Involvement of the tumour necrosis factor receptor system in glioblastoma cell death induced by palbociclib-heptamethine cyanine dye conjugate.

Glioblastoma is the most common and aggressive primary brain tumour in adults. The development of anti-brain cancer agents are challenged by the blood-brain barrier and the resistance conferred by the local tumour microenvironment. Heptamethine cyanine dyes (HMCDs) are a class of near-infrared fluorescence compounds that have recently emerged as promising agents for drug delivery. We conjugated palbociclib, a cyclin-dependent kinase (CDK) 4/6 inhibitor, to an HMCD, MHI-148, and conducted drug activity analysis on primary patient-derived glioblastoma cell lines. In addition to the expected cytostatic activity, our in vitro studies revealed that palbociclib-MHI-148 conjugate resulted in an almost 100-fold increase in cytotoxicity compared to palbociclib alone. This shift of palbociclib from cytostatic to cytotoxic when conjugated to MHI-148 was due to increased DNA damage, as indicated by an increase in γH2AX foci, followed by an increased expression of key extrinsic apoptosis genes, including TP53, TNFR1, TRAIL, FADD and caspase 8. In addition, we observed a time-dependent increase in the cell surface expression of TNFR1, consistent with an observed increase in the secretion TNFα, followed by TNFR1 endocytosis at 48 h. The treatment of patient GBM cells with the palbociclib-MHI-148 conjugate prevented TNFα-induced NFκB translocation, suggesting conjugate-induced TNFR1 signalling favoured the TNFR1-mediated apoptotic response rather than the pro-inflammatory response pathway. Notably, pharmacological inhibition of endocytosis of TNFR1, and siRNA-knockdown of TNFR1 reversed the palbociclib-MHI-148-induced cell death. These results show a novel susceptibility of glioblastoma cells to TNFR1-dependent apoptosis, dependent on inhibition of canonical NFκB signalling using our previously reported palbociclib-HMCD conjugate. Video Abstract.

Elucidating the cellular uptake mechanisms of heptamethine cyanine dye analogues for their use as an anticancer drug-carrier molecule for the treatment of glioblastoma.

The development of chemotherapies for glioblastoma is hindered by their limited bioavailability and toxicity on normal brain function. To overcome these limitations, we investigated the structure-dependent activity of heptamethine cyanine dyes (HMCD), a group of tumour-specific and BBB permeable near-infrared fluorescent dyes, in both commercial (U87MG) and patient-derived GBM cell lines. HMCD analogues with strongly ionisable sulphonic acid groups were not taken up by patient-derived GBM cells, but were taken up by the U87MG cell line. HMCD uptake relies on a combination of transporter uptake through organic anion-transporting polypeptides (OATPs) and endocytosis into GBM cells. The uptake of HMCDs was not affected by p-glycoprotein efflux in GBM cells. Finally, we demonstrate structure-dependent cytotoxic activity at high concentrations (EC50 : 1-100 µM), likely due to mitochondrial damage-induced apoptosis. An in vivo orthotopic glioblastoma model highlights tumour-specific accumulation of our lead HMCD, MHI-148, for up to 7 days following a single intraperitoneal injection. These studies suggest that strongly ionisable groups like sulphonic acids hamper the cellular uptake of HMCDs in patient-derived GBM cell lines, highlighting cell line-specific differences in HMCD uptake. We envisage these findings will help in the design and structural modifications of HMCDs for drug-delivery applications for glioblastoma.

Analyzing pericytes under mild traumatic brain injury using 3D cultures and dielectric elastomer actuators.

