微囊化转TH基因人成纤维细胞脑内移植治疗帕金森病大鼠模型的研究

目的　探讨微囊化转酪氨酸羟化酶 (TH)基因的细胞在帕金森病 (PD)大鼠模型脑内存活、组织反应及对异常行为的治疗效果。　方法　以人 TH基因作为目的基因 ,重组到逆转录病毒载体感染人成纤维细胞 ,将细胞包裹在 APA半透膜中进行微囊化后 ,植入 6 -羟多巴胺单侧损毁的 PD大鼠模型纹状体内 ,观察移植物的存活状况和功能作用 16周。　结果　体外和植入体内的微囊化转基因细胞具有良好的存活能力。移植微囊化细胞可以使大鼠异常运动明显改善 ,移植位点周围的免疫反应较小。　结论　微囊化对转基因细胞异种移植以进行基因治疗具有显著意义     

帕金森病大鼠未注射侧纹状体和黑质酪氨酸羟化酶的表达

目的:观察不同病程偏侧帕金森病(PD)大鼠未注射侧纹状体和黑质酪氨酸羟化酶(TH)的表达.方法:6-羟基多巴胺(6-OHDA)右侧前脑内侧束立体定位注射1周,阿朴吗啡旋转实验筛选PD模型大鼠,随机分为2、4周和6周模型组,另设正常对照组.行嘴侧纹状体节段和黑质节段连续冠状石蜡切片,采用焦油紫染色定位,以TH抗体免疫组织化学阳性显示多巴胺(DA)能神经元胞体和纤维.结果:正常对照组和2周模型组大鼠左侧纹状体有较强的TH表达,而4周和6周模型组左侧纹状体的TH表达强度较上述两组降低,4周和6周模型组之间无差异.4组大鼠左侧黑质TH表达阳性细胞数无差异.正常对照组、2周和4周模型组左侧黑质有较强的TH表达,3组的表达强度无差异,而6周模型组左侧黑质的TH表达强度较上述3组均降低.结论:6-OHDA单侧注射制备的PD模型大鼠,注射侧的长期病变致未注射侧纹状体和黑质TH的表达减弱.     

携带酪氨酸羟化酶基因的质粒和逆转录病毒在大鼠成纤维细胞和脑胶质细胞中表达效率的比较

目的　为提高体外转基因 (exvivo)治疗帕金森病大鼠模型的疗效 ,本实验拟比较两种基因表达载体介导的外源基因在两种不同运载细胞的瞬时表达效率。　方法　分别将酪氨酸羟化酶 (TH)基因的重组表达质粒和重组逆转录病毒导入原代培养的大鼠成纤维细胞和脑胶质细胞 ,用免疫组织化学检测TH的表达效率 ;Westernblot法检测样品中TH特异性条带并转换成A值 ,以比较其在不同细胞中表达的相对含量。　结果　免疫组织化学检测表明 ,表达质粒的转染率为 5 %～ 7% ,逆转率病毒的感染率为 18%～ 2 0 % ;根据GDNF标准品蛋白条带含量与Westernblot结果的相应A值的标准曲线 ,推断出质粒转染和逆转率病毒感染的成纤维细胞中单个阳性细胞表达的TH相对平均含量分别为 4 76× 10 - 2 A和 4 35× 10 - 2 A ,质粒转染和逆转率病毒感染的脑胶质细胞分别是 5 4 5×10 - 2 A和 5 0 5× 10 - 2 A。　结论　不论是质粒载体还是逆转录病毒载体所携带的外源基因在两种细胞的单个阳性细胞中的表达无显著性差异。但由于逆转录病毒载体的感染率高于质粒载体 ,对于原代培养的成纤维细胞和脑胶质细胞 ,逆转率病毒载体是一种更好的表达载体。     

