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Neural Tissues from the Implanted Stem Cells

#G-657


Morphological, Electrophysiological and Behavioral Investigations of the Nervous Tissue Developed from the Embryonic Matrix Zone Cells of the Dorsolateral Walls of Lateral Ventricles, Implanted into the Lesioned Regions of the Adult Rat's Brain

Tech Area / Field

  • MED-OTH/Other/Medicine
  • BIO-RAD/Radiobiology/Biotechnology

Status
3 Approved without Funding

Registration date
26.12.2000

Leading Institute
Tbilisi State University, Georgia, Tbilisi

Supporting institutes

  • Ministry of Education and Science of Georgia / Beritashvili Institute of Physiology, Georgia, Tbilisi

Collaborators

  • Chemical Diversity Labs, Inc., USA, CA, San Diego

Project summary

The aim of the present project is determination of peculiarities of structurally functional organization of nervous tissue formed from embryonal matrix cells grafted into damaged fields of a brain cortex of adult animals, as well as working up the methods of stimulation of their proliferation, growth and differentiation.

The impressive achievements in fundamental biological disciplines during the last 30 years turned out to be indeed revolutionary. They became a basis for creating new area of scientific knowledge named transplantalogy, and have discovered completely unexpected opportunities of their usage for human’s needs.

In contrast to the transplantation of an internals which become alongside with implantation of high technologies in medicine a major part of public health services and the only alternative at diseases, incompatible to life, the works on a transplantation of a nervous tissue in present time are basically at the stage of experimental development.

The basic experimental model in neurotransplantalogy is the transplantation of an embryo nervous tissue into a damaged brain of an adult organism. It has demonstrated a principal opportunity of the similar operation: the cell elements of a graft grow, differentiate, form the afferent and efferent links with a brain of the recipient. At the same time the serious defects of a given model were also detected. They were revealed, in particular, in incomplete healing up of a graft caused by restricted immunological privileges of a brain; destruction of some of graft cells as a result of its mechanical damage at extraction from the donor’s brain, and also in injured zone of a defective brain of the recipient; in forming the glial cicatrix on the border between a graft and defective nervous tissue of the recipient, as a result of which graft can turn into abortive formation; in incomplete restoration of topographic organization of afferent orifices, characteristic for an intact cortex, and in a number of cases the absence of its stratification as well as restriction of ability to precise analysis of specific sensorial signals in projection cortex zones displaying in essential dilating of receptive fields of graft neurones and in appearance of multimodal responses in many of them.

Above mentioned dictates the necessity of usage of other models without marked above disadvantages. One of them, in our view, is the transplantation of the subventricular matrix zone of an embryo’s brain. In the essence the cells of indicated zone are initially stem and during a proliferation, migration, growth and differentiation, determine the cytogenesis of a cortex and other structures of a brain.

The scientific collective, for the project realization, is represented by the highly qualified experts, with 5 doctors of sciences and 6 candidates of sciences with the major experience of work in neuromorphology and neurophysiology among them. This collective is composed of the employees of 4 scientific laboratories (morpho-physiological, developmental biology, neurocybernetics and applied physiology) and of department of an applied electronics of I.Djavakishvili Tbilisi State University and of two scientific laboratories of I.Beritashvili Institute of physiology of the Georgian Academy of Sciences (the laboratory of the brain cortex physiology and the laboratory of a brain ultrastructure studies).

The neurogenesis of a brain cortex was a subject of long standing investigations of morpho-physiological laboratory of Tbilisi State University. In particular, it was established, that at early stages of postnatal development in matrix zone of a subventrical dorsolateral wall there is some reserve of indifferent cells, which by the way of proliferation, migrations and subsequent differentiation continue to replenish a brain cortex composition with new glial cells, and also with a small amount of neurones. The paces of postnatal realization of matrix zone for immature born animals have appeared to be in direct relation to external factors: the functional loads during the long period (light flashes) furthered the activation of proliferation processes of cells and, on the contrary, it was essentially depressed at sensory derivation (anucleation, animals holding in darkness during the long period). The opportunity of involvement of template cells in a reparation of cortex damaged in early postnatal period was also demonstrated. So, at a one-sided partial decortication of a brain of one month aged pups the activation of proliferative processes in the indicated cells and their intensive migration to a injury location was revealed alongside with an degeneration and disintegration of nervous devices in damage zone. In due course the cortex defect was decreased thanks to the newly derived cortex structure. If the subventricular matrix zone was damaged simultaneously with a matrix damage, this phenomenon was not observed any more.

In the same laboratory for the first time in neurotransplantalogy practice the transplantation of a subventrical matrix zone in a damaged field of an adult rats brain cortex was realized. Therewith the growth and differentiation of neuroblasts and penetration of their processes in the recipient brain nervous tissue was observed. The transplantation success had appeared to be in the dependence with donor age: the best results were scored at transplantation of stem cells of an embryo, rather than of newly born rats.

Thus if the embryo nervous tissue predominantly matures only at the expense of growth and differentiation of the cell elements which are in this tissue at the moment of the transplantation, then in case when an embryo subventrical matrix zone is used as a graft the neoplasm of a nervous tissue will take place first of all as a result of a proliferation of the EMC and after that due to their growth and differentiation.

