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K Mukhida, M Hong,
G B Miles,
T Phillips,
B A Baghbaderani,
M McLeod,
N Kobayashi,
A Sen,
L A Behie,
R M Brownstone,
I Mendez
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ABSTRACT: The current transplantation paradigm for Parkinson's disease that places foetal dopaminergic cells in the striatum neither normalizes neuronal activity in basal ganglia structures such as the substantia nigra (SN) and subthalamic nucleus (STN) nor leads to complete functional recovery. It was hypothesized that restoration of parkinsonian deficits requires inhibition of the pathological overactivity of the STN and SN in addition to restoration of dopaminergic activity in the striatum. To achieve inhibition, a multitargeted basal ganglia transplantation strategy using GABAergic cells derived from either foetal striatal primordia (FSP) cells or human neural precursor cells (hNPCs) expanded in suspension bioreactors was investigated. In hemiparkinsonian rats, transplantation of foetal rat dopaminergic cells in the striatum in conjunction with GABAergic grafts in the STN and/or SN promoted significant improvement in forelimb akinesia and motor function compared to transplantation of intrastriatal dopaminergic grafts alone or in conjunction with undifferentiated hNPCs. In culture, FSP cells exhibited neuronal electrophysiological properties. However, recordings from GABAergic hNPCs revealed limited ionic conductances and an inability to fire action potentials. Despite this, they were almost as efficacious as FSP cells in inducing functional recovery following transplantation, suggesting that such recovery may have been mediated by secretion of GABA rather than by functional integration into the host. Thus, restoration of dopaminergic activity to the striatum in concert with inhibition of the STN and SN by GABAergic grafts may be beneficial for improving clinical outcomes in patients with Parkinson's disease and potential clinical application of this strategy may be enhanced by the use of differentiated hNPCs.
Brain 09/2008; 131(Pt 8):2106-26. · 9.46 Impact Factor
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ABSTRACT: Although neural transplantation of fetal dopaminergic cells is a promising therapy for Parkinson's disease, poor transplanted cell survival limits its efficacy. In the present study it was hypothesized that the use of Poloxamer 188 (P188), a non-ionic surfactant, during cell preparation and transplantation may protect cells from associated mechanical injury and thus improve transplanted cell survival in a rat model of Parkinson's disease. Fetal rat dopaminergic tissue was dissociated in media with or without P188 and then cultured for 1 week or transplanted into the striatum of rats with unilateral 6-hydroxydopamine lesions of the nigrostriatal dopaminergic pathway. Fetal dopaminergic cell survival and reinnervation of the host brain were examined using tyrosine hydroxylase immunohistochemistry and stereological quantification. The number of surviving tyrosine hydroxylase-immunoreactive cells in vitro and in vivo was significantly increased by 2.2-fold by incubating fetal dopaminergic cells with P188 during tissue dissociation. Furthermore, the striatal reinnervation in parkinsonian rats that received intrastriatal transplants of P188-exposed dopaminergic cells was significantly enhanced (1.8-fold increase) compared with rats that received non-P188-treated cells. In conclusion, P188 protects fetal dopaminergic cells from mechanical injury by increasing cell survival and enhances dopaminergic fibre outgrowth into the transplanted striatum. Use of P188 may thus be an important adjunct to improve the clinical efficacy of neural transplantation for Parkinson's disease.
European Journal of Neuroscience 02/2008; 27(1):43-52. · 3.63 Impact Factor
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ABSTRACT: Glial cell-line derived neurotrophic factor (GDNF) enhances dopamine (DA) cell survival and fiber outgrowth, and may be beneficial in enhancing cell restorative strategies for Parkinson's disease (PD). However, GDNF may have different roles for transplanted DA cell sub-types. The present in vitro study investigated the effect of GDNF on the survival of rat DA cells displaying a phenotype consistent with either the substantia nigra [A9 cells immunopositive for tyrosine hydroxylase (TH) and G-protein-gated inwardly rectifying potassium channel subunit 2 (GIRK2)] or with the ventral tegmental area [A10 cells immunopositive for TH and calbindin]. It was found that a single exposure of GDNF enhanced the number of DA cells of an A9 phenotype, without affecting DA cells of an A10 phenotype. Conversely, repeated GDNF exposure did not alter the survival of A9 phenotypic cells, but doubled the percentage of A10 cells. It was concluded that GDNF administration may affect dopaminergic cells differently depending on time and degree of GDNF exposure. For cell transplantation in PD, long-term GDNF administration may result in detrimental effects for transplanted A9 TH+ cells as this may introduce competition with A10 TH+ cells for survival and fiber outgrowth into the host striatum. These results may have important implications for clinical neural transplantation in PD.
