Brain, Vol. 125, No. 1, 14-21,
January 1, 2002
© 2002 Oxford University Press
Olfactory ensheathing cells promote locomotor recovery after delayed transplantation into transected spinal cord
1Neural Injury Research Unit, School of Anatomy, University of New South Wales, Sydney and 2Centre for Molecular Neurobiology, School of Biomolecular and Biomedical Science, Griffith University, Brisbane, Australia Correspondence to: Dr Phil Waite, Neural Injury Research Unit, School of Anatomy, University of New South Wales, Sydney, NSW 2052, Australia or Dr Alan Mackay-Sim, Centre for Molecular Neurobiology, School of Biomolecular and Biomedical Science, Griffith University, Brisbane QLD 4111, Australia E-mail: P.Waite{at}unsw.edu.au or A.Mackay-Sim{at}sct.gu.edu.au
Received May 17, 2001. Revised August 6, 2001. Accepted August 20, 2001. .
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We demonstrated recently that transplantation of olfactory ensheathing cells from the nasal olfactory mucosa can promote axonal regeneration after complete transection of the spinal cord in adult rat. Ten weeks after transection and transplantation there was significant recovery of locomotor behaviour and restoration of descending inhibition of spinal cord reflexes, accompanied by growth of axons across the transection site, including serotonergic axons arising from the brainstem raphe nuclei. The present experiment was undertaken to determine whether olfactory ensheathing cells from the olfactory mucosa are capable of promoting regeneration when transplanted into the spinal cord 4 weeks after transection. Under general anaesthesia, thoracic spinal cord at the T10 level was transected completely in adult rats. Four weeks later, the scar tissue and cavities at the transection site were removed to create a 3–4 mm gap. Into this gap, between the cut surfaces of the spinal cord, pieces of olfactory lamina propria were placed. Ten weeks later, the locomotor activity of these animals was significantly improved compared with control animals, which received implants of either pieces of nasal respiratory lamina propria or collagen (Basso, Beattie, Bresnahan Locomotor Rating Scale scores 4.3 + 0.8, n = 6 versus 1.0 + 0.2, n = 10, respectively; P < 0.001). Ten weeks after transplantation the behavioural recovery was still improving. Regrowth of brainstem raphe axons across the transplant site was shown by the presence of serotonergic axons in the spinal cord caudal to the transection site, and by retrograde labelling of cells in the nucleus raphe magnus after injections of fluorogold into the caudal spinal cord. Neither serotonergic axons nor labelled brainstem cells were observed in the control animals. These results indicate that olfactory ensheathing cells from the nasal olfactory lamina propria have the ability to promote spinal cord regeneration when transplanted 4 weeks after complete transection. Olfactory ensheathing cells are accessible and available in the human nose; the present study further supports clinical use of these cells in repairing the human spinal cord via autologous transplantation.
Keywords: rat; transplantation; spinal cord injury; paraplegia
Abbreviation: BBB= Basso, Beattie, Bresnahan Locomotor Rating Scale
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Introduction |
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For many years spinal cord injury has been seen as clinically irreversible, although many attempts have been made in animals to regenerate the spinal cord using a variety of transplanted cell types. These include Schwann cells (Martin et al., 1991
; Paino and Bunge, 1991; Paino et al., 1994), oligodendrocyte precursors (Blakemore et al., 1995; Rosenbluth et al., 1997), foetal neural tissue (Kunkel-Bagden and Bregman, 1990; Bregman and Bernstein-Goral, 1991; Bernstein-Goral and Bregman, 1993; Iwashita et al., 1994), peripheral nerves (David and Aguayo, 1981; Richardson et al., 1984; Houle, 1991; Cheng et al., 1996) and stem cells, which can differentiate into multiple classes of neurones or glia (Kalyani et al., 1998; McDonald et al., 1999; Liu et al., 2000).
