NGF-like trophic support from peripheral nerve for grafted rhesus adrenal chromaffin cells

Recipient Reaction and Composition of Autologous Sural Nerve Tissue Grafts into the Human Brain

Parkinson's disease (PD) is a severe neurological disease for which there is no effective treatment or cure, and therefore it remains an unmet need in medicine. We present data from four participants who received autologous transplantation of small pieces of sural nerve tissue into either the basal forebrain containing the nucleus basalis of Meynert (NBM) or the midbrain substantia nigra (SN). The grafts did not exhibit significant cell death or severe host-tissue reaction up to 55 months post-grafting and contained peripheral cells. Dopaminergic neurites showed active growth in the graft area and into the graft in the SN graft, and cholinergic neurites were abundant near the graft in the NBM. These results provide a histological basis for changes in clinical features after autologous peripheral nerve tissue grafting into the NBM or SN in PD.

Role of the Peripheral Nervous System in PD Pathology, Diagnosis, and Treatment

Studies on Parkinson disease (PD) have mostly focused on the central nervous system—specifically, on the loss of mesencephalic dopaminergic neurons and associated motor dysfunction. However, the peripheral nervous system (PNS) is gaining prominence in PD research, with increasing clinical attention being paid to non-motor symptoms. Researchers found abnormal deposition of α-synuclein and neuroinflammation in the PNS. Attempts have been made to use these pathological changes during the clinical diagnosis of PD. Animal studies demonstrated that combined transplantation of autologous peripheral nerves and cells with tyrosine hydroxylase activity can reduce dopaminergic neuronal damage, and similar effects were observed in some clinical trials. In this review, we will systematically explain PNS performance in PD pathology and its clinical diagnostic research, describe PNS experimental results [especially Schwann cell (SC) transplantation in the treatment of PD animal models] and the results of clinical trials, and discuss future directions. The mechanism by which SCs produce such a therapeutic effect and the safety of transplantation therapy are briefly described.

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 Transplantation of Cells Expressing the Anti-Apoptotic Gene Bcl-2

Long-term survival of grafted neural cells is a major goal of neural transplantation, but typical survival rates of grafted fetal neurons are in the range of 5-10%. Whether the death of transplanted neural cells is apoptotic or necrotic is unknown. The expression of the proto-oncogene bcl-2 inhibits both apoptotic and necrotic neural cell death. In a 6-OHDA induced rat model of Parkinson's disease, Hoechst 33258 prelabelled conditionally immortalized nigral cells engineered to express bcl-2 were stereotactically transplanted into the striatum ipsilaterally to the lesioned nigrostriatal pathway. Sixteen rats received bcl-2 transfected cells, 15 received cells transfected with vector alone, and 12 received either a nondopaminergic cell line or were sham transplanted as controls. Four wk following transplantation, the rats with grafts containing bcl-2 expressing cells showed an approximately 43% decrease in apomorphine-induced rotational behavior. In contrast, 12% improvement occurred in the rats with transplanted cells transfected with vector alone (p < 0.05), and no improvement occurred in sham-operated animals (p < 0.05). Histological examination showed no tumor formation. Despite the difference in behavioral effect, no clear difference in Hoechst fluorescent staining or staining for TH, GFAP was noted; therefore, it is unknown at present whether the observed effect was due to a difference in survival or to increased efficacy per surviving transplanted neural cell, or both.

Long-Term Viability of Isolated Bovine Adrenal Medullary Chromaffin Cells following Intrastriatal Transplantation

Adrenal medullary grafts generally exhibit poor viability when grafted into the striatum. Previous work in our laboratory demonstrated that chromaffin cells can survive well for up to 2 mo following grafting into the intact rat striatum after cells are isolated from the nonchromaffin supporting cells (fibroblasts and endothelial cells) of the adrenal medulla. The aim of the present study was to assess the long-term viability of isolated bovine chromaffin cells following grafting into the intact rat striatum. The viability of grafted bovine adrenal medullary chromaffin cells was compared in rats receiving either (a) perfused adrenal medulla; (b) isolated chromaffin cells; or (c) isolated chromaffin cells that were subsequently recombined with their nonchromaffin supporting cells. One year postimplantation, all graft types which included fibroblasts and endothelial cells were infiltrated with macrophages and demonstrated an abundance of cellular debris. No viable chromaffin cells were observed. In contrast, healthy tyrosine hydroxylase (TH) and dopamine beta hydroxylase (DβH) immunoreactive chromaffin cells survived for 1 yr posttransplantation when grafted in isolation from the nonchromaffin constituents of the adrenal medulla. Good xenograft survival was achieved in this group despite the fact that these rats were only immunosuppressed for 1 mo postimplantation. Grafted cells demonstrated morphological characteristics of chromaffin cells in situ and these implants were not accompanied by macrophage infiltration. These data demonstrate that long-term survival of chromaffin cells can be achieved following intrastriatal implantation and the viability of grafted chromaffin cells is dependent upon the removal of the nonchromaffin supporting cells.

Intrastriatal Cografts of Autologous Adrenal Medulla and Sural Nerve in MPTP-Induced Parkinsonian Macaques: Behavioral and Anatomical Assessment

To examine the effects of autologous sural nerve and adrenal medullary tissue intrastriatal cografts upon voluntary motor performance in parkinsonism, a non-human primate 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) model was employed to quantitatively assess skilled hand movements. Motor performance was studied in normal, MPTP-induced parkinsonian, and then cografted states. Reaction and movement times were prolonged and variability increased in experimental and control animals in the parkinsonian state. Animals undergoing autologous cografts demonstrated improved motor performance whereas the control animal continued in a chronic, stable parkinsonian state. Intrastriatal cografts of autologous adrenal medullary tissue and sural nerve resulted in good to excellent chromaffin cell survival. The mechanism of the restoration of function in the cografted monkeys remains to be determined.