GDNF转基因成纤维细胞脑内移植治疗帕金森病大鼠模型

为了观察表达胶质细胞系源性神经营养因子 (GDNF)的基因工程细胞在脑内移植后对帕金森病大鼠的治疗作用 ,将 6-羟基多巴胺脑内定位单侧 (损伤侧 )注射制备大鼠帕金森病模型。随机将动物分为实验组 (2 0只 )和对照组 (15只 ) ,分别植入GDNF和 Lac Z转基因的原代培养大鼠成纤维细胞于损伤侧纹状体内 ,动态观察动物单侧旋转行为以及多巴胺及其代谢产物 3 ,4-二羟苯乙酸和高香草酸含量的变化。结果表明 :实验组帕金森病大鼠单侧旋转行为明显减少 ,为移植前旋转圈数的 (64 .8± 5 .8) % (P<0 .0 5 ) ;其纹状体内多巴胺含量显著提高 ,恢复至移植前水平的 (14 .5± 2 .2 ) % (P<0 .0 5 ) ,而对照组仅为 (1.92± 0 .15 ) % ;转基因细胞在脑内可存活 1年以上。本研究结果提示 GDNF基因治疗对大鼠帕金森病具有潜在的临床应用价值。     

重组人改构体酸性成纤维细胞生长因子减少帕金森病大鼠黑质酪氨酸羟化酶免疫阳性神经元丢失

目的 探讨重组人改构体酸性成纤维细胞生长因子(Mrh-aFGF)对帕金森病(PD)大鼠旋转行为和酪氨酸羟化酶(TH)免疫阳性神经元的影响.方法 6-OHDA分别注入黑质和腹侧被盖区后建立PD大鼠模型,侧脑室内注射Mrh-aFGF,用阿扑吗啡诱导旋转行为,免疫细胞化学染色观察TH免疫阳性神经元和纤维,并进行定量分析.结果 对照组均未引出旋转行为;PD组术后旋转启动时间缩短,持续时间延长,速度加快;生理盐水(NS)处理组旋转行为未见明显改善;Mrh-aFGF处理组旋转启动时间延长,持续时间缩短,速度减慢(P＜0.01).各组大鼠健侧黑质TH阳性神经元的数量维持在相近的水平.同组内健侧和损毁侧阳性神经元比较,对照组损毁侧无明显改变;PD组、NS处理组和Mrh-aFGF处理组损毁侧阳性神经元与健侧比较均明显减少(P＜0.01).其中PD组损毁侧黑质TH免疫阳性神经元数量随时问延长逐渐减少(P＜0.01).NS处理组损毁侧黑质TH免疫阳性神经元的变化与PD组相似;Mrh-aFGF处理组损毁侧黑质阳性神经元较PD组及NS处理组有明显改善,阳性神经元的数量明显增加(P＜0.01).结论 Mrh-aFGF能减少PD大鼠黑质TH免疫阳性神经元的丢失,并改善其旋转行为.     

大鼠胚脑皮质和中脑神经干细胞移植治疗PD模型鼠的比较研究

为比较大鼠胚胎大脑皮质和中脑神经干细胞(NSCs)移植入Parkinson病(PD)模型鼠后动物行为的改善和植入细胞分化为酪氨酸羟化酶(TH)阳性神经元的情况,本研究将大鼠胚胎大脑皮质和中脑NSCs在体外分离、扩增、BrdU标记后,添加或不加白细胞介素-1α(IL-1α)、白细胞介素-11(IL-11)、白血病抑制因子(LIF)和胶质细胞源性神经营养因子(GDNF)等因子,分别移植入PD模型鼠病侧纹状体中。术后每隔2周进行动物旋转行为的检测,第12周时用免疫荧光双重标记方法检测BrdU和TH双标神经元。结果显示:中脑NSCs+因子移植组,动物的旋转行为得到明显改善;单纯中脑NSCs移植组次之;而单纯皮质NSCs移植组、皮质NSCs+因子移植组及生理盐水对照组动物的行为无明显改善。免疫荧光双重染色结果显示,中脑NSCs+因子组和单纯中脑NSCs组BrdU和TH双标神经元的数量明显多于其它组,而中脑NSCs+因子组又多于单纯中脑NSCs组。以上结果提示,大鼠胚胎中脑NSCs移植治疗PD模型的疗效明显优于胚胎皮质NSCs,IL-1α、IL-11、LIF和GDNF等因子能促进移植的中脑NSCs分化为TH阳性神经元。     

