Clinical study of fetal mesencephalic intracerebral transplants for the treatment of Parkinson's disease

View Point: Disease Modification and Cell Secretome Based Approaches in Parkinson's Disease: Are We on the Right Track?

The term idiopathic Parkinson's disease describes an entity of various not well-characterized disorders resembling each other. They are characterized by chronic neuronal dying originating from various disease mechanisms. They result in the onset of motor and related non-motor features, both of which respond to administration of personalized drug combinations and surgical therapies. The unmet need is beneficial disease course modification with repair and neurogenesis. Objectives are to discuss the value of cell secretome based treatments including neuronal graft transplantation and to suggest as an alternative the stimulation of an endogenous available approach for neuronal repair. Chronic neurodegenerative processes result from different heterogeneous, but complementing metabolic, pathological cascade sequences. Accumulated evidence from experimental research suggested neuron transplantation, stem cell application and cell secretome-based therapies as a promising future treatment with cure as an ultimate goal. To date, clinical testing of disease-modifying treatments has focused on substitution or repair of the remaining dopamine synthesizing neurons following diagnosis. At diagnosis, many of the still surviving and functioning, but already affected neurons have lost most of their axons and are primed for cell death. A more promising therapeutic concept may be the stimulation of an existing, endogenous repair system in the peripheral and central nervous systems. The abundant protein repulsive guidance molecule A blocks restoration and neurogenesis, both of which are mediated via the neogenin receptor. Inhibition of the physiological effects of repulsive guidance molecule A is an endogenous available repair pathway in chronic neurodegeneration. Antagonism of this protein with antibodies or stimulation of the neogenin receptor should be considered as an initial repair step. It is an alternative to cell replacement, stem cell or associated cell secretome concepts.

Persistent dyskinesias in patients with fetal tissue transplantation for Parkinson disease

Cell transplants are being developed for patients with Parkinson disease (PD) who have insufficient benefit with standard medical treatment. We describe the clinical features of five patients who developed persistent dyskinesias after fetal dopaminergic tissue transplantation. All had levodopa-induced dyskinesias preoperatively. We implanted fetal mesencephalic dopaminergic tissue into the putamina bilaterally in 34 patients with advanced PD. They were not immunosuppressed. Five of 34 patients (15%) developed troublesome choreic or dystonic dyskinesias that persisted despite lowering or discontinuing medications. Attempts to treat the involuntary movements with amantadine, clozapine, anticholinergics, dopamine depletors and other medicines had limited success. Metyrosine eliminated dyskinesias but led to the parkinsonian “off” state. Increasing the dose of levodopa worsened the dyskinesias. Three patients required placement of pallidal stimulators, bilaterally in two and unilaterally in one patient who had only contralateral dyskinesias. The two with the bilateral stimulators had improvement in dyskinesias. The patient with the unilateral pallidal stimulator had a substantial reduction of the dyskinesias, but attempts to treat residual “off” symptoms with levodopa were limited by worsening dyskinesias. Although the number of patients developing these persistent dyskinesias was small, these five patients had dramatic improvement after transplant. As a group, they had milder Parkinson signs at baseline and improved to the point of having minimal parkinsonism, with reduction or elimination of levodopa therapy prior to developing persistent dyskinesias. These involuntary movements establish the principle that fetal dopaminergic tissue transplants can mimic the effects of levodopa, not only in reducing bradykinesia, but also in provoking dyskinesias.

Co-Existence of tau and α-synuclein pathology in fetal graft tissue at autopsy: A case report

INTRODUCTION

Transplant of fetal ventral mesencephalic tissue into the striatum of Parkinson's disease (PD) patients has been performed to increase dopamine production and stimulate neuronal regeneration. Analysis of fetal graft tissue at autopsy has demonstrated 6 cases of α-synuclein pathology in PD patients, one case with both α-synuclein and tau pathology in a PD patient, and two cases of tau pathology within a Huntington's Disease patient.

METHODS

A 49 year old man with PD underwent bilateral fetal ventral mesencephalic cell transplants into the striatum. Autopsy at age 70 included immunohistochemical staining of host and graft tissue with antibodies to phosphorylated α-synuclein and phosphorylated tau protein.