Traumatic brain injury (TBI) is defined as brain damage due to an external force that negatively impacts brain function. Up to 90% of all TBI are considered in the mild severity range (mTBI) but there is still no therapeutic solution available. Therefore, further understanding of the mTBI pathology is required. To assist with this understanding, we developed a cell injury device (CID) based on a dielectric elastomer actuator (DEA), which is capable of modeling mTBI via injuring cultured cells with mechanical stretching. Our injury model is the first to use patient-derived brain pericyte cells, which are ubiquitous cells in the brain involved in injury response. Pericytes were cultured in our CIDs and mechanically strained up to 40%, and by at least 20%, prior to gene expression analysis. Our injury model is a platform capable of culturing and stretching primary human brain pericytes. The heterogeneous response in gene expression changes in our result may suggest that the genes implicated in pathological changes after mTBI could be a patient-dependent response, but requires further validation. The results of this study demonstrate that our CID is a suitable tool for simulating mTBI as an in vitro stretch injury model, that is sensitive enough to induce responses from primary human brain pericytes due to mechanical impacts.

Single-cell image analysis reveals over-expression of organic anion transporting polypeptides (OATPs) in human glioblastoma tissue.

Background: Glioblastoma (GBM) is the most common and aggressive primary brain tumor in adults. Whilst the role of the efflux transporters are well established in GBM, the expression and function of uptake transporters, such as the organic anion transporting polypeptide (OATP) family, are not well understood. OATPs possess broad substrate specificity that includes anti-cancer agents; therefore, we sought to investigate the expression of four OATP isoforms in human GBM cell types using patient tumor tissue. Methods: We used fluorescent immunohistochemical labeling of paraffin-embedded surgically resected tissues and single-cell image analysis methods to explore the expression of the OATP isoforms in different tumor cell types through co-labeling with cell-type specific markers, such as IBA1 (pan-myeloid), GFAP (tumor cell), PDGFRß (stromal cell), and UEA-1-lectin (endothelial). Results: We found significant over-expression of all the OATP isoforms (OATP1A2, 2B1, 1C1 and 4A1) in GBM tumor sections when compared to non-neoplastic brain. A single-cell image analysis revealed that OATPs were significantly upregulated throughout the tumor parenchyma, with significantly higher expression found on lectin-positive blood vessels and IBA1-positive myeloid cells in GBM compared to non-tumor brain tissue. Qualitative analysis of the four OATP isoforms demonstrated greater expression of OATP4A1 in peri-necrotic regions of GBM tissue, which correlated with hypoxia-related markers within the Ivy GAP RNAseq dataset. Conclusion: Here, we demonstrate, for the first time, the protein expression of four OATPs in human GBM tissue, including upregulation within the tumor microenvironment by myeloid cells and tumor vasculature, and isoform-specific upregulation within hypoxic niches.

Human pericytes degrade diverse α-synuclein aggregates.

Parkinson's disease (PD) is a progressive, neurodegenerative disorder characterised by the abnormal accumulation of α-synuclein (α-syn) aggregates. Central to disease progression is the gradual spread of pathological α-syn. α-syn aggregation is closely linked to progressive neuron loss. As such, clearance of α-syn aggregates may slow the progression of PD and lead to less severe symptoms. Evidence is increasing that non-neuronal cells play a role in PD and other synucleinopathies such as Lewy body dementia and multiple system atrophy. Our previous work has shown that pericytes-vascular mural cells that regulate the blood-brain barrier-contain α-syn aggregates in human PD brains. Here, we demonstrate that pericytes efficiently internalise fibrillar α-syn irrespective of being in a monoculture or mixed neuronal cell culture. Pericytes cleave fibrillar α-syn aggregates (Fibrils, Ribbons, fibrils65, fibrils91 and fibrils110), with cleaved α-syn remaining present for up to 21 days. The number of α-syn aggregates/cell and average aggregate size depends on the type of strain, but differences disappear within 5 five hours of treatment. Our results highlight the role brain vasculature may play in reducing α-syn aggregate burden in PD.

Pericytes take up and degrade α-synuclein but succumb to apoptosis under cellular stress.

