The research was supported by a grant from the Ministry of Education and Science and the Russian Science Foundation.
The findings were published in the ACS Applied Bio Materials (Q1; IF:4.7) and Materials Today Bio (Q1; IF:8.2).
Repair of damaged nerves becomes a problematic process due to the low regenerative capacity of mature neurons. Today, nerve transplantation is the most common approach in clinical practice to close lesions. However, this method is associated with a number of costs, including donor site morbidity, donor shortage, and the need for resurgery. Therefore, the development of an effective therapeutic strategy is an urgent task for world science.
An effective tool for shaping soft tissues, including nerves, is electrical stimulation, which can be provided by electroactive materials. Scientists of the Research School of Chemistry & Applied Biomedical Sciences of Tomsk Polytechnic University have created magnetic conductors based on the biocompatible polymer poly-3-oxybutyrate (POB), which has piezoelectric properties. This project was completed in cooperation with colleagues from Lomonosov Moscow State University and the Research Center of Biotechnology RAS.
The magnetic conductor is electroformed, resulting in a highly porous microfiber structure. It mimics the structure of the extracellular matrix of nerves, guiding the growth of nerve tissue along the fibers and providing transport of various associated metabolites and nutrients to the nerve. In addition, we have functionalized the conductor with biocompatible magnetite nanoparticles that are "sewn" into the fibers. They are capable of direct magnetomechanical stimulation of nerve tissue in an external magnetic field. Even in a magnetic field, magnetite acts mechanically on the polymer, activating the piezoelectric response. Therefore, unlike available analogs, our conduits provide additional magnetomechanical and electrical stimulation for nerve repair,
A conduit is a hollow tube that can be manufactured with customized dimensions and structure. It is implanted in the area of a nerve defect; during surgery, the ends of the damaged nerve are inserted into the tube, which is then restored inside the conduit. This happens because of its properties - composition, microstructure, porosity. As the nerve is repaired, the conduit dissolves in the body with the formation of safe degradation products. As a result, only the repaired nerve remains in the area of injury.
The project included in vitro and in vivo biological studies. They showed that the conductor supported the growth of rat mesenchymal stem cells and neuron-like cells in a low-frequency magnetic field. And after implantation of the conduit to treat rat sciatic nerve injury, the material was shown to be biocompatible and to provide a barrier function that promotes nerve regeneration.
Electrical stimulation is particularly important for the repair of electrosensitive tissues such as nerves. A neural network is a complex bioelectrical circuit consisting of many neurons connected by chemical and electrical synapses. Signal transmission in this network is controlled by the electric field and is based on a system of electrical charges, neurotransmitters, and action potentials. Thus, the neural network is highly sensitive to external electric fields. We believe that restoring a normal electrical environment by implanting an electroactive biomaterial is an effective therapy for peripheral nerve injury,
In the next stage of the project, the scientists plan to improve the fiber structure of the conduits by orienting the fibers in a specific direction. This structure is the most promising because it more closely mimics the morphology of the native extracellular matrix of nerves and nerve fibers. In addition, research is underway to improve the physicochemical properties of the conductors, such as piezoelectric response and surface hydrophilicity.