A scientific team, which included employees from several St. Petersburg universities and institutes, has developed a unique method for replacing defects in peripheral nerve fibers. It is proposed to “repair” nerves using a composite material including chitosan and carbon nanotubes. Chitosan is a substance obtained from the shells of crustaceans. And carbon nanotubes are patterns rolled into hollow cylinders from a sheet of graphene. Of course, the smallest diameter – no more than a few tens of nanometers.
Successful experiments on animals have already been carried out. The results were published in the international scientific journal Polymers.
Non-toxic, but non-conductive
In the laboratory “Polymer materials for tissue engineering and transplantology” of Peter the Great St. Petersburg Polytechnic University (SPbPU), they have long been creating bioduplicators – all kinds of implants that can replace worn out or damaged parts of the human body without causing damage.
Head of the laboratory, Professor Vladimir Yudin I’m especially fascinated by the idea of forming structures from biodegradable polymers for implantation into living tissue. In the language of science, they are called scaffolds (from the English scaffold – “framework”, “template”). This is a kind of polymer matrix with cells grown on it.
In particular, chitosan was chosen as the optimal material for such matrices. It is obtained from chitin, which makes up the shells of crustaceans. Chitosan has high biocompatibility and good bactericidal properties. It is non-toxic and does not cause allergies.
But here’s the problem: chitosan fibers are not electrically conductive. This means that with their help it will not be possible to restore nervous tissue, because it must conduct electric current!
“One way to improve the functional characteristics of chitosan threads and improve cellular communication and tissue response is to obtain composite materials that contain an electrically conductive polymer or filler—in particular, carbon nanoparticles,” the scientists write in their paper.
Case for a damaged nerve
Professor Yudin’s laboratory has invented and used special tubes made of electrically conductive polymer fibers—conduits. They contain those same carbon nanoparticles. And with their help, scientists are going to restore damaged nerves.
“We received a tubular matrix, the so-called conduit, the length of which was 1-1.5 centimeters. Chitosan fibers with different contents of carbon nanotubes were prepared separately. Then the conduit and fibers were combined, that is, the fibers were introduced into the inner lumen of the tube and secured. And with the help of this design, the two ends of the peripheral nerve were connected,” she told the Scientific Russia portal. one of the study participants, graduate student of SPbPU Nurdjemal Tagandurdiyeva.
Again. The ends of the severed nerve are placed on opposite sides into a conduit, a very thin tube made of nanoparticles. Impulses are transmitted from one end of the damaged nerve to the other. The tube, like a case, isolates them from the surrounding biological environment, and its porous walls promote metabolic processes. Directed tissue growth occurs – the nerve grows together. As a result, its lost fragment is formed, and the conduit safely decomposes in the body.
The development was experimentally tested on rats. They cut out part of the sciatic nerve and then replaced it with a test sample created in the laboratory. A few months later, an analysis was carried out – the defect disappeared, the nerve cells were restored.
Helps even with radiculitis
It turns out that the phrase “nerve cells do not recover” has lost its relevance? In fact, operations to regenerate nerve tissue have been carried out for a long time. This is also done using conduits. But existing analogues are not capable of replacing nerve ruptures of more than 3 centimeters. And the development of St. Petersburg scientists provides such an opportunity.
A new tissue engineering method will come to the aid of those who have lost or damaged peripheral nerves due to injury, neurodegenerative diseases (Alzheimer’s or Parkinson’s) and even the familiar sciatica.
“Such injuries occur quite often in people,” says Professor Vladimir Yudin. — As a result of the injury, motor or sensory dysfunction is observed. Such injuries are common among both civilians and military personnel. There are no such implants for nerve fibers on our market.”
Now scientists will continue research using a bioprinter. It can be used to print “cases” for nerves that are closer in structure to natural tissue. This will give better results and speed up the healing process.