Restorative Neurology and Neuroscience - Volume 2, issue 4-6

Authors: Chen, M. | Harvey, A.R. | Dyson, S.E.

Article Type: Research Article

Abstract: Attempts were made to enhance the regrowth of retinal axons which had been lesioned in the brachial region of the rat optic tract. Pieces of nitrocellulose paper (Millipore) were placed into the lesioned area between the dorsal lateral geniculate nucleus (dLGN) and superior colliculus (SC) in 13- to 18-day-old Wistar rats. Five types of implant were used: (1) uncoated implants, (2) coated with Poly-l-lysine (PLL), (3) coated on one side with cortical astrocytes, (4) coated with tectal astrocytes and (5) coated with Schwann cells. About half the Schwann cell-covered implants were precoated with PLL. Schwann cell-coated implants (16–40 × 103 …cells per implant) were placed with the cells lying on either the dorsal or ventral (inverted) surface of the paper. 5–7 weeks after surgery, eyes were injected with WGA-HRP, the animals were perfused and frozen or vibratome sections (40–50 μm) processed for TMB histochemistry. Selected sections containing retinal axons were osmicated and prepared for electron microscopic examination. 45 out of 86 implants were found attached to the caudal dLGN. A small number of retinal axons were found growing onto the rostral end of one uncoated implant, two PLL-coated implants and over the surface of 4 of the astrocyte-coated implants. The densest and most extensive growth was seen on the Schwann cell-coated implants. In 15 of the 30 animals with such implants attached to the dLGN, retinal axons were found regrowing for 50–1120 μm (mean 530 μum). In about half of these rats (8 out of 15), the regrowth involved relatively large numbers of optic axons which were sometimes densely packed together. In the subgroup of Schwann cell-coated implants where the cells were placed upwards, retinal axons regrew on the dorsal surface of the paper for more than 500 μm in 7 animals. Almost no growth was seen on the uncoated (ventral) surface of the implants. In the subgroup of inverted implants, where the Schwann cells were placed downwards, in 4 animals retinal axon regrowth was densest on the ventral surface and extended for 300–550 μm. In 3 cases, occasional axons were also seen on the dorsal implant surface. Myelin sheaths surrounding some of the regenerating axons had PNS characteristics, suggesting that they were formed by the implanted Schwann cells, but most of the myelin appeared to be of central origin. The data suggest that Schwann cells placed just caudal to the dLGN and adjacent to lesioned retinal axons can enhance and direct the regrowth of these axons in the rat optic tract. Show more

Keywords: Tissue culture, Schwann cell: Astrocyte, Transplantation, Lateral geniculate nucleus, Superior colliculus, Optic tract, Regeneration

DOI: 10.3233/RNN-1991-245611

Citation: Restorative Neurology and Neuroscience, vol. 2, no. 4-6, pp. 233-248, 1991

Authors: Schnell, L. | Schwab, M.E.

Article Type: Research Article

Keywords: Spinal cord, Lesion, Transplant, Development, Neurite growth, Oligodendrocyte

DOI: 10.3233/RNN-1991-245612

Citation: Restorative Neurology and Neuroscience, vol. 2, no. 4-6, pp. 249-250, 1991

Authors: Wilson, David Hedley

Article Type: Research Article

Abstract: Portions of 1 cm length of the sensory radial nerve from the cat forelimb were used to replace an excised portion of the dorsal columns in the upper lumbar spinal cord. Observations were made on the clinical recovery of the animals, and cine recordings were made of their ability to traverse a horizontal ladder 5 months after the grafting procedure. Evoked sensory potential studies performed 6 months after grafting showed that an impulse arising from a stimulus applied to the sciatic nerve could be recorded in the spinal cord caudal to the graft, in the graft and in the spinal …cord rostral to the graft in 5 out of 8 animals. Tracing of nerve connections with injection of horseradish peroxidase into the grafts resulted in labelling of nerve cell bodies in dorsal root ganglia and the grey matter of the lumbar spinal cord up to a distance of 10 mm away from the graft. These results confirm that peripheral nerve grafts can provide a satisfactory environment for the regrowth of ascending fibres in the dorsal columns of the spinal cord. However, there is as yet no evidence that the regenerated fibres succeed in forming useful synaptic connections with other nerve cell bodies. Show more

Keywords: Spinal cord grafting, Cat, Horseradish peroxidase, Peripheral nerve graft

DOI: 10.3233/RNN-1991-245613

Citation: Restorative Neurology and Neuroscience, vol. 2, no. 4-6, pp. 251-254, 1991

Authors: Beneš Jr, V. | Druga, R. | Rokyta, R. | Štastný, J.

