Adrenal medulla grafts enhance functional activity of the striatal dopamine system following substantia nigra lesions

Adrenal medulla grafts in the lateral ventricle reduce the behavioral manifestations of striatal dopamine depletion in an animal model of Parkinson's disease. Using microdialysis in freely moving rats, the present experiments determined that dopamine was not detectable in cerebrospinal fluid (CSF). However, adrenal medulla grafts were associated with an increase in dopamine turnover and amphetamine-stimulated striatal dopamine release was increased in animals with behaviorally effective adrenal medulla grafts. Therefore, adrenal medulla grafts increase striatal dopamine activity without an appreciable release of dopamine into the CSF. Adrenal medulla grafts also increased serum dopamine concentrations, and the increase in serum dopamine was directly correlated with the behavioral efficacy of the grafts. We suggest that dopamine, produced by adrenal medulla grafts, may gain access to the striatum via the blood supply and then leak out into the host striatum through permeable blood vessels adjacent to the graft. Through this mechanism, adrenal medulla grafts may increase functional dopaminergic activity in the striatum. These results may be important for understanding how autografts of adrenal medulla cells produce a putative alleviation of the symptoms of Parkinson's disease.     

Does adrenal graft enhance recovery of dopaminergic neurons in Parkinson's disease?

A 54-year-old man with a 5-year history of Parkinson's disease was treated with and autograft of adrenal medulla into the right caudate nucleus and died 4 months after surgery. Postmortem examination revealed that the graft was necrotic. It consisted mainly of reticulin and collagen fibrosis without catecholaminergic cell bodies identified either by immunohistochemistry or by in situ hybridization with labeled human tyrosine hydroxylase (TH) cDNA probe. Sparse TH-immunoreactive fibers, which did not stain for dopamine-beta-hydroxylase (DBH), ran through the graft. In contrast, intense staining for these catecholaminergic markers was found in the untransplanted adrenal medulla. Densely packed TH-positive, DHB-negative fibers were found in a restricted zone of the host striatum at the periphery of the graft. This effect was selective since the density of other neurons was not modified. The present study describes an additional patient in whom adrenal medulla autotransplantation failed to improve the parkinsonian disability. It suggests, however, that adrenal medulla grafts may stimulate the sprouting of striatal dopaminergic fibers in a limited zone of the grafted striatum.     

Cografts of adrenal medulla with peripheral nerve enhance the survivability of transplanted adrenal chromaffin cells and recovery of the host nigrostriatal dopaminergic system in MPTP-treated young adult mice

Schwann cells from transected peripheral nerve segments are known to produce nerve growth factor (NGF). We performed adrenal medullary grafts or cografts of adrenal medulla and sciatic nerve into the striatum of MPTP-treated young adult mice, and compared the survivability of grafted chromaffin cells and the recovery of intrinsic host DA fibers using computerized image analysis of tyrosine hydroxylase (TH)-immunoreactive (IR) fibers and neurochemical analysis with high performance liquid chromatography (HPLC). Adrenal medullary chromaffin cells cografted with sciatic nerve survived better than those in adrenal grafts alone; host DA fiber recovery was more prominent in mice with cografts than in mice with adrenal grafts alone. A large number of TH-IR surviving cells in cografted mice showed long neuronal processes which were rarely seen in the mice receiving adrenal graft alone. We conclude that cograft of adrenal medulla and sciatic nerve promotes intrinsic host DA fiber recovery better than adrenal medulla grafts alone, and that survivability of grafted chromaffin cell may promote host DA fiber recovery. Adrenal medullary autografts have been used in patients with Parkinson's disease; we suggest that if this approach is to be used in the future, methods to increase the survivability of grafted chromaffin cells, such as co-grafting with pieces of peripheral nerve, be considered to enhance the survivability of the chromaffin cells, which might be closely related to the functional recovery of the patients by this grafting procedure. Of course, such strategies as the present cografting approach must be demonstrated to work in older animals using older donor tissue before proceeding to this next step in humans.     

