Homotopic transplantation of embryonic neocortical tissue into the brain of adult rats after its damage

Structural characteristics (survival, growth, connections) have been studied in the transplant of the cerebral cortex tissue in Wistar rat embryos (18-day-old), implanted into the brain of mature rats of the same line at various time after a partial lesion of the sensomotor cortex. In 3-5 months after transplantation the light microscopy methods demonstrate that spatial interconnections of the transplant and the injured brain of the recipient depend on time interval between the cerebral lesion and transplantation of the embryonal nervous tissue. Horseradish peroxidase (HP) is ionophoretically injected into the recipient's cerebral tissue away from the place of transplantation. In the transplant retrogradely labelled HP neurons are revealed. This demonstrates efferent connections of the implanted tissue with the host's brain. Presence of the anterogradely labelled nervous terminals in the transplant tissue demonstrates existence of afferent connections of the transplant with the recipient's tissue. Possible mechanisms of survival, growth and formation of connections of the transplant in the injured brain of the mature animal are discussed.     

Quantitative and qualitative changes in protein biosynthesis induced by hypoxia and transplantation of embryonic nerve tissue into the brain of adult mammals

The changes in biochemical processes in brain cortex in rats with experimental hypoxia and hypoxia with consequent transplantation of embryonic nervous tissue into brain of adults have been studied. A small increase (2-3 times) in incorporation of biosynthesis precursors was observed as a result of transplantation both in normal and in hypoxic rats. These changes could be observed 100 days after the transplantation. These changes in biosynthesis led to selective increase in the amounts of 40-45 and 35-39 kDa proteins, which are characteristic both for local trauma caused by transplantation and for general one caused by hypoxia. The effect observed may be explained as a reaction of nervous cells on damage, and not on the presence of an embryonic brain transplant.     

Implantation of embryonic brain tissue into regenerating peripheral nerve

Dynamics of development of the cerebral cortex tissue anlage in 17-day-old embryos of Wistar rats, implanted into the sciatic nerve of mature rats with the aim to establish new relay and trophic centers in the regenerating nerve have been studied. By means of certain morphological methods (silver nitrate impregnation after Bielschowsky-Gros, Sudan black, hematoxylin-eosin, toluidine blue after Nissl stainings) it has been stated that the implanted nerve cells not only preserve their viability, but also differentiate from neuroblasts up to young and mature neurons during 2 months. Already in 14 days after the operation there are blood vessels in the implants; by the 2d month massive myelinization of axons begins in the implant. A part of the regenerating myelin fibers of the nerve gets into the implant and branches. In similar cases connections between the implanted neurons and the host peripheral nervous fibers are supposed to be established.     

Changes in the activity of different classes of enzymes in the cerebral cortex of rats in ontogeny and after the transplantation of embryonic nerve tissue

The activity of lactate dehydrogenase (LDH), indophenol oxidase, aspartate aminotransferase (AsAT), alkaline phosphatase, acid phosphatase and aldolase at different stages of rat development was measured. We have also determined changes in the activity of these enzymes resulting from transplantation of embryonic nerve tissue (ENT) into the brain of adult animals. During development from the embryo to the adult animal, LDH and AsAT activities increased, while alkaline phosphatase activity diminished. After ENT transplantation, the most prominent changes were in the alkaline phosphatase activity whereas the activity of LDH, AsAT and acid phosphatase remained unchanged and similar to that in the brain cortex of intact adult animals. Changes in the enzyme activity resulting from ENT transplantation changed in a manner characteristic of the transplant. Local brain damage did not change the activity of the studied enzymes fifty days after surgery.     

Changes in the brain neurons of the recipient around an embryonic nerve tissue transplant

Ultrastructure of adult neurons (sensomotor cortex) of recipient brain tissue localized in the vicinity of developing embryonic nervous tissue transplant has been studied. Partial dedifferentiation of pyramidal neurons has been revealed four days after the transplantation. The following changes were observed: dispersion and nearly complete absence of granular endoplasmic reticulum: appearance of a multitude of small mitochondria and disappearance of large ones; the presence of a large number of free polysomes; marked clearing of nuclei, and the presence of large nucleoli. No destructive processes in neurons were observed.     