胚胎神经上皮干细胞脑内移植治疗大鼠帕金森病

背景：研究表明胚胎干细胞移植可改善血管性痴呆大鼠的学习记忆功能,增强神经的可塑性,诱导自身定向迁移并分化为成熟神经元。 目的：观察胚胎神经上皮干细胞脑内移植治疗帕金森病大鼠及移植细胞的迁徙情况。 方法：将绿色荧光蛋白转基因鼠的胚胎神经上皮干细胞分别移植到帕金森病大鼠的黑质、纹状体和侧脑室内,移植后检测移植细胞的存活、迁徙与分化;利用高效液相色谱法检测实验动物脑内多巴胺神经递质的含量;对比实验动物旋转行为的改变,评估胚胎神经上皮干细胞移植对帕金森病大鼠的治疗作用。 结果与结论：移植细胞存活良好且分化出了酪氨酸羟化酶阳性细胞,向黑质纹状体环路迁徙趋势明显;脑内多巴胺含量增加,动物旋转行为改善明显。表明移植到帕金森病大鼠脑内的神经上皮干细胞多向黑质纹状体环路迁徙,且可增加脑内多巴胺神经递质的含量治疗帕金森病。中国组织工程研究杂志出版内容重点：干细胞;骨髓干细胞;造血干细胞;脂肪干细胞;肿瘤干细胞;胚胎干细胞;脐带脐血干细胞;干细胞诱导;干细胞分化;组织工程全文链接：     

帕金森病模型大鼠中脑腹侧被盖区酪氨酸羟化酶免疫阳性神经元的改变

目的探讨帕金森病(PD)模型大鼠中脑腹侧被盖区(VTA)酪氨酸羟化酶(TH)免疫阳性神经元的改变。方法将6-羟基多巴胺(6-OHDA)分别注入实验组大鼠左侧黑质致密部和中脑被盖腹侧区以建立帕金森病模型,于术后4d、7d、14d、21d、28d腹腔注射阿扑吗啡(apomorphine,APO),观察并记录大鼠行为学变化情况,利用Nissl染色、酪氨酸羟化酶(TH)免疫细胞化学染色观察大鼠中脑腹侧被盖区神经组织及TH免疫阳性神经元的改变。结果APO诱发实验组PD大鼠均向健侧(右侧)旋转,旋转启动时间逐渐缩短,持续时间逐渐延长,旋转速度逐渐加快,至术后2周旋转行为趋于稳定;Nissl染色见实验组PD大鼠损毁侧(左侧)中脑VTA区神经元数目显著减少,尼氏体模糊,颗粒及密度均降低,伴有大量胶质细胞增生,术后2周、4周注射侧神经元数目较术后1周明显减少(P<0.05);实验组PD大鼠损毁侧(左侧)中脑VTA的TH阳性神经元明显减少,神经元胞体轮廓及突起不清晰,TH阳性纤维也明显减少,分布稀疏,术后2周、4周注射侧阳性神经元数目较术后1周明显减少(P<0.05)。结论PD大鼠损毁侧中脑VTA神经组织有明显破坏,TH阳性神经元显著减少,提示中脑腹侧被盖区TH免疫阳性神经元的改变参与了PD模型大鼠的病理学变化。     