Adrenal medullary graft induces recovery of the host nigrostriatal dopaminergic system in MPTP-induced mouse model of Parkinson's disease

C57BL/6 mice show decreased dopaminergic fibers and dopamine concentration in the striatum following systemic injection of 1-methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine (MPTP). We have investigated the effect of adrenal medullary grafts into the striatum of young mice treated with MPTP. Enhanced recovery of the host nigrostriatal dopaminergic system was observed in those adrenal medullary grafted mice. However, this recovery was influenced by the survivability of grafted chromaffin cells and adrenal chromaffin cells from younger donors survived better than those from older donors. Since adrenal chromaffin cells contain several kinds of neurotrophic factors such as basic fibroblast growth factor and gangliosides, survivability of those grafted chromaffin cells may play an important role concerning recovery of the host intrinsic dopaminergic fibers. Adrenal medullary grafts to the patients with Parkinson's disease are currently under way in a large number of hospitals and we suggest more consideration be given to methods which lead to enhance the grafted chromaffin cell survival, since those survivability might be closely related to the functional recovery of these patients.     

Adrènal medulla grafts survice and exhibit catecholamine-specific fluorescence in the primate brain

Parkinson's disease most consistently involves pathologic changes in the substantia nigra, which is the major source of dopamine to the striatum. It has been shown that either fetal substantia nigra or adrenal medulla tissue implanted into the rat brain survives, produces dopamine, and improves behavioral abnormalities induced by deprivation of the caudate nucleus of its dopaminergic innervation. Thus, catecholaminecontaining grafts could be potential replacements for destroyed or damaged dopaminergic neurons in patients with Parkinson's disease. To explore the potential of this therapeutic approach, fetal substantia nigra or host adrenal medulla were grafted to the denervated caudate nucleus of the rhesus monkey. Under the specific conditions of our experiment, fetal substantia nigra did not survive in either of two animals tested. On the other hand, some tissue from adrenal medulla grafts survived in all four animals tested. These grafted cells contained catecholamines, as indicated by the presence of specific glyoxylic acid-induced catecholamine fluorescence. In two of the four animals, however, the grafts contained fewer than 10 surviving cells, and in the other two animals, about 190 and 300 cells were found, respectively. Despite the small numbers of cells, this is the first demonstration that peripheral tissue autografts can survive implantation into the nonhuman primate central nervous system.     

Intranigral transplantation of solid tissue ventral mesencephalon or striatal grafts induces behavioral recovery in 6-OHDA-lesioned rats

Parkinson's disease (PD) is characterized by a degeneration of the dopamine (DA) pathway from the substantia nigra (SN) to the basal forebrain. Prior studies in unilateral 6-hydroxydopamine (6-OHDA)-lesioned rats have primarily concentrated on the implantation of fetal ventral mesencephalon (VM) into the striatum in attempts to restore DA function in the target. We implanted solid blocks of fetal VM or fetal striatal tissue into the SN to investigate whether intra-nigral grafts would restore motor function in unilaterally 6-OHDA-lesioned rats. Intra-nigral fetal striatal and VM grafts elicited a significant and long-lasting reduction in apomorphine-induced rotational behavior. Lesioned animals with ectopic grafts or sham surgery as well as animals that received intra-nigral grafts of fetal cerebellar cortex showed no recovery of motor symmetry. Subsequent immunohistochemical studies demonstrated that VM grafts, but not cerebellar grafted tissue expressed tyrosine hydroxylase (TH)-positive cell bodies and were associated with the innervation by TH-positive fibers into the lesioned SN as well as adjacent brain areas. Striatal grafts were also associated with the expression of TH-positive cell bodies and fibers extending into the lesioned SN and an induction of TH-immunolabeling in endogenous SN cell bodies. This finding suggests that trophic influences of transplanted fetal striatal tissue can stimulate the re-expression of dopaminergic phenotype in SN neurons following a 6-OHDA lesion. Our data support the hypothesis that a dopaminergic re-innervation of the SN and surrounding tissue by a single solid tissue graft is sufficient to improve motor asymmetry in unilateral 6-OHDA-lesioned rats.     