Intracerebral transplants of embryonic nerve tissue result in the recovery of the ultrastructure of dystrophic neurons following hypoxia in adult rats]

Fragments of the intact rat embryonic brain cortex were transplanted into sensomotor cortex of adult Wistar rats subjected to hypoxia 26 days before surgery. Ultrastructure of the host brain was studied 4, 100, 130 days, 1.5, and 2 years after the operation using electron microscopy. The observed regeneration of ultrastructure of the host's neurons appears to be due to either recovery or de novo formation of the organelles.     

Survival of embryonic amygdala tissue grafted into various parts of the adult rat brain

It was found during the course of histological examination of preparations containing Nissl and Golgi stained neurons that portions of the embryonic amygdala can successfully survive in the intact adult rat brain. A number of parameters were used enabling development of the graft to be assessed objectively: parenchymal integration index, growth potential, cell density, and vascularization index. By comparing qualitative and quantitative findings of our analyses we showed that location within the host brain is one of the principal factors determining success in graft survival. Grafts transplanted into the cortex survived least well, ventricular cavity transplants fared better, and optimum results were observed with tissue grafted onto the subcortical structures. Normal nerve and glial cells were differentiated in grafts which had taken successfully: capillaries grew into the grafted tissue and common neuropil formed between the graft and the host brain. Structural integration between donor tissue and host brain provides a good model for studying both functional interaction and recovery of function impaired by damage to the host amygdala.Institute of Higher Nervous Activity and Neurophysiology, Academy of Sciences of the USSR, Moscow. Translated from Neirofiziologiya, Vol. 19, No. 5, pp. 606–612, September–October, 1987.     

Implantation of embryonic neocortex and spinal cord into injured peripheral nerve of adult rats

Spinal cord and cerebral cortex of 14-day-old embryos of Wistar rats were implanted into the sciatic nerve of mature rats in order to study dynamics of the development of neuronal and neuroglial elements in ectopic sites. By means of light and electron microscopy it has been stated that the implanted nerve cells of the cortex and spinal cord survive during 5 month and differentiate from neuroepithelial cells and neuroblasts up to young and mature neurons. It was found that thirty days after operation the spinal cord implants contained myelinated nerve fibers and numerous synapses. The data obtained suggest that the implants of fetal spinal cord are more favorable for regeneration of the injured nervous stems than the cerebral cortex.     

Effect of transplantation of embryonic neural tissue on the dynamics of brain edema following experimental craniocerebral trauma

The effect of transplantation of embryonic neural tissue (ENT) on the dynamics of brain edema following heavy craniocerebral trauma (CCT) made to the left parietotemporal area was studied in rats. The brain tissue impedance was measured in the damaged and contralateral hemispheres 1 to 30 days after the trauma in the animals of three groups: (i) without any procedures after the CCT, (ii) with surgical treatment of the damaged brain area, and (iii) with transplantation of 1–2 mm³ sensorimotor cortex fragments from 18-day-old rats grafted into the cavity created by this treatment. At the first day after CCT, the impedance in the damaged hemisphere decreased by 30–37%, while the impedance in the contralateral hemisphere decreased approximately by 20%, compared with the control, which was evidence of the development of intensive generalized edema. In the group of animals with the ENT transplantation, the edema involuted noticeably faster than in the other two groups: the mean impedance value reached 97.9% of the control value (before the damage) already by the 7th post-traumatic day. Complete recovery of the impedance by the 30th day was observed only in the animals with transplantation. The adequacy of an impedancemetric technique for investigation of the dynamics of water-electrolyte re-distribution in the brain tissue, and the mechanisms underlying corrective effect of ENT transplantation on the edema dynamics in the post-traumatic period are discussed.     

Changes in the bioelectrical activity of the brain cortex in rats with infraorbital nerve compression]

Bioelectrical activity of the somatosensory cortex was studied in the Wistar rats with chronic (1.5-2 months) compression of the infraorbital nerve produced by two partial ligations. In 20% of rats spike-slow wave complex and slow waves were observed. Electrostimulation of the skin on the injured nerve side resulted in a considerable increase in the amplitude of early components of the contralaterally evoked potentials in comparison with the non-injured side stimulation in 75% of rats. A decrease in the evoked potential thresholds on the injured nerve stimulation was shown in both hemispheres. In most of the animals a hypersynchronous late component of the evoked potential was observed.     