Neuroscience 08/2007; 147(3):712-9. · 3.38 Impact Factor
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ABSTRACT: Low dopaminergic cell survival and suboptimal fiber reinnervation are likely major contributing factors for the limited benefits of neural transplantation in Parkinson's disease (PD) patients. Glial cell lined-derived neurotrophic factor (GDNF) has been shown to enhance dopaminergic cell survival and fiber outgrowth of the graft site as well as promote behavioral recovery in rodent models of PD, while erythropoietin (EPO) can produce dopaminergic neuroprotective effects against 6-hydroxydopamine (6-OHDA) exposure on cultured neurons and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-treated mice. The aim of this study was to determine if fetal ventral mesencephalic (FVM) tissue exposed to hibernation media containing a combination of GDNF and EPO could enhance dopaminergic graft survival, striatal reinnervation and functional recovery in a 6-OHDA rodent model of PD. FVM tissue was dissected from 14-day-old rat fetuses and placed for 6 days in hibernation media alone, and in hibernation media that received either a daily administration of GDNF, EPO or a combination of GDNF and EPO. Following hibernation, FVM cells were transplanted as a single cell suspension into the striatum of unilateral 6-OHDA-lesioned rats. Rotational behavioral assessment revealed animals that received FVM tissue exposed to GDNF, EPO or the combination of both drugs had accelerated functional recovery. Immunohistochemical and stereological assessment revealed a significant increase in graft fiber density and angiogenesis into the graft when compared with control. These findings suggest that the hibernation of FVM tissue in a combination of GDNF and EPO can enhance graft efficacy and may have important implications for tissue preparation protocols for clinical neural transplantation in PD.
European Journal of Neuroscience 08/2006; 24(2):361-70. · 3.63 Impact Factor
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ABSTRACT: The development of new cell replacement strategies using neural stem cells (NSC) may provide an alternative and unlimited cell source for clinical neural transplantation in neurodegenerative diseases such as Parkinson's and Huntington's disease. The clinical application of neural transplantation using NSC will therefore depend upon the availability of clinical grade NSC that are generated in unlimited quantities in a standardized manner. In order to investigate the utility of NSC in clinical neural transplantation, undifferentiated murine NSC were first expanded for an extended period of time in suspension bioreactors containing a serum-free medium. Following expansion in suspension bioreactors, NSC were still able to differentiate in vitro into both astrocytes and neurons after exposure to brain-derived neurotrophic factor (BDNF), suggesting that bioreactor expansion does not alter cell lineage potentiality. Undifferentiated bioreactor-expanded NSC were then transplanted into the rodent striatum. Immunohistochemical examination revealed undifferentiated bioreactor-expanded NSC survived transplantation for up to 8 weeks and expressed the astrocytic immunohistochemical marker glial fibrillary acidic protein (GFAP), suggesting that the host striatal environment influences NSC cell fate upon transplantation. Moreover, no tumor formation was observed within the graft site, indicating that NSC expanded in suspension bioreactors for an extended period of time are a safe source of tissue for transplantation. Future studies should focus on predifferentiating NSC towards specific neuronal phenotypes prior to transplantation in order to restore behavioral function in rodent models of neurodegenerative disease.
Cell Transplantation 02/2006; 15(8-9):689-97. · 5.13 Impact Factor
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ABSTRACT: The current transplantation strategy in experimental and clinical Parkinson's disease (PD) has been to place nigral dopaminergic grafts not in their ontogenic site (substantia nigra) but in their target area (striatum). Although intrastriatal dopaminergic grafts are capable of reinnervating the striatum, they fail to reinnervate the nigra, which may be an important factor limiting the efficacy of fetal tissue transplantation in parkinsonian patients. We have previously shown that simultaneous intrastriatal and intranigral dopaminergic grafts (double grafts) may provide a more complete restoration of the nigrostriatal circuitry (Mendez et al. [1996] J Neurosci 16:7216-7227; Mendez and Hong [1997] Brain Res 778:194-205). In the present study, we investigated the contribution of the intranigral graft to functional recovery in double-grafted hemiparkinsonian rats. Twenty Wistar rats with unilateral 6-hydroxydopamine (6-OHDA) lesions of the nigrostriatal pathway were divided into two groups and received either double grafts (n = 10) or intrastriatal grafts alone (n = 10). Following transplantation, both intrastriatally and double-grafted animals had a significant decrease in rotational behavior. However, only animals with double grafts exhibited a significant increase in contralateral adjusting step performance. The intranigral graft was subsequently lesioned by a second 6-OHDA injection. Following the second lesion, animals with double grafts exhibited a significant reversal of rotational behavior and a 51% reduction in contralateral adjusting step performance. The reversal in functional recovery correlated with a significant loss of intranigral grafted neurons. These results suggest that the intranigral graft has an important role in the functional recovery of double-grafted animals. Restoration of dopaminergic innervation to both the nigra and the striatum may be crucial for optimizing graft efficacy and may be a superior strategy in neural transplantation for PD.