Evidence for target-specific nerve fiber outgrowth from subpopulations of grafted dopaminergic neurons: a retrograde tracing study using in oculo and intracranial grafting

Efforts have been made to counteract the symptoms of Parkinson's disease by substituting the loss of dopaminergic neurons with fetal ventral mesencephalic grafts. One of the postulated limiting factors in this treatment is the relatively poor cell survival and limited graft-derived fiber outgrowth. Recent results documenting enhanced survival of grafted dopaminergic neurons showed no positive correlation to enhanced innervation of the striatal target. Therefore this study was undertaken to investigate whether all surviving grafted dopaminergic neurons projected to the striatal target. Hence, fetal ventral mesencephalic tissue was implanted adjacent to mature versus immature striatal tissue using in oculo and intraventricular grafting techniques. In in oculo grafting, fetal ventral mesencephalon was implanted simultaneously with fetal lateral ganglionic eminence (immature striatal target) or to already matured striatal in oculo grafts (mature striatal target). Furthermore, fetal ventral mesencephalon was implanted into the lateral ventricle adjacent to mature dopamine-depleted striatum. The retrograde tracer fluorogold was injected into the striatal portion of the in oculo cografts and into reinnervated areas of the adult brain. Immunohistochemistry revealed that a significantly larger proportion of tyrosine hydroxylase-positive neurons in the ventral mesencephalic graft was innervating in oculo immature striatal tissue, and hence was fluorogold-positive, in comparison with the number of tyrosine hydroxylase-positive neurons innervating mature striatal tissue. Moreover, intracranial transplantations showed that tyrosine hydroxylase-positive neurons were distributed within the grafts in dense clusters of cells. In most clusters tyrosine hydroxylase-positive cells were fluorogold-negative but calbindin-positive. In a few tyrosine hydroxylase-positive cell clusters, neurons were coexpressing fluorogold but were calbindin-negative. In conclusion, significantly more dopamine neurons projected to immature than to mature striatal tissue and thus, a subpopulation of grafted dopaminergic neurons was not projecting into adult striatum. Thus, the results from this study show that further attempts to enhance survival of grafted dopamine neurons in purpose to enhance graft-derived fiber outgrowth and efficacy should also consider different subtypes of dopamine neurons.     

Lesioning of the striatum reverses motor asymmetry in the 6-hydroxydopamine rodent model of parkinsonism.

In the rat several paradigms of grafting of adrenal medulla into the striatum were studied following the induction of a parkinsonian model, using a unilateral 6-hydroxydopamine (6-OHDA) lesion of the substantia nigra. Direct autologous grafting of adrenal medulla into the caudate-putamen complex, a radiofrequency lesion of the striatum alone, and a radiofrequency lesion followed by delayed grafting of adrenal medulla were compared by analyzing rotational behavior. Direct grafting of adrenal medulla produced an overall reduction in apomorphine induced turning behavior by 43.5% when compared with controls. Radiofrequency lesioning of the striatum without graft showed the best improvement over control animals with a 92% reduction in the total number of rotations induced by apomorphine. Delayed grafting into the caudate lesion cavity also produced a dramatic reduction in motor asymmetry but did not improve the behavioral outcome over that of the lesion alone. Animals receiving only radiofrequency lesions exhibited a band of increased tyrosine hydroxylase like immunoreactivity bordering the lesion cavity. Graft survival was limited in the non-lesioned animals but appeared enhanced in the animals whose striatum was previously lesioned. Lesion location within the striatum influenced the behavioral outcome. Large reductions in apomorphine-induced rotations could result from small lesions of the dorso-lateral striatum. These findings indicate that selective destruction of the caudate-putamen complex without tissue transplantation produces a dramatic reduction in the motor asymmetry of 6-OHDA treated rats. Suggested explanations for the decrease in induced rotational behavior with radiofrequency lesions include a decrease in the number of striatal dopamine receptors following cell destruction and lesion-induced recovery of host dopaminergic afferents. Striatal damage in critical areas can reverse some of the motor behavior associated with the 6-OHDA model and needs to be considered when evaluating the effects of neural grafting in this model.     