Behavioral Effects of Neural Transplantation

Considerable evidence suggests that transplantation of fetal neural tissue ameliorates the behavioral deficits observed in a variety of animal models of CNS disorders. However, it is also becoming increasingly clear that neural transplants do not necessarily produce behavioral recovery, and in some cases have either no beneficial effects, magnify existing behavioral abnormalities, or even produce a unique constellation of deficits. Regardless, studies demonstrating the successful use of neural transplants in reducing or eliminating behavioral deficits in these animal models has led directly to their clinical application in human neurodegenerative disorders such as Parkinson's disease. This review examines the beneficial and deleterious behavioral consequences of neural transplants in different animal models of human diseases, and discusses the possible mechanisms by which neural transplants might produce behavior recovery.

Encapsulated PC 12 Cell Transplants into Hemiparkinsonian Monkeys: A Behavioral, Neuroanatomical, and Neurochemical Analysis

Four cynomolgus monkeys were trained on a hand reaching task and then rendered hemiparkinsonian with an intracarotid injection of n-methyl 4 phenyl 1,2,3,6, tetrahydropyridine (MPTP). Performance on this task with the limb contralateral to the MPTP injection was significantly impaired following the lesion. Three monkeys received implants of polymer-encapsulated containing PC12 cells into the caudate nucleus and putamen. One monkey received identical implants of empty capsules and served as a control. After a transient improvement, limb use in the control monkey dissipated and returned to post-MPTP disability. Two of the three PC12 cell grafted monkeys recovered performance on the hand reach task to near normal levels for up to 6.5 mo posttransplantation. Capsules retrieved from the monkeys who recovered limb function postimplantation contained numerous viable PC12 cells that continued to release levodopa, basal dopamine, and potassium evoked dopamine. In contrast, capsules retrieved from the PC12 cell-grafted monkey which did not recover limb use on the hand reach task contained few cells which secreted negligible or undetectable levels of levodopa and dopamine. Interestingly, functional disability was not reinstated following removal of the capsules. Neuroanatomical and neurochemical evaluation of the grafted striatum did not reveal a host-derived sprouting response of catecholaminergic or indolaminergic fibers. These data indicate that xenografts of PC12 cells can survive for up to 6.5 mo in nonimmunosuppressed monkeys when immunoisolated via polymer encapsulation. Moreover, these cells continue to secrete high levels of levodopa and dopamine and induce recovery of motor function in parkinsonian nonhuman primates.

Neural Transplantation: Prospects for Clinical use

Neural transplantation has been extensively applied in Parkinson's disease, including numerous clinical studies, studies in animal models, and related basic research on cell biology. There is evidence that the clinical trials of both adrenal medulla transplantation and fetal substantia nigra transplantation have produced a detectable clinical effect, although it is not yet clear whether the clinical benefit is sufficient to justify a more widespread application of these procedures. Studies of long-term outcome and quantitative tests are important in assaying the degree of benefit produced by transplantation procedures in Parkinson's disease and for developing improved and refined procedures. Other disease-related applications of neural transplantation are beginning to be developed. These include Huntington's disease, chronic pain, epilepsy, spinal cord injury, and perhaps even demyelinating diseases and cortical ischemic injury. Although most of these applications lie in the future, it is not too soon to begin to consider the scientific justification that should be required for initiation of human clinical trials.

Short-Term Immunosuppression Enhances Long-Term Survival of Bovine Chromaffin Cell Xenografts in Rat Cns

Xenogeneic donors, a largely untapped resource, would solve many of the problems associated with the limited availability of human donor tissue for neural transplantation. Previous work in our laboratory has revealed that xenografts of isolated bovine chromaffin cells survive transplantation into the periaqueductal gray (PAG) of immunosuppressed adult rats. Electron microscopic analysis reveals that graft sites contain healthy chromaffin cells, but do not contain host immune cells typical of graft rejection.

The aim of the current study was to assess the necessary conditions for long-term survival of bovine chromaffin cell xenografts in the central nervous system (CNS). In particular, the need for short-course vs. permanent immunosuppressive therapy with cyclosporine A (CsA) for the long-term survival of grafted bovine chromaffin cells was addressed. Grafts from animals receiving continuous CsA treatment for either 3, 6, or 12 wk contained large clumps of dopamines-β-hydroxylase (DBH) positive cells in contrast to the few surviving cells observed in nonimmunosuppressed animals. In addition, grafts from animals that had CsA treatment terminated at 3 or 6 wk contained similarly large clumps of DBH-positive cells. Furthermore, short-term immunosuppression (3 wk) appeared to enhance the long-term survival of grafted cells, since clumps of DBH staining cells could still be positively identified in the host PAG at least 1 yr after transplantation.

Complete rejection of graft tissue depends on several factors, such as blood–brain barrier integrity, the presence of major histocompatability complex (MHC) antigens in either the host or graft, and the status of the host immune system. By using a suspension of isolated bovine chromaffin cells, potential MHC antigen presenting cells, such as endothelial cells, are eliminated. In addition, CsA treatment may negate the immunologic consequences of increased blood–brain barrier permeability following surgical trauma by attenuating the host cell mediated response. In summary, long-term survival of isolated chromaffin cell xenografts in the rat CNS may be attained by a short-term course of CsA.

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 ).

Thinking about repairing thinking

The work of Sinden et al. suggests that it may be possible to produce improvement in the “highest” areas of brain function by transplanting brain tissue. What appears to be the limiting factor is not the complexity of the mental process under consideration but the discreteness of the lesion which causes the impairment and the appropriateness and accuracy of placement of the grafted tissue.

Therapeutic uses for neural grafts: Progress slowed but not abandoned

In spite of Stein and Glasier's justifiable conclusion that initial optimism concerning the immediate clinical applicability of neural transplantation was premature, there exists much experimental evidence to support the potential for incorporating this procedure into a therapeutic arsenal in the future. To realize this potential will require continued evolution of our knowledge at multiple levels of the clinical and basic neurosciences.