Article Type: Research Article

Abstract: Spinal cord (SC) injury followed by autodestruction and resection of damaged tissue necessarily leads to the formation of a gap between the disconnected cord stumps. For any attempts to reconstruct the transected cord it may accordingly be useful to narrow or close this gap. Physically this can be achieved by vertebral resection with shortening of the spinal column. In cats and rabbits the dynamics of SC autodestruction was examined, and a technique for removal of autodestructed tissue developed, together with a surgical technique for resection of the second lumbar vertebra. By means of these techniques the volume of the gap …between the SC stumps in rabbits was reduced from 200 mm3 to almost zero. In future research this should allow use of neural grafts of a reasonably small volume. Show more

Keywords: Spinal cord reconstruction

DOI: 10.3233/RNN-1991-245614

Citation: Restorative Neurology and Neuroscience, vol. 2, no. 4-6, pp. 255-260, 1991

Authors: Bernstein, Jerald J. | Goldberg, William J.

Article Type: Research Article

Abstract: In a ‘double blind’ study, 2 series of adult rats were trained to traverse a narrow bar or a horizontal ladder for a water reward. Hindlimb placement (measured as hindlimb foot slips) of the subjects trained on the narrow platform was ranked. The subjects traversing the ladder were videotaped and the number of hindlimb slips counted. After reaching criterion (10 complete traverses on each of 2 consecutive days), all animals had the fasciculus gracilis (FG) of the third cervical spinal cord segment (C3 ) aspirated to sever hindlimb dorsal column afferents. After aspiration of C3FG the subjects were randomly placed …in an aspiration-only (controls) or aspiration + graft group. All grafts were prelabeled with the plant lectin Phaseolus vulgaris leucoagglutinin (PHAL) as a graft-derived cell marker. The grafts were either unoriented whole pieces of E14 fetal spinal cord or 105 purified, cultured, E14 fetal spinal cord astrocytes. Subjects were tested at intervals over 90 days. Aspiration of C3FG and a graft of whole pieces of E14 fetal spinal cord resulted in a statistically significant improvement in hindlimb placement at 21 and 90 days (P < 0.05) when compared to controls. In contrast, animals with cultured, purified, E14 fetal spinal cord astrocyte grafts had significantly worse (P < 0.05) hindlimb placement than controls. Immunohistochemical double staining for PHAL and glial fibrillary acidic protein in the same cell showed that astrocytes from both types of grafts migrated to the nucleus gracilis (NG) of the medulla of the host. The grafted fetal astrocytes from the whole piece grafts prevented denervation atrophy of the host NG neurons, whereas cultured grafted fetal astrocytes did not demonstrate this effect. After grafting donor tissue that contained astrocytes into the injured spinal cord there were two accompanying classes of astrocytes. One class derived from whole piece, E14, fetal spinal cord grafts migrated to the NG of the host, prevented atrophy of host NG cluster and interneurons, and improved hindlimb placement. The other class, derived from cultures of E14 fetal spinal cord astrocytes, migrated to the NG of the host, failed to maintain the size of cluster neurons and interneurons of the host NG, and resulted in a greater hindlimb placement deficit when compared to controls. These data suggest that improvement of hindlimb placement due to graft-derived fetal astrocytes in injured host spinal cord was due to the ability of the astrocytes to maintain host neurons and neuronal networks. Show more

Keywords: Spinal cord, Transplant, Astrocyte, Neuronal rescue, Return of function

DOI: 10.3233/RNN-1991-245615

Citation: Restorative Neurology and Neuroscience, vol. 2, no. 4-6, pp. 261-270, 1991

Authors: Finsen, Bente R. | Sørensen, Torben | González, Berta | Castellano, Bernardo | Zimmer, Jens