Adrenal medullary autografts into the basal ganglia of Cebus monkeys: injury-induced regeneration

Questions arising from recent clinical neural transplantation trials in Parkinson's disease have under-scored the necessity for a thorough experimental evaluation of the structural and functional consequences of this procedure. The present study investigated the neuroanatomical host reaction to intrastriatal implants in normal and 1-methyl-4-phenyl-1,2,5,6-tetrahydropyridine (MPTP)-treated nonhuman primates. Nine monkeys (Cebus apella) received intrastriatal implants using either a stereotactic approach with a silver tissue carrier or an open microsurgical procedure. Seven of these animals received intrastriatal adrenal medullary autografts, while two received control implants consisting of the tissue carrier alone. One month following transplantation, the hosts' brains were evaluated via immunohistochemical and routine histologic methods. In both MPTP-treated and normal monkeys, enhanced ipsilateral expression of tyrosine hydroxylase-like immunoreactive (TH-IR) fibers in the caudate nucleus was observed, despite minimal survival of adrenal chromaffin cells in the implants. The intensity of this response was greatest adjacent to the implant site, but a clearly increased degree of ipsilateral striatal fiber staining also could be seen several millimeters from the graft. TH-IR fibers also were more dense and of thicker caliber throughout the nigrostriatal and mesolimbic pathways ipsilateral to the implant. Control stereotactic implants, consisting of a silver tissue carrier alone, produced a similar enhancement of immunoreactive fibers, suggesting an induction of TH-IR fibers by the parenchymal injury produced during surgical implantation. There are two major hypotheses proposed to explain why adrenal medullary grafts may promote functional recovery in human parkinsonism: (1) replacement of lost striatal neurotransmitter (dopamine) by the viable grafted tissue, or (2) induction of recovery of remaining host dopaminergic systems by the implantation procedure. Our current data appear to support the latter.     

Influence of mesostriatal afferents on the development and transmitter regulation of intrastriatal grafts derived from embryonic striatal primordia.

Embryonic striatal grafts develop a modular organization in which patches of tissue enriched in many transmitter substances characteristic of striatum (P regions) are embedded in surrounds (NP regions) expressing only low levels of these substances. Catecholaminergic fibers from the host brain, identified by their expression of tyrosine hydroxylase (TH), grow into such grafts and selectively terminate in the striatum-like P regions. This terminal pattern suggests that cell-cell affinities between neurons of the substantia nigra and striatum may play a role either in the aggregation of the striatal cells into P regions, or in the targeting of the TH-positive fibers to the cell clusters. In the present study, we tested the first of these possibilities. Striatal grafts derived from embryonic day 15 striatal primordia were implanted into the ibotenate-damaged host striatum of rats previously treated with 6-hydroxydopamine (6-OHDA) to destroy TH-containing dopaminergic nigrostriatal afferents. The 6-OHDA lesions that eliminated nearly all TH-like immunostaining in the host striatum also resulted in disappearance of nearly all TH-positive fibers in the grafts. In this dopamine-depleted environment, the grafts nevertheless developed a clear modular organization. They contained striatum-like patches with neurons expressing many of the neurochemicals characteristic of striatum (ACh, ChAT, calbindin-D28KD, met-enkephalin, and dopamine- and adenosine 3':5'-monophosphate-regulated phosphoprotein-32,000 or DARPP-32), and these patches were surrounded by graft tissue expressing few of these striatal markers. These observations suggest that the ingrowth of TH-positive fibers from the host is not obligatory for the sorting out of striatal from nonstriatal cells during the formation of P regions in embryonic striatal grafts. Despite the fact that dopaminergic denervation of the host striatum did not disrupt either the aggregation of grafted cells into P regions or the acquisition of striatal neurochemical phenotypes by cells in the P regions, there were clear differences between the staining patterns of these grafts and grafts placed into dopamine-innervated striatum. Most striking was a sharp increase of met-enkephalin-like immunostaining in the P zones of the denervated grafts. Upregulation of met-enkephalin is known to occur in the dopamine-depleted mature striatum, and was observed in the parts of host striatum surrounding the grafts on the side ipsilateral to the 6-OHDA lesions. This result suggests that functional interactions between dopaminergic and enkephalinergic systems can occur in the striatal circuits reconstructed by embryonic striatal grafting. More generally, our results suggest that TH-containing afferents from the host striatum, though not required for induction and maintenance of striatal phenotypy in striatal grafts, can chronically regulate neurotransmitter/neuromodulator expression in neurons of the striatum-like P zones in a manner similar to that found for the normal striatum.     