Significant progress has been made recently with the transplantation of olfactory ensheathing cells into spinal cord injuries. Following transplantation into a localized electrolytic lesion of the corticospinal tract in adult rats, olfactory ensheathing cells supported unbranched, regenerative growth of corticospinal axons and restoration of a corticospinal-dependent paw-reaching function (Li et al., 1997, 1998). Olfactory ensheathing cells promoted regeneration after complete transection of the spinal cord (Rámon-Cueto et al., 1998, 2000) and restored rapid and secure conduction across the transected dorsal columns of the rat spinal cord (Imaizumi et al., 2000) with recovery of motor function (Rámon-Cueto et al., 2000).
Given the remarkable behavioural recovery observed in the rat, could olfactory ensheathing cells be used to repair the human spinal cord? Before moving to human therapy there are several issues which should be addressed: (i) whether human olfactory ensheathing cells can also repair the damaged spinal cord; (ii) an accessible source of cells for human therapy; and (iii) the fact that human transplantation therapy is unlikely to commence for some time after the injury in order to allow the system to recover without intervention. The first issue has been addressed in part: human olfactory ensheathing cells were recently shown to remyelinate the demyelinated spinal cord of the rat (Barnett et al., 2000; Kato et al., 2000), although there are no studies of human olfactory ensheathing cells transplanted into the experimental models of spinal cord trauma.
The source of olfactory ensheathing cells for all the studies above, rat and human, was the olfactory nerve layer of the olfactory bulb. In rat these cells are quite accessible through the frontal bone of the skull. In adult humans, access to the olfactory bulb is very difficult and usually only accessible during major surgical procedures of the skull base, making this a problematic source for therapy. Olfactory bulbs could be obtained from aborted foetuses, but this raises serious ethical issues in addition to the technical issues of host–graft disease. Another source of olfactory ensheathing cells, not usually considered in the literature, is the olfactory mucosa in the nose where these cells ensheath the olfactory sensory axons as they pass through the lamina propria before entering the cranium through the cribriform plate. The use of nasal olfactory ensheathing cells raises the attractive possibility of autologous transplantation. Biopsy of the human olfactory mucosa is relatively straightforward and can be done under either general or local anaesthesia (Féron et al., 1998, 1999). In the rat, the lamina propria has been separated from the overlying epithelium, and the olfactory ensheathing cells within it grown in vitro (Féron et al., 1999). We recently used this source of ensheathing cells for transplantation into the completely transected spinal cord of the adult rat (Lu et al., 2001). Ten weeks after transection and transplantation there was significant recovery of locomotor behaviour and recovery of descending inhibition of spinal cord reflexes, accompanied by growth of axons across the transection site, including serotonergic axons arising from the brainstem raphe nuclei.
A key issue in the translation of these ideas to the clinic is whether nasal olfactory ensheathing cells could promote spinal cord regeneration if transplantation was delayed after the initial spinal cord transection. Neurosurgeons would be reluctant to do any transplantation during the acute injury phase for fear of aggravating injury or impeding recovery of residual function. In the rat there is evidence that the damaged spinal cord retains the ability for repair for at least 4 weeks. Chronically injured spinal axons can regenerate into intraspinal peripheral nerve grafts 4 weeks after injury (Houle, 1991), and axonal regeneration of supraspinal neurones is enhanced by growth factors 4 weeks after injury (Ye and Houle, 1997). The aim of the present study, therefore, was to investigate the potential of olfactory ensheathing cells to stimulate spinal cord regeneration when transplanted 4 weeks after complete transection.
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Adult female Sprague–Dawley rats (250 g) were used in this study. They were housed singly with free access to food and water. All experimental protocols and procedures were approved by the animal ethics committees at the University of New South Wales and Griffith University in accordance with guidelines of the National Health and Medical Research Council of Australia for animal research.
Rats were rendered paraplegic via a complete transection of the spinal cord at the T10 level as previously described (Lu et al., 2001). Four weeks later the injury was resected in six animals and pieces of olfactory lamina propria containing olfactory ensheathing cells were placed into the gap created in the spinal cord (Lu et al., 2001). Seven control animals received transplants of pieces of respiratory lamina propria, which do not contain olfactory ensheathing cells, and an additional three controls received implants of a collagen matrix alone. Locomotor behaviour was monitored weekly until 10 weeks after the transplantation, which was the maximum period allowed by the ethics committees. The animals were then killed and their spinal cords and brains assessed histologically.
