Guido Nikkhah

Molecular predictors of progression-free and overall survival in patients with newly diagnosed glioblastoma: A prospective translational study of the German Glioma Network

PURPOSE The prognostic value of genetic alterations characteristic of glioblastoma in patients treated according to present standards of care is unclear. PATIENTS AND METHODS Three hundred one patients with glioblastoma were prospectively recruited between October 2004 and December 2006 at the clinical centers of the German Glioma Network. Two hundred fifty-eight patients had radiotherapy, 199 patients had temozolomide, 189 had both, and seven had another chemotherapy as the initial treatment. The tumors were investigated for TP53 mutation, p53 immunoreactivity, epidermal growth factor receptor, cyclin-dependent kinase CDK 4 or murine double minute 2 amplification, CDKN2A homozygous deletion, allelic losses on chromosome arms 1p, 9p, 10q, and 19q, O(6)-methylguanine methyltransferase (MGMT) promoter methylation, and isocitrate dehydrogenase 1 (IDH1) mutations. RESULTS Median progression-free (PFS) and overall survival (OS) were 6.8 and 12.5 months. Multivariate analysis revealed younger age, higher performance score, MGMT promoter methylation, and temozolomide radiochemotherapy as independent factors associated with longer OS. MGMT promoter methylation was associated with longer PFS (relative risk [RR], 0.5; 95% CI, 0.38 to 0.68; P < .001) and OS (RR, 0.39; 95% CI, 0.28 to 0.54; P < .001) in patients receiving temozolomide. IDH1 mutations were associated with prolonged PFS (RR, 0.42; 95% CI, 0.19 to 0.91; P = .028) and a trend for prolonged OS (RR, 0.43; 95% CI, 0.15 to 1.19; P = .10). No other molecular factor was associated with outcome. CONCLUSION Molecular changes associated with gliomagenesis do not predict response to therapy in glioblastoma patients managed according to current standards of care. MGMT promoter methylation and IDH1 mutational status allow for stratification into prognostically distinct subgroups.

Histological findings on fetal striatal grafts in a Huntington's disease patient early after transplantation.

Cell transplantation is a promising therapeutic approach that has the potential to replace damaged host striatal neurons and, thereby, slow down or even reverse clinical signs and symptoms during the otherwise fatal course of Huntingtons disease (HD). Open-labeled clinical trials with fetal neural transplantation for HD have demonstrated long-term clinical benefits for HD patients. Here we report a postmortem analysis of an individual with HD 6 months after cell transplantation and demonstrate that cells derived from grafted fetal striatal tissue had developed into graft-derived neurons expressing dopamine-receptor related phosphoprotein (32 kDa) (DARPP-32), neuronal nuclear antigen (NeuN), calretinin and somatostatin. However, a fully mature phenotype, considered by the expression of developmental markers, is not reached by engrafted neurons and not all types of interneurons are being replaced at 6 months, which is the earliest time point human fetal tissue being implanted in a human brain became available for histological analysis. Host-derived tyrosine hydroxylase (TH) fibers had already heavily innervated the transplants and formed synaptic contacts with graft-derived DARPP-32 positive striatal neurons. In parallel, the transplants contained a considerable number of immature neuroepithelial cells (doublecortin+, Sox2+, Prox-1+, ss3-tubulin+) that exhibited a pronounced migration into the surrounding host striatal tissue and considerable mitotic activity. Graft-derived astrocytes could also be found. Interestingly, the immunological host response in the grafted area showed localized increase of immunocompetent host cells within perivascular spaces without deleterious effects on engrafted cells under continuous triple immunosuppressive medication. Thus this study provides for a better understanding of the developmental processes of grafted human fetal striatal neurons in HD and, in addition, has implications for stem cell-based transplantation approaches in the CNS.

Microtransplantation of dopaminergic cell suspensions: further characterization and optimization of grafting parameters.

Intracerebral transplantation of dopaminergic (DA) cells is currently further explored as a potential restorative therapy for Parkinsons disease (PD). However, before they can be considered for a more widespread clinical use a number of critical issues have to be resolved, including an optimized transplantation protocol. This study has been performed in a rat 6-hydroxydopamine model of PD and is based on the microtransplantation approach. The results demonstrate a reduced survival (threefold) for a single cell suspension of E14 rat ventral mesencephalon compared to a fragment suspension when a metal cannula is used for implantation. However, fragment suspensions result in a more variable graft survival and ectopically placed cells along the implantation tract. When a glass capillary is used for implantation, the survival of the single cell suspension (so-called “micrograft”) improved by fourfold (vs. single cells/metal cannula) and is superior to the combination of the metal cannula and fragment suspension (+40%). The micrografts show a reduced variability in DA neuron survival as well as fewer ectopically placed cells. Moreover, the implantation time can significantly be reduced from 19 to 7 min in micrografted animals without a compromise in DA graft survival and functional behavioral outcome. Using the microtransplantation approach graft size can be tailored effectively by varying the density of the final cell suspension at least between 11,000 and 320,000 cells/μl, resulting in comparable survival of tyrosine hydroxylase (TH)-positive neurons in the range of 2–4%. With this approach no more than 100 surviving TH-positive neurons are necessary to produce functional effects in the amphetamine-induced rotation test. Interestingly, we found that DA micrografts into lesion striatum present 20% higher survival rates of TH neurons in comparison to the intact striatum. In summary, these results provide further evidence for the usefulness of the microtransplantation approach and allow for a more precise and tailored adaptation of the implantation parameters for further studies on DA, and possibly also other neural-, glial-, and stem cell-derived grafts.