Non-dopaminergic neurons in ventral mesencephalic transplants make widespread axonal connections in the host brain

Motor dysfunction in Parkinson's disease (PD) can be effectively alleviated through intra-striatal transplantation of fetal ventral mesencephalic tissue. The success of this approach is dependent on the survival, axonal outgrowth and synaptic integration of newly grafted dopamine neurons with the host striatum. The functional outcome of transplantation therapy has, however, been highly variable, particularly in PD patients, but also in animal models of PD, and thus there is a need for a deeper understanding of possible mechanisms underlying this variability such as graft composition and the resulting graft–host connectivity. Here we describe a series of transplantation experiments whereby mouse VM tissue has been grafted into the striatum of 6-hydroxydopamine lesioned rats. Six weeks after grafting immunohistochemical analysis using the mouse specific ‘M2M6’ antibodies revealed both dopaminergic and non-dopaminergic components of graft-derived fibre outgrowth into the host brain. We report here that while dopaminergic outgrowth was predominately confined to the striatum, there was also a significant degree of non-dopaminergic outgrowth to extra-striatal structures including the thalamus, cortex and midbrain. Retrograde tracing experiments showed that grafted neurons of GABAergic identity contribute to this non-dopaminergic outgrowth. In line with our recent findings on the function of serotonergic neurons in fetal VM grafts, these results further underscore the potential impact that non-dopaminergic neurons may have on the functional outcome of intrastriatal fetal VM grafts.     

联合培养胚鼠的黑质及纹状体LGE细胞脑内移植治疗帕金森病大鼠的实验研究

目的　观察并检测胚鼠纹状体外侧节突 (LGE)对多巴胺能 (DA)细胞存活性的促进和营养导向作用。方法　将帕金森病 (PD)模型随机分成四组 :Co -culture组 (n =12 ) ;Cograft组 (n =12 ) ;Solo -VM组 (n =12 ) ;Con trol组 (n =8)。将胚鼠LGE细胞和腹侧中脑组织 (VM )制成细胞悬液 ,植入Control组外的其他各组动物的尾壳核。 2周后进行PD鼠行为学检测 ,连续观察 2 4周 ,继之将各组大鼠处死 ,进行免疫组化染色。结果　Co -culture组和Co - graft组大鼠移植后旋转行为较Solo -VM组大鼠明显减少。CO -culture组和CO - graft组之间大鼠的旋转行为比较 ,无统计学差异。免疫组化观察证实LGE和VM离体培养移植和新鲜移植均能提高DA细胞的存活性 ,增加宿主纹状体内DA纤维重新支配的密度 ,并形成明显的DA细胞团。结论　LGE细胞对VM移植物有明显的营养导向作用 ,并可增强DA细胞的存活 ,促进移值后DA细胞功能持久维持 ,并增加DA细胞再支配的密度     

Human ventral mesencephalic xenografts to the catecholamine-depleted striata of athymic rats: ultrastructure and immunocytochemistry

On the basis of animal studies, grafts of fetal human dopaminergic cells have been suggested as a therapy for Parkinson's disease. The purpose of this study was to characterize the ultrastructure and immunocytochemistry of human ventral mesencephalic xenografts placed into the catecholamine-depleted striata of athymic "nude" rats. Human fetal tissue was obtained from tissue fragments derived from elective abortions during the first trimester of pregnancy. Small pieces of the basal mesencephalon were grafted into the catecholamine-depleted striata of four athymic nude rats. The rats were allowed to survive from 3 to 6 months after grafting; following fixation, the striatal tissue containing the grafts was labeled with antibodies against tyrosine hydroxylase and serotonin. Immunocytochemistry revealed tyrosine-hydroxylase-like-immunoreactive (THLI) and serotoninlike-immunoreactive (5HTLI) cell bodies within the human grafts. Both 5HTLI and THLI fibers crossed the graft-host interface and innervated the previously lesioned striatum. Both types of fibers also entered the host cortex from the adjacent human graft. At the ultrastructural level, THLI and 5HTLI fibers and synaptic terminals were observed in the host neuropil. THLI and 5HTLI dendrites and axon terminals were also observed in the neuropil of the grafts themselves. THLI axon terminals are not normally present in the substantia nigra. The results of our study indicate that human xenografts can survive in the neuropil of the host striatum and form morphologically appropriate synapses within the host brain.     

