Cell tracking, survival, and differentiation capacity of adipose-derived stem cells after engraftment in rat tissue.

Adipose tissue is an important source of adipose derived stem cells (ADSCs). These cells have the potential of being used for certain therapies, in which the main objective is to recover the function of a tissue/organ affected by a disease. In order to contribute to repair of the tissue, these cells should be able to survive and carry out their functions in unfavorable conditions after being transplanted. This process requires a better understanding of the biology involved: such as the time cells remain in the implant site, how long they stay there, and whether or not they differentiate into host tissue cells. This report focuses on these questions. ADSC were injected into three different tissues (substantia nigra, ventricle, liver) and they were tracked in vivo with a dual GFP-Luc reporter system. The results show that ADSCs were able to survive up to 4 months after the engraftment and some of them started showing resident cell tissue phenotype. These results demonstrate their long-term capacity of survival and differentiation when injected in vivo.

Therapeutic effects of intranigral transplantation of mesenchymal stem cells in rat models of Parkinson's disease.

Stem cell transplantation is a promising tool for the treatment of neurodegenerative disorders, including Parkinson's disease (PD); however, the therapeutic routes and mechanisms of mechanical approaches to stem cell transplantation must be explored. This study tests the therapeutic effect of transplantation of rat bone marrow mesenchymal stem cells (MSCs) into the substantia nigra (SN) of the PD rat. 5-Bromo-2-deoxyuridine-labeled rat MSCs were transplanted into the SN of the 6-hydroxydopamine-injected side of PD rat brains. The behavioral changes in PD rats were examined before and 4 and 8 weeks after MSC transplantation. The expression of tyrosine hydroxylase (TH) in the SN and the striatum and the survival and differentiation of MSCs were assessed by immunohistochemical and double immunofluorescence techniques. Abnormal behavior of PD rats was significantly improved by the administration of bone marrow MSCs, and the number of TH-positive cells in the SN and the optical density of TH-positive fibers in the striatum were markedly increased. Transplanted MSCs can survive and migrate in the brain and differentiate into nestin-, neuron-specific enolase-, and GFAP-positive cells. Our findings suggest that transplantation of rat bone marrow MSCs into the SN of PD rats may provide therapeutic effects. © 2016 Wiley Periodicals, Inc.

Electrophysiological validation of STN-SNr boundary depicted by susceptibility-weighted MRI.

BACKGROUND: Direct targeting of subthalamic nucleus (STN) without secondary electrophysiological verification during deep brain stimulation (DBS) is replacing atlas-based indirect targeting techniques. Recent groups have reported increased contrast and better delineation of STN and substantia nigra (SNr) in susceptibility-weighted imaging protocols (SWI). We aim to validate the STN-SNr boundary seen in MRI- SWI by correlating with intraoperative microelectrode recordings (MER) as a part of developing a multi-contrast DBS MRI planning protocol. METHODS: Prospective service evaluation involving electrophysiological verification by correlation of MER trajectory and STN-SNr boundary seen in SWI in seven consecutive patients undergoing DBS surgery were analyzed. The angle of inclination of the STN-SNr boundary and DBS trajectory in the coronal plane were calculated. Considering 4-mm dispersion of a coronal 3 MER array, we predicted, measured, and correlated the depths at which each electrode engaged the boundary. RESULTS: All central microelectrodes identified the STN-SNr boundary within 1 mm of the predicted depth with 100 % accuracy. Ninety percent of the lateral MER identified the STN-SNr boundary as predicted from SWI and angle of the encounter of the MER front. CONCLUSIONS: The study demonstrates that STN morphology can be depicted using SWI MRI and coincides reliably with the electrophysiological MER boundary. Thus, this imaging modality can be used to refine STN direct targeting protocols in DBS surgery for PD.

Embryonic stem cell-derived L1 overexpressing neural aggregates enhance recovery in Parkinsonian mice.