Preparation of olfactory lamina propria
Rats were deeply anaesthetized with sodium pentobarbitol (100 mg/kg) and killed by decapitation. The nasal septum was freed by removal of the lower jaw, the upper teeth and the turbinate bones. The two olfactory mucosae lining the posterior part of the nasal septum and two similarly sized pieces of the respiratory mucosa lining the anterior part of the septum were dissected and immediately placed in ice-cold DMEM (Dulbecco’s Modified Eagle Medium) (Gibco, Mulgrave, Queensland, Australia). The olfactory mucosa is easily identified in the rat by its posterior position on the nasal septum and by the yellowish appearance of the epithelial surface. Care was taken to avoid the anterior edge of the olfactory mucosa, which could be contaminated with respiratory epithelium. Respiratory epithelium was removed from the dorsoanterior region of the septum. The respiratory and the olfactory tissues were incubated separately for 45 min at 37°C in a 2.4 units/ml dispase II solution (Boehringer, Castle Hill, NSW, Australia) and, in both cases, laminae propriae were carefully separated from the epithelium under the dissection microscope with a micro-spatula. Before grafting, laminae propriae were incubated in a 10% solution of nuclear fluorochrome bisbenzimide (Sigma) for 2 h at 37°C, and then rinsed three times with DMEM without serum.
Transplantation of olfactory lamina propria
The animals were placed on a heating blanket under general anaesthesia (ketamine/xylazine: 90/10 mg/kg, intraperitoneally). Complete transections of the spinal cord at the T10 level were performed as described previously (Lu et al., 2001). Four weeks later, animals were re-anaesthetized and the dorsal laminectomy was extended to the T9 and T11 level. Under the surgical microscope, the scar tissue, intramedullary necrosis and cavities from the previous transection site were removed until normal cross-sections appeared in the spinal cord. After removal of the scar tissues the gap between the caudal and rostral stumps extended rostrocaudally 3–4 mm. This gap was irrigated with 0.9% saline and packed with Gelfoam to stop haemorrhage. Pieces of lamina propria (three to five large pieces, cut into 1 mm2 pieces) were then placed into the gap and covered with Gelfoam. As indicated above, experimental animals received transplants of olfactory lamina propria whereas controls received pieces of respiratory lamina propria, or Gelfoam alone. The wound was sutured closed keeping the muscle and skin layers separate. Postoperative care was as described previously (Lu et al., 2001), including housing under a heating lamp during the first postoperative week, expression of urine twice daily until a bladder reflex was re-established and prophylactic antibiotics to prevent urinary tract infection.
Behavioural assessment
The use of the legs during locomotion was measured by placing the animal in an open field (150 x 100 cm). All rats were manipulated to express the bladder before testing in order to eliminate behaviours related to bladder fullness. Locomotion was scored according to the Basso, Beattie, Bresnahan Locomotor Rating Scale (BBB) (Basso et al., 1995). This scale measures hindlimb movements with a score of 0 indicating no spontaneous movement, with increasing scores for use of individual joints, coordinated joint movement, coordinated limb movement, weight-bearing and so on to a maximum score of 21. The rats were scored each week by two observers blind to treatment.
Retrograde labelling of descending axons
Ten weeks after transplantation, rats were anaesthetized as described above and the spinal cord was exposed below the transplantation site. Microinjections of the retrograde tracer, fluorogold, were made into the spinal cord caudal to the transection site. Three injections (0.05 µl each) were made at the midline (at 0.5, 0.8 and 1.5 mm deep) and 1 mm lateral (0.4, 0.8 and 1.2 mm deep) on each side, to penetrate the dorsal columns and lateral funiculi. Injections were made at T12, 
8–9 mm or two segments below the lesion.