Walking pattern analysis after unilateral 6-OHDA lesion and transplantation of foetal dopaminergic progenitor cells in rats

Functional sensorimotor recovery after transplantation of mesencephalic dopaminergic (DAergic) neurons has been well documented in the rat 6-hydroxydopamine (6-OHDA) model of Parkinsons disease. However, the functional restoration of more specific gait-related patterns such as skilled walking, balance, and individual limb movements have been insufficiently studied. The purpose of this study was to investigate the behavioural effects of intrastriatal DA grafts on different aspects of normal and skilled walking in rats following unilateral 6-OHDA lesions of the medial forebrain bundle. Rats were subjected to drug-induced rotation, detailed footprint analysis, and assessment of skilled walking in the ladder rung walking test prior and after the transplantation of E14 ventral mesencephalon-derived progenitor cells. Good DAergic graft survival, as revealed by immunohistochemistry, was accompanied by a compensation of drug-induced rotational asymmetries. Interestingly, the analysis of walking patterns displayed a heterogeneous graft-induced response in skilled and non-skilled limb use. Grafted animals made fewer errors with their contralateral limbs in skilled walking than the sham-transplanted rats, and they improved their ipsi- and contralateral limb rotation. However, the parameter distance between feet showed a delayed recovery, and the stride length was not affected by the DA grafts at all. These findings indicate that ectopic intrastriatal transplantation of E14 ventral mesencephalon-derived cells promotes recovery of gait balance and stability, but does not ameliorate the shuffling gait pattern associated with 6-OHDA lesions. A full restoration of locomotor gait pattern might require a more complete and organotypic reconstruction of the mesotelencephalic DAergic pathway.

Isolation and Culture of Ventral Mesencephalic Precursor Cells and Dopaminergic Neurons from Rodent Brains

The ability to isolate ventral midbrain (VM) precursor cells and neurons provides a powerful means to characterize their differentiation properties and to study their potential for restoring dopamine (DA) neurons degenerated in Parkinsons disease (PD). Preparation and maintenance of DA VM in primary culture involves a number of critical steps to yield healthy cells and appropriate data. Here, we offer a detailed description of protocols to consistently prepare VM DA cultures from rat and mouse embryonic fetal-stage midbrain. We also present methods for organotypic culture of midbrain tissue, for differentiation as aggregate cultures, and for adherent culture systems of DA differentiation and maturation, followed by a synopsis of relevant analytical read-out options. Isolation and culture of rodent VM precursor cells and DA neurons can be exploited for studies of DA lineage development, of neuroprotection, and of cell therapeutic approaches in animal models of PD.

Striatal transplantation in a rodent model of multiple system atrophy: Effects on L‐Dopa response

Progressive degeneration of striatal projection neurons is thought to account for the loss of L‐Dopa response observed in the majority of patients with the parkinsonian variant of multiple system atrophy (MSA‐P). Here we have investigated the effects of E14 embryonic striatal allografts on dopaminergic responsiveness in the unilateral double‐lesion rat model of MSA‐P by using tests of complex motor behavior. Both sham and graft animals showed an increase in apomorphine‐induced rotations as well as an improvement in cylinder test performance following surgical intervention. In contrast, L‐Dopa responsiveness of stepping behavior was improved only in grafted animals. The restoration of apomorphine‐induced rotation correlated with the P‐zone volume of grafts. Our findings indicate that transplantation of embryonic striatal grafts might, at least to some extent, restore responsiveness to L‐Dopa in tasks of complex motor behavior. Therefore, striatal transplantation should be further defined preclinically as a possible therapeutic option for patients with MSA‐P and a failing L‐Dopa response.

Pattern of Long-Term Sensorimotor Recovery following Intrastriatal and -Accumbens DA Micrografts in a Rat Model of Parkinson's Disease

The functional restorative capacity of fetal dopaminergic (DA) transplants is governed by a number of critical parameters including graft location, survival of DA neurons, and transplantation technique. In addition, there is an ongoing controversy whether “too much” or “too little” survival of DA neurons is responsible for the incomplete functional recovery observed in some transplanted Parkinsons disease (PD) patients. Here we investigated two implantation sites, the nucleus accumbens (NAc) and the caudate‐putamen unit (CPU), and two different graft distributions within the CPU, i.e., two 0.75 μL deposits (CPU‐2) versus six 0.25 μL deposits (CPU‐6) in a rat model of PD. Grafts were derived from E14 rat ventral mesencephalon and the long‐term functional outcome was evaluated with a wide range of complex‐sensorimotor behavioral tests. The data show that forelimb stepping, balancing behavior, and skilled forelimb reaching behavior was more restored in CPU‐6‐grafted animals as compared to CPU‐2 animals, although the number surviving dopaminergic neurons and dopamine release were similar in the two groups. Furthermore, a correlation analysis revealed a number of inverse relationships between the rate of DA neuron survival and sensorimotor performances, e.g., for skilled forelimb use. DA grafts placed into the NAc induced a partial recovery in drug‐induced rotation tests but failed to restore any of the other sensorimotor behaviors tested. Taken together, these data have important implications both for a better understanding of the complex functional graft–host interactions as well as for the further optimization of clinical neural transplantation strategies in neurodegenerative diseases. J. Comp. Neurol. 515:41–55, 2009.