And that is the principal novelty of the above-stated neutrotransplantalogical experimental model offered by the employees of the morpho-physiological laboratory at the end of 80-s (Unfortunately, because of the difficulties invoked by well known political events in the former USSR, by armed conflicts on the territory of Georgia and by absent of financing the neurotransplantation work started in the morpho-physiological laboratory of Tbilisi State University was temporarily paused). The doubtless advantages of this model are:

– high proliferative activity of EMC. It will provide formation of more full value (with a great quantity of neurones) nervous tissue;

– expressed migratory capacity of so-called juvenile postmitotic neurones that appears at pision of EMC. They can penetrate into the damaged nervous tissue of the recipient and form there the new neurones instead of perished ones as a result of injury;

– heterochronia of the neuro- and gliogenesis. It will allow to control the cell composition formed from EMC of a nervous tissue;

– opportunity of keeping of the EMC in culture in the state of proliferation.

Embryos (donor) and adult inpiduals (recipient) of the Vistar rats are the objects of investigation. For the 13-day aged donors the fragments of dorsolateral subventrical matrix zone of a brain are extracted by the operating and are grafted in beforehand damaged cortex fields of the recipient brain.

To realize the project carrying out of complex investigations are envisaged: morphological- for the detection of features of structural organization of the nfnt, electrophysiological- for the evaluation of the functional state of nervous and glial cell elements of the nfnt behavioral investigations- for the evaluation of the recovery extent of function disturbed as a result of brain cortex damage. Such systemic approach, in our view, will allow to check up more entirely and determine quantitatively the character of the disturbance caused by brain damage, to trace its changes after the transplantation in an injured place of the EMC in dynamics and to judge of the nfnt state and its integration in the recipient’s brain by the reactions to the different actions.

The newly formed from grafted EMC nervous tissue will be investigated in two damaged cortex regions: sensomotoral and prefrontal. In the first case the dynamics of the restoration of the structural organization and the topographic specificity, inherent in the given projection zone, will be traced. In the second case the object of investigation is the associative cortex zone, where the perception and integration of the pers modal signals and the signals from projection cortex zones take place, and the formation of the commands that are implemented in the pers behavioral acts of an organism.

Light and electronmicroscopy, recording of (EEC and EcoG) evoked potentials, ultra cellular potentials of the nervous and the glial cells, and also broad spectrum of the behavioral reactions will be utilized as a criterion of an evaluation of the structurally functional organization of the nfnt and its integration into a recipient brain for study of the spatual orientation, memory and training, installation, motor activity and so on.

Apparently, the processes of the EMC proliferation, growth and differentiation of their progeny and the transformation into full value nervous and glial cells can be subjected to the particular actions with the purpose of their intensification and by that more prompt formation of a nervous tissue from the EMC. (The given direction of the investigation is the field of work of the project participants of a category I). Earlier one of the design participants built the theoretical model on the base of the own experimental data, according to which the super small exposure doses of penetrating radiation provide the noticeable boosting influence on the pision of the cells (A.A.Kozlov). To impact upon the growth and the differentiation of cell devices the electrical stimulation will be utilized in the zone of the EMC implantation in the damaged brain. (By this time for improving the health of the neurosurgerical patients with the extensive damages of a brain an electrical stimulation through electrodes implanted in a brain is used in some clinics). With this purpose the specialized instrument complex,will be developed and manufactured; this complex will allow to record biopotentials from a brain cortex surface before its damage and transformation of these potentials into the electrical signals with the similar properties. It is supposed, that they will be most optimal for the impact on the nervous tissue trophicity, on the appendixes growth and on the formation of the sinaptical connections between the separate nervous cells.

For reaching the project purpose, the following problems will be resolved:

1. Light, electronmicroscopic and immunocytochemical investigation of the nfnt structural organization.


2. Investigation of function organization nfnt on the basis of electrophysiological parameters.
3. Investigation of the behavioral reaction of the adult rats with nfnt.
4. Study of the influence of the supersmall doses of the chronic (g-irradiating on the processes of the EMC proliferation.

Development and manufacture of the complex instrument – generator of the electrical signals with the given parameters to stimulate the process of nervous tissue formation processes EMC.

As a result of the project accomplishment the structurally functional features of a nervous tissue derived from the grafted EMC in the damaged zones of the brain cortex of the adult animals will be detected; the recommendations on the usage of the supersmall radiation doses and electrical stimulation as the stimulation for the neurografts will be given.

The experimental data obtained at the solution of problems, to be achieved, can be utilized for the public health services needs at the development of the strategy of the most perspective directions in the neurotransplantalogy for the treatment inherent or caused by the trauma insult and for the perse cerebral pathologies.

The list of the terms and the abbreviations, used in the project:

VCT – ventropostero lateral core of thalamus,


NFNT – newly formed nervous tissue,
CI – complex instrument,
EMC – embryonic matrix cells,
PP – produced potentials,
Ecog – Electro corticogram.


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