Parkinson's disease is the second most common neurodegenerative disease, after Alzheimer's disease, and the most common movement disorder. Drug treatment and deep brain stimulation can ameliorate symptoms, but the progressive degeneration of dopaminergic neurons in the substantia nigra eventually leads to severe motor dysfunction. The transplantation of stem cells has emerged as a promising approach to replace lost neurons in order to restore dopamine levels in the striatum and reactivate functional circuits. We have generated substrate-adherent embryonic stem cell-derived neural aggregates overexpressing the neural cell adhesion molecule L1, because it has shown beneficial functions after central nervous system injury. L1 enhances neurite outgrowth and neuronal migration, differentiation and survival as well as myelination. In a previous study, L1 was shown to enhance functional recovery in a mouse model of Huntington's disease. In another study, a new differentiation protocol for murine embryonic stem cells was established allowing the transplantation of stem cell-derived neural aggregates consisting of differentiated neurons and radial glial cells into the lesioned brain. In the present study, this embryonic stem cell line was engineered to overexpress L1 constitutively at all stages of differentiation and used to generate stem cell-derived neural aggregates. These were monitored in their effects on stem cell survival and differentiation, rescue of endogenous dopaminergic neurons and ability to influence functional recovery after transplantation in an animal model of Parkinson's disease. Female C57BL/6J mice (2 months old) were treated with the mitochondrial toxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine intraperitoneally to deplete dopaminergic neurons selectively, followed by unilateral transplantation of stem cell-derived neural aggregates into the striatum. Mice grafted with L1 overexpressing stem cell-derived neural aggregates showed better functional recovery when compared to mice transplanted with wild-type stem cell-derived neural aggregates and vehicle-injected mice. Morphological analysis revealed increased numbers and migration of surviving transplanted cells, as well as increased numbers of dopaminergic neurons, leading to enhanced levels of dopamine in the striatum ipsilateral to the grafted side in L1 overexpressing stem cell-derived neural aggregates, when compared to wild-type stem cell-derived neural aggregates. The striatal levels of gamma-aminobutyric acid were not affected by L1 overexpressing stem cell-derived neural aggregates. Furthermore, L1 overexpressing, but not wild-type stem cell-derived neural aggregates, enhanced survival of endogenous host dopaminergic neurons after transplantation adjacent to the substantia nigra pars compacta. Thus, L1 overexpressing stem cell-derived neural aggregates enhance survival and migration of transplanted cells, differentiation into dopaminergic neurons, survival of endogenous dopaminergic neurons, and functional recovery after syngeneic transplantation in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine mouse model of Parkinson's disease.

Replacing what's lost: a new era of stem cell therapy for Parkinson's disease.

Background: Stem cells hold tremendous promise for regenerative medicine because they can be expanded infinitely, giving rise to large numbers of differentiated cells required for transplantation. Stem cells can be derived from fetal sources, embryonic origins (embryonic stem cells or ESCs) or reprogrammed from adult cell types (induced pluripotent stem cells or iPSCs). One unique property of stem cells is their ability to be directed towards specific cell types of clinical interest, and can mature into functional cell types in vivo. While transplantations of fetal or ESC-derived tissues are known to illicit a host immunogenic response, autologous transplantations using cell types derived from one's own iPSCs eliminate risks of tissue rejection and reduce the need for immunosuppressants. However, even with these benefits, cell therapy comes with significant hurdles that researchers are starting to overcome. In this review, we will discuss the various steps to ensure safety, efficacy and clinical practicality of cell replacement therapy in neurodegenerative diseases, in particular, Parkinson's disease. Main body: Parkinson's disease (PD) results from a loss of dopaminergic neurons from the substantia nigra and is an ideal target for cell replacement therapy. Early trials using fetal midbrain material in the late 1980s have resulted in long term benefit for some patients, but there were multiple shortcomings including the non-standardization and quality control of the transplanted fetal material, and graft-induced dyskinesia that some patients experience as a result. On the other hand, pluripotent stem cells such as ESCs and iPSCs serve as an attractive source of cells because they can be indefinitely cultured and is an unlimited source of cells. Stem cell technologies and our understanding of the developmental potential of ESCs and iPSCs have deepened in recent years and a clinical trial for iPSC-derived dopaminergic cells is currently undergoing for PD patients in Japan. In this focused review, we will first provide a historical aspect of cell therapies in PD, and then discuss the various challenges pertaining to the safety and efficacy of stem cell-based cell transplantations, and how these hurdles were eventually overcome. Conclusion: With the maturity of the iPSC technology, cell transplantation appears to be a safe and effective therapy. Grafts in non-human primates survive and remain functional for more than 2 years after transplantation, with no signs of tumorigenesis, indicating safety and efficacy of the treatment. However, immunosuppressants are still required because of the lack of "universal stem cells" that would not evoke an immune response. The results of ongoing and upcoming trials by a global consortium known as GForce-PD would be highly anticipated because the success of these trials would open up possibilities for using cell therapy for the treatment of PD and other degenerative diseases.