Survival and early functional integration of dopaminergic progenitor cells following transplantation in a rat model of Parkinson's disease.

Dopaminergic (DA) grafts in rat models of Parkinsons disease (PD) have previously been derived from embryonic day (E) 14 grafts. Because there is an increasing interest in the restorative capacity of DA stem and progenitor cells, in the present study we examined the survival and early and late functional behavioral effects of DA progenitor cells derived from E12, E13, E14, and E15 grafts transplanted into rats with unilateral 6‐hydroxydopamin lesions. DA transplant–induced functional recovery was already observed in postural balancing reactions after 10 days and in stepping behavior after 13 days, that is, in spontaneous complex behaviors, and later, after 16 days, in the amphetamine‐induced rotation test. Three distinct patterns of functional recovery could be observed at 6–9 weeks posttransplantation. First, behavioral improvements in drug‐induced rotational asymmetry, stepping, and skilled forelimb behavior were directly related to DA neuron survival and TH‐positive fiber reinnervation. Second, recovery in postural balancing reactions was closely related to a specific developmental time window of donor age, for example, only seen in E13 and E14 grafts. Finally, no functional graft effects were seen in the table lift test. Interestingly, DA neuron graft survival, TH‐positive fiber outgrowth, and graft volume were significantly influenced by the developmental time window in which the DA progenitor cells were dissected from the ventral mesencephalon, that is, from E12, E13, E14, or E15 rat embryos. These data highlight the complexity of graft–host interactions and provide novel insights into the dynamics of DA progenitor graft‐mediated functional recovery in animal models of Parkinsons disease.

Neurochirurgische Standards bei tiefer Hirnstimulation

Surgery combining stereotactically guided implantation of brain electrodes in subcortical key structures of the brain with the connection of these brain electrodes to subcutaneously implanted impulse generators is one precondition for the therapeutic application of deep brain stimulation (DBS). During the last 10-15 years minimal requirements concerning this surgery have been formulated, addressing in particular technical equipment and operational procedures and being also in parts supported quantitatively by systematic investigations. Only appropriate patient management, high technical standards and an adequate surgical technique can minimize the frequency of those complications, which are supposed to be directly caused by surgery. High-resolution imaging is the basis for target definition, determination of the surgical approach, documentation of final electrode position and postoperative exclusion of iatrogenic intracerebral haemorrhage. In addition, the quality of treatment planning depends largely on the image processing and viewing possibilities provided by specific planning software. Further issues, for which standards are defined, address electrophysiological and clinical examinations to be performed intraoperatively and general surgical measures, which should be considered during implantation of DBS systems. This review summarizes and evaluates requirements imposed on the aforementioned system components and working steps, taking into consideration data from the literature.

STEREOTACTIC INTERSTITIAL RADIOSURGERY WITH THE PHOTON RADIOSURGERY SYSTEM (PRS) FOR METASTATIC BRAIN TUMORS: A PROSPECTIVE SINGLE-CENTER CLINICAL TRIAL

PURPOSE To evaluate the efficacy and the treatment outcome of tumor patients being treated stereotactically with a miniature X-ray generator (Photon Radiosurgery System, PRS). METHODS AND MATERIALS Thirty-five patients with histologically diagnosed cerebral metastases were treated with a single fraction of stereotactic interstitial irradiation (median, 18 Gy). Clinical and neuroimaging evaluation were assessed at 2-, 6-, and 12-week intervals postoperatively and every 3 months thereafter. Survival, local control, and distant and overall brain freedom from progression were obtained using the Kaplan-Meier method. RESULTS Median survival was 7.37 months and the actuarial survival rates at 6 and 12 months were 60.0% and 34.3%, respectively. Acute complications on six patients were associated with shorter survival. Local tumor control at the initial stage and at the last follow-up were 82% and 50%. Eighteen patients (53%) developed distant brain metastases after treatment. At 1 year, the local control rate and distant and overall brain freedom from progression were 33.0%, 43.3%, and 14.7%, respectively. A shorter local tumor control was observed by PRS treatment of a recurrent tumor and by irregular tumor configuration. CONCLUSIONS Interstitial radiosurgery with the PRS requires continued investigation. It allows for an immediate and potentially cost-efficient treatment for patients with singular, small (<or= 6.36 cm(3); or <or= 2.3 cm) spherical brain metastasis subsequent to a stereotactic biopsy.