Pattern of synaptophysin immunoreactivity within mesencephalic grafts following transplantation in a parkinsonian primate model

The majority of investigations into the degree of restoration of neural circuitry following transplantation of the embryonic ventral mesencephalon to the striatum have focused upon the particular neurochemical subtypes of the fibers exchanged between graft and host. Visualization of neurites of specific neurotransmitter type while informative regarding the specificity of graft–host interactions, vastly underrepresents overall synaptogenesis as it may occur in the grafting situation. The present approach of using a molecular marker characteristic of all normal, functional synapses provides broader information about the synaptic remodeling that occurs after tissue grafting. Synaptophysin (SY), an integral membrane protein of the synaptic vesicle, is a reliable marker of nerve terminal differentiation. Immunohistochemical staining with antibodies directed against SY and the dopamine synthetic enzyme tyrosine hydroxylase (TH) was used to assess overall synaptic differentiation as well as the relationship between SY immunoreactivity and the distribution of grafted dopamine (DA) neurons and processes in mesencephalic grafts and mesencephalic-striatal co-grafts implanted in the striatum of MPTP-treated African green monkeys. Grafted embryonic cerebellar tissue was used as a comparison graft type that does not normally exchange prominent direct projections with striatum. Dense pericellular arrays of SY-positive terminals were associated with TH-positive neurons in mesencephalic grafts. In mixed mesencephalic-striatal co-grafts, TH-positive fiber patches within the striatal portion of the graft demonstrated a high degree of correspondence with SY immunoreactivity. In contrast, grafts of cerebellar tissue did not display the same pattern of prominent pericellular arrays of SY staining. These observations suggest that functional synapses are abundantly present within grafted mesencephalon, and that these contacts are enriched in areas of the graft occupied by DA neurons. Implantation of an inappropriate striatal target, the cerebellum, results in visibly diminished innervation. The pattern of SY labeling observed suggests that tissue grafts are extensively innervated, probably both from extrinsic and intrinsic sources, and that the pattern and density of this innervation corresponds to the appropriateness of the graft–host interaction.     

Fetal ventral mesencephalic grafts functionally reduce the dopamine D2 receptor supersensitivity in partially dopamine reinnervated host striatum

Grafting of ventral mesencephalic tissue in Parkinson's disease results in a partial dopaminergic reinnervation of host brain and dopamine agonist-induced rotational behavior is not completely reversed. To study a possible malfunction of the grafts, extracellular recordings with local applications of quinpirole were utilized and the neurophysiological results showed that a normalization of the upregulated dopamine D2 receptor supersensitivity occurred in reinnervated areas of the host striatum as well as in noninnervated areas remote from the graft innervation. Furthermore, the inhibitory effects on striatal nerve cell firing rate by the D1 receptor agonist SKF 81297 were not different in noninnervated or reinnervated areas of the striatum compared to the control side as seen from the dose-response curves. However, spontaneous striatal neuronal firing was significantly upregulated in noninnervated areas, while it was normalized in areas reached by graft-derived nerve fibers. Dual-probe microdialysis studying potassium-evoked glutamate release revealed that there was no difference in extracellular glutamate levels measured within or lateral to graft dopamine reinnervation. Thus, the upregulated spontaneous activity was not due to a difference in extracellular glutamate levels. The remaining rotational behavior seen after grafting was studied and recordings were performed in the striatum following systemic injection of the D1/D2 agonist apomorphine. The results revealed that apomorphine at the dose used to elicit turning behavior (0.05 mg/kg) still affected striatal neurons in noninnervated areas, while no effect was detected in reinnervated areas and in the intact side. However, a lower dose of apomorphine (0.005 mg/kg) showed no effects on striatal firing in graft reinnervated striata but only after dopamine depletion. In conclusion, the D2 supersensitivity is downregulated in graft-reinnervated striatum as well as in striatal areas lateral to the reinnervation when using selective D2 agonists, but the downregulation is not completely normalized when studying combined effects of D1/D2 agonists. Furthermore, the striatal neurons were firing significantly faster in noninnervated areas compared to reinnervated areas of graft-reinnervated striatum, which was most likely not due to changes in the glutamatergic input.     