RESULTS

Autopsy confirmed the diagnosis of PD. Immunohistochemical staining of graft tissue demonstrated frequent neuronal perikaryal inclusions of phosphorylated α -synuclein and tau in the left graft only.

CONCLUSION

Speculations on the formation of pathology include: 1) α-synuclein and tau pathology spread from host to the graft in a neuron-neuron manner. 2) The nature of the fetal cells themselves, or transplantation process, may render fetal tissue more susceptible to the spontaneous generation of pathology. 3) Factors within host environment caused native tau and α-synuclein in fetal tissue graft to become phosphorylated.

Restorative Strategies in Movement Disorders: the Contribution of Imaging

Purpose of Review

The purpose of this review was to review the imaging, particularly positron emission tomography (PET), findings in neurorestoration studies in movement disorders, with specific focus on neural transplantation in Parkinson’s disease (PD) and Huntington’s disease (HD).

Recent Findings

PET findings in PD transplantation studies have shown that graft survival as reflected by increases in dopaminergic PET markers does not necessarily correlate with clinical improvement. PD patients with more denervated ventral striatum and more imbalanced serotonin-to-dopamine ratio in the grafted neurons tended to have worse outcome. In HD transplantation studies, variable graft survival and clinical responses may be related to host inflammatory/immune responses to the grafts.

Summary

Information gleaned from imaging findings in previous neural transplantation studies has been used to refine study protocol and patient selection in future trials. This includes identifying suitable candidates for transplantation using imaging markers, employing multiple and/or novel PET tracers to better assess graft functions and inflammatory responses to grafts.

Induced pluripotent stem cell technology and direct conversion: new possibilities to study and treat Parkinson's disease

Recent developments in in vitro disease modeling and regenerative medicine have placed induced pluripotent stem cells (iPSCs) in the center of attention as a unique source to study Parkinson's disease. After only 5 years of intensive research, human iPSCs can be generated without viral integration and under xeno-free conditions. This, combined with increasingly sophisticated methods to differentiate iPSCs into functional dopaminergic (DA) neurons, led us to recapitulate the most important findings concerning the use of iPSC technology as a prospective tool to treat symptoms of Parkinson's disease as well as to obtain insight in disease related cell pathogenesis. Moreover, we touch upon some of the latest discoveries in which patient-derived autologous DA neurons come into even more direct reach thanks to a method that allows transdifferentiation of fibroblasts into DA neurons.

Fetal derived embryonic-like stem cells improve healing in a large animal flexor tendonitis model

Introduction

Tendon injury is a common problem in athletes, with poor tissue regeneration and a high rate of re-injury. Stem cell therapy is an attractive treatment modality as it may induce tissue regeneration rather than tissue repair. Currently, there are no reports on the use of pluripotent cells in a large animal tendon model in vivo. We report the use of intra-lesional injection of male, fetal derived embryonic-like stem cells (fdESC) that express Oct-4, Nanog, SSEA4, Tra 1-60, Tra 1-81 and telomerase.

Methods

Tendon injury was induced using a collagenase gel-physical defect model in the mid-metacarpal region of the superficial digital flexor tendon (SDFT) of eight female adult Thoroughbred or Thoroughbred cross horses. Tendon lesions were treated one week later with intra-lesional injection of male derived fdESCs in media or media alone. Therapy was blinded and randomized. Serial ultrasound examinations were performed and final analysis at eight weeks included magnetic resonance imaging (MRI), biochemical assays (total DNA, glycosaminoglycan, collagen), gene expression (TNC, TNMD, SCX, COL1A1, COL3A1, COMP, DCN, MMP1, MMP3, MMP13, 18S) and histology. Differences between groups were assessed with Wilcoxon's rank sum test.

Results

Cell survival was demonstrated via the presence of the SRY gene in fdESC treated, but not control treated, female SDFT at the end of the trial. There were no differences in tendon matrix specific gene expression or total proteoglycan, collagen or DNA of tendon lesions between groups. Tissue architecture, tendon size, tendon lesion size, and tendon linear fiber pattern were significantly improved on histologic sections and ultrasound in the fdESC treated tendons.