The structure, operation, and functionality of intracerebral grafts

The concept of structure, operation, and functionality, as they may be understood by clinicians or researchers using neural transplantation techniques, are briefly defined. Following Stein & Glasier, we emphasize that the question of whether an intracerebral graft is really functional should be addressed not only in terms of what such a graft does in a given brain structure, but also in terms of what it does at the level of the organism.

The NGF superfamily of neurotrophins: Potential treatment for Alzheimer's and Parkinson's disease

Stein & Glasier suggest embryonic neural tissue grafts as a potential treatment strategy for Alzheimer's and Parkinson's disease. As an alternative, we suggest that the family of nerve growth factor-related neurotrophins and their trk (tyrosine kinase) receptors underlie cholinergic basal forebrain (CBF) and dopaminergic substantia nigra neuron degeneration in these diseases, respectively. Therefore, treatment approaches for these disorders could utilize neurotrophins.

Some practical and theoretical issues concerning fetal brain tissue grafts as therapy for brain dysfunctions

Grafts of embryonic neural tissue into the brains of adult patients are currently being used to treat Parkinson's disease and are under serious consideration as therapy for a variety of other degenerative and traumatic disorders. This target article evaluates the use of transplants to promote recovery from brain injury and highlights the kinds of questions and problems that must be addressed before this form of therapy is routinely applied. It has been argued that neural transplantation can promote functional recovery through the replacement of damaged nerve cells, the reestablishment of specific nerve pathways lost as a result of injury, the release of specific neurotransmitters, or the production of factors that promote neuronal growth. The latter two mechanisms, which need not rely on anatomical connections to the host brain, are open to examination for nonsurgical, less intrusive therapeutic use. Certain subjective judgments used to select patients who will receive grafts and in assessment of the outcome of graft therapy make it difficult to evaluate the procedure. In addition, little long-term assessment of transplant efficacy and effect has been done in nonhuman primates. Carefully controlled human studies, with multiple testing paradigms, are also needed to establish the efficacy of transplant therapy.

Models of neurological defects and defects in neurological models

The transition from research to patient following advances in transplantation research is likely to be disappointing unless it includes a better understanding of critically relevant characteristics of the neurological disorder and improvements in the animal models, particularly the behavioral features. The appropriateness of the model has less to do with the species than with how the species is used.

Neurotrophic activity of extracts from distal stumps of pre-degenerated peripheral rat nerves varies according to molecular mass spectrum

OBJECTIVE

We investigated neurotrophic activity of extracts from pre-degenerated and non-pre-degenerated peripheral nerves (complete extracts and extracts with fractions of narrower range of molecular weight) on the injured hippocampus.

METHODS

The experiment was carried out on male Wistar C rats. The complete extracts or fractions with different ranges of molecular weight were introduced to the site of injury with the autologous connective tissue chambers. We examined DiI-labeled hippocampal cell and AChE-positive nerve endings to assess the regeneration intensity.

RESULTS

The highest number of labeled hippocampal cells was observed in the group treated with fraction of molecular weight 10-100 kDa (72.5 +/- 13.7) obtained from pre-degenerated nerves. We observed the presence of AChE-positive fibers inside all examined chambers.

DISCUSSION

These results demonstrate that suitable modification of CNS environments by introducing the protein fractions obtained from peripheral nerves can initiate the regeneration of the damaged hippocampal structure in adult rats. Moreover, it is possible to intensify their neurotrophic effect by former pre-degeneration of peripheral nerves and extraction from the entire extract proteins of molecular weight of 10-100 kDa.

Quantitative and qualitative analysis of proteins in rat peripheral nerves predegenerated for 7 days

OBJECTIVES

In contrast to peripheral nerves, central neurons do not regrow spontaneously after injury. Our previous studies showed that transplantation of degenerating peripheral nerves or their extracts can induce regeneration in the injured central nervous system. Non-predegenerated nerves show much weaker neurotrophic activity. The aim of the present work was to examine quantitatively and qualitatively the protein composition of rat sciatic nerve extracts.

MATERIAL AND METHODS

The experiments were carried out on male Wistar C rats. Distal fragments were collected immediately after transection or after 7 day-long predegeneration. The nerves were homogenized, centrifuged and ultracetrifuged. Extracts were analyzed by means of two-dimensional electrophoresis.

RESULTS

The two-dimensional electrophoresis showed 69 protein subfractions with isoelectric points ranging from 4.2 to 7.0 pH and molecular weight ranging from 13.5 kDa to 335.4 kDa in extracts obtained from nonpredegenerated nerves. In predegenerated nerve extracts 114 subfractions with isoelectric points ranging from 4.2 to 7.4 pH and molecular weight from 21.1 kDa to 335.4 kDa were found. Fractions: 25.5 kDa, 31.6 kDa, 36 kDa, 38.4 kDa, 42.4 kDa, 46.6 kDa, and 50.5 kDa showed significant increase and two fractions: 68.5 kDa and 335.4 kDa demonstrated significant decrease in the number of subfractions in predegenerated nerves. Fractions 160.8 kDa, 236.1 kDa, and 5 fractions below 21.1 kDa were present only in extracts from non-predegenerated nerves.

CONCLUSIONS

In conclusion, the results of our study demonstrate that the most intense changes in protein composition in degenerating nerves take place in low molecular weight fractions.

Neuropathological study 16 years after autologous adrenal medullary transplantation in a Parkinson's disease patient

To date, there is no clinicopathological correlation of adrenal medullary transplant cases in patients with survival beyond a few years. Postmortem examination of a brain from a patient with Parkinson's disease (PD), 16 years after autologous adrenal medullary transplant, was performed using tyrosine hydroxylase (TH) and chromogranin A. The patient experienced a four-year initial improvement in motor function followed by resumption of the progressive nature of her disease that continued until her death. She expired 16 years following grafting. At autopsy, TH stain of the brain revealed severe loss of TH-immunoreactivity in the substantia nigra and Lewy bodies, confirming the diagnosis of PD. The transplant site was identified by the presence of scarring and there was complete absence of any TH staining cells at the site of the transplant. There were few surviving cells staining with chromogranin A. The absence of TH-staining cells in the transplant 16 years after surgery provides further evidence that adrenal medullary transplants do not survive in the long term.