Histological assessment
Two to three days after fluorogold injection, all animals were perfused transcardially with 4% paraformaldehyde in 0.2 M phosphate buffer. The spinal cord encompassing the transplantation site, and the brainstem, were removed, post-fixed for 2 h in the same fixative, cryo-protected in 30% sucrose and prepared for cryo-sectioning. The spinal cord was sectioned longitudinally at 30 µm. The brainstem was cut coronally at 50 µm. Three animals in each group were used to assess lesion morphology and spread of fluorescent label from the injection site. Fluorescent labelling of retrogradely labelled cells in the brainstem was observed using confocal laser microscopy. The remaining animals (three experimental and seven controls) were used for immunohistochemistry on the spinal cord, for assessment of nerve fibres expressing serotonin. After blocking with 5% normal goat serum, the sections were incubated in primary antibody [rabbit antiserotonin (DiaSorin Inc.) diluted 1 : 1000 in phosphate-buffered saline]. The following day, sections were washed with phosphate-buffered saline and incubated for 1 h in the secondary antibody (biotinylated goat anti-rabbit IgG, Sigma; diluted 1 : 200 in phosphate-buffered saline and 0.5% Triton X-100). This was followed by the Vector ABC procedure and visualization with 3,3'-diaminobenzidine. The specificity of immunostaining was verified by omission of the primary antibody. Normal rat brainstem raphe neurones were used as positive controls.
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Recovery of locomotor behaviour
In the 4 weeks after the initial transection of the spinal cord, BBB scores were in the range 0–2, the same range found in the control animals (Fig. 1). Following transplantation of the olfactory lamina propria, use of the hind limbs increased gradually, starting 2–3 weeks after transplantation (Fig. 1). By 10 weeks after transplantation, five of the six animals displayed BBB scores greater than that achieved by any of the 13 controls (Fig. 1). The mean BBB score for the animals receiving olfactory transplants was 4.3 ± 0.8 (mean ± standard error) compared with the control mean of 1.0 ± 0.3. This difference was significant (P < 0.001, t-test). Four of the six experimental animals had ankle, knee and hip movements in one or both legs, but did not obviously bear weight on the hind limbs.
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Motor axon regeneration
Regeneration of brainstem motor neurones was assessed in two ways. Axonal regrowth of the brainstem serotonergic system was assessed using immunohistochemistry in the caudal spinal cord to identify axons which had regenerated past the transection site. Axonal regeneration was also assessed by retrograde transport of fluorogold from a caudal injection site into the brainstem.
Serotonin-immunoreactive axons were observed in the grey matter of the spinal cord caudal to the transection site in two of three animals receiving olfactory transplants (Fig. 2). Similar immunoreative axons were never observed caudal to the transection site in the controls (seven animals examined), although such fibres were always seen rostrally in all animals (Fig. 2). In the olfactory-transplanted rats, the mean distance of serotonergic axons from the caudal interface of the graft was 3.2 ± 0.6 mm, the longest distance being 4 mm. All of these serotonergic fibres were located in the grey matter of the dorsal horn.
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The injection site and lesioned cord was checked in three animals in each group to confirm that there was no spread of fluorogold across the lesion. Brainstem raphe neurones were retrogradely labelled with fluorogold only in animals that received transplants of olfactory lamina propria (Fig. 3). There was no retrograde transport of fluorogold in control animals.
