Scientists from St Petersburg University together with researchers from Karolinska Institutet (Sweden) have been the first to show that, inside a living mammal, it is possible to create targeted cells of the central nervous system that will perform their usual functions and repair the damaged spinal cord in case of injuries. It turned out that the lining cells of the central canal of the spinal cord can be transformed into oligodendrocytes. It is these cells that form the ‘insulating material’ around the axons of nerve cells. The research findings are published in the peer-reviewed academic journal Science.
Experts in neuroscience are well aware that the phrase ‘nerve cells are not restored’ is just a naive warning against unnecessary anxiety, which has little to do with scientific facts. In the brain of even an adult, neurogenesis - that is, the formation of new neurons - still occurs. This ability is enough to keep cognitive functions in order. However, it is not enough, for example, to restore the spinal cord of a driver who has injured his/her spine in a car accident. After such an injury, a ‘glial’ scar appears in the nerve tissue, and the former functions of the spinal cord cannot be fully repaired.
However, a group of researchers has managed to take a step towards learning how to repair damaged tissues of the central nervous system inside a living organism. The researchers are from Karolinska Institutet and St Petersburg University, and are headed by Professor Jonas Frisén, the pioneer in the field of brain stem cell research. The experiments were carried out on mice using transgenic technologies. The scientists have proved that with various spinal cord injuries in mice, it is possible to trigger in a controlled way the formation of full-fledged oligodendrocytes, which will perform their functions of myelination of the nerve cell axons of the damaged tissue. It is oligodendrocytes that, when wrapping their processes around the axons of nerve cells, form the so-called myelin sheaths. It is a special ‘insulating material’ that promotes the rapid propagation of nerve impulses in the central nervous system (CNS).
Oligodendrocyte production was derived from ependymal cells that line the central canal of the spinal cord. To achieve this, they used genetic technologies to cause artificially the appearance in these cells of a special protein, the transcription factor Olig2. This protein naturally controls the programme for the formation of specific properties (differentiation) of oligodendrocyte cells in the CNS during embryonic development.
‘The recovery processes in the nervous system, unfortunately, are extremely limited,’ said Oleg Shupliakov, one of the authors of the article in Science, head of the Laboratory of Synapse Biology at the Institute of Translational Biomedicine, Professor at St Petersburg University and Karolinska Institutet. ‘We know that primitive vertebrates, for example, salamanders, but not humans, possess such abilities by nature. Thanks to such scientific research, in the future we might be able to restore completely lesions in the central nervous system in humans.’
The next steps of the researchers are: to study in detail programmes for triggering the differentiation of nerve cells of various modalities in vertebrates; and to develop medical technologies that will help restore the functions of the central nervous system after CNS injuries and in neurodegenerative diseases in humans.
Scientists from the Institute of Translational Biomedicine at St Petersburg University are currently actively cooperating with colleagues from Karolinska Institutet, one of the largest medical universities in Europe. Within the framework of a cooperation agreement, they are carrying out joint research, and are also designing programmes for training young specialists.
‘This publication in Science is a good example of academic international collaboration. The ability to work and think together makes it possible to address a problem using a broader approach, a multidisciplinary approach, and to achieve world-class results that could not be obtained in one laboratory. For several years now, the Institute of Translational Biomedicine at St Petersburg University has been working on: the search for new methods for restoring the functions of the spinal cord and brain; and the development of new methods of reprogramming and differentiation of cells. Unique genetic technologies are being developed within the framework of this work. They will give a fresh impetus to these areas and enable the Institute's experts to solve the key problems of modern biomedicine in a new way,’ says Professor Raul Gainetdinov, Director of the Institute of Translational Biomedicine at St Petersburg University and Academic Supervisor of the Pirogov Clinic of High Medical Technologies of St Petersburg University.
The research has been supported by a grant from St Petersburg University (project No 51132811).