Functional and Morphological Characteristics of Bovine Adrenal Chromaffin Cells on Macroporous Poly(D,L-lactide-co-glycolide) Scaffolds

Adrenal chromaffin cells (ACCs) secrete several neuroactive substances that are effective in influencing pain sensitivity in the central nervous system as well as enhancing the recovery of the intrinsic nigrostriatal dopaminergic system in patients with Parkinson's disease. ACC transplantation may be upregulated by the use of three-dimensional (3-D) scaffolds. In this study, we determined whether biodegradable poly(D,L-lactic-coglycolic acid) (PLGA) (85:15) sponges could be used as support for chromaffin cells. ACCs were isolated from bovine adrenal glands by standard perfusion (95% purity) followed by additional purification (>99.5% purity). ACC (approximately 5 x 10(5) cells) suspension in collagen (type I) was seeded on prewetted sponges and cultured in DMEM-F12 (1:1) medium (5% fetal bovine serum). The catecholamine and enkephalin levels of the samples were measured by high-performance liquid chromatography and radioimmunoassay. Cell morphology was examined by transmission electron microscopy. Morphological evidence showed prolonged viability of chromaffin cells on scaffolds having pores of 250-400 microm. Cell counts and scanning electron microscopy demonstrated that the majority of seeded cells were located within the scaffold. Chromaffin cells exhibited higher levels of enkephalins and catecholamines on PLGA scaffold compared with their monolayer cultures. By the use of 3-D PLGA as support for ACCs, it is possible to upregulate metabolic function and localize a high number of morphologically healthy-looking cells. Highly purified ACCs cultured on PLGA scaffold may have promise in transplantation studies, because these cells are less immunogenic and may be applied to in vivo settings by using short-term immunosuppression.

Systemic administration of the immunophilin ligand GPI 1046 in MPTP-treated monkeys

Systemic administration of immunophilin ligands provides trophic influences to dopaminergic neurons in rodent models of Parkinson's disease (PD) resulting in the initiation of clinical trials in patients with Parkinson's disease. We believe that prior to clinical trials, novel therapeutic strategies should show safety and efficacy in nonhuman models of PD. The present study assessed whether oral administration of the immunophilin 3-(3-pyridyl)-1-propyl (2S)-1-(3,3-dimethyl-1,2-dioxopentyl)-2-pyrrollidinecarboxylate (GPI 1046) could prevent the structural and functional consequences of n-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) administration in nonhuman primates. Twenty-five rhesus monkeys received daily oral administration of vehicle (n = 5) or one of four doses of GPI 1046 (0.3 mg/kg, n = 5; 1.0 mg/kg, n = 5; 3.0 mg/kg, n = 5; 10.0 mg/kg, n = 5). Two weeks after starting the drug treatment, all monkeys received a unilateral intracarotid injection of MPTP-HCl (3 mg). Daily drug administration continue for 6 weeks postlesion after which time the monkeys were sacrificed. Monkeys were assessed for performance on a hand reach task, general activity, and clinical dysfunction based on a clinical rating scale. All groups of monkeys displayed similar deficits on each behavioral measure as well as similar losses of tyrosine hydroxylase (TH)-immunoreactive (ir) nigral neurons, TH-mRNA, and TH-ir striatal optical density indicating that in general treatment failed to have neuroprotective effects.

Effects of graft placement site on the survival of adrenal medulla transplants into the brain and its relation with the recovery of motor function

BACKGROUND

Because of their lack of long-term viability, adrenal tissue transplants have shown limited success in alleviating the motor disturbances associated with experimental and pathologic striatal dopamine denervation. In this study, we examined how the graft placement site influences adrenal medulla transplant survival and its relation with the reduction of motor deficits in rats bearing unilateral 6-OHDA lesion.

METHODS

One or 5 microL of fetal adrenal medullar tissue was grafted either inside the striatal parenchyma or into the lateral ventricle in contact with the dopamine-denervated striatum. Motor disturbances, as assessed by apomorphine-induced rotation, were correlated to the graft morphologic survival features.

RESULTS

Apomorphine-induced rotation showed a marginal reduction of 11% in all groups independently of graft survival features or placement site. Intrastriatal transplants showed limited viability characterized by a substantial loss of graft initial volume as well as fewer and smaller chromaffin cells compared to ventricular grafts, which had a reduced loss of graft initial volume and more and larger chromaffin cells.

CONCLUSIONS

Although the lateral ventricle may favor adrenal medulla transplant viability, their induced motor outcome is comparable to that induced by less viable intrastriatal grafts, suggesting that the implanted dopamine-producing cells may interact and influence striatal neurons better when placed in close proximity.

Behavioral evaluation of hemiparkinsonian MPTP monkeys following dopamine pharmacological manipulation and adrenal co-graft transplantation

Bradykinesia and rigidity are the symptoms that most directly correlate with loss of striatal dopamine in Parkinson's disease. In the hemiparkinsonian (HP) monkey, this is represented by paucity of movement as measured by coli puterized movement analysis, diminished manual dexterity on clinical examination, and diminished performance on operant behavioral tasks. The present study used an MPTP-induced HP model in rhesus monkeys to evaluate the effectiveness of adrenal medullary and peripheral nerve co-grafts in diminishing parkinsonian symptoms. Unoperated controls (N = 4), surgical controls with caudate lesioning (N = 4), and caudate co-grafted (N = 4) HP monkeys demonstrated diminished movement in the home cage following MPTP. This behavior persisted in unoperated controls, but improved in both surgical control and co-grafted monkeys. Functional hand dexterity evaluations demonstrated similar impairment in all three groups but only surgical controls and co-grafted monkeys demonstrated improvement. In general, rotational behavior in response to apomorphine was consistent with recovery of function in surgical controls and co grafted monkeys, but marked between-subject variability precluded group statistical analyses. None of the monkeys could perform the operant task using the affected limb following MPTP. However, the performance of two co-grafted animals demonstrated partial recovery. L-dopa improved operant performance, demonstrating a dopaminergic component to the task. The results demonstrate recovery of behavioral function after surgical treatment, with adrenal co-grafted monkeys showing the greatest degree of improvement.