Article Type: Research Article

Abstract: Immunological rejection is a lasting, although highly variable, threat to allo- and xenogeneic neural tissue grafted to the CNS of rodents, monkeys and man. One major determinant for rejection of intracerebral CNS grafts appears to be induction of major histocompatibility complex (MHC) antigens on the donor CNS cells. We have previously examined the cellular immune response against neural mouse xenografts undergoing rejection in the adult rat brain. In this study we focus on the astro- and microglial reactions within and around the graft, and the potential of individual host rat and donor mouse brain cells to express MHC antigens. Previous …light microscopical observations of expression of rat MHC antigen class I by endothelial cells, microglial cells, and invading leukocytes were extended to the ultrastructural level and found to include a few astrocytes. Rat and mouse MHC antigen class II was only detected on leukocytes and activated microglial cells. The findings imply that within grafts of brain or spinal cord tissue donor astrocytes, microglial cells and endothelial cells can be induced to act as target cells for class I specific host T cytotoxic cells, while only (graft and host) microglial cells can be induced to express MHC antigen class II and present antigen to sensitized (and possibly also resting) host T helper cells. Show more

Keywords: Central nervous system, Transplant, Immunology, Major histocompatibility complex antigen, Glial cell

DOI: 10.3233/RNN-1991-245616

Citation: Restorative Neurology and Neuroscience, vol. 2, no. 4-6, pp. 271-282, 1991

Authors: Nothias, Fatiha | Cadusseau, Josette | Dusart, Isabelle | Peschanski, Marc

Article Type: Research Article

Abstract: Lesioning the spinal cord with an excitotoxic agent provides a model of neuronal degeneration while sparing afferent axons. The present study has been undertaken to determine whether homotypic fetal neurons transplanted as a cell suspension were able to rebuild a neural circuitry in the neuron-depleted adult cord. Fetal spinal cords, taken from rat embryos (gestational day E12–13), were transplanted as cell suspensions into an area of the lumbar cord previously depleted of neurons using kainic acid. The excitotoxic lesion extended over ventral and intermediate horns, implying the death of all motoneurons with consequent paralysis and muscular atrophy of corresponding hindlimb. …During the first month after injection, the damaged cord was characterized by proliferation and recruitment of various glial cell and Schwann cell populations. First to appear were activated microglia/macrophages and next reactive astrocytes which entered the lesion from its borders with the intact tissue. Schwann cells also ensheathed central axons. Differential sensitivity of various afferents to loss of postsynaptic target neurons was observed: rubrospinal and corticospinal afferents decreased in density while no conspicuous changes were observed for immunostained CGRP-containing or monoaminergic fibers. Two to fourteen months after surgery, transplants occupied most of the neuron-depleted area. The grafts did not display a laminar organization. Monoaminergic afferents grew for a long distance and formed a network within transplants. Similarly, primary sensory CGRP-immunoreactive fibers entering in the dorsal roots penetrated deeply into transplants. In contrast, cortico- and rubrospinal afferents entered only the most peripheral portion of transplants. Our results indicate that fetal spinal neurons can be successfully transplanted into the adult neuron-depleted spinal cord. Host-to-graft connections can be formed, although their spatial extent in the transplants may depend upon features of the afferent fiber systems. Show more

Keywords: Neural graft, Motoneuron, Amyotrophic lateral sclerosis, Embryonic tissue, Excitotoxin, Kainic acid, Neurodegeneration, Neuroplasticity

DOI: 10.3233/RNN-1991-245617

Citation: Restorative Neurology and Neuroscience, vol. 2, no. 4-6, pp. 283-288, 1991

Authors: Horvat, Jean-Claude | Baillet-Derbin, Claude | Ye, Jian Hui | Rhrich, Fatiha | Affane, Fatima

Article Type: Research Article

Abstract: The present study is the first of a series of experiments designed to investigate the possibilities of reconstructing the severely injured spinal cord by means of transplantation techniques. Special attention has been given here to the capability of transplanted embryonic neurons to extend axons into autologous peripheral nerve grafts (PNGs). A cavity, made unilaterally in the cervical enlargement of the spinal cord of adult rats, was filled with solid pieces of different embryonic tissues: spinal cord (SC), cortex (CT) or dorsal root ganglia (DRG). In more than half of the transplanted animals, one end of a PNG was inserted into …the center of the transplants, while the other, extraspinal end, was crushed and tied to peripheral tissues. After a postgrafting period ranging from 1 to 6 months, we found that the 3 types of transplants in general had survived and become integrated with the host spinal cord, although their overall organization remained atypical. Surviving graft neurons had developed processes, some of which had become myelinated. The ability of the grafted neurons to extend axons into the PNG differed strikingly from one type of graft to another, being apparently non-existent for cortical grafts, moderate for spinal cord grafts and quite extensive for dorsal root ganglia transplants. Interestingly, these differences reflected what was observed for the corresponding, fully differentiated qeurons in adult animals, when their cut axons were put in contact with non-neuronal components of peripheral nerves. Show more

Keywords: Spinal cord reconstruction, Fetal CNS graft, DRG transplant, PNS grafts, Retrograde axonal tracing

DOI: 10.3233/RNN-1991-245618

Citation: Restorative Neurology and Neuroscience, vol. 2, no. 4-6, pp. 289-298, 1991

Authors: Clowry, G.J. | Vrbová, G.

