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Rowland NC, Starr PA, Larson PS, Ostrem JL, Marks WJ, Lim DA. Combining cell transplants or gene therapy with deep brain stimulation for Parkinson's disease. Mov Disord 2014; 30:190-5. [DOI: 10.1002/mds.26083] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2014] [Accepted: 10/16/2014] [Indexed: 01/15/2023] Open
Affiliation(s)
- Nathan C. Rowland
- Department of Neurological Surgery; University of California; San Francisco CA USA
| | - Philip A. Starr
- Department of Neurological Surgery; University of California; San Francisco CA USA
- Parkinson's Disease Research; Education, and Clinical Center at the San Francisco Veterans Affairs Medical Center, University of California; San Francisco CA USA
| | - Paul S. Larson
- Department of Neurological Surgery; University of California; San Francisco CA USA
- Parkinson's Disease Research; Education, and Clinical Center at the San Francisco Veterans Affairs Medical Center, University of California; San Francisco CA USA
| | - Jill L. Ostrem
- Department of Neurology; San Francisco Veterans Affairs Medical Center, University of California; San Francisco CA USA
- Parkinson's Disease Research; Education, and Clinical Center at the San Francisco Veterans Affairs Medical Center, University of California; San Francisco CA USA
| | - William J. Marks
- Department of Neurology; San Francisco Veterans Affairs Medical Center, University of California; San Francisco CA USA
- Parkinson's Disease Research; Education, and Clinical Center at the San Francisco Veterans Affairs Medical Center, University of California; San Francisco CA USA
| | - Daniel A. Lim
- Department of Neurological Surgery; University of California; San Francisco CA USA
- Parkinson's Disease Research; Education, and Clinical Center at the San Francisco Veterans Affairs Medical Center, University of California; San Francisco CA USA
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Wide-bore 1.5T MRI-guided deep brain stimulation surgery: initial experience and technique comparison. Clin Neurol Neurosurg 2014; 127:79-85. [DOI: 10.1016/j.clineuro.2014.09.017] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2013] [Revised: 06/10/2014] [Accepted: 09/24/2014] [Indexed: 10/24/2022]
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Chen CC, White NS, Farid N, Kobalka P, Hansen L, Pearn M, Dale AM. Pre-operative cellularity mapping and intra-MRI surgery: potential for improving neurosurgical biopsies. Expert Rev Med Devices 2014; 12:1-5. [DOI: 10.1586/17434440.2015.975118] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Image-guided interventional therapy for cancer with radiotherapeutic nanoparticles. Adv Drug Deliv Rev 2014; 76:39-59. [PMID: 25016083 DOI: 10.1016/j.addr.2014.07.001] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2014] [Revised: 06/09/2014] [Accepted: 07/01/2014] [Indexed: 12/18/2022]
Abstract
One of the major limitations of current cancer therapy is the inability to deliver tumoricidal agents throughout the entire tumor mass using traditional intravenous administration. Nanoparticles carrying beta-emitting therapeutic radionuclides that are delivered using advanced image-guidance have significant potential to improve solid tumor therapy. The use of image-guidance in combination with nanoparticle carriers can improve the delivery of localized radiation to tumors. Nanoparticles labeled with certain beta-emitting radionuclides are intrinsically theranostic agents that can provide information regarding distribution and regional dosimetry within the tumor and the body. Image-guided thermal therapy results in increased uptake of intravenous nanoparticles within tumors, improving therapy. In addition, nanoparticles are ideal carriers for direct intratumoral infusion of beta-emitting radionuclides by convection enhanced delivery, permitting the delivery of localized therapeutic radiation without the requirement of the radionuclide exiting from the nanoparticle. With this approach, very high doses of radiation can be delivered to solid tumors while sparing normal organs. Recent technological developments in image-guidance, convection enhanced delivery and newly developed nanoparticles carrying beta-emitting radionuclides will be reviewed. Examples will be shown describing how this new approach has promise for the treatment of brain, head and neck, and other types of solid tumors.