Alpha-synuclein induces migration of BV-2 microglial cells by up-regulation of CD44 and MT1-MMP.

Although there is known to be a marked concentration of reactive microglia in the substantia nigra pars compacta (SNpc) of patients with Parkinson's disease (PD), a disorder in which alpha-synuclein plays a key pathogenic role, the specific roles of alpha-synuclein and microglia remains poorly understood. In this study, we investigated the effects of alpha-synuclein and the mechanisms of invasive microglial migration into the SNpc. We show that alpha-synuclein up-regulates the expressions of the cell adhesion molecule CD44 and the cell surface protease membrane-type 1 matrix metalloproteinase through the extracellular regulated kinases 1/2 pathway. These concurrent inductions increased the generation of soluble CD44 to liberate microglia from the surrounding extracellular matrix for migration. The effects of alpha-synuclein were identical in BV-2 murine microglial cells subjected to cDNA transfection and extracellular treatment. These inductions in primary microglial cultures of C57Bl/6 mice were identical to those in BV-2 cells. alpha-Synuclein-induced microglial migration into the SNpc was confirmed in vivo using a 6-hydroxydopamine mouse model of PD. Our data demonstrate a correlation between alpha-synuclein-induced phenotypic changes and microglial migration. With the recruitment of the microglial population into the SNpc during dopaminergic neurodegeneration, alpha-synuclein may play a role in accelerating the pathogenesis of PD.

Anatomical and functional reconstruction of the nigrostriatal pathway by intranigral transplants.

The main transplantation strategy in Parkinson's disease has been to place dopaminergic grafts not in their ontogenic site, the substantia nigra, but in their target area, the striatum with contrasting results. Here we have used green fluorescent protein transgenic mouse embryos as donors of ventral mesencephalic cells for transplantation into the pre-lesioned substantia nigra of an adult wild-type host. This allows distinguishing the transplanted cells and their projections from those of the host. Grafted cells integrated within the host mesencephalon and expressed the dopaminergic markers tyrosine hydroxylase, vesicular monoamine transporter 2 and dopamine transporter. Most of the dopaminergic cells within the transplant expressed the substantia nigra marker Girk2 while a lesser proportion expressed the ventral tegmental area marker calbindin. Mesencephalic transplants developed projections through the medial forebrain bundle to the striatum, increased striatal dopamine levels and restored normal behavior. Interestingly, only mesencephalic transplants were able to restore the nigrostriatal projections as dopamine neurons originating from embryonic olfactory bulb transplants send projections only in the close vicinity of the transplantation site that did not reach the striatum. Our results show for the first time the ability of intranigral foetal dopaminergic neurons grafts to restore the damaged nigrostriatal pathway in adult mice. Together with our previous findings of efficient embryonic transplantation within the pre-lesioned adult motor cortex, these results demonstrate that the adult brain is permissive to specific and long distance axonal growth. They further open new avenues in cell transplantation therapies applied for the treatment of neurodegenerative disorders such as Parkinson's disease.

Selective deep brain stimulation in the substantia nigra reduces myoclonus in progressive myoclonic epilepsy: a novel observation and short review of the literature.

We report the case of a patient suffering from pharmacotherapy-resistant bilateral progressive myoclonic epilepsy (PME) showing a beneficial response upon selective deep brain stimulation (DBS) of the substantia nigra pars reticulata. As an individual experimental therapeutic approach, we implanted DBS electrodes in the transitional zone between the subthalamic nucleus (STN) and the substantia nigra pars reticulata (SNr). Electrode placement allowed for a selective stimulation of either the STN, SNr, or both targets. Postoperatively, we observed a moderate subjective and objective improvement in positive and negative myoclonus by high-frequency DBS of the STN/SNr transitional zone. However, a systematic exploration of different stimulation settings revealed that monopolar stimulation of the substantia nigra alone was more effective than high-frequency monopolar DBS of either the motor STN (monopolar) or stimulation of both targets (STN/SNr). This observation confirms earlier findings showing that patients with PME benefit from high-frequency DBS. However, in contrast to previous reports stimulating the STN/SNr transitional zone, our patient showed the most significant effect upon selective stimulation of the SNr. We propose that in patients undergoing DBS for myoclonus, at least one electrode contact should be placed in the SNr allowing for selective monopolar stimulation of this target.

