalmus viridescens) to study the ERK (extracellular signal-regulated kinases) pathway - a chain of proteins inside a cell that carries signals from the surface to the DNA in the nucleus. In salamanders, this pathway is constantly active in and around the area where a body part is cut off, sending reprogramming information to the nucleus to form new cells which grow into the new body part. According to Yun, it could work the same in humans:
Say you lose most of your arm; you need to generate enough cells to create a new arm. The way [these proteins] do it is to reprogram the adult cells that remain in the stump, and those adult cells proliferate to make more of themselves and differentiate to make new tissues.
Unfortunately, human and mammal cells can only briefly activate the ERK pathway. Yun’s team was able to stimulate the pathway in human cells for up to two hours, far short of the time needed to create a new limb. However, the knowledge of the ERK pathway will help future scientists unlock the process, according to Yun.
We’d have to find ways of activating the ERK pathway in the adult tissues in humans, in this case to regrow an arm. There are probably other things that we have to manipulate for the process to go well, but this is quite an important part of it.
Now, if salamanders could only show us how to grow limbs that can climb walls.