New findings could bring advances in human medicine
Paraplegia has so far been considered incurable. However, new therapeutic approaches are constantly being developed to restore the function of injured nerves. US researchers at Duke University in Durham, North Carolina, may have now found a key protein for repairing injured spinal cord by experimenting with zebrafish. The results of the research work raise hope because the protein is also found in a similar form in humans. The results of the study were published in the renowned science magazine.
Paraplegia due to spinal cord injury
The spinal cord is located in the bony spinal canal of the spine and, together with the brain, forms the central nervous system (CNS). Among other things, its task is to communicate between the brain and the internal organs as well as the skin and muscles. It is also responsible for monitoring motor skills and body movements. Are the nerve pathways in the spinal cord e.g. injured by an accident, permanent paraplegia threatens. So far, this has not been curable, but the paralysis mostly persists for life.
Zebrafish manage to heal themselves
However, this does not apply to zebrafish, according to a message from Duke University in Durham, North Carolina. If the spinal cord of animals - also known as zebrafish - is injured, they will also experience paralysis that is similar to that of humans.
But unlike us, a healing process then begins, in which so-called glial cells initially bridge the gap between the ends of the separated nerve fibers, the university informs. This is followed by nerve cells through which the interruption is gradually closed.
Fish are healed after eight weeks
After about eight weeks, the new nerve tissue has filled the gap and the symptoms of paralysis have completely disappeared. In mammals, however, the scar tissue that arises, among other things, blocks a renewed growth of the nerve cells and thus a connection of the ends.
"This is one of the most remarkable tricks of natural regeneration," Kenneth Poss of Duke University is quoted in the release. "Given the limited number of successful therapies available today for repairing lost tissue, we need to look for new evidence in animals such as zebrafish on how to stimulate regeneration," the scientist added.
Researchers discover special protein molecules
But how can this extraordinary ability of the zebra fish be explained? To answer this question, a team of researchers led by Kenneth Poss observed the animals during the regeneration process and came to astonishing results. The experts succeeded in identifying seven special genes that are responsible for the production of certain protein molecules in the event of fish spinal cord injury. One of these, the growth factor CTGF (Connective Tissue Growth Factor), was formed in the glial cells, which in the first step of healing form the bridge between the separated nerve endings.
Humans have a similar protein
"We suspected that CTGF could be important because it only activated in specific cells after the injury," said co-author Mayssa Mokalled, according to the release. A similar protein, whose structure differs only by ten percent from zebrafish CTGF, also occurs in humans. The researchers used the human form of CTGF in animals with spinal cord injuries and recognized that in this case, too, the regeneration of nerve tissue increased.
“The previously paralyzed fish swam again in the aquarium. The effect of the protein is impressive, ”reports Mokalled. "I don't think CTGF is the whole secret, but we have something in our hands that gives us starting points for the goal of promoting regeneration," summarizes Poss. Experiments with mice are now planned to find out at what point in time and in which cell type CTGF is produced. (No)