Conclusions

Such profound structural effects lend further support to the notion that pluripotent stem cells can effect musculoskeletal regeneration, rather than repair, even without in vitro lineage specific differentiation. Further investigation into the safety of pluripotent cellular therapy as well as the mechanisms by which repair was improved seem warranted.

Dyskinesias and dopamine cell replacement in Parkinson's disease: a clinical perspective

Both increased and decreased dyskinesias have been reported from open label clinical trials of transplantation of human embryonic dopamine rich tissue in Parkinson's disease patients. In the first double-blind clinical transplantation trial, 15% of the grafted patients developed severe postoperative dyskinesias in the "off" phase. Since then, postoperative off-medication dyskinesias have been reported from two additional series of grafted patients. However, such dyskinesias are probably not a novel phenomenon. These dyskinesias have shown a different temporal development postoperatively compared to the antiparkinsonian graft effects, and no significant relationship with the magnitude of graft-derived dopaminergic reinnervation or symptomatic relief. However, positron emission tomography studies have indicated that an unbalanced putaminal dopaminergic function may contribute to this postoperative complication. While there is little doubt that intrastriatal grafts can induce dyskinesias, these appear to differ from common drug-induced dyskinesias. The term graft-induced dyskinesias (GID) is therefore suggested to more clearly identify this complication. While GID bear some phenomenological resemblance to biphasic drug induced dyskinesias, the mechanism(s) behind this complication remains obscure. Available data are scarce but allow for hypotheses to be generated that could (and should) be addressed in experimental animals.

Glial cell line-derived neurotrophic factor-supplemented hibernation of fetal ventral mesencephalic neurons for transplantation in Parkinson disease: long-term storage

OBJECT

Transplantation of fetal dopaminergic tissue is being investigated in animal models and clinical trials for its potential as a treatment for advanced Parkinson disease. At the same time, the availability of fetal tissue is limited, making its storage time prior to transplantation a key practical issue. Although it results in a smaller percentage of surviving cells. a longer storage time enables fetal tissue obtained over several days to be pooled for transplantation in a recipient. Glial cell line-derived neurotrophic factor (GDNF) has been shown to improve survival of human dopaminergic tissue that has been stored prior to transplantation. The objective of this study was to evaluate the effects on fetal dopaminergic tissue of GDNF-supplemented hibernation for extended periods of 6 to 15 days.

METHODS

The ventral mesencephalon (VM) was harvested in a total of 27 14-day-old rat fetuses, and three VMs were cultured immediately (fresh control group). The remaining 24 VMs were divided sagittally along the midline to yield 48 equal pieces of hemimesencephalon. Twenty-four pieces were stored with GDNF-supplemented hibernation medium for 6, 9, 12, or 15 days, and the 24 "partner" hemimesencephalon pieces were stored in control hibernation medium for the same periods of time. Tissue was cultured for 48 hours and processed for tyrosine hydroxylase (TH) immunoreactivity and double-stained with cresyl violet. Cell counts for all cultures and the percentage of TH-immunoreactive cells were obtained. The percentage of TH-immunoreactive cells for the fresh control group was 6.3 +/- 0.5%. The percentage of TH-immunoreactive cells in cultures derived from tissue stored in GDNF-supplemented medium was significantly increased at 6 and 9 days posthibernation compared with the fresh control group and the "partner" groups stored in hibernation medium only. No significant increase in the percentage of TH-immunoreactive cells was observed in the 12- and 15-day groups.

CONCLUSIONS

In this study the authors have demonstrated that fetal dopaminergic tissue can be safely stored for up to 9 days in GDNF-supplemented hibernation medium. Furthermore, the percentage of TH-immunoreactive cells is significantly increased after 6 and 9 days of storage in this medium, improving the yield of TH-immunoreactive cells prior to transplantation. These observations have practical clinical implications for collecting fetal dopaminergic cells and improving their survival after transplantation.