Mesenchymal stem cells therapy exerts neuroprotection in a progressive animal model of Parkinson's disease.

Parkinson's disease is a common progressive neurodegenerative disorder caused by the loss of dopaminergic neurons in the substantia nigra. We investigated whether cell therapy with human mesenchymal stem cells (hMSCs) had a protective effect on progressive dopaminergic neuronal loss in vitro and in vivo. In primary mesencephalic cultures, hMSCs treatment significantly decreased MG-132-induced dopaminergic neuronal loss with a significant reduction of caspase-3 activity. In rats received systemic injection of MG-132, hMSCs treatment in MG-132-treated rats dramatically reduced the decline in the number of tyrosine hydroxylase (TH)-immunoreactive cells, showing an approximately 50% increase in the survival of TH-immunoreactive cells in the substantia nigra compared with the MG-132-treated group. Additionally, hMSC treatment significantly decreased OX-6 immunoreactivity and caspase-3 activity. Histological analysis showed that the number of NuMA-positive cells was 1.7% of total injected hMSCs and 35.7% of these cells were double-stained with NuMA and TH. Adhesive-removal test showed that hMSCs administration in MG-132-treated rats had a tendency to decrease in the mean removal time. This study demonstrates that hMSCs treatment had a protective effect on progressive loss of dopaminergic neurons induced by MG-132 in vitro and in vivo. Complex mechanisms mediated by trophic effects of hMSCs and differentiation of hMSCs into functional TH-immunoreactive neurons may work in the neuroprotective process.

Benefits and risks of intranigral transplantation of GABA-producing cells subsequent to the establishment of kindling-induced seizures.

Neural transplantation has been investigated experimentally and clinically for the purpose of developing new treatment options for intractable epilepsy. In the present study we assessed the anticonvulsant efficacy and safety of bilateral allotransplantation of genetically engineered striatal GABAergic rat cell lines into the substantia nigra pars reticulata (SNr). Rats with previously-established seizures, induced by amygdala kindling, were used as a model of temporal lobe epilepsy. Three cell lines were transplanted: (1) immortalized GABAergic cells (M213-2O) derived from embryonic rat striatum; (2) M213-2O cells (CL4) transfected with human GAD67 cDNA to obtain higher GABA synthesis than the parent cell line; and (3) control cells (121-1I), also derived from embryonic rat striatum, but which did not show GAD expression. A second control group received injections of medium alone. Transplantation of M213-2O cells into the SNr of kindled rats resulted in significant but transient anticonvulsant effects. Neither control cells nor medium induced anticonvulsant effects. Strong tissue reactions were, however, induced in the host brain of kindled but not of non-kindled rats, and only in animals that received grafts of genetically modified CL4 cells. These tissue reactions included graft rejection, massive infiltration of inflammatory immune cells, and gliosis. The anticonvulsant effect of M213-2O cells emphasizes the feasibility of local manipulations of seizures by intranigral transplantation of GABA-producing cells. On the other hand, the present data suggest that kindling-induced activation of microglia in the SNr can enhance immune reactions to transplanted cells. In this case, under conditions of further immunological stimulation by CL4 cells, transfected with a human cDNA, substantial immune reactions occurred. Thus, it appears that the condition of the host brain and the production of foreign proteins by transplanted cells have to be considered in estimating the risks of rejection of transplants into the brain.

Regional-specific regulation of BDNF and trkB correlates with nigral dopaminergic cell sprouting following unilateral nigrostriatal axotomy.