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.

Promoter-activated expression of nerve growth factor for treatment of neurodegenerative diseases

Genetic transfer approaches have received recent consideration as potential treatment modalities for human central and peripheral nervous system (CNS and PNS, respectively) neurodegenerative disorders, including Parkinson's disease, Alzheimer's disease, and amyotrophic lateral sclerosis. Transplantation of genetically modified cells into the brain represents a promising strategy for the delivery and expression of specific neurotrophic factors, neurotransmitter-synthesizing enzymes, and cellular regulatory proteins for intervention in neurodegenerative diseases. The use of specific regulatable promoters may also provide potential control of gene expression required for dose-specific or time-specific therapeutic strategies. In this article, we review the potential use of activated promoters in ex vivo systems for the potential genetic therapy of neurodegenerative disorders, and then describe our own studies using the zinc-inducible metallothionein promoter for the regulated expression of nerve growth factor (NGF) in rodent brain transplants.

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.

Clinical outcome of cotransplantation of peripheral nerve and adrenal medulla in patients with Parkinson's disease. Clínica Puerta de Hierro Neural Transplantation Group

OBJECT

Transplants of adrenal medulla (AM) and fetal ventral mesencephalon (FVM) are currently being tested as therapeutic alternatives in patients with Parkinson's disease (PD). At the Clínica Puerta de Hierro in Madrid, a controlled clinical trial is underway to establish which donor tissue, if any, is the best for open surgical implantation in patients with PD.

METHODS

Since 1987, varying degrees of clinical improvement have been achieved in Grade IV and V parkinsonian patients by implanting perfused AM and FVM into the right caudate nucleus. To investigate further whether implantation of different types of donor tissues results in qualitatively and quantitatively different degrees of recovery, four patients with Grade IV or V PD received implants of pre-coincubated autologous AM and intercostal nerve in the caudate nucleus. Four nonsurgically treated patients served as a control group. Three years posttransplantation, longer on phases (46.2%+/-10.4% of the day presurgery to 87.5%+/-10.4% of the day 36 months postsurgery) and improved symptoms in on and off phases persist in all four cases, with reduced dyskinesias (67.1%+/-9.2% of the day in on phases presurgery to 17%+/-13.8% of the day in on phases 36 months postsurgery). Progress appears to be stepwise, starting within weeks of tranplantation and becoming clinically significant in the 2nd and 3rd months (similar to our AM- and sooner than in our FVM-implanted patients), followed by a period of stability and, after a second wave of improvement 12 to 18 months posttransplantation (similar to FVM implants), has continued (87.5+/-7 points presurgery to 46+/-5.6 points 36 months postsurgery). In the experimental group, doses of levodopa have been reduced by more than 60% and dopamine agonist use has not resumed. In contrast, there have been no significant clinical changes in the control group.

CONCLUSIONS

Implantation of tissue other than fetal tissue can promote a long-term improvement in the clinical symptomatology of seriously disabled parkinsonian patients. This finding is supported by the autopsy report of a patient with PD who had undergone grafting of AM plus peripheral nerve in which it was demonstrated that a large number of tyrosine hydroxylase-positive cells survive 1 year after implantation. In addition, there was a dense network of host dopaminergic fibers around the graft.

Neural transplantation for Parkinson's disease

1. Neural transplantation is one promising approach for the treatment of Parkinson's disease. Fetal substantia nigra cells are a good source of dopamine, but in order to avoid ethical and immunological problems, adrenal medullary chromaffin cells have been investigated as an alternative source. 2. Grafted adrenal medullary chromaffin cells can provide dopamine as well as several neurotrophic factors that affect dopaminergic neurons in the brain. 3. We review experimental studies for application of neural transplantation techniques in Parkinson's disease, including immunological studies, cryopreservation, microvasculature, donor tissue, and direct gene delivery studies performed in our laboratory. Our clinical experience and new approach involving a polymer-encapsulated cell grafting procedure are also described.

Effect of stereotaxic intrastriatal cografts of autologous adrenal medulla and peripheral nerve in Parkinson's disease: two-year follow-up study

Studies in nonhuman primates with experimental parkinsonism have shown that intrastriatal cografts of autologous adrenal medulla and peripheral nerve yield greater behavioral improvement and graft survival than do adrenal medulla grafts alone. To test these observations, five patients with advanced Parkinson's disease were selected to receive unilateral intrastriatal adrenal medulla-intercostal nerve cografts. They were evaluated using the Core Assessment Program for Intracerebral Transplantation (CAPIT) protocol. Three of these patients also underwent quantitative motor testing for the measurement of upper limb bradykinesia (movement time; MT). Following right flank adrenalectomy, cografts consisting of small fragments of adrenal medullary tissue and minced intercostal nerve were stereotaxically implanted into three targets in the right striatum using computerized tomography guidance. Surgery was uneventful and postoperative magnetic resonance imaging revealed accurate placement of the grafts. No morbidity was encountered. Results of 24 months of clinical and quantitative motor assessments postoperatively are reported. Total UPDRS motor scores in the "off" state improved from a mean preoperative score of 39.5 to 32.1 at 3, 29.7 at 6, 27.6 at 9, 28.5 at 12, 31.4 at 18, and 26.5 at 24 months after surgery. Total timed motor test scores during the "off" state improved 17.9% at 6, 23.3% at 9, 18.2% at 12, 38.2% at 18, and 34.9% at 24 months postoperatively compared to baseline. Movement time showed statistically significant improvement (repeated measures ANOVA, P < 0.05) in the left arm (contralateral to surgery) in all three patients tested. These results indicate that stereotaxic intrastriatal implantation of autologous adrenal medulla-peripheral nerve cografts can be performed safely and clinical improvement from this procedure is sustained for a period of 24 months. The clinical improvement was paralleled by improvement in objective, quantitative motor testing.