Article Type: Research Article

Abstract: We have previously shown that motoneurone-like cells from embryonic grafts survive and migrate into the host neuropil of adult rat spinal cord, depleted of some of its own motoneurones. We moreover demonstrated that a muscle, when connected at the site of the graft to the spinal cord of the host by its own nerve, was reinnervated by motoneurones that could be identified by retrograde labelling with HRP [11]. However, it was not clear whether these retrogradely labelled motoneurones were of graft origin. In this study we combined the use of an embryonic marker with retrograde labelling to demonstrate that grafted …neurones of embryonic origin can indeed innervate a soleus muscle implant. Embryonic donor cells were labelled with bromodeoxyuridine (BrDU) by its incorporation into replicating DNA during neurogenesis. The nuclei of grafted cells were then identified in host cords by immunocytochemistry, visualising the BrDU positive nuclei with the fiuorophore Texas Red, while the fluorescent dyes Fast Blue and Diamidino Yellow were used for retrograde labelling. Examination of frozen spinal cord sections by fluorescence microscopy, at wavelengths appropriate to each fiuorophore, showed that about 12% of the neurones innervating the muscle implant also contained detectable amounts of BrDU and therefore were of graft origin. Show more

Keywords: Motoneuron, Neural transplantation, Retrograde labelling, Reinnervation, Muscle, Immunocytochemistry

DOI: 10.3233/RNN-1991-245619

Citation: Restorative Neurology and Neuroscience, vol. 2, no. 4-6, pp. 299-302, 1991

Authors: Martin, D. | Delrée, P. | Schoenen, J. | Rogister, B. | Rigo, J.-M. | Leprince, P. | Stevenaert, A. | Moonen, G.

Article Type: Research Article

Abstract: Neurons and non-neuronal cells were harvested from adult rat dorsal root ganglia and transplanted to syngeneic adult rat spinal cord. Transplants were performed in intact rats and after acute traumatic paraplegia induced by inflation of a subdural microballoon. Only the first histopathological results are presented here. Transplants were well tolerated and fused with the surrounding host tissue. Survival of neurons within the grafts appeared better in the injured cords than in the intact ones. Some of them expressed neuropeptides known to be present in DRG in situ. Few interactions were found with morphological methods between the transplants and the host …spinal cord. Some peptidergic fibers were seen crossing the graft-host interface; most fibers probably originated from host spinal fiber systems. The perspectives and limitations of the presently described type of spinal transplantation are discussed. Show more

Keywords: Spinal cord injury, Neural transplantation, Adult sensory neurons, Transmitter immunocytochemistry, Neuronal plasticity

DOI: 10.3233/RNN-1991-245620

Citation: Restorative Neurology and Neuroscience, vol. 2, no. 4-6, pp. 303-308, 1991

Authors: Anderson, Douglas K. | Reier, Paul J. | Wirth III, Edward D. | Theele, Daniel P. | Mareci, Thomas | Brown, Stacy A.

Article Type: Research Article

Abstract: This review summarizes a series of experiments involving transplants of embryonic feline CNS tissue into chronic compression lesions of the adult cat spinal cord. Fetal spinal cord (FSC), caudal brainstem (BSt), neocortex (NCx) or a combination of either FSC/NCx or FSC/BSt was transplanted as solid pieces or as a suspension of dissociated cells into the developed cystic cavities produced by static-load compression trauma 2–10 weeks prior to grafting. All cats were immunosuppressed with cyclosporin A and their locomotor function was assessed for 6–30 weeks. Following the period of evaluation, all recipients were perfused with fixative and tissue specimens, taken at …the transplantation site, were processed for general histological and/or immunocytochemical analysis. Viable graft tissue was found in all animals with the exception of two cats which showed active rejection of their transplants. All of the viable intraspinal grafts were extensively vascularized and did not show any signs of imminent or on-going tissue rejection. Fetal cat CNS grafts showed an extended maturational phase in that features of immature neural tissue (e.g. a paucity of myelination) were still seen even 6–9 weeks after transplantation. By 20–30 weeks, FSC and BSt grafts had attained a more advanced stage of maturation. Transplants in these chronic lesions were extensively blended with both the gray and white matter of the host spinal cord and could be visualized by magnetic resonance imaging (MRI). MRI could also detect regions of cavitation at the graft–host interface, as well as within some transplants. While preliminary evidence from behavioral studies suggest that the FSC and BSt grafts may improve or spare locomotor function in some recipients, a more rigorous analysis of post-grafting locomotor function is required to determine conclusively the functionality of these transplants. Show more