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Discussion |
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The present study shows that olfactory lamina propria grafts can promote functional recovery after complete transection of the spinal cord, even when the initial transection was made 4 weeks previously. There was no recovery when respiratory lamina propria grafts were made in place of olfactory lamina propria. The locomotor recovery observed after delayed transplantation of olfactory lamina propria (the present experiments) is similar to that seen after transplantation of olfactory lamina propria and cultured nasal olfactory ensheathing cells and at the time of spinal transection (‘acute transplants’) (Lu et al., 2001
). This locomotor recovery appears to be dependent upon descending spinal motor pathways, as it is abolished after spinal cord re-transection (Lu et al., 2001). In both the delayed and acute transplants, there was a gradual increase in the movement of the hindlimbs over the 10-week observation period following the transplantation, with differences between controls and transplanted animals evident after 3 or 4 weeks. At the end of the observation period of 10 weeks, the use of the hindlimbs was still improving. The BBB scores reflect this. None of the control animals in either study (a total of 29 animals) achieved a score of more than 2. In comparison, five out of the six animals in the present study achieved a score of at least 3 (83%), a similar proportion to that achieved in the acute transplantation study (15 out of 19; 79%). The BBB scale is a 21-point scale, designed to assess hindlimb locomotor recovery after thoracic spinal cord injury (Basso et al., 1995). This scale categorizes combinations of hindlimb joint movements, trunk position and stability, stepping coordination, paw placement, toe clearance and tail position. The scale represents sequential stages of recovery that rats attain after spinal cord injury; it is widely known and accepted and provides a useful comparison with other studies. In the present study, the maximum score obtained 10 weeks after transplantation was a score of 6. This represents movement in ankle, knee and hip joints and dorsiflexion of the foot with no coordination of movement between fore and hindlimbs and no weight-bearing. The maximum score after acute transplantation was 8, achieved 10 weeks after olfactory lamina propria transplants and 8 weeks after transplants of purified olfactory ensheathing cells (Lu et al., 2001). The BBB score we observed here 10 weeks after delayed transplantation is similar to that observed 20 weeks after acute transplantation of activated macrophages into the transected spinal cord (Rapalino et al., 1998). This BBB score is also similar to the hindlimb movements reported previously 2 months after acute transplantation of olfactory ensheathing cells isolated from the olfactory bulb (Rámon-Cueto et al., 2000). It is possible that the BBB score would improve with further time after delayed transplantation, but this could not be explored further because the time-limit used here was imposed by the university ethics committees.
The regeneration of descending brainstem axons into the spinal cord caudal to the transection and graft site agrees with our earlier finding (Lu et al., 2001), and was also observed after acute transplantations of olfactory bulb ensheathing cells into the transected spinal cord (Rámon-Cueto et al., 2000). Brainstem nuclei, such as raphe magnus neurones, brainstem reticular formation and locus coeruleus and red nucleus, normally project their axons to all levels of the spinal cord (Tracey, 1985). Of these, we observed regeneration of axons from the raphe nucleus 10 weeks after delayed transplantation, although after acute transplantation we additionally observed regeneration of cells from the nucleus gigantocellularis (Lu et al., 2001). These descending serotonergic paths are known to modulate spinal reflexes (Magladery et al., 1951; Anderson, 1983; Burke et al., 1984) as well as regulating transmission in sensory pathways (Frazer et al., 1990; Marlier et al., 1991). The degree of behavioural recovery after delayed transplantation would be consistent with the modulation of segmental reflexes as shown after acute implantation (Lu et al., 2001). Thus, it is possible that the serotonergic regeneration seen here could have provided the modulation needed for the degree of ankle, knee or hip movement.
Transplantation of olfactory lamina propria has the dual advantage of being a reservoir for olfactory ensheathing cells as well as providing a physical bridge between the exposed stumps of the spinal cord. The respiratory lamina propria provides a similar bridging function but contains no olfactory ensheathing cells (Lu et al., 2001), although it does contain most of the other cell types present in the olfactory lamina propria. The olfactory lamina propria integrates with the host to the extent that many cells move from the transplant and migrate significant distances rostrally and caudally into the spinal cord (Lu et al., 2001). Although we did not confirm that these were olfactory ensheathing cells immunochemically, similar migration of cells was not observed after respiratory lamina propria transplants, ruling out a contribution from shared cell types such as fibroblasts, endothelium or Schwann cells from the trigeminal nerve.
The normal role of olfactory ensheathing cells is to assist the growth of new axons during the continual regeneration of the olfactory sensory neurones, which occurs well into old age (Murrell et al., 1996). Mechanisms for the promotion of spinal regeneration by olfactory ensheathing cells are not known, but a contributing factor may be their local secretion of growth factors, as is postulated for Schwann cells (Heumann et al., 1987; Meyer et al., 1992). Spinal axon regeneration can be stimulated up to 4 weeks post-injury by local application of growth factors such as nerve growth factor, brain-derived growth factor and ciliary neurotrophic factor (Ye and Houle, 1997). This may explain, in part, the efficacy of olfactory ensheathing cells, since they express all these growth factors (Guthrie et al., 1997; Woodhall et al., 2001). Olfactory ensheathing cells also express a variety of other growth factors that could promote growth and survival of surrounding cells after transplantation including acidic and basic fibroblast growth factors, transforming growth factor-
, platelet-derived growth factors- and -ß and insulin-like growth factor-I and -II (for a recent review, see Mackay-Sim and Chuah, 2000).