Reconstructive neurosurgery for Parkinson's disease: a systematic review and preliminary meta-analysis

This systematic review and meta-analysis aimed to identify the determinants for best practice and establish current benchmarks for recovery following reconstructive neurosurgery for people with Parkinson's disease. Eleven studies reporting results for 95 grafted patients were selected on the grounds of using optimal surgical techniques and the Core Assessment Program for Intracerebral Transplantation (CAPIT) protocol for data collection. Consistent trends demonstrating high levels of recovery were identified on most outcome measures. Determinants for best practice were identified as selecting younger patients; using low dose immunosuppression; bilateral grafting; and employing strategies to ensure the quantity and viability of the grafted cells. Secondary analysis of data demonstrated a correlation of rho=0.666 (P<0.05) between increases in striatal dopaminergic activity and UPDRS Motor (off) scores. Overall effect size 'd' was found to be 1.129 UPDRS Motor (off) condition and 0.719 for UPDRS Total (off) condition. The design of the studies and the variable standards for reporting the data precluded the use of more powerful and accurate meta-analyses. It was recommended that the creation of a collaborative database would improve the extraction of data and allow for more powerful statistical analyses for evaluating the overall harm and benefits associated with reconstructive neurosurgery.

Glial cell line-derived neurotrophic factor-supplemented hibernation of fetal ventral mesencephalic neurons for transplantation in Parkinson disease: long-term storage

OBJECT

Investigation of fetal dopaminergic tissue transplantation is being conducted in animal models and clinical trials as a potential treatment for advanced Parkinson disease (PD). Because the availability of fetal tissue is limited, however, the duration of its storage prior to transplantation is a key practical issue. Longer storage times may enable fetal tissue obtained over several days to be pooled together for transplantation in a recipient. Glial cell line-derived neurotrophic factor (GDNF) has been shown to improve survival of stored human dopaminergic tissue prior to transplantation. The objective of this study was to evaluate GDNF-supplemented hibernation of fetal dopaminergic tissue for extended periods of 6 to 15 days.

METHODS

A total of 27 rat ventral mesencephalons (VMs) were obtained in gestation Day 14 rat fetuses, and three were cultured immediately (fresh-culture control group). The remaining 24 VMs were divided sagittally along the midline to form 48 equal pieces of hemimesencephalons. Twenty-four pieces were stored with GDNF-supplemented hibernation medium for 6, 9, 12, or 15 days, and the 24 "partner" hemimesencephalons were stored in control hibernation medium for the same periods of time. Tissue was cultured for 48 hours and processed for tyrosine hydroxylase (TH) immunoreactivity and cresyl violet. Cell counts for all cultures and percentage of TH-immunoreactive cells were obtained. The percentage of TH-positive cells for the fresh control group was 6.3 +/- 0.5%; that measured in cultures derived from tissue hibernated in GDNF-supplemented medium was significantly increased at 6 and 9 days posthibernation compared with the fresh-culture control group and the partner groups stored in hibernation medium only. No significant increase in percentage of TH-immunoreactive cells was observed in the 12- and 15-day hibernation groups.

CONCLUSIONS

In summary the authors found that fetal dopaminergic tissue can safely be stored up to 9 days in GDNF-supplemented hibernation medium. Furthermore the percentage of TH-immunoreactive cells is significantly increased after 6 and 9 days of storage in this medium, improving the yield of TH-positive cells prior to transplantation. These observations may have important clinical implications for collecting fetal dopaminergic cells and improving their survival after transplantation.

Transplantation of embryonic dopamine neurons for severe Parkinson's disease

BACKGROUND

Transplantation of human embryonic dopamine neurons into the brains of patients with Parkinson's disease has proved beneficial in open clinical trials. However, whether this intervention would be more effective than sham surgery in a controlled trial is not known.