Long-term enhanced chromaffin cell survival and behavioral recovery in hemiparkinsonian rats with co-grafted polymer-encapsulated human NGF-secreting cells

The transplantation of genetically modified cells represents one potential means of delivering trophic factors to the brain to support the survival of host neurons and to increase the survival of co-grafted cells. The present study examined the ability of encapsulated baby hamster kidney (BHK) fibroblasts, which were genetically modified to produce human nerve growth factor (hNGF), to provide long-term trophic support to co-grafted adrenal chromaffin cells. Following polymer encapsulation, BHK-hNGF cells were grafted into the striatum of hemiparkinsonian rats together with unencapsulated adrenal medullary chromaffin cells. Secretion of hNGF from the encapsulated cells, morphology of these cells, apomorphine-induced rotational behavior of the host animals, and survival of the co-grafted chromaffin cells were examined 1, 6, and 12 months after transplantation. Analysis of retrieved capsules revealed that the BHK cells survived and continued to release hNGF at a level of 2-3 ng/day even 12 months after transplantation. Although the animals receiving adrenal medulla alone did not show recovery of apomorphine-induced rotational behavior, the animals receiving adrenal medulla intrastriatal hNGF-secreting cells showed a significant decrease (40-50%) in apomorphine-induced rotation within 1 month postimplantation that remained stable for the 12-month test period. Tyrosine hydroxylase immunocytochemistry further revealed that while survival of chromaffin cells without hNGF support was poor, co-grafting of adrenal medulla and BHK-hNGF cells dramatically 926- to 32-fold) increased chromaffin cell survival 1, 6, and 12 months after transplantation. These results demonstrate that (1) encapsulated BHK cells survive for extended periods of time in vivo while continuing to secrete hNGF, (2) the continued secretion of hNGF provides trophic support for co-grafted adrenal chromaffin cells, and (3) the increased chromaffin cell survival is associated with long-term, stable behavioral recovery. These data further support the potential use of this approach for treating Parkinson's disease.

Long-term transgene expression in fetal rat suprachiasmatic nucleus neurografts following ex vivo adenoviral vector-mediated gene transfer

Ex vivo gene transfer to fetal suprachiasmatic nucleus (SCN)-containing solid piece neurografts was explored using a first-generation prototype adenoviral vector containing the reporter gene LacZ (Ad-LacZ). Transgene expression was examined at different intervals following grafting in the IIIrd ventricle of rat brain and was compared to that of explant cultures. Large numbers of beta-galactosidase-positive cells were observed 8 days postgrafting. The number of stained cells had decreased considerably at 21 days but transduced cells were still present at 70 days. In vitro culturing of infected SCN tissue revealed high expression up to 21 days, indicating that the in vivo and in vitro fates of Ad-LacZ-infected cells were different. The main reason for this difference appeared to be cell loss by necrosis in the initial phase after transplantation, a phenomenon not related to the infection with Ad-LacZ since it similarly occurred in control grafts. In vivo inflammatory responses, observed after immunostaining for macrophages and T-lymphocytes, were also comparable in control and Ad-LacZ-treated transplants, except that cytotoxic T-cells were observed in the Ad-LacZ-treated transplants and not in controls. The recruitment of these cells was, however, minor and primarily observed at 8 days postgrafting, indicating that a major immunological rejection of the transduced graft did not occur. In both control and Ad-LacZ-infected transplants similar survival and intraimplant neuritic growth of SCN cells were visible. Ex vivo gene transfer of solid piece fetal SCN grafts with adenoviral vectors therefore appeared to be a nontoxic long-term gene-introducing procedure. This would in principle enable the local production of neurotrophic factors within the transplant and has the potential to improve functional SCN neurografting.

Dopaminergic transplants in patients with Parkinson's disease: neuroanatomical correlates of clinical recovery

For the past 15 years, patients with Parkinson's disease have participated in clinical trials evaluating the efficacy of intrastriatal dopamine transplants. Principally, two donor tissues have been employed, the chromaffin cells of the adrenal medulla and fetal ventral mesencephalon. The clinical response following each type of transplant has been variable. In general, the magnitude and the duration of the clinical response is greater with fetal dopaminergic neurons than with adrenal medullary grafts. Postmortem studies of patients receiving adrenal medullary grafts or fetal nigral implants provide a neuroanatomical framework for the clinical response. Adrenal grafts survive poorly following implantation into the striatum, but they are capable of inducing sprouting of host-derived fibers within a the caudate nucleus. In contrast, robust survival of fetal nigral implants can be achieved within the human brain which can provide extensive reinnervation to the parkinsonian striatum. These findings are strikingly similar to what has been seen in rodent and nonhuman primate models of PD. This paper describes the neuroanatomical correlates of dopamine brain grafting in humans and elucidates the pattern of changes seen in dopaminergic systems which are associated with clinical benefit.

In vitro assessment of neurotrophic activity from the striatum of aging rats

Neurotrophic factors are produced in the striatum following trauma and have a demonstrable effect on in vitro bioassays and on in vivo graft survival. We have previously measured the in vitro effect of these factors following trauma to the striatum of young rats. However, the effect of age on this neurotrophic response has not been evaluated. In this study we report on the in vitro effects of extracts (obtained from gelfoam) removed from striatal cavities 7 days following trauma. Gelfoam extract from aged rats (18-24 months) had a reduced neurite-promoting response in dorsal root ganglia (DRG) and SH-SY5Y (a dopamine-producing neuroblastoma cell line) assays, compared to gelfoam from young rats (2-3 months). In contrast, extracts from both young and old rats showed significant neuroprotection of SH-SY5Y cells from the dopaminergic neurotoxins N-methy-4phenylpyridinium ion (MPP +) and 6-hydroxydopamine (6-OHDA). The results suggest that the striatum of aged individuals may have (1) a diminished capacity of neurite promotion and/ or (2) that neurite outgrowth and neuroprotection may be influenced by different factors or different levels of the same factors. The direct implication is that aged animals would be the most appropriate models to study experimental therapies for Parkinson's disease.