Parkinson's disease (PD) is characterised by the progressive loss of midbrain dopaminergic neurons and the presence of aggregated α-synuclein (α-syn). Pericytes and microglia, two non-neuronal cells contain α-syn in the human brain, however, their role in disease processes is poorly understood. Pericytes, found surrounding the capillaries in the brain are important for maintaining the blood-brain barrier, controlling blood flow and mediating inflammation. In this study, primary human brain pericytes and microglia were exposed to two different α-synuclein aggregates. Inflammatory responses were assessed using immunocytochemistry, cytometric bead arrays and proteome profiler cytokine array kits. Fixed flow cytometry was used to investigate the uptake and subsequent degradation of α-syn in pericytes. We found that the two α-syn aggregates are devoid of inflammatory and cytotoxic actions on human brain derived pericytes and microglia. Although α-syn did not induce an inflammatory response, pericytes efficiently take up and degrade α-syn through the lysosomal pathway but not the ubiquitin-proteasome system. Furthermore, when pericytes were exposed the ubiquitin proteasome inhibitor-MG132 and α-syn aggregates, there was profound cytotoxicity through the production of reactive oxygen species resulting in apoptosis. These results suggest that the observed accumulation of α-syn in pericytes in human PD brains likely plays a role in PD pathogenesis, perhaps by causing cerebrovascular instability, under conditions of cellular stress.

Characterisation of PDGF-BB:PDGFRß signalling pathways in human brain pericytes: evidence of disruption in Alzheimer's disease.

Platelet-derived growth factor-BB (PDGF-BB):PDGF receptor-ß (PDGFRß) signalling in brain pericytes is critical to the development, maintenance and function of a healthy blood-brain barrier (BBB). Furthermore, BBB impairment and pericyte loss in Alzheimer's disease (AD) is well documented. We found that PDGF-BB:PDGFRß signalling components were altered in human AD brains, with a marked reduction in vascular PDGFB. We hypothesised that reduced PDGF-BB:PDGFRß signalling in pericytes may impact on the BBB. We therefore tested the effects of PDGF-BB on primary human brain pericytes in vitro to define pathways related to BBB function. Using pharmacological inhibitors, we dissected distinct aspects of the PDGF-BB response that are controlled by extracellular signal-regulated kinase (ERK) and Akt pathways. PDGF-BB promotes the proliferation of pericytes and protection from apoptosis through ERK signalling. In contrast, PDGF-BB:PDGFRß signalling through Akt augments pericyte-derived inflammatory secretions. It may therefore be possible to supplement PDGF-BB signalling to stabilise the cerebrovasculature in AD.

Tracking Antioxidant Status in Spinal Cord Injured Rodents: A Voltammetric Method Suited for Clinical Translation.

BACKGROUND: Spinal cord injury (SCI) triggers a signalling cascade that produces oxidative stress and damages the spinal cord. Voltammetry is a clinically accessible technique to detect, monitor, and guide correction of this potentially reversible secondary injury mechanism. Voltammetry is well suited for clinical translation because the method is inexpensive, simple, rapid, and portable. Voltammetry relies on the measurement of anodic current from a reagent-free, electrochemical reaction on the surface of a small electrode. METHODS: The present study tested the use of new disposable carbon nanotube based screen printed electrodes (CNT-SPE) for the voltammetric measurement of antioxidant current (AC). Spinal cord, cerebrospinal fluid, and plasma were obtained from Sprague-Dawley rats after SCI. Locomotor function after SCI was assessed by using the Basso, Beattie, Bresnahan (BBB) score. RESULTS: The more severe SCI caused a decline in spinal cord AC419 at 10 minutes (P < 0.05), 4 hours (P < 0.0001), and 1 day (P < 0.01) after injury compared with sham controls. It also caused a decline in plasma AC375 at 1 (P < 0.001) and 3 days (P < 0.05) after injury compared with their pre-injury baseline. Spinal cord AC419 correlated with plasma AC375 (r = 0.49, P < 0.01) and BBB score (r = 0.66, P < 0.0001) at 1 day after SCI. CONCLUSIONS: AC measured by CNT-SPE demonstrated a time- and severity-dependent decline after SCI. Plasma AC could serve as a surrogate marker for spinal cord AC.