帕金森病大鼠同种异体脑内移植免疫反应的实验研究

目的: 观察帕金森病 (Parkison’sdisease, PD)模型大鼠同种异体脑内移植是否存在免疫反应以及免疫反应的特点。方法: 取新生SD大鼠腹侧中脑(ventralmesencephalon,VM)组织制成单细胞悬液, 借助脑立体定位仪移植到SD大鼠PD模型的纹状体内, 于 2、4、6wk时采用行为学检测后分批处死, 再行HE、酪氨酸羟化酶 (TH)和MHCⅡ抗原免疫组化染色。结果: PD模型移植组 2wk时, MHCⅡ表达明显增高(P<0. 05), 4wk时开始下降, 6wk以后消失; 2wk时移植区可见少量TH阳性神经元, 4~6wk数量显著增加(P<0. 05)。假手术组在 2wk时见少量MHCⅡ阳性细胞(P>0. 05), 4wk时消失, 各时间点都未见TH阳性神经元; 对照组在各时间点都未见TH阳性神经元和MHCⅡ阳性细胞。各实验组各时间点行为学检测无明显改变 (P>0. 05 )。结论: 同种异体脑内移植是存在免疫排斥反应的, 这种反应可能是由MHCⅡ抗原不同而诱发的, 免疫反应与移植物内TH神经元的存活和发育密切相关, 同种异体脑内移植加用免疫抑制剂还是必要的。     

微囊化转TH基因人成纤维细胞脑内移植治疗帕金森病大鼠模 …

目的 探讨微囊化转酷氨酸羟化酶（ＴＨ）基因的细胞在帕金森病（ＰＤ）大鼠模型脑内活活、组织反应及对异常行为的治疗效果。 方法 以入ＴＨ基因作为目的基因，重组到逆转录病毒载体感染入成纤维细胞，将细胞包裹在ＡＰＡ半透膜中进行微囊化后，植入６－羟多巴胺单侧损毁的ＰＤ大鼠模型纹状体内，观察移植物的存活状况和功能作用１６周。结果 体外和植入体内的微囊化转基因具有良好的存活能力。移植微囊化细胞可以使大鼠异常运动     

Behavioural effects of human fetal dopamine neurons grafted in a rat model of Parkinson's disease

Summary The ventral mesencephalon, containing the developing dopaminergic neurons of the substantia nigra-ventral tegmental region, was obtained from aborted human fetuses of 9–19 weeks of gestation. The tissue was grafted into the striatum of rats previously subjected to a 6-hydroxydopamine lesion of the mesostriatal dopamine pathway. The graft recipients were immunosuppressed by daily injections of Cyclosporin A. Amphetamine-induced motor asymmetry was reduced, and finally totally reversed, only in rats receiving grafts from the 9-week old fetal donor. The fluorescence microscopic analysis revealed large numbers of surviving dopamine neurons, and extensive fiber outgrowth into the host striatum, in these rats. By contrast, rats receiving grafts from 11–19 week old donors had at most only few surviving dopamine neurons. These results indicate that human fetal mesencephalic tissue may be an efficient source of dopamine neurons for functional intracerebral grafting in patients with Parkinson's disease.A preliminary account of some of the results from this study was presented at the New York Academy of Sciences meeting on Cell and tissue transplantation into the adult brain, New York, April 4, 1986     

Astrocyte line SVG-TH grafted in a rat model of Parkinson's disease

The present review describes gene transfer into the brain using extraneuronal cells with an ex vivo approach. The mild immunological reactions in the central nervous system to grafts provided the rationale and empirical basis for brain-transplantation, to replace dying cells, of potential clinical relevance. Fetal human astrocytes were genetically engineered to express tyrosine hydroxylase, the rate-limiting enzyme for the synthesis of catecholamines. These cells were also found to produce constitutively and secrete GDNF and interleukins. Therefore, these cells may prove as a drug-delivery system for the treatment of neurological degenerative conditions such as Parkinson's disease (PD). The field of neuronal reconstruction has reached a critical threshold and there is a need to evaluate the variables that will become critical as the field matures. One of the needs is to characterize the neurochemical alterations in the microenvironment in the context of grafted-host connectivity. This review discusses the functional effects of the pharmacologically-active construct, which consists of astrocytes producing L-DOPA and GDNF. The striatum in PD that lacks the dopaminergic projection from the substantia nigra metabolizes and releases dopamine differently from normal tissue and may react to different factors released by the grafted cells. Moreover, neurochemicals of the host tissue may effect grafted cells as well. An understanding of the way in which these neurochemicals are abnormal in PD and their role in the grafted brain is critical to the improvement of reconstructive strategies using cellular therapeutic strategies.     