The Journal of Comparative Neurology 11/2000; 426(1):106-16. · 3.81 Impact Factor
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I Mendez,
A Dagher, M Hong,
A Hebb,
P Gaudet,
A Law,
S Weerasinghe,
D King,
J Desrosiers,
S Darvesh,
T Acorn,
H Robertson
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ABSTRACT: The authors have studied the ability of glial cell line-derived neurotrophic factor (GDNF) to promote survival of human fetal dopaminergic tissue after a storage period of 6 days and subsequent implantation into the human putamen. The results indicate that GDNF promotes survival of stored dopaminergic cells. Cells stored without GDNF had a 30.1% decrease in survival time compared with those exposed to GDNF. Two patients with Parkinson's disease received bilateral putaminal implants of fetal dopaminergic cells exposed to GDNF for 6 days and showed enhancement of graft survival as assessed by positron emission tomography scanning. A mean increase of 107% in putaminal fluorodopa uptake from baseline values was observed 12 months postgrafting.
Journal of Neurosurgery 06/2000; 92(5):863-9. · 2.96 Impact Factor
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ABSTRACT: Experimental and clinical studies of neural transplantation in Parkinson's disease have focused on the placement of fetal dopaminergic grafts not in their ontogenic site (substantia nigra) but in the main nigral target area (striatum). The reason for this is the apparent inability of intranigral nigral grafts to extend axons for long distances reinnervating the ipsilateral striatum. This review presents previous work by our laboratory [I. Mendez, M. Hong, Reconstruction of the striato-nigro-striatal circuitry by simultaneous double dopaminergic grafts: a tracer study using fluorogold and horseradish peroxidase, Brain Res. 778 (1997) 194-205; I. Mendez, D. Sadi, M. Hong., Reconstruction of the nigrostriatal pathway by simultaneous intrastriatal and intranigral dopaminergic transplants, J. Neurosci. 16 (1996) 7216-7227] using a new transplantation strategy aimed at restoring dopaminergic innervation of the nigra and striatum by simultaneous dopaminergic transplants placed in the substantia nigra and ipsilateral striatum (double grafts) in the 6-hydroxydopamine lesioned adult rat brain. These double grafts achieve not only greater striatal reinnervation than the standard intrastriatal grafts but also produce a faster and more complete behavioural recovery six weeks after transplantation. Injection of the retrograde tracer fluorogold into the striatum and nigra resulted in fluorescent labeled cells within the intranigral graft and the intrastriatal graft and surrounding striatum, respectively suggesting that these double grafts promote at least partial reconstruction of the nigrostriatal dopaminergic pathway. This double graft strategy may have potential implications in clinical neural transplantation for Parkinson's disease.
Brain Research Reviews 05/2000; 32(1):328-39. · 10.34 Impact Factor
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ABSTRACT: The clinical findings on neural transplantation for Parkinson's disease (PD) reported thus far are promising but many issues must be addressed before neural transplantation can be considered a routine therapeutic option for PD. The future of neural transplantation for the treatment of neurological disorders may rest in the discovery of a suitable alternative cell type for fetal tissue. One such alternative may be neurons derived from a human teratocarcinoma (hNT). hNT neurons have been shown to survive and integrate within the host brain following transplantation and provide functional recovery in animal models of stroke and Huntington's disease. In this study, we describe the transplantation of hNT neurons in the substantia nigra (SN) and striatum of the rat model for PD. Twenty-seven rats were grafted with one of three hNT neuronal products; hNT neurons, hNT-DA neurons, or lithium chloride (LiCl) pretreated hNT-DA neurons. Robust hNT grafts could be seen with anti-neural cell adhesion molecule and anti-neuron-specific enolase immunostaining. Immunostaining for tyrosine hydroxylase (TH) expression revealed no TH-immunoreactive (THir) neurons in any animals with hNT neuronal grafts. THir cells were observed in 43% of animals with hNT-DA neuronal grafts and all animals with LiCl pretreated hNT-DA neuronal grafts (100%). The number of THir neurons in these animals was low and not sufficient to produce significant functional recovery. In summary, this study has demonstrated that hNT neurons survive transplantation and express TH in the striatum and SN. Although hNT neurons are promising as an alternative to fetal tissue and may have potential clinical applications in the future, further improvements in enhancing TH expression are needed.