Regeneration process of the nerve tissue in brain transplantation in young rabbits

Neocortex has been transplanted into the right brain hemisphere of rabbits aged from 2 to 4 days. Brain regeneration at the tissue levels manifested in less macroglyocytes. Some observations are indicative of great regenerative potentials of the brain. Sometimes the development of glyofibrotic capsule was less distinct, which gives an impression of mutual penetration of fibers between the transplanted and recipient brain.     

The differentiation of the nerve and glial cells of neocortical transplants placed into the brain of adult rats

Embryonal neural tissue of 17-day-old rat embryos was transplanted into the brain of adult Wistar rats to test the differentiation of transplants with reference to the normal cerebral cortex development. The control and the experimental rats were decapitated 2, 5, 7, 10, 15, 20, 25, and 35 days after the transplantation. Differentiation of neural tissue was studied using monoclonal antibodies against neurofilaments as well as by counting the proportion of differentiated neurons. The glial differentiation was studied by immunohistochemical method using monoclonal antibodies against acid glial fibrillar protein and vimentin. The differentiation of neural cells of transplants proved to be synchronous with the normal ones while the differentiation of glial cells accelerates.     

Changes in the lactate dehydrogenase isoenzyme spectrum during T-lymphocyte differentiation

The pattern of lactate dehydrogenase isoenzyme spectrum changes on different stages of T-lymphocyte differentiation was studied An enriched population of stem cells has LDH-5, 4 and 3 isoenzymes, and much less LDH-2 activity. The isoenzyme pattern of thymic cell precursors consists of LDH-5, 4, 3 and 2. All the five LDH isoenzymes were found in cortical thymocytes. Medullary thymocytes reveal LDH-5, 4 and 3 isoenzymes. T-lymphocytes of peripheral lymphoid organs contain mainly LDH-5 and in a lesser degree LDH-4 activity.     

Expression of c-jun in the lateral vestibular nucleus following spinal cord injury and peripheral nerve graft transplantation in adult rats

Brain Cell Biology - The time course of c-jun expression and the effect of a peripheral nerve (PN) graft on axonal regeneration and c-jun expression in the lateral vestibular nucleus (LVN) were...     

Effect of embryonic brain tissue transplantation on structural changes in the rat brain after craniocerebral trauma

The effect of homotopic allotransplantation of embryonic cerebral cortex tissue on structural changes in the brain were studied on rats who had suffered a severe craniocerebral trauma (CCT) and subsequent traumatonesis of an injured region. Using Nissl and Golgi-Cox techniques, we showed that the presence of a viable graft in the cavity created by the traumatonesis procedure prevented formation of coarse gliofibrous expansions and extensive dead zones within the perifocal region of the injury locus. Transplantation performed immediately after the CCT and traumatonesis appeared to be most effective. In this case, the graft growth was more intensive and it was better integrated into the recipient's brain; branching of neurons in the graft was more abundant, and their dendrites were densely covered with spines. Thus, the use of early transplantation prevents the development of destructive and dystrophic changes evoked by severe CCT and can be regarded as a promising direction in neurosurgical practice.Neirofiziologiya/Neurophysiology, Vol. 27, No. 5/6, pp. 350–360, September–December, 1995.     

The effect of nembutal on the cellular pulse trains of embryonic nerve tissue transplanted into the brain of the rat

Under nembutal anaesthesia the mean frequency of single unit discharges recorded from allografts of the rat brain was four times lower than the one measured in unanaesthetized animals. A diminished variability was revealed of firing rates and discharge patterns of the cells within grafts in anaesthetized rat brain. In comparison to unanaesthetized animals the number of graft units reacting to a tactile stimulation of contralateral hindlimb of the operated animals was twice lower. Nembutal anaesthesia provoked a full blockade of reactions to the tactile stimuli applied to the ipsilateral side of the animal body.