Human olfactory mucosa is relatively easy to biopsy via a simple endoscopic procedure under general (Féron et al., 1998) or local anaesthesia (Féron et al., 1999b). Although there is no published method for culturing olfactory ensheathing cells from humans, they can be cultured from rat olfactory mucosa. The olfactory lamina propria containing the olfactory ensheathing cells can be removed from the overlying olfactory epithelium (Féron et al., 1999a), dissociated and cultured to produce a population of 50% olfactory ensheathing cells (Lu et al., 2001). Current experiments in our laboratory are directed towards developing this method for the culture of human olfactory ensheathing cells from nasal biopsies, with the aim of providing large numbers of pure olfactory ensheathing cells for transplantation.
The present results provide an important step towards the use of nasal olfactory ensheathing cell transplantation for human clinical therapy by demonstrating that these cells can be useful in promoting functional recovery when transplantation is delayed after the original spinal cord injury. Although it is hard to compare the relative time-delay in humans represented by 1 month in the rat, the present results provide further evidence for the potential for use of nasal olfactory ensheathing cells in autologous transplantation in humans (Lu et al., 2001).
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Acknowledgements |
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We thank Ms Cathy Gorrie for her technical assistance. A.M.-S. is supported by the Garnett Passe and Rodney Williams Memorial Foundation. F.F. is supported by Queensland Health.
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 S. D. Primeaux, M. Tong, and G. M. Holmes Effects of chronic spinal cord injury on body weight and body composition in rats fed a standard chow diet Am J Physiol Regulatory Integrative Comp Physiol, September 1, 2007; 293(3): R1102 - R1109. [Abstract] [Full Text] [PDF]
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 Z. Su, L. Cao, Y. Zhu, X. Liu, Z. Huang, A. Huang, and C. He Nogo enhances the adhesion of olfactory ensheathing cells and inhibits their migration J. Cell Sci., June 1, 2007; 120(11): 1877 - 1887. [Abstract] [Full Text] [PDF]
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 P. Lu, H. Yang, M. Culbertson, L. Graham, A. J. Roskams, and M. H. Tuszynski Olfactory Ensheathing Cells Do Not Exhibit Unique Migratory or Axonal Growth-Promoting Properties after Spinal Cord Injury J. Neurosci., October 25, 2006; 26(43): 11120 - 11130. [Abstract] [Full Text] [PDF]
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 D. Bouhy, B. Malgrange, S. Multon, A.-L. Poirrier, F. Scholtes, J. Schoenen, and R. Franzen Delayed GM-CSF treatment stimulates axonal regeneration and functional recovery in paraplegic rats via an increased BDNF expression by endogenous macrophages FASEB J, June 1, 2006; 20(8): 1239 - 1241. [Abstract] [Full Text] [PDF]
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 J- M Nothias, T. Mitsui, J. S. Shumsky, I. Fischer, M. D. Antonacci, and M. Murray Combined Effects of Neurotrophin Secreting Transplants, Exercise, and Serotonergic Drug Challenge Improve Function in Spinal Rats Neurorehabil Neural Repair, December 1, 2005; 19(4): 296 - 312. [Abstract] [PDF]
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F. Feron, C. Perry, J. Cochrane, P. Licina, A. Nowitzke, S. Urquhart, T. Geraghty, and A. Mackay-Sim Autologous olfactory ensheathing cell transplantation in human spinal cord injury Brain, December 1, 2005; 128(12): 2951 - 2960. [Abstract] [Full Text] [PDF]
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M. W. Richter, P. A. Fletcher, J. Liu, W. Tetzlaff, and A. J. Roskams Lamina Propria and Olfactory Bulb Ensheathing Cells Exhibit Differential Integration and Migration and Promote Differential Axon Sprouting in the Lesioned Spinal Cord J. Neurosci., November 16, 2005; 25(46): 10700 - 10711. [Abstract] [Full Text] [PDF]