Routine culture and study of adult human brain cells from neurosurgical specimens.

When modeling disease in the laboratory, it is important to use clinically relevant models. Patient-derived human brain cells grown in vitro to study and test potential treatments provide such a model. Here, we present simple, highly reproducible coordinated procedures that can be used to routinely culture most cell types found in the human brain from single neurosurgically excised brain specimens. The cell types that can be cultured include dissociated cultures of neurons, astrocytes, microglia, pericytes and brain endothelial and neural precursor cells, as well as explant cultures of the leptomeninges, cortical slice cultures and brain tumor cells. The initial setup of cultures takes ~2 h, and the cells are ready for further experiments within days to weeks. The resulting cells can be studied as purified or mixed population cultures, slice cultures and explant-derived cultures. This protocol therefore enables the investigation of human brain cells to facilitate translation of neuroscience research to the clinic.

Cytoprotective agent troxipide-cyanine dye conjugate with cytotoxic and antiproliferative activity in patient-derived glioblastoma cell lines.

Cytoprotective agents are mainly used to protect the gastrointestinal tract linings and in the treatment of gastric ulcers. These agents are devoid of appreciable cytotoxic or cytostatic effects, and medicinal chemistry efforts to modify them into anticancer agents are rare. A drug repurposing campaign initiated in our laboratory with the primary focus of discovering brain cancer drugs resulted in drug-dye conjugate 1, a combination of the cytoprotective agent troxipide and heptamethine cyanine dye MHI 148. The drug-dye conjugate 1 was evaluated in three different patient-derived adult glioblastoma cell lines, commercially available U87 glioblastoma, and one paediatric glioblastoma cell line. In all cases, the conjugate 1 showed potent cytotoxic activity with nanomolar potency (EC50: 267 nM). Interestingly, troxipide alone does not show any cytotoxic and cytostatic activity in the above cell lines. We also observe a synergistic effect of 1 with temozolomide (TMZ), the standard drug used for glioblastoma treatment, even though the cell lines we used in this study were resistant to TMZ treatment. Herein we disclose the synthesis and in vitro activity of drug-dye conjugate 1 for treatment of difficult-to-treat brain cancers such as glioblastoma.

Single-cell image analysis reveals a protective role for microglia in glioblastoma.

BACKGROUND: Microglia and tumor-associated macrophages (TAMs) constitute up to half of the total tumor mass of glioblastomas. Despite these myeloid populations being ontogenetically distinct, they have been largely conflated. Recent single-cell transcriptomic studies have identified genes that distinguish microglia from TAMs. Here we investigated whether the translated proteins of genes enriched in microglial or TAM populations can be used to differentiate these myeloid cells in immunohistochemically stained human glioblastoma tissue. METHODS: Tissue sections from resected low-grade, meningioma, and glioblastoma (grade IV) tumors and epilepsy tissues were immunofluorescently triple-labeled for Iba1 (pan-myeloid marker), CD14 or CD163 (preferential TAM markers), and either P2RY12 or TMEM119 (microglial-specific markers). Using a single-cell-based image analysis pipeline, we quantified the abundance of each marker within single myeloid cells, allowing the identification and analysis of myeloid populations. RESULTS: P2RY12 and TMEM119 successfully discriminated microglia from TAMs in glioblastoma. In contrast, CD14 and CD163 expression were not restricted to invading TAMs and were upregulated by tumor microglia. Notably, a higher ratio of microglia to TAMs significantly correlated with increased patient survival. CONCLUSIONS: We demonstrate the validity of previously defined microglial-specific genes P2RY12 and TMEM119 as robust discriminators of microglia and TAMs at the protein level in human tissue. Moreover, our data suggest that a higher proportion of microglia may be beneficial for patient survival in glioblastoma. Accordingly, this tissue-based method for myeloid population differentiation could serve as a useful prognostic tool.