Keywords: Spinal cord transplantation, Fetal spinal cord, Brainstem and neocortical grafts, Compression spinal cord injury

DOI: 10.3233/RNN-1991-245621

Citation: Restorative Neurology and Neuroscience, vol. 2, no. 4-6, pp. 309-325, 1991

Authors: Bregman, Barbara Sypniewski | Bernstein-Goral, Holli | Kunkel-Bagden, Ellen

Article Type: Research Article

Abstract: We are using neural tissue transplantation after spinal cord injury to identify the rules which determine the response of young neurons to injury, to identify the mechanisms underlying anatomical plasticity and recovery of function following spinal cord injury, and to determine the conditions which change during development, leading to the more restricted growth capacity of mature neurons following injury. Spinal cord lesions at birth interrupt different pathways at different relative stages in their development. Neural tissue transplants modify the response of the immature central nervous system neurons to injury. In the current studies, we have used neuroanatomical and behavioral methods …to compare the response of the late-developing corticospinal pathway with that of brainstem–spinal pathways which are intermediate in their development and that of the relatively mature dorsal root pathway. We find that both late-developing and regenerating neuronal populations contribute to the transplant-induced anatomical plasticity, and suggest that this anatomical plasticity underlies the transplant-mediated sparing and recovery of function. Show more

Keywords: Regeneration, Red nucleus, Corticospinal tract, Development, Dorsal root, Neonatal lesion

DOI: 10.3233/RNN-1991-245622

Citation: Restorative Neurology and Neuroscience, vol. 2, no. 4-6, pp. 327-338, 1991

Authors: Goldberger, Michael E.

Article Type: Research Article

Abstract: The mechanisms underlying recovery of function following damage to the CNS, although suspected, are virtually unknown. After damage to the adult cat spinal cord, recovery of motor behavior depends on which systems have been interrupted and which remain intact. For example, following hemisection, overground (voluntary) and reflex locomotion recover and, although a normal kinematic pattern recovers, accurate placement of the limb during locomotion does not return to normal levels. This recovery is associated with lowering of thresholds for postural reflexes suggesting that increased afferent input may compensate for diminished descending control. In contrast, after unilateral loss of afferent input by …lumbosacral deafferentation, (L1 -S2 dorsal roots cut) overground locomotion recovers but a permanently abnormal kinematic pattern is used; reflex locomotion (bipedal locomotion on a treadmill) does not recover at all in the deafferented hindlimb. The specificity of the recovery suggests that increased input from descending pathways, which is required for overground but not reflex locomotion may compensate for loss of afferent input. Anatomical sequellae of these two lesion types have been examined. Studies after hemisection support the notion of a permanently increased dorsal root input as mapped by monoclonal antibody ‘rat 102’. This is associated with a transient increase in GAP-43 labeling in the dorsal horn. In contrast, after deafferentation an increase is found in the descending serotonergic input to the deafferented side. These observations suggest that recovery of specific locomotor behavior can be used to predict compensatory changes in spared pathways. For the study of the effects of transplants, we have used complete spinal transections in newborn kittens with transplantation of E26 cat spinal cord into the transection site. The normal kitten develops overground locomotion beginning the end of the first week postnatal but reflex locomotion is delayed until the end of the second week. After transection on the first day of life, with or without a transplant, reflex locomotion begins precociously. Overground locomotion fails to develop in transection-only animals but does develop in animals with transection and transplant. This locomotion although clearly abnormal, shows postnatal development in terms of weight support and lateral stability. Furthermore, there is some indication of coordination between fore and hind limbs. These observations suggest that the transplants permit the development of some descending control although the anatomical correlates of this sparing/recovery of function are uncertain; the transplant rescues neurons caudal to the transection and also permits regeneration of some descending pathways into the transplant and caudally into host spinal cord. Show more

DOI: 10.3233/RNN-1991-245623

Citation: Restorative Neurology and Neuroscience, vol. 2, no. 4-6, pp. 339-350, 1991