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J. G. Boyd, R. Doucette, and M. D. Kawaja Defining the role of olfactory ensheathing cells in facilitating axon remyelination following damage to the spinal cord FASEB J, May 1, 2005; 19(7): 694 - 703. [Abstract] [Full Text] [PDF]
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M. J. Ruitenberg, D. B. Levison, S. V. Lee, J. Verhaagen, A. R. Harvey, and G. W. Plant NT-3 expression from engineered olfactory ensheathing glia promotes spinal sparing and regeneration Brain, April 1, 2005; 128(4): 839 - 853. [Abstract] [Full Text] [PDF]
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M. A. Oatway, Y. Chen, J. C. Bruce, G. A. Dekaban, and L. C. Weaver Anti-CD11d Integrin Antibody Treatment Restores Normal Serotonergic Projections to the Dorsal, Intermediate, and Ventral Horns of the Injured Spinal Cord J. Neurosci., January 19, 2005; 25(3): 637 - 647. [Abstract] [Full Text] [PDF]
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M. D. Dunning, A. Lakatos, L. Loizou, M. Kettunen, C. ffrench-Constant, K. M. Brindle, and R. J. M. Franklin Superparamagnetic Iron Oxide-Labeled Schwann Cells and Olfactory Ensheathing Cells Can Be Traced In Vivo by Magnetic Resonance Imaging and Retain Functional Properties after Transplantation into the CNS J. Neurosci., November 3, 2004; 24(44): 9799 - 9810. [Abstract] [Full Text] [PDF]
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M. Sasaki, K. L. Lankford, M. Zemedkun, and J. D. Kocsis Identified Olfactory Ensheathing Cells Transplanted into the Transected Dorsal Funiculus Bridge the Lesion and Form Myelin J. Neurosci., September 29, 2004; 24(39): 8485 - 8493. [Abstract] [Full Text] [PDF]
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 J. G. Boyd, J. Lee, V. Skihar, R. Doucette, and M. D. Kawaja LacZ-expressing olfactory ensheathing cells do not associate with myelinated axons after implantation into the compressed spinal cord PNAS, February 17, 2004; 101(7): 2162 - 2166. [Abstract] [Full Text] [PDF]
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N. Keyvan-Fouladi, G. Raisman, and Y. Li Functional Repair of the Corticospinal Tract by Delayed Transplantation of Olfactory Ensheathing Cells in Adult Rats J. Neurosci., October 15, 2003; 23(28): 9428 - 9434. [Abstract] [Full Text] [PDF]
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Y. Li, Y. Sauve, D. Li, R. D. Lund, and G. Raisman Transplanted Olfactory Ensheathing Cells Promote Regeneration of Cut Adult Rat Optic Nerve Axons J. Neurosci., August 27, 2003; 23(21): 7783 - 7788. [Abstract] [Full Text] [PDF]
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M. J. Ruitenberg, G. W. Plant, F. P. T. Hamers, J. Wortel, B. Blits, P. A. Dijkhuizen, W. H. Gispen, G. J. Boer, and J. Verhaagen Ex Vivo Adenoviral Vector-Mediated Neurotrophin Gene Transfer to Olfactory Ensheathing Glia: Effects on Rubrospinal Tract Regeneration, Lesion Size, and Functional Recovery after Implantation in the Injured Rat Spinal Cord J. Neurosci., August 6, 2003; 23(18): 7045 - 7058. [Abstract] [Full Text] [PDF]
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A. Lakatos, P. M. Smith, S. C. Barnett, and R. J. M. Franklin Meningeal cells enhance limited CNS remyelination by transplanted olfactory ensheathing cells Brain, March 1, 2003; 126(3): 598 - 609. [Abstract] [Full Text] [PDF]
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Y. Li, P. Decherchi, and G. Raisman Transplantation of Olfactory Ensheathing Cells into Spinal Cord Lesions Restores Breathing and Climbing J. Neurosci., February 1, 2003; 23(3): 727 - 731. [Abstract] [Full Text] [PDF]
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