Axotomy is a powerful stimulus of axon growth and plastic changes. We investigated the potential role of BDNF/trkB signaling in the sprouting of dopaminergic nigral axons in response to axotomy of the medial forebrain bundle. Tyrosine hydroxylase immunohistochemistry revealed the existence of sprouting mechanisms in the axotomized substantia nigra (SN). Time-course changes of trkB mRNA expression demonstrated a robust increase in an area projecting from the rostral tip of the SN to the glial scar, which coincided with evidence of nigral dopaminergic sprouting. In addition, we found an early loss of this messenger in areas related to the knife cut, which recovered by 7 days postlesion. TrkB down-regulation appeared to be associated to the lesion-induced local damage, as it was restricted to an area showing Fluoro-Jade B- and TUNEL positive cells. In trkB-depleted areas, an inverse correlation between mRNA expressions of BDNF and trkB was apparent. Specific induction of BDNF mRNA was mostly seen in border of areas devoid of trkB mRNA. In contrast, in the areas exhibiting trkB mRNA expression, no BDNF mRNA was detected. We suggest that trkB levels could be a determinant element in regulating BDNF expression. Finally, the search for molecules involved in either promoting or inhibiting axonal growth, demonstrated up-regulation of GAP-43 and Nogo-A mRNA at sites close to the knife transections as early as 1 day postlesion. However, overall, Nogo-A induction was more robust than that seen for GAP-43.

Intranigral transplants of a GABAergic cell line produce long-term alleviation of established motor seizures.

We have previously shown that intranigral transplants of immortalized GABAergic cells decrease the number of kainic acid-induced seizures [Castillo CG, Mendoza S, Freed WJ, Giordano M. Intranigral transplants of immortalized GABAergic cells decrease the expression of kainic acid-induced seizures in the rat. Behav Brain Res 2006;171:109-15] in an animal model. In the present study, recurrent spontaneous behavioral seizures were established by repeated systemic injections of this excitotoxin into male Sprague-Dawley rats. After the seizures had been established, cells were transplanted into the substantia nigra. Animals with transplants of control cells (without hGAD67 expression) or with sham transplants showed a death rate of more than 40% over the 12 weeks of observation, whereas in animals with M213-2O CL-4 transplants, the death rate was reduced to less than 20%. The M213-2O CL-4 transplants significantly reduced the percentage of animals showing behavioral seizures; animals with these transplants also showed a lower occurrence of stage V seizures than animals in the other groups. In vivo and in vitro analyses provided evidence that the GABAergic cells show sustained expression of both GAD67 and hGAD67 cDNA, as well as increased gamma-aminobutyric acid (GABA) levels in the ventral mesencephalon of transplanted animals. Therefore, transplantation of GABA-producing cells can produce long-term alleviation of behavioral seizures in an animal model.

Peripheral nerve grafts implanted into the substantia nigra in patients with Parkinson's disease during deep brain stimulation surgery: 1-year follow-up study of safety, feasibility, and clinical outcome.

OBJECTIVECurrently, there is no treatment that slows or halts the progression of Parkinson's disease. Delivery of various neurotrophic factors to restore dopaminergic function has become a focus of study in an effort to fill this unmet need for patients with Parkinson's disease. Schwann cells provide a readily available source of such factors. This study presents a 12-month evaluation of safety and feasibility, as well as the clinical response, of implanting autologous peripheral nerve grafts into the substantia nigra of patients with Parkinson's disease at the time of deep brain stimulation (DBS) surgery.METHODSStandard DBS surgery targeting the subthalamic nucleus was performed in 8 study participants. After DBS lead implantation, a section of the sural nerve containing Schwann cells was harvested and unilaterally grafted to the substantia nigra. Adverse events were continually monitored. Baseline clinical data were obtained during standard preoperative evaluations. Clinical outcome data were obtained with postoperative clinical evaluations, neuropsychological testing, and MRI at 1 year after surgery.RESULTSAll 8 participants were implanted with DBS systems and grafts. Adverse event profiles were comparable to those of standard DBS surgery with the exception of 1 superficial infection at the sural nerve harvest site. Three participants also reported numbness in the distribution of the sural nerve distal to the harvest site. Motor scores on Unified Parkinson's Disease Rating Scale (UPDRS) part III while the participant was off therapy at 12 months improved from baseline (mean ± SD 25.1 ± 15.9 points at 12 months vs 32.5 ± 9.7 points at baseline). An analysis of the lateralized UPDRS scores also showed a greater overall reduction in scores on the side contralateral to the graft.CONCLUSIONSPeripheral nerve graft delivery to the substantia nigra at the time of DBS surgery is feasible and safe based on the results of this initial pilot study. Clinical outcome data from this phase I trial suggests that grafting may have some clinical benefit and certainly warrants further study to determine if this is an efficacious and neurorestorative therapy.Clinical trial registration no.: NCT01833364 (clinicaltrials.gov).