Survival and function of aggregate cultures of rat fetal dopamine neurons grafted in a rat model of Parkinson's disease

Summary The ability to maintain tissue in culture prior to grafting would greatly facilitate the widespread application of graft therapy to neurological diseases such as Parkinson's disease. However, neurons cultured on planar substrata can be easily damaged when they are removed from the substrata and redissociated for use in grafting procedures. To overcome this limitation we utilized aggregate tissue culture methods, which allowed dopamine (DA)-rich neuronal tissue to be grafted directly following culture, without an additional redissociation. Fetal rat dopamine-neuron-containing ventral mesencephalon was cultured for 9 days in rotating flasks. The cells formed many small spheres (280 m mean diameter), each estimated to contain about 10000 cells. Forty such aggregate spheres were injected via a 22G needle into the DA-denervated striata of host Parkinsonian rats. A significant reduction of amphetamine-induced rotation was seen onward from 6 weeks post-transplantation, with a complete reversal of rotational asymmetry by 15 weeks post-transplantation. Well placed, surviving grafts were found in all behaviorally compensated rats (N = 6). Grafts contained an average of 517 tyrosine hydroxylase (TH)-positive neurons, as well as TH-positive fibers seen extending into the host striatum. These results suggest that aggregate culture methods are a promising means to maintain and deliver tissue for transplant therapy.     

移植间充质干细胞治疗帕金森病大鼠

目的移植骨髓间充质干细胞(MSCs)治疗大鼠帕金森病(PD)。方法将BrdU标记的MSCs移植到单侧注射6-OHDA制备的PD大鼠模型损毁侧纹状体内,由阿朴吗啡诱导大鼠的旋转行为,用免疫组化和免疫荧光法检测大鼠黑质TH的表达和移植细胞的存活、迁移和分化,用1H-MRS检测大鼠双侧纹状体N-乙酰门冬氨酸(NAA)、胆碱类化合物(Cho)、肌酸(Cr)的信号强度。结果骨髓MSCs定向移植术后8周,PD大鼠的旋转行为较术前明显改善,损毁侧黑质TH阳性细胞数较术前增加;BrdU阳性细胞散在分布于移植侧脑组织内,可表达神经胶质纤维酸性蛋白(GFAP)和微管相关蛋白2(MAP-2);PD大鼠损毁侧纹状体NAA/Cr较术前升高(P<0.05),Cho/Cr下降(P<0.05)。结论植入纹状体内骨髓MSCs能够存活并对PD模型大鼠有治疗作用。     

Restorative effects of uridine plus docosahexaenoic acid in a rat model of Parkinson's disease

Administering uridine-5'-monophosphate (UMP) and docosahexaenoic acid (DHA) increases synaptic membranes (as characterized by pre- and post-synaptic proteins) and dendritic spines in rodents. We examined their effects on rotational behavior and dopaminergic markers in rats with partial unilateral 6-hydroxydopamine (6-OHDA)-induced striatal lesions. Rats receiving UMP, DHA, both, or neither, daily, and intrastriatal 6-OHDA 3 days after treatment onset, were tested for d-amphetamine-induced rotational behavior and dopaminergic markers after 24 and 28 days, respectively. UMP/DHA treatment reduced ipsilateral rotations by 57% and significantly elevated striatal dopamine, tyrosine hydroxylase (TH) activity, TH protein and synapsin-1 on the lesioned side. Hence, giving uridine and DHA may partially restore dopaminergic neurotransmission in this model of Parkinson's disease.     