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Fiandaca MS, Federoff HJ. Using viral-mediated gene delivery to model Parkinson's disease: Do nonhuman primate investigations expand our understanding? Exp Neurol 2014; 256:117-25. [DOI: 10.1016/j.expneurol.2013.03.014] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2012] [Revised: 02/08/2013] [Accepted: 03/14/2013] [Indexed: 12/21/2022]
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Chittiboina P, Heiss JD, Warren KE, Lonser RR. Magnetic resonance imaging properties of convective delivery in diffuse intrinsic pontine gliomas. J Neurosurg Pediatr 2014; 13:276-82. [PMID: 24410126 PMCID: PMC4294184 DOI: 10.3171/2013.11.peds136] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
OBJECT Coinfused surrogate imaging tracers can provide direct insight into the properties of convection-enhanced delivery (CED) in the nervous system. To better understand the distributive properties of CED in a clinical circumstance, the authors analyzed the imaging findings in pediatric diffuse intrinsic pontine glioma (DIPG) patients undergoing coinfusion of Gd-DTPA and interleukin-13-Pseudomonas exotoxin (IL13-PE). METHODS Consecutive patients undergoing CED (maximal rates of 5 or 10 μl/minute) of Gd-DTPA (1 or 5 mM) and IL13-PE (0.125 μg/ml or 0.25 μg/ml) for DIPG were included. Real-time MRI was performed during infusions, and imaging results were analyzed. RESULTS Four patients (2 males, 2 females; mean age at initial infusion 13.0 ± 5.3 years; range 5-17 years) underwent 5 infusions into DIPGs. Brainstem infusions were clearly identified on T1-weighted MR images at 1-mM (1 infusion) and 5-mM (4 infusions) coinfused Gd-DTPA concentrations. While the volume of distribution (Vd) increased progressively with volume of infusion (Vi) (mean volume 2.5 ± 0.9 ml; range 1.1-3.7 ml), final Vd:Vi ratios were significantly reduced with lower Gd-DTPA concentration (Vd:Vi for 1 mM of 1.6 compared with a mean Vd:Vi ratio for 5 mM of 3.3 ± 1.0) (p = 0.04). Similarly, anatomical distribution patterns were affected by preferential flow along parallel axial fiber tracts, into prior infusion cannula tracts and intraparenchymal air pockets, and leak back around the infusion cannula at the highest rate of infusion. CONCLUSIONS Magnetic resonance imaging of a coinfused Gd-DTPA surrogate tracer provided direct insight into the properties of CED in a clinical application. While clinically relevant Vds can be achieved by convective delivery, specific tissue properties can affect distribution volume and pattern, including Gd-DTPA concentration, preferential flow patterns, and infusion rate. Understanding of these properties of CED can enhance its clinical application. Part of clinical trial no. NCT00880061 ( ClinicalTrials.gov ).
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Affiliation(s)
- Prashant Chittiboina
- Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke, Bethesda, Maryland
| | - John D. Heiss
- Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke, Bethesda, Maryland
| | - Katherine E. Warren
- Pediatric Oncology Branch, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland
| | - Russell R. Lonser
- Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke, Bethesda, Maryland,Department of Neurological Surgery, The Ohio State University Wexner Medical Center, Columbus, Ohio
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57
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Ryapolova-Webb E, Afshar P, Stanslaski S, Denison T, de Hemptinne C, Bankiewicz K, Starr PA. Chronic cortical and electromyographic recordings from a fully implantable device: preclinical experience in a nonhuman primate. J Neural Eng 2014; 11:016009. [PMID: 24445430 DOI: 10.1088/1741-2560/11/1/016009] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
OBJECTIVE Analysis of intra- and perioperatively recorded cortical and basal ganglia local field potentials in human movement disorders has provided great insight into the pathophysiology of diseases such as Parkinson's, dystonia, and essential tremor. However, in order to better understand the network abnormalities and effects of chronic therapeutic stimulation in these disorders, long-term recording from a fully implantable data collection system is needed. APPROACH A fully implantable investigational data collection system, the Activa® PC + S neurostimulator (Medtronic, Inc., Minneapolis, MN), has been developed for human use. Here, we tested its utility for extended intracranial recording in the motor system of a nonhuman primate. The system was attached to two quadripolar paddle arrays: one covering sensorimotor cortex, and one covering a proximal forelimb muscle, to study simultaneous cortical field potentials and electromyography during spontaneous transitions from rest to movement. MAIN RESULTS Over 24 months of recording, movement-related changes in physiologically relevant frequency bands were readily detected, including beta and