Cardiac glycosides target barrier inflammation of the vasculature, meninges and choroid plexus.

Neuroinflammation is a key component of virtually all neurodegenerative diseases, preceding neuronal loss and associating directly with cognitive impairment. Neuroinflammatory signals can originate and be amplified at barrier tissues such as brain vasculature, surrounding meninges and the choroid plexus. We designed a high content screening system to target inflammation in human brain-derived cells of the blood-brain barrier (pericytes and endothelial cells) to identify inflammatory modifiers. Screening an FDA-approved drug library we identify digoxin and lanatoside C, members of the cardiac glycoside family, as inflammatory-modulating drugs that work in blood-brain barrier cells. An ex vivo assay of leptomeningeal and choroid plexus explants confirm that these drugs maintain their function in 3D cultures of brain border tissues. These results suggest that cardiac glycosides may be useful in targeting inflammation at border regions of the brain and offer new options for drug discovery approaches for neuroinflammatory driven degeneration.

A long-term follow-up of safety and clinical efficacy of NTCELL® [Immunoprotected (Alginate-encapsulated) porcine choroid plexus cells for xenotransplantation] in patients with Parkinson's disease.

INTRODUCTION: In 2019, we published the results of a Phase IIb randomized controlled trial of putaminal encapsulated porcine choroid plexus cell (termed NTCELL®) administration in patients with Parkinson's disease. This study failed to meet its primary efficacy end-point of a change in UPDRS part III score in the 'off' state at 26-weeks post-implant. However, a number of secondary end-points reached statistical significance. We questioned whether with longer follow-up, clinically significant improvements would be observed. For this reason, we decided to follow-up all patients periodically to week 104. Herein, we report the results of this long-term follow-up. METHODS: All 18 patients included in the original study were periodically re-assessed at weeks 52, 78 and 104 post-implant. At each time-point, motor and non-motor function, quality of life and levodopa equivalent daily dose was assessed using a standardized testing battery. RESULTS: At week 104, no significant differences in UPDRS part III scores in the 'off' state were observed in any of the treatment groups compared to baseline. Only a single serious adverse event - hospitalisation due to Parkinson's disease rigidity not responding to changes in medications - was considered potentially related to the implant procedure. There was no evidence of xenogeneic viral transmission. CONCLUSION: Un-blinded, long-duration follow-up to week 104 post-implantation showed no evidence that putaminal NTCELL® administration produces significant clinical benefit in patients with moderately advanced Parkinson's disease.

Isolation and culture of functional adult human neurons from neurosurgical brain specimens.

The ability to characterize and study primary neurons isolated directly from the adult human brain would greatly advance neuroscience research. However, significant challenges such as accessibility of human brain tissue and the lack of a robust neuronal cell culture protocol have hampered its progress. Here, we describe a simple and reproducible method for the isolation and culture of functional adult human neurons from neurosurgical brain specimens. In vitro, adult human neurons form a dense network and express a plethora of mature neuronal and synaptic markers. Most importantly, for the first time, we demonstrate the re-establishment of mature neurophysiological properties in vitro, such as repetitive fast-spiking action potentials, and spontaneous and evoked synaptic activity. Together, our dissociated and slice culture systems enable studies of adult human neurophysiology and gene expression under normal and pathological conditions and provide a high-throughput platform for drug testing on brain cells directly isolated from the adult human brain.

PARP inhibitor cyanine dye conjugate with enhanced cytotoxic and antiproliferative activity in patient derived glioblastoma cell lines.