Dopaminergic differentiation of grafted GFP transgenic neuroepithelial stem cells in the brain of a rat model of Parkinson's disease

Neuroepithelial stem cells (NEPs) possess multipotent potential for self-renewal and neuronal differentiation. Using green fluorescent protein (GFP) positive NEPs, we explored, firstly, the survival and differentiation of grafted NEPs in the host rat and, secondly, whether or not transplantation of NEPs is a feasible therapeutic option for treating Parkinson's disease. NEPs were harvested from the neural tube of enhanced GFP transgenic embryos. In culture, GFP(+) NEPs generated abundant neurospheres and differentiated into both neurons and glia. When stereotaxically transplanted into the 6-hydroxydopamine (6-OHDA)-lesioned striatum of rats, NEPs survived and tyrosine hydroxylase (TH)-positive cells were detected in the graft. Furthermore, these grafted GFP(+) NEPs significantly ameliorated Parkinsonian behavioral symptoms compared with controls which were treated only with normal saline. Our results suggest that transplanted NEPs accomplish dopaminergic differentiation may be used for treating Parkinson's disease.     

美满霉素对帕金森病大鼠黑质多巴胺能神经元损伤的保护作用

目的观察美满霉素(MC)对脂多糖(LPS)所致帕金森病(PD)大鼠黑质多巴胺能(DA)神经元损伤的保护作用。方法黑质内注射LPS制作PD大鼠模型。应用MC对实验动物进行处理。采用行为学、酪氨酸羟化酶(TH)、核因子-κB(NF-κB)等免疫组化及免疫印迹技术观察MC的神经保护作用。结果对照组大鼠无行为变化,PD组大鼠平均旋转圈数为196.90±9.52,MC组为120.03±10.50,差异非常显著(p<0.01)。免疫组化表明对照组TH阳性神经元数量较多,PD组神经元数量明显减少或消失(p<0.01),MC组TH阳性神经元数与PD组相比明显增加(p<0.01);对照组黑质仅见少数NF-κB阳性细胞,无明显核转位现象,PD组黑质NF-κB阳性细胞较多,部分细胞有明显核转位现象,与PD组相比,MC组NF-κB阳性细胞数明显减少(p<0.01);对照组黑质OX-42小胶质细胞呈分枝状,胞体较小突触细长,PD组黑质小胶质细胞大部分呈圆形,突起少而短甚至消失,与PD组相比,MC组呈激活状态的小胶质细胞数量明显减少。Western blotting分析结果相同。结论 MC可防护LPS所致黑质DA能神经元损伤,具有神经保护作用。     

Human fetal dopamine neurons grafted in a rat model of Parkinson's disease: ultrastructural evidence for synapse formation using tyrosine hydroxylase immunocytochemistry

