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In this study, a modified infusion procedure and a novel infusion device designed for use in humans (Clinical Device B) were evaluated for delivery of recombinant adeno-associated virus (AAV2) to brain. The device is composed of 1.2 m of fused silica inserted through a 24.6-cm surgical steel cannula designed to fit a standard Leksell clinical stereotaxic frame and micro-infusion syringe pump. AAV2 encoding the human aromatic l-amino acid decarboxylase gene (AAV-hAADC-2) was infused into the putamen of 4 normal rhesus monkeys as a supportive study for a clinical trial in Parkinson's disease (PD) patients. Two infusion protocols were tested: a ramped procedure (slow stepwise increases in rate from 0.2 muL/min to 1 muL/min), thought to be essential for convection-enhanced delivery (CED), and a non-ramped infusion at a constant rate of 1 muL/min. The primary endpoints were safety evaluation of the infusion procedures and assessment of transgene expression at 5.5 weeks post-infusion. Clinical observations after vector infusions revealed no behavioral abnormalities during the study period. No differences in gross pathology with either the ramped or non-ramped infusion procedure were observed. Histopathology of the putamen was comparable with both procedures, and revealed only minimal localized inflammatory tissue reaction along the needle track in response to cannula placement and vector infusion. AADC immunohistochemistry demonstrated that vector was distributed throughout the putamen, with no significant difference in volume of immunostaining with either infusion procedure. Serum antibody levels against AAV2 vector exhibited a minor increase after infusion. These results validate the clinical utility of this new infusion device and non-ramped infusion conditions for intraputamenal gene therapy, and have the potential to impact a number of human diseases in which delivery of therapeutics to brain is indicated.

Human retinal pigment epithelial (hRPE) cells produce L-dopa, are easily harvested and expanded in culture, and, attached to microcarriers, can survive in the brain without immunosuppression. Studies in rats, primates, and parkinsonian patients have demonstrated that striatally implanted hRPE cells attached to gelatin microcarriers (RPE-GM) are able to improve parkinsonian symptoms and are well tolerated for extended periods. In moderately to severely impaired monkeys with bilateral 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine hydrochloride (MPTP)-induced parkinsonism receiving a unilateral RPE-GM implant in the putamen, there was a 39% improvement in clinical scores over the first 2 months post-implant. Positron emission tomography (PET) with [18F]fluoro-L-dopa (FDOPA) showed increased accumulation in the implanted putamen and a concomitant decrease in [11C]raclopride binding in the same area, suggesting increased dopamine release compared to the contralateral putamen. We report the first in vivo visualization of hRPE cells and their effects, implicating a dopaminergic mechanism of action.

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

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.

Grafts of embryonic nigral tissue were made into the striatum of marmosets (Callithrix jacchus) which had previously received a unilateral 6-hydroxydopamine (6-OHDA) lesion of the nigrostriatal bundle. The grafts comprised injections of cell suspensions prepared from embryonic (74 day) marmoset ventral mesencephalic tissue targeted at multiple striatal sites in the caudate nucleus, the putamen, and the nucleus accumbens on the same side as the initial lesion. A series of behavioral tests was used to assess the monkeys prior to surgery, following the 6-OHDA lesion, and at regular intervals for 6 months after transplantation surgery. Lesioned and grafted (n = 6) or lesion alone (n = 4) monkeys were matched as far as possible with respect to their scores prior to transplantation so that explicit graft-derived recovery could be distinguished from any spontaneous recovery that might occur. Sham-lesioned or unoperated monkeys served as further controls (n = 5). The grafts were functionally effective as measured by a reduction, and in some cases a reversal, of spontaneous, amphetamine- and apomorphine-induced rotation. The reversal of amphetamine-induced rotation correlated with the number of dopaminergic neurons in the grafts visualized by tyrosine hydroxylase immunohistochemistry. Successful use of the hands was restored by the grafts on tasks in which the monkeys reached into tubes to retrieve food. However, functional recovery was not seen on some other behavioral tests. In particular, grafts did not influence ipsilateral biases induced by the lesion, including the position of the head with respect to the rest of the body, hand preference while reaching for food at a conveyor belt, and neglect of contralateral stimuli either at the conveyor belt or of adhesive labels placed around the feet. Indeed, the graft group was impaired compared with the lesion group in the accuracy of reaches at the conveyor belt. Overall, these results indicate that embryonic nigral grafts can yield a partial recovery from the symptoms induced by unilateral nigrostriatal lesions in a primate model of hemiparkinsonism.