Applications of gene therapy to the CNS

Gene therapy is a new method with potential for treating a broad range of acquired and inherited neurologic diseases, where the causative gene defect or deletion has been identified. In addition to gene replacement the application of gene products that reduce cellular dysfunction or death represent new therapeutic options. Gene transfer techniques to express novel proteins using different viral vectors in vitro and in vivo, as well as animal models and human trials will be reviewed in this article. We will focus on a new lentiviral vector as a recent gene transfer method and degenerative disorders of the CNS, and their related model systems.

Functional fetal nigral grafts in a patient with Parkinson's disease: chemoanatomic, ultrastructural, and metabolic studies

A patient with Parkinson's disease received bilateral fetal human nigral implants from six donors aged 6.5 to 9 weeks post-conception. Eighteen months following a post-operative clinical course characterized by marked improvement in clinical function, this patient died from events unrelated to the grafting procedure. Post-mortem histological analyses revealed the presence of viable grafts in all 12 implant sites, each containing a heterogeneous population of neurons and glia. Approximately 210,146 implanted tyrosine hydroxylase-immunoreactive (TH-ir) neurons were found. A greater number of TH-ir grafted neurons were observed in the right (128,162) than the left (81,905) putamen. Grafted TH-ir neurons were organized in an organotypic fashion. These cells provided extensive TH-ir and dopamine transporter-ir innervation to the host striatum which occurred in a patch-matrix fashion. Quantitative evaluations revealed that fetal nigral grafts reinnervated 53% and 28% of the post-commissural putamen on the right and left side, respectively. Grafts on the left side innervated a lesser area of the striatum, but optical density measurements were similar on both sides. There was no evidence that the implants induced sprouting of host TH-ir systems. Electron microscopic analyses revealed axo-dendritic and occasional axo-axonic synapses between graft and host. In contrast, axo-somatic synapses were not observed. In situ hybridization for TH mRNA revealed intensely hybridized grafted neurons which far exceeded TH mRNA expression within residual host nigral cells. In addition, gamma-amino butyric acid (GABA)-ergic neurons were observed within the graft that formed a dense local neuropil which was confined to the implant site. Serotonergic neurons were not observed within the graft. Cytochrome oxidase activity was increased bilaterally within the grafted post-commissural putamen, suggesting increased metabolic activity. In this regard, a doubling of cytochrome oxidase activity was observed within the grafted post-commissural putamen bilaterally relative to the non-grafted anterior putamen. The grafts were hypovascular relative to the surrounding striatum and host substantia nigra. Blood vessels within the graft stained intensely for GLUT-1, suggesting that this marker of blood--brain barrier function is present within human nigral allografts. Taken together, these data indicate that fetal nigral neurons can survive transplantation, functionally reinnervate the host putamen, establish synaptic contacts with host neurons, and sustain many of the morphological and functional characteristics of normal nigral neurons following grafting into a patient with PD.

Cografting with polymer-encapsulated human nerve growth factor-secreting cells and chromaffin cell survival and behavioral recovery in hemiparkinsonian rats

Encapsulated cell grafting is one approach for the delivery of neurotransmitters and/or neurotrophic factors to the brain. Baby hamster kidney (BHK) cells were genetically modified to secrete high levels of human nerve growth factor (hNGF). Following polymer encapsulation, these cells were implanted into the left lateral ventricle or the left striatum 1.5 mm away from striatally cografted unencapsulated adrenal medullary chromaffin cells in hemiparkinsonian rats. Although the animals receiving adrenal medulla alone or adrenal medulla with intraventricular hNGF-secreting cell grafting did not show recovery of apomorphine-induced rotational behavior, the animals receiving adrenal medulla with intrastriatal hNGF-secreting cell implants showed a significant recovery of rotational behavior 2 and 4 weeks after transplantation. Histological analysis revealed that in animals receiving adrenal medulla with intraventricular hNGF-secreting cell grafting, the number of tyrosine hydroxylase-immunoreactive (TH-IR) surviving chromaffin cells tended to be higher (approximately five to six times) than in animals receiving adrenal medulla alone; however, this increase did not reach statistical significance. In contrast, in animals receiving adrenal medullary cells together with intrastriatal hNGF-secreting cells, the number of TH-IR surviving chromaffin cells was more than 20 times higher than that in animals receiving adrenal medullary cells alone. Analysis of retrieved capsules revealed that hNGF continued to be released by encapsulated BHK-hNGF cells after 4 weeks in vivo. Moreover, histological analysis confirmed the presence of numerous viable encapsulated BHK-hNGF cells. These results indicate the potential use of intrastriatal implantation of encapsulated hNGF-secreting cells for augmenting the survival of cografted chromaffin cells as well as promoting the functional recovery of hemiparkinsonian rats. These data indicate that this approach may have potential application for treating Parkinson's disease.

Chromaffin cell survival and host dopaminergic fiber recovery in a patient with Parkinson's disease treated by cografts of adrenal medulla and pretransected peripheral nerve. Case report

A 55-year-old woman with severe Parkinson's disease was treated by cografting adrenal medulla with pretransected peripheral nerve into the bilateral caudate nuclei. The patient showed modest improvement of her akinesia; this effect persisted for 1 year after transplantation, when she suddenly died from upper gastrointestinal bleeding unrelated to the grafting procedure. At autopsy, a large number of tyrosine hydroxylase-immunoreactive chromaffin cells were observed within the caudate graft sites and a dense network of host dopaminergic fibers was visualized. This autopsy finding is very important for the field of experimental and clinical chromaffin cell grafting because it is the first evidence that cografts using pretransected peripheral nerve might enhance the survival of chromaffin cells and the recovery of host dopaminergic fibers in humans suffering from Parkinson's disease.