Summary Human fetal mesencephalic dopamine (DA) neurons, obtained from 6.5–9 week old aborted fetuses, were grafted to the striatum of immunosuppressed rats with 6-hydroxydopamine lesions of the ascending mesostriatal DA pathway. The effects on amphetamine-induced motor asymmetry were studied at various timepoints after grafting. At eight weeks, functional graft effects were not evident but after 11 weeks small effects on motor asymmetry could be monitored and rats tested 19–21 weeks after grafting exhibited full reversal of the lesion-induced rotational behaviour. Four rats were sacrificed at different timepoints between 8 and 20 weeks and the grafted DA neurons were studied in tyrosine hydroxylase (TH) immunocytochemically stained sections at the light and electronmicroscopic level. The grafts contained a total of 500–700 TH-positive neurons in each rat. In one rat sacrificed 8 weeks after grafting the grafted neurons were TH-positive but exhibited virtually no fiber outgrowth. In another rat, sacrificed after 11 weeks, a sparse TH-positive fiber plexus was seen to extend into the adjacent host neostriatum. Two rats sacrificed after 20 weeks both contained TH-positive neurons that gave rise to a rich fiber network throughout the entire host neostriatum, and this fiber network was also seen to extend into the globus pallidus and nucleus accumbens. Very coarse TH-positive processes, identified as dendrites in the electron microscope, projected up to 1.5–2.0 mm from the graft into the host striatum. Ultrastructural analysis revealed that the grafted neurons had formed no TH-positive synaptic contacts with host striatal neurons after 8 weeks, and at 11 weeks some few TH-positive synapses were identified. Twenty weeks after transplantation, abundant TH-positive synaptic contacts with host neurons were seen throughout the neostriatum, and such contacts were identified in the globus pallidus as well. Thus, the present study provides tentative evidence for a time-link between the development of synaptic contacts and the appearance of functional graft effects. Similar to the normal mesostriatal DA pathway, ingrowing TH-positive axons formed symmetric synapses and were mainly seen to contact dendritic shafts and spines. However, in comparison to the normal rat striatum there was a higher incidence of TH-immunoreactive boutons forming synapses onto neuronal perikarya. The TH-positive dendrites that extended into the host striatum were seen to receive non-TH-immunoreactive synaptic contacts, presumably arising from the host neurons. These results suggest that human fetal DA neurons are able to develop a reciprocal synaptic connectivity with the host rat when grafted to the adult brain. Grafting of human fetal DA neurons may therefore be expected to provide a means of restoring regulated synaptic DA release in patients with Parkinson's disease.Some of the results of this study were presented at the Schmitt Neurological Sciences Symposium on Transplantation into the Mammalian CNS, Rochester, NY, USA, June 30, 1987     

Human fetal dopamine neurons grafted in a rat model of Parkinson's disease: immunological aspects,spontaneous and drug-induced behaviour,and dopamine release

Summary We have used a rat model of Parkinson's disease (PD) to address issues of importance for a future clinical application of dopamine (DA) neuron grafting in patients with PD. Human mesencephalic DA neurons, obtained from 6.5–8 week old fetuses, were found to survive intracerebral cell suspension xenografting to the striatum of rats immunosup-pressed with Cyclosporin A. The grafts produced an extensive new DA-containing terminal network in the previously denervated caudate-putamen, and they normalized amphetamine-induced, apomorphine-induced and spontaneous motor asymmetry in rats with unilateral lesions of the mesostriatal DA pathway. Grafts from an 11.5-week old donor exhibited a lower survival rate and smaller functional effects. As assessed with the intracerebral dialysis technique the grafted DA neurons were found to restore spontaneous DA release in the reinnervated host striatum to normal levels. The neurons responded with large increases in extracellular striatal DA levels after the intrastriatal administration of the DA-releasing agent d-amphetamine and the DA-reuptake blocker nomifensine, although not to the same extent as seen in striata with an intact mesostriatal DA system. DA fiber outgrowth from the grafts was dependent on the localization of the graft tissue. Thus, grafts located within the striatum gave rise to an extensive axonal network throughout the whole host striatum, whereas grafted DA neurons localized in the neocortex had their outgrowing fibers confined within the grafts themselves. In contrast to the good graft survival and behavioural effects obtained in immunosuppressed rats, there was no survival, or behavioural effects, of human DA neurons implanted in rats that did not receive immunosuppression. In addition, we found that all the graft recipients were immunized, having formed antibodies against antigens present on human T-cells. This supports the notion that the human neurons grafted to the non-immunosuppressed rats underwent immunological rejection. Based on an estimation of the survival rate and extent of fiber outgrowth from the grafted human fetal DA neurons, we suggest that DA neurons that can be obtained from one fetus may be sufficient to restore significant DA neurotransmission unilaterally, in one putamen, in an immunosuppressed PD patient.The results of this study were presented at the Schmitt Neurological Sciences Symposium on Transplantation into the Mammalian CNS, Rochester, NY, USA, June 30, 1987