Neural stem cells display an inherent mechanism for rescuing dysfunctional neurons.

We investigated the hypothesis that neural stem cells (NSCs) possess an intrinsic capacity to "rescue" dysfunctional neurons in the brains of aged mice. The study focused on a neuronal cell type with stereotypical projections that is commonly compromised in the aged brain-the dopaminergic (DA) neuron. Unilateral implantation of murine NSCs into the midbrains of aged mice, in which the presence of stably impaired but nonapoptotic DA neurons was increased by treatment with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), was associated with bilateral reconstitution of the mesostriatal system. Functional assays paralleled the spatiotemporal recovery of tyrosine hydroxylase (TH) and dopamine transporter (DAT) activity, which, in turn, mirrored the spatiotemporal distribution of donor-derived cells. Although spontaneous conversion of donor NSCs to TH(+) cells contributed to nigral reconstitution in DA-depleted areas, the majority of DA neurons in the mesostriatal system were "rescued" host cells. Undifferentiated donor progenitors spontaneously expressing neuroprotective substances provided a plausible molecular basis for this finding. These observations suggest that host structures may benefit not only from NSC-derived replacement of lost neurons but also from the "chaperone" effect of some NSC-derived progeny.

Surgical treatment of ventral mesencephalic cavernoma.

The treatment of an intrinsic midbrain tumour has always been controversial due to the precarious nature of its location. We report a rare example of a cavernoma located in the ventral mesencephalon and presented clinically as Holmes' tremor. In order to access this vital portion of midbrain, we chose a fronto-temporal trans-sylvian route via an orbito-zygomatic craniotomy. The cavernoma was removed en bloc with a longitudinal pial incision between the fronto-pontine fibers and the pyramidal tracts in the peduncle. After the operation, the tremor dramatically disappeared. Through a review and analysis of the literature, we discuss the surgical strategy for management of an anterior midbrain cavernoma. With an optimal surgical approach, fairly safe entry zones on the anterior face of the rostral brainstem may be accessible, which makes it possible for successful resection of a ventral mesencephalic cavernoma without postoperative complications.

Implantation of autologous peripheral nerve grafts into the substantia nigra of subjects with idiopathic Parkinson's disease treated with bilateral STN DBS: a report of safety and feasibility.

OBJECTIVE One avenue of intense efforts to treat Parkinson's disease (PD) involves the delivery of neurotrophic factors to restore dopaminergic cell function. A source of neurotrophic factors that could be used is the Schwann cell from the peripheral nervous system. The authors have begun an open-label safety study to examine the safety and feasibility of implanting an autologous peripheral nerve graft into the substantia nigra of PD patients undergoing deep brain stimulation (DBS) surgery. METHODS Multistage DBS surgery targeting the subthalamic nucleus was performed using standard procedures in 8 study participants. After the DBS leads were implanted, a section of sural nerve containing Schwann cells was excised and unilaterally delivered into the area of the substantia nigra. Adverse events were continuously monitored. RESULTS Eight of 8 participants were implanted with DBS systems and grafts. Adverse event profiles were comparable to those of standard DBS surgery. Postoperative MR images did not reveal edema, hemorrhage, or significant signal changes in the graft target region. Three participants reported a patch of numbness on the outside of the foot below the sural nerve harvest site. CONCLUSIONS Based on the safety outcome of the procedure, targeted peripheral nerve graft delivery to the substantia nigra at the time of DBS surgery is feasible and may provide a means to deliver neurorestorative therapy. Clinical trial registration no.: NCT01833364 ( clinicaltrials.gov ).

Intranigral transplants of immortalized GABAergic cells decrease the expression of kainic acid-induced seizures in the rat.