Potential of neurotrophic factors in therapy of Parkinson's disease

Neurotrophic factors of dopaminergic neurons may represent a potential neuroprotective therapy for PD. This article reviews published experiments that demonstrate the effects of neurotrophic factors on dopaminergic neurons in vitro and in vivo. At present this issue is predominantly investigated in basic neuroscientific research. Its possible future clinical relevance is discussed.

Parkinson's disease, trophic factors, and adrenal medullary chromaffin cell grafting: basic and clinical studies

Neural transplantation is one of the promising approaches for the treatment of Parkinson's disease. Although the strategy of using adrenal medulla as donor tissue, rather than fetal nigra tissue, started as an alternative method, recent experimental studies demonstrated the efficacy of adrenal medulla grafting as a neurotrophic source. Many methods to increase the survival of grafted chromaffin cells have been developed, some of which have already been applied clinically with encouraging results. This review summarizes the advancements of adrenal medulla grafting in basic and clinical studies. Special attention is focused on the relationship with neurotrophic factors and how we can enhance the survival of grafted chromaffin cells.

Genetically Modified Pc 12 Brain Grafts: Survivability and Inducible Nerve Growth Factor Expression

Neural transplantation of genetically modified cells has been successfully employed to reverse functional deficits in animal models of neurodegenerative disorders, including Parkinson's disease. While implanted PC12 cells secrete dopamine in vivo and can ameliorate dopamine deficiency in parkinsonian rat model systems, these cells either degenerate within 2-3 wk postimplantation (presumably due to the lack of neural trophic factor support at the site of implantation), or in some cases, form a tumor mass leading to the death of the host animal. To address these limitations, we have developed a genetically modified PC12 cell line that can synthesize nerve growth factor (NGF) under the control of a zinc-inducible metallothionein promoter. When implanted in the rat striatum and under in vivo zinc stimulation, these cells will neurodifferentiate, express tyrosine hydroxylase, and will undergo survival through potential autocrine trophic support. This regulatable cell line and general approach may provide additional insight on the potential utilization of cell transplants for treatment of Parkinson's disease and other neurodegenerative disorders.

Clinical experience with cotransplantation of peripheral nerve and adrenal medulla in patients with Parkinson's disease

Coimplants of adrenal medulla (AM) and peripheral nerve (PN) in animal models of Parkinson's disease (PD) have shown that AM cells survive longer, tend to show neuronal phenotype, and enhance sprouting of host fibers. Since 1987, our implants of perfused AM and fetal ventral mesencephalon (FVM) in PD patients have achieved varying degrees of clinical improvement. If the donor tissue determines the improvement, different types of implants should result in qualitatively and quantitatively different degrees of improvement. The purpose of this study is to determine whether or not the clinical course, improvement slope, and reduction of medication observed in PD patients who undergo tissue transplantation (Tx) depend on the donor tissue type. In a pilot study, four grade IV-V PD patients received implants of precoincubated autologous AM and intercostal nerve in the caudate nucleus (open surgery). Clinical assessment was based on international scales (UPD) as reported for Tx of FVM and perfused AM. There were no systemic or neurologic complications. Four years post-Tx, longer On phases and improved PD symptoms (ADL and motor-UPD) in On and Off persist in four cases, with reduced dyskinesias. Progress appears to be stepwise, starting within weeks of Tx (similar to AM and sooner than our FVM implants), followed by a period of stability and, after a second wave of improvement 12-18 months post-Tx (similar to FVM implants), continues to date. L-dopa medication has been reduced by more than 60% and dopamine agonist use has not resumed. We conclude that our recipients continue to be clinically better than prior to Tx. The course of recovery after co-Tx of AM and PN differs from that of FVM or AM implants. This fact may be related to the etiological factors that produce the improvement.

Increased susceptibility to MPTP toxicity in middle-aged rhesus monkeys

In the present study, age-associated effects of the neurotoxin 1-methyl-4-phenyl-1,2,3,6 tetrahydropyridine (MPTP) administered via the right carotid artery were evaluated pre- and post-MPTP treatment in 26 female rhesus monkeys ranging in age from young adulthood to middle age (5 to 23 years old). A significant inverse correlation was seen between age and MPTP dose needed to produce stable, moderate parkinsonian features. Rhesus in the 5- to 9-year-old group required approximately three times the amount of MPTP as 20- to 23-year-old animals. Even though they received less MPTP, the older animals consistently displayed more severe bradykinesia, upper limb rigidity, and balance and gait abnormalities. Prior to MPTP treatment, home cage activity levels were strongly age dependent, with animals in the 10- to 19-year and 20- to 23-year groups displaying significantly less daytime activity than 5- to 9-year-old rhesus. Home cage activity levels tended to decrease in all age groups following MPTP treatment, but significant decreases were only measured in daytime activity in the 10- to 19- and 20- to 23-year age groups.

Two-year follow-up study of a patient with Parkinson's disease and severe motor fluctuations treated by co-grafts of adrenal medulla and peripheral nerve into bilateral caudate nuclei: case report

We performed co-grafts of adrenal medulla and peripheral nerve into the bilateral caudate nuclei of a 43-year-old patient with advanced Parkinson's disease who showed severe daily motor fluctuations before surgery. There were no postoperative complications, and a 2-year follow-up result is presented. The patient showed a gradual and significant amelioration of the parkinsonian symptoms starting 2 weeks after transplantation. The alleviation of akinesia during "off" periods was the most apparent clinical improvement and continued for 2 years after surgery. The dosage of L-dopa/benserazide was significantly reduced after surgery compared with that before surgery. The results indicate that co-grafts of adrenal medulla with peripheral nerve may be useful for the treatment of Parkinson's disease in the long term.