Behavioral and histochemical observation in rotational rat with adrenal medulla transplantation--comparison of two different graft sites (striatum v.s. lateral ventricle)

Effect of adrenal medullary allograft to two different sites of the brain (striatum and lateral ventricle) was compared on rotation rat. Rotation rats were prepared by chemical ablation of the right nigro-striatal system by 6-hydroxy-dopamine (6-OHDA). In this experiment, adrenal medulla was transplanted to the rotation rat brain and effects of the transplantation was evaluated by behavioral change of the rats, i.e., reduction in rotation behavior, and by histochemical examination of the grafts sites, i.e., presence and morphology of dopaminergic cells. The animals were divided in to 2 groups. The first group received the graft to the striatum (striatum group) and the second group to the lateral ventricle close to the striatum (ventricle group). Six weeks after grafting, the rotation behavior in striatum group and ventricle group was reduced by 43% (p less than 0.01) and 35% (p less than 0.01) respectively as compared to that in the pretransplantation state. Twelve weeks after grafting, the comparable figures were 30% (p less than 0.05) and 17% (n.s.) respectively. Histochemical examination of graft site was similar in both groups: Six weeks after grafting, many transplanted cells transformed into nerve cells which were considered to be capable of producing dopamine and, twelve weeks after grafting, honeycomb shaped fluorescence positive area without apparent viable cells. From above results, it was concluded that the striatum was somewhat superior to the lateral ventricle as the graft site. However, the effect of the transplantation was short lasting, being most manifest at six weeks after transplantation, and started to wear off as the grafted cells perished.     

Limited recovery of striatal dopaminergic fibers by adrenal medullary grafts in MPTP-treated aging mice

Systemic injection of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) damages the dopaminergic (DA) nigrostriatal system in C57BL/6 mice. We have investigated the effect of MPTP neurotoxicity and subsequent adrenal medullary grafts into the striatum of young (2-3 months) and aging (12 months) mice. MPTP treatment (4 X 20 mg/kg ip given 3 or 12 h apart in young mice and 12 h apart in aging mice) resulted in 80-90% depletion of striatal DA and virtual disappearance of tyrosine hydroxylase (TH)-immunoreactive (IR) fibers in both young and aging mice 1 week following treatment. Only partial recovery of TH-IR fibers was seen 5 weeks after MPTP treatment in young mice, while virtually no recovery was seen in aging mice. Adrenal medullary minced pieces were grafted into the striatum of young and aging mice 1 week after MPTP treatment. In young mice, dense TH-IR fibers were observed in the striatum on the grafted side 4 weeks later, far denser than those in sham-operated striatum. Although this staining was most prominent around the grafts, many TH-IR fibers also were found in the ventral striatum close to the nucleus accumbens. No such increase in TH-IR fibers was found on the nongrafted side. DA concentration on the grafted side recovered to 45% of the control level. In aging mice receiving similar grafts, TH-IR fibers also were observed in the grafted striatum, but were less dense and more restricted around the site of the graft compared with young mice. DA concentration on the grafted side was 29% of the control level. We conclude that the MPTP-depleted nigrostriatal DA system in aging mouse brain can recover partially following adrenal medullary grafts, but the degree of recovery is more limited compared with that in young brain.     

Striatal implants of fetal striatum or gelfoam protect against quinolinic acid lesions of the striatum