Experimental Neurology 05/2000; 162(2):350-60. · 4.70 Impact Factor
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ABSTRACT: The authors present a simple, reliable, and safe system for performing neural transplantation in the human brain. The device consists of a transplantation cannula and microinjector system that has been specifically designed to reduce implantation-related trauma and to maximize the number of graft deposits per injection. The system was evaluated first in an experimental rat model of Parkinson's disease (PD). Animals in which transplantation with this system had been performed showed excellent graft survival with minimal trauma to the brain. Following this experimental stage, the cannula and microinjector system were used in eight patients with PD enrolled in the Halifax Neural Transplantation Program who received bilateral putaminal transplants of fetal ventral mesencephalic tissue. A total of 16 transplantation operations and 64 trajectories were performed in the eight patients, and there were no intraoperative or perioperative complications. Magnetic resonance imaging studies obtained 24 hours after surgery revealed no evidence of tissue damage or hemorrhage. Transplant survival was confirmed by fluorodopa positron emission tomography scans obtained 6 and 12 months after surgery. As neural transplantation procedures for the treatment of neurological conditions evolve, the ability to deliver viable grafts safely will become critically important. The device presented here has proved to be of value in maximizing the number of graft deposits while minimizing implantation-related trauma to the host brain.
Journal of Neurosurgery 04/2000; 92(3):493-9. · 2.96 Impact Factor
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ABSTRACT: The goal of this study was to investigate the ability of fetal dopaminergic neurons to improve complex sensorimotor behavior.
The authors obtained ventral mesencephalic tissue from 14-day-old rat fetuses. The cells were exposed to glial cell line-derived neurotrophic factor (GDNF) prior to transplantation into rats with unilateral 6-hydroxydopamine lesions of the dopaminergic nigrostriatal pathway. Animals that received 400,000 cells exposed to GDNF demonstrated significant improvement in contralateral forelimb function and showed improvement in rotational behavior faster than animals that received cells not exposed to GDNF. Increasing the number of implanted cells to 800,000 exposed to GDNF did not result in any additional improvement in functional recovery.
As neural grafting procedures in the nervous system evolve and genetically engineered cells or stem cells replace fetal tissue, crucial questions about cell number and trophic regulation will need to be addressed. This study demonstrates that grafting of 400,000 cells exposed to GDNF before transplantation has a beneficial effect in the restoration of complex sensorimotor behavior.
Journal of Neurosurgery 07/1998; 88(6):1088-95. · 2.96 Impact Factor
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ABSTRACT: Glial cell line-derived neurotrophic factor, the newest member of the transforming growth factor-beta superfamily, has been shown to promote the survival and differentiation of dopaminergic neurons in the ventral mesencephalon. Glial cell line-derived neurotrophic factor has been implicated in both the in vitro and in vivo recovery of mesencephalic dopaminergic cells challenged with the neurotoxins 1-methyl-4-phenylpyridinium and 6-hydroxydopamine. Previous studies have shown increased survival of intrastriatally transplanted dopaminergic cells when followed by infusion of neurotrophic factors such as basic fibroblast growth factor, brain-derived neurotrophic factor and glial cell line-derived neurotrophic factor. However, the effects of glial cell line-derived neurotrophic factor co-administered with dopaminergic cells prior to implantation in the host striatum have not been studied. In the present study, the hypothesis was that treating fetal ventral mesencephalic tissue containing the dopaminergic substantia nigra with glial cell line-derived neurotrophic factor either during storage or at the time of transplantation, would enhance grafted dopaminergic cell survival and functional reinnervation of the host striatum in the unilaterally 6-hydroxydopamine-lesioned rat. To test this hypothesis, two experiments were performed. In the first experimental group (n = 7), fetal ventral mesencephalons from embryonic day 14 rats were maintained in hibernation medium containing glial cell line-derived neurotrophic factor (1 migrogram/ml) at 4 degrees C for six days prior to dissociation and stereotactic implantation into the host striatum: the control group (n = 5) received tissue hibernated without glial cell line-derived neurotrophic factor. The second experimental group (n = 8) received fresh fetal ventral mesencephalic tissue treated with glial cell line-derived neurotrophic factor (0.2 microgram/microliter) while the control group (n = 5) received the fresh graft with no glial cell line-derived neurotrophic factor. Transplantation success was assessed by behavioural analysis (rotometry) and tyrosine hydroxylase immunohistochemistry. Cell counts of tyrosine hydoxylase-stained sections revealed a statistically significant increase in tyrosine hydroxylase-positive neurons in grafts exposed to glial cell line-derived neurotrophic factor during hibernation as compared to control grafts. In addition, there was a statistically significant enhancement of fibre density in the glial cell line-derived neurotrophic factor hibernation graft group as compared to the glial cell line-derived neurotrophic factor fresh graft group. Behavioural analysis three weeks post-grafting exhibited a statistically significant decrease in amphetamine-induced rotations in animals transplanted with glial cell line-derived neurotrophic factor grafts as compared to control grafts. These findings suggest that storing dopaminergic cells in a glial cell line-derived neurotrophic factor-containing medium prior to transplantation increases graft survival, graft derived fibre outgrowth, and behavioural recovery in the adult host. This observation has potential implications for enhancing the efficacy of neural transplantation in the treatment of Parkinson's disease.