METHODS

We randomly assigned 40 patients who were 34 to 75 years of age and had severe Parkinson's disease (mean duration, 14 years) to receive a transplant of nerve cells or sham surgery; all were to be followed in a double-blind manner for one year. In the transplant recipients, cultured mesencephalic tissue from four embryos was implanted into the putamen bilaterally. In the patients who received sham surgery, holes were drilled in the skull but the dura was not penetrated. The primary outcome was a subjective global rating of the change in the severity of disease, scored on a scale of -3.0 to 3.0 at one year, with negative scores indicating a worsening of symptoms and positive scores an improvement.

RESULTS

The mean (+/-SD) scores on the global rating scale for improvement or deterioration at one year were 0.0+/-2.1 in the transplantation group and -0.4+/-1.7 in the sham-surgery group. Among younger patients (60 years old or younger), standardized tests of Parkinson's disease revealed significant improvement in the transplantation group as compared with the sham-surgery group when patients were tested in the morning before receiving medication (P=0.01 for scores on the Unified Parkinson's Disease Rating Scale; P=0.006 for the Schwab and England score). There was no significant improvement in older patients in the transplantation group. Fiber outgrowth from the transplanted neurons was detected in 17 of the 20 patients in the transplantation group, as indicated by an increase in 18F-fluorodopa uptake on positron-emission tomography or postmortem examination. After improvement in the first year, dystonia and dyskinesias recurred in 15 percent of the patients who received transplants, even after reduction or discontinuation of the dose of levodopa.

CONCLUSIONS

Human embryonic dopamine-neuron transplants survive in patients with severe Parkinson's disease and result in some clinical benefit in younger but not in older patients.

IGF-I and bFGF improve dopamine neuron survival and behavioral outcome in parkinsonian rats receiving cultured human fetal tissue strands

To promote dopamine cell survival in human fetal tissue strands transplanted into immunosuppressed 6-OHDA-lesioned rats, we have preincubated tissue in insulin-like growth factor-I (IGF-I, 150 ng/ml) and basic fibroblast growth factor (bFGF, 15 ng/ml) in vitro for 2 weeks. Growth factor treatment did not affect the rate of homovanillic acid production in vitro but increased overall dopamine neuron survival in animals after transplant from 1240 +/- 250 to 2380 +/- 440 neurons (P < 0.05). Animals in the growth factor-treated group had a significantly greater reduction in methamphetamine-induced rotation (66%) compared to control transplants (30%, P < 0.05). We conclude that in vitro preincubation of human fetal tissue strands with IGF-I and bFGF improves dopamine cell survival and the behavioral outcome of transplants.

Outcomes and complications of fetal tissue transplantation in Parkinson's disease

This study was undertaken to investigate the outcomes, complication rates and risk factors of stereotactic intrastriatal neurotransplantation for Parkinson's disease (PD). Bilateral stereotactic neurotransplantation was performed (as previously described) in 60 patients with idiopathic PD. Clinical outcome was evaluated using the Unified Parkinson's Disease Rating Scale (UPDRS). The incidence of complication was evaluated by retrospective analysis of the clinical outcomes of the transplanted patients. Patients demonstrated significant improvement in UPDRS scores 12 months after transplantation. Nine patients experienced adverse effects after neurotransplantation, 3 requiring surgical intervention. Patients showed a significant overall improvement and no greater incidence of risk than that of other intracranial procedures.

Development of fetal neural transplantation as a treatment for Parkinson's disease

Since 1988, patients with Parkinson's disease have participated in clinical trials evaluating the efficacy of transplantation of human fetal dopamine cells into the caudate and putamen. Transplantation of fetal tissue leads to clinical benefits in some patients which is associated with a reduction of the amount of LDOPA administered. Major issues in transplant research need to be addressed before this technique can be widely applied. In this review, a pool of 35 patients was generated from the published cases of human fetal tissue transplantation. This group of transplant recipients was examined for motor improvement and reduction in L-DOPA dosage at one year post-transplant. Issues addressed in this review include the benefits of unilateral vs bilateral transplantation, age of the transplant recipient, solid vs suspensions of fetal mesencephalon and the number of fetal donors per recipient.