Previous studies in our laboratory have shown that intrastriatal implants of fetal striatum significantly attenuate excitotoxic damage resulting from a 240 nmol quinolinic acid (QA) challenge delivered 7 days later. In contrast, animals with intrastriatal implants of other tissue types (adipose tissue, peripheral nerve or adrenal medulla) demonstrate a more limited, but consistent trend in protection from QA excitotoxicity. The present study was designed to test the hypothesis that partial striatal protection found in animals receiving peripheral tissue grafts is due to the transplantation procedure eliciting a host response which attenuates excitotoxicity. Adult female Long-Evans rats received either cellular (fetal striatum) or acellular (gelfoam) implants followed 1 week later by a unilateral injection of 240 nmol QA into the grafted striatum. Animals were tested for rotational asymmetries before grafting, post-implantation, and after lesioning. Compared to baseline rotational behavior, rats which received implants did not show changes in ipsilateral turning after QA lesions. This protective effect was not limited to rotational behavior since improvements in spontaneous locomotor activity were evident. In addition, the adipsia and aphagia often associated with striatal lesions were ameliorated in both groups of grafted animals. Morphometric analysis demonstrated that endogenous dopaminergic, cholinergic and enkephalinergic systems in the two transplanted groups sustained less excitotoxic damage than in the QA lesioned, non-grafted animals. These results are consistent with the hypothesis that a host generated response activated by the implantation provides a protective effect against QA excitotoxicity.     

The nigrostriatal dopaminergic system in MPTP-treated mice shows more prominent recovery by syngeneic adrenal medullary graft than by allogeneic or xenogeneic graft

Following systemic injection of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), young (2-month-old) C57BL/6 mice show decreased dopaminergic (DA) nigrostriatal fibers and DA concentration in the striatum. We transplanted syngeneic, allogeneic and xenogeneic adrenal medullary grafts into the striatum of the MPTP-treated young mice and compared the survivability of grafted chromaffin cells and the recovery of intrinsic host DA fibers using computerized image analysis of tyrosine hydroxylase (TH)-immunoreactive (IR) fibers and high performance liquid chromatography with electrochemical detection (LCEC). The grafted syngeneic adrenal chromaffin cells survived better than allogeneic or xenogeneic chromaffin cells, and host DA nigrostriatal fiber recovery was more prominent in mice with a syngeneic graft than in mice with an allogeneic or xenogeneic graft. However, the degree of host fiber recovery in mice with allogeneic or xenogeneic mice was greater than in mice with a sham operation alone, even though the allografts and xenografts had no surviving chromaffin cells. Allografts and xenografts showed prominent rejection responses, with T lymphocyte infiltration in addition to macrophages. We conclude that a syngeneic adrenal graft survives better than an adrenal allograft or xenograft and promotes recovery of the intrinsic host nigrostriatal DA fibers. We also conclude that grafted chromaffin cell survivability influences the degree of host DA fiber recovery following MPTP depletion. Adrenal medullary grafts to Parkinsonian patients are currently under way in a large number of hospitals; we suggest that greater attention be paid to methods which lead to enhanced survival of the grafted chromaffin cells, since survivability might be closely related to the functional recovery of these patients.     

Transplantation strategies in the treatment of Parkinson's disease: experimental basis and clinical trials

Abstract– Neural grafting has over the last decade emerged as a possible tool for the substitution of damaged neurons in the central nervous system and for the promotion of symptomatic recovery after brain damage.
Transplantation studies in the 6-hydroxydopamine lesion rat model of Parkinson's disease were initiated in the late seventies. The first studies were based on the neuronal replacement paradigm, using developing dopamine brain cells obtained from the substantia nigra region of embryonic cadavers. When implanted into the striatum such grafts were found to reinnervate part of the previously denervated striatum and restore dopamine turnover and release to near-normal levels. In both rats and monkeys the nigral grafts have been shown to normalize some, but not all, Parkinson-like symptoms in the dopamine deficient recipients.
Grafting of adrenal medullary tissue was introduced in the early eighties as an alternative to the use of embryonic cadaver tissue. The adrenal medullary grafts have, however, so far shown poor long-term survival in both rats and monkeys, and consistent with this no sustained dopamine release have been observed in the brain of long-term grafted animals. Likewise, no long-lasting effects of adrenal medullary grafts on spontaneous motor or sensori-motor behavior have so far been documented in either the rat or the monkey model.
The results so far reported from trials using adrenal medullary grafts in patients with Parkinson's disease appear to conform to the available animal experimental data at least in two important respects: significant long-term graft survival has not been possible to document, and any clear-cut functional effects consistent with sustained graft-induced dopamine release have not been demonstrated. Initial results from ongoing trials using grafts of fetal nigral tissue are presented and discussed.