Neuroscience 04/1998; 83(2):363-72. · 3.38 Impact Factor
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ABSTRACT: The main strategy in neural transplantation for Parkinson's disease (PD) has been the ectopic placement of dopaminergic grafts in the striatum in order to restore dopaminergic innervation to the host striatum. Although intrastriatal transplants usually improve asymmetric rotational behavior in the 6-hydroxydopamine lesioned rodent model of PD, they are less likely to completely restore the more complex sensorimotor behavioral deficits induced by dopamine loss. Re-establishment of the nigrostriatal circuitry and dopaminergic reinnervation of the substantia nigra may be necessary to promote a more complete restoration of function in the dopamine depleted brain and improve the clinical efficacy of dopaminergic transplants. Recently, we demonstrated the reconstruction of the nigrostriatal pathway by simultaneous intrastriatal and intranigral dopaminergic transplants [Mendez et al., J. Neurosci. 16 (1996) 7216-7227.]. Using this strategy, it was found that placing a graft of embryonic ventral mesencephalic tissue in the striatum promoted the growth and guidance of axons from a similar graft placed homotopically in the ventral mesencephalon. Since it is apparent that developing tissue has the ability to promote axonal growth and guidance along the nigrostriatal pathway, the double grafting strategy may contribute to re-establishing host-graft connectivity. The current study provides evidence of reconstruction of the striato-nigro-striatal loop circuitry by simultaneous intrastriatal and intranigral dopaminergic transplants. Injection of the retrograde tracer fluorogold (FG) into the striatum resulted in fluorescent labeled cells within the intranigral grafts. Similarly injection of FG into the nigra resulted in fluorescent labeled cells within the intrastriatal graft and surrounding striatum. Injection of the anterograde tracer horseradish peroxidase (HRP) resulted in the presence of HRP reaction product throughout the target striatum. These results strongly support the re-establishment of nigrostriatal and striatonigral connections between simultaneous intrastriatal and intranigral dopaminergic transplants and suggest reconstruction of the striato-nigro-striatal loop circuitry.
Brain Research 01/1998; 778(1):194-205. · 2.73 Impact Factor
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ABSTRACT: The main strategy in experimental and clinical neural transplantation in Parkinson's disease has been to place fetal nigral grafts not in their ontogenic site (substantia nigra) but in their target area (striatum). The reason for this ectopic placement is the apparent inability of nigral grafts placed in the ventral mesencephalon (VM) of the adult host to grow axons for long distances that are capable of reaching the ipsilateral striatum and thus restoring the nigrostriatal pathway. The present study demonstrates for the first time that simultaneous dopaminergic transplants (double grafts) placed in the substantia nigra and ipsilateral striatum of rats bearing unilateral 6-hydroxydopamine lesions reconstruct the dopaminergic nigrostriatal pathway in the adult rat brain. Numerous tyrosine hydroxylase-immunoreactive axons were observed arising from the intranigral graft and growing rostrally along the internal capsule and medial forebrain bundle to reinnervate the ipsilateral striatum, which also had received a dopaminergic graft. These double grafts achieved not only greater striatal reinnervation than the standard intrastriatal graft but also a faster and more complete rotational recovery to amphetamine challenge 6 weeks after transplantation. These results suggest strongly that embryonic nigral transplants implanted in the striatum are capable of promoting growth and providing guidance to axons arising from a dopaminergic graft placed homotopically in the VM, resulting in restoration of the dopaminergic nigrostriatal projection. Reconstruction of the nigrostriatal pathway by double grafts may not only achieve substantial striatal reinnervation but may also contribute to the reestablishment of dopaminergic regulation of the nigrostriatal circuitry.
Journal of Neuroscience 12/1996; 16(22):7216-27. · 7.11 Impact Factor