Repeated systemic administration of low doses of kainic acid (KA) induces spontaneous convulsive seizures [Hellier JL, Patrylo PR, Buckmaster PS, Dudek FE. Recurrent spontaneous motor seizures after repeated low-dose systemic treatment with kainate: assessment of a rat model of temporal lobe epilepsy. Epilepsy Res 1998;31:73-84]. In this study, male Sprague-Dawley animals received intranigral transplants of a control cell line M213-2O, or a cell line transfected with human GAD67 cDNA (M213-2O CL4) [Conejero-Goldberg C, Tornatore C, Abi-Saab W, Monaco MC, Dillon-Carter O, Vawter M, et al. Transduction of human GAD67 cDNA into immortalized striatal cell lines using an Epstein-Barr virus-based plasmid vector increases GABA content. Exp Neurol 2000;161:453-61], or no transplant. Eight weeks after transplantation surgery, KA was administered (5 mg/kg/h) until animals reached stage V seizures as described by Racine [Racine RJ. Modification of seizure activity by electrical stimulation. II. Motor seizure. Electroencephalogr Clin Neurophysiol 1972;32:281-94]. The group transplanted with CL4 required a larger dose of KA and a longer latency to reach a stage V seizure. In addition, this group exhibited significantly fewer stage III and IV seizures. These results indicate that intranigral transplants of a GABA-producing cell line can decrease the number of kainic acid-induced seizures.

[Neuroprotective and neurorestorative therapies for the treatment of Parkinson's disease]. / Terapias neuroprotectoras y neurorestauradoras en el tratamiento de la enfermedad de Parkinson.

Parkinson's disease is the second most common neurodegenerative disorder after Alzheimer's disease. Current therapies are symptomatic and, although these therapies are efficacious during the early stages of the disease, they present important side effects when they are used for a long time. The ideal therapy would be the one that would slow down or stop the progression of the disease. This can be achieved, for instance, with neuroprotective and neurorestorative therapies. Among them, cell therapy and therapy with trophic factors such as glial cell line derived neurotrophic factor (GDNF) are the most challenging and promising ones for the scientific community. Although the use of GDNF as a treatment for Parkinson s disease was proposed several years ago, it is necessary to develop alternative strategies to deliver GDNF appropriately to concrete areas of the brain. Here, the use of microspheres as the most suitable tool for the administration of this neurotrophic factor is discussed.

Synchronized neuronal discharge in the basal ganglia of parkinsonian patients is limited to oscillatory activity.

It has been proposed that an increase in synchronization between neurons in the basal ganglia contributes to the clinical features of Parkinson's disease (PD). To examine this hypothesis, we looked for correlations in the discharge activity of pairs of neurons in the globus pallidus internus (GPi), globus pallidus externus (GPe), and the substantia nigra pars reticulata (SNr). Recordings were performed in PD patients undergoing functional stereotactic mapping for pallidotomy (eight patients) or subthalamic nucleus deep brain stimulation (four patients). A double-microelectrode setup was used to simultaneously record from neurons separated by distances as small as 250 microm. In the five pallidotomy patients without limb tremor during the procedure, none of the 73 GPi pairs and 15 GPe pairs displayed synchronous activity. In the three pallidotomy patients with limb tremor, 6 of 21 GPi pairs and 5 of 29 GPe pairs displayed oscillatory synchronization in the frequency range of the ongoing limb tremor (3-6 Hz) or at higher frequencies (15-30 Hz). Synchronized activity was not observed in the SNr (10 pairs). The findings indicate that oscillatory synchronization between pairs of GPi or GPe neurons is found in patients with limb tremor. These results also suggest that overt neuronal synchronization, which may be attributable to an increase in direct synaptic connections or common collateral afferent inputs, is not present in the basal ganglia of patients with PD.

Functional regeneration in a rat Parkinson's model after intrastriatal grafts of glial cell line-derived neurotrophic factor and transforming growth factor beta1-expressing extra-adrenal chromaffin cells of the Zuckerkandl's organ.

Intrabrain transplantation of chromaffin cell aggregates of the Zuckerkandl's organ, an extra-adrenal paraganglion that has never been tested for antiparkinsonian treatment, induced gradual improvement of functional deficits in parkinsonian rats. These beneficial effects were related to long survival of grafted cells, striatal reinnervation, and enhancement of dopamine levels in grafted striatum. Grafted cells were not dopaminergics, but they expressed glial cell line-derived neurotrophic factor (GDNF) and transforming growth factor-beta(1). These factors were detected in the host striatal tissue, indicating that chromaffin cells secreted them after grafting. Because glial cell line-derived neurotrophic factor possesses neurorestorative properties over dopaminergic neurons, and transforming growth factor-beta(1) is a cofactor that potentiates the neurotrophic actions of GDNF, functional regeneration was likely caused by the chronic trophic action of neurotrophic factors delivered by long-surviving grafted cells. This work should stimulate research on the clinical applicability of transplants of the Zuckerkandl's organ in Parkinson's disease.