We describe the synthesis and in vitro activity of drug-dye conjugate 1, which is a combination of the PARP inhibitor rucaparib and heptamethine cyanine dye IR-786. The drug-dye conjugate 1 was evaluated in three different patient-derived glioblastoma cell lines and showed strong cytotoxic activity with nanomolar potency (EC50: 128 nM), which was a 780 fold improvement over rucaparib itself. We also observe a synergistic effect of 1 with temozolomide (TMZ), the standard drug for treatment for glioblastoma even though these cell lines were resistant to TMZ treatment. We envisage such conjugates to be worth exploring for their utility in the treatment of various brain cancers.

Development and Validation of a Multivariate Prediction Model of Perioperative Mortality in Neurosurgery: The New Zealand Neurosurgical Risk Tool (NZRISK-NEURO).

BACKGROUND: Multivariate risk prediction models individualize prediction of adverse outcomes, assisting perioperative decision-making. There are currently no models specifically designed for the neurosurgical population. OBJECTIVE: To develop and validate a neurosurgical risk prediction model, with 30-d, 1-yr, and 2-yr mortality endpoints. METHODS: We accessed information on all adults in New Zealand who underwent neurosurgery or spinal surgery between July 1, 2011, and June 30, 2016, from an administrative database. Our dataset comprised of 18 375 participants, split randomly into derivation (75%) and validation (25%) datasets. Previously established covariates tested included American Society of Anesthesiologists physical status grade (ASA-PS), surgical acuity, operative severity, cancer status, and age. Exploratory covariates included anatomical site, gender, diabetes, trauma, ethnicity, and socioeconomic status. Least absolute shrinkage and selection operator (LASSO) regression analysis was used to construct 30-d, 1-yr, and 2-yr mortality models. RESULTS: Our final models included 8 covariates: age, ASA-PS grade, surgical acuity, cancer status, anatomical site, diabetes, ethnicity, and trauma. The area under the receiver operating curve for the 30-d, 1-yr, and 2-yr mortality models was 0.90, 0.91, and 0.91 indicating excellent discrimination, respectively. Calibration also showed excellent performance with McFadden's pseudo R2 statistics of 0.28, 0.37, and 0.41 and calibration plot slopes of 0.93, 0.95, and 0.94, respectively. The strongest predictors of mortality were ASA-PS 4 and 5 (30 d) and cancer (1 and 2 yr). CONCLUSION: NZRISK-NEURO is a robust multivariate calculator created specifically for neurosurgery, enabling physicians to generate data-driven individualized risk estimates, assisting shared decision-making and perioperative planning.

Metastatic melanoma: Surgical treatment of brain metastases - Analysis of 110 patients.

New Zealand has one of the highest rates of melanoma in the world. In up to 10% of cases, the disease is metastatic at diagnosis. Cerebral metastatic involvement carries a particularly poor prognosis. 110 patients were included in the analysis. A retrospective consecutive series of patients treated surgically at Auckland City Hospital were studied, with parameters of demographics, tumour characteristics, surgery, pathology, systemic therapy and survival analysed. Mean age was 59.9 years (range 22-81 years). Median survival from date of surgery was 8.1 months (95% CI 6.9-9.4 months). Of the 58 patients tested for BRAF mutation, 28 were positive, similar to previously published data. This conferred a better prognosis with median overall survival of 12.3 months (95% CI 7.2-17.3 months) compared to 7.8 months (95% CI 5.6-10 months) for those who were negative (p < 0.05). Survival correlated positively with extent of surgical resection. Both BRAF positive status and targeted and/or immunotherapy were significant predictors of improved survival. In this cohort, radiation therapy did not show a statistically significant improvement in overall survival. Survival from resection of cerebral metastases from melanoma is improving. Survival benefit is conferred by BRAF mutation, solitary metastasis and gross total resection of lesion.

Human in vitro systems for examining synaptic function and plasticity in the brain.