An overview of central nervous system transplantation in human disease

Although its roots date back over a century, the field of neurotransplantation has been shaped mostly by advances over the past 30 years. Animal models of nigrostriatal disconnection in the 1970s allowed investigators to explore the feasibility of neural grafting. By the end of that decade, functional and behavioral effects had been demonstrated using fetal tissue grafts. In the 1980s, animal experimentation continued, as did clinical trials involving patients with idiopathic Parkinson's disease. Both autologous adrenal medullary tissue and fetal allografts were tested in the clinical setting, with the latter proving to yield superior results. Animal models of striatal cell loss provided the impetus for limited clinical trials in patients with Huntington's disease by the early 1990s, and work with both diseases continues today. Although much has been learned, neural grafting remains experimental. Broader applications are being explored even now, though, as transplant techniques are applied to animal models of dementia, spinal cord injury, cortical injury, and pain. Some very limited human trials have already begun in some of these areas. In this review some of the advances in the field are highlighted.

Activation of neurotransplants in humans

Clinical studies report symptomatic benefit in most fetal neurotransplantation treated Parkinson's disease patients. The underlying mechanism is incompletely explained. We investigated whether neural connections between host and transplanted tissue are established. Two Parkinson's disease patients with clinically excellent outcome after transplantation were studied with functional magnetic resonance imaging. A repetitive motor task that provided robust stimulation in the contralateral putamen in volunteers activated graft bearing regions of putamen in patients. In response to contralateral motor tasks, activation was recorded consistently in left putamen in patient 1 and in right putamen in patient 2. Functional magnetic resonance imaging suggests that neuronal rewiring contributes to the functioning of neurotransplants in vivo in humans.

Safety of intrastriatal neurotransplantation for Huntington's disease patients

Fetal neural transplantation has been shown to be a feasible, safe, and according to a number of recent reports, effective treatment for Parkinson's disease (PD). Fetal striatal transplantation may be as feasible, safe, and effective a treatment for Huntington's disease (HD), a disorder for which there is currently no effective treatment. This report describes our experience with fetal striatal transplantation to adult striatum in three HD patients. Three moderately advanced, nondemented HD patients received transplantation of fetal striatal tissue. The striatal precursor was selectively obtained from the lateral ganglionic eminence. Each patient received bilateral grafts from five to eight donors, placed into the caudate nucleus (one graft on each side) and the putamen (four grafts on each side). All three patients had HD as documented by family history, DNA heterozygosity (17-20 and 48-51 repeats), magnetic resonance imaging (MRI) revealing striatal atrophy, and 2-deoxyglucose positron emission tomography revealing striatal hypometabolism. All patients had been evaluated using the Unified Huntington's Disease Rating Scale and appropriate neuropsychological tests for at least 3 months prior to transplantation. One year following transplantation, MRI of all three patients revealed that the grafts survived and grew within the striatum without displacing the surrounding tissue. No patients demonstrated adverse effects of the surgery or the associated cyclosporin immunosuppression, nor did any patient exhibit deterioration following the procedure. The limited experience provided by these three patients indicates that fetal tissue transplantation can be performed in HD patients without unexpected complications.

Long-term survival of human central nervous system progenitor cells transplanted into a rat model of Parkinson's disease

Progenitor cells were isolated from the developing human central nervous system (CNS), induced to divide using a combination of epidermal growth factor and fibroblast growth factor-2, and then transplanted into the striatum of adult rats with unilateral dopaminergic lesions. Large grafts were found at 2 weeks survival which contained many undifferentiated cells, some of which were migrating into the host striatum. However, by 20 weeks survival, only a thin strip of cells remained at the graft core while a large number of migrating astrocytes labeled with a human-specific antibody could be seen throughout the striatum. Fully differentiated graft-derived neurons, also labeled with a human-specific antibody, were seen close to the transplant site in some animals. A number of these neurons expressed tyrosine hydroxylase and were sufficient to partially ameliorate lesion-induced behavioral deficits in two animals. These results show that expanded populations of human CNS progenitor cells maintained in a proliferative state in culture can migrate and differentiate into both neurons and astrocytes following intracerebral grafting. As such these cells may have potential for development as an alternative source of tissue for neural transplantation in degenerative diseases.