The human brain shows remarkable complexity in its cellular makeup and function, which are distinct from nonhuman species, signifying the need for human-based research platforms for the study of human cellular neurophysiology and neuropathology. However, the use of adult human brain tissue for research purposes is hampered by technical, methodological, and accessibility challenges. One of the major problems is the limited number of in vitro systems that, in contrast, are readily available from rodent brain tissue. With recent advances in the optimization of protocols for adult human brain preparations, there is a significant opportunity for neuroscientists to validate their findings in human-based systems. This review addresses the methodological aspects, advantages, and disadvantages of human neuron in vitro systems, focusing on the unique properties of human neurons and synapses in neocortical microcircuits. These in vitro models provide the incomparable advantage of being a direct representation of the neurons that have formed part of the human brain until the point of recording, which cannot be replicated by animal models nor human stem-cell systems. Important distinct cellular mechanisms are observed in human neurons that may underlie the higher order cognitive abilities of the human brain. The use of human brain tissue in neuroscience research also raises important ethical, diversity, and control tissue limitations that need to be considered. Undoubtedly however, these human neuron systems provide critical information to increase the potential of translation of treatments from the laboratory to the clinic in a way animal models are failing to provide.

The synthesis of a novel Crizotinib heptamethine cyanine dye conjugate that potentiates the cytostatic and cytotoxic effects of Crizotinib in patient-derived glioblastoma cell lines.

We describe the synthesis of drug-dye conjugate 1 between anaplastic lymphoma kinase inhibitor Crizotinib and heptamethine cyanine dye IR-786. The drug-dye conjugate 1 was evaluated in three different patient-derived glioblastoma cell lines and showed potent cytotoxic activity with nanomolar potency (EC50: 50.9 nM). We also demonstrate evidence for antiproliferative activity of 1 with single digit nanomolar potency (IC50: 4.7 nM). Furthermore, the cytotoxic effects conveyed a dramatic, 110-fold improvement over Crizotinib. This improvement was even more pronounced (492-fold) when 1 was combined with Temozolomide, the standard drug for treatment for glioblastoma. This work lays the foundation for future exploration of similar tyrosine kinase inhibitor drug-dye conjugates for the treatment of glioblastoma.

A phase IIb, randomised, double-blind, placebo-controlled, dose-ranging investigation of the safety and efficacy of NTCELL® [immunoprotected (alginate-encapsulated) porcine choroid plexus cells for xenotransplantation] in patients with Parkinson's disease.

INTRODUCTION: Regenerative therapies in Parkinson's disease aim to slow neurodegeneration and re-establish damaged neuronal circuitry. Neurotrophins are potent endogenous regulators of neuronal survival, development and regeneration. They represent an attractive regenerative treatment option in Parkinson's disease. Porcine choroid plexus produces a number of neurotrophins, and can be safely delivered to the striatum in an encapsulated formulation (termed NTCELL®) to protect them from immune attack. NTCELL® has shown regenerative potential in animal models of stroke, Huntington's disease and Parkinson's disease. Following promising results from an initial open label safety study of intra-striatal delivery of NTCELL® in human subjects, we sought to specifically investigate the safety and efficacy of NTCELL® for the treatment of Parkinson's disease. METHODS: 18 patients aged 56-65 years with idiopathic Parkinson's disease of at least 5 years duration were randomised to receive either sham surgery (general anaesthesia and partial thickness burr holes) or intra-striatal delivery of NTCELL® (the 3 groups in the treatment arm receiving incremental NTCELL® doses). RESULTS: At 26 weeks, we found no significant difference in total UPDRS scores ('on' and 'off'), UPDRS motor scores ('on' and 'off'), PDQ-39, UDysRS, timed walk or modified Hoehn and Yahr stage between patients implanted with NTCELL® and patients undergoing sham procedure. There were no serious adverse events or xenogeneic viral transmission during the study. CONCLUSION: The study did not meet its primary efficacy end-point of a change in UPDRS at 26 weeks post-intervention compared with baseline. Stereotactic NTCELL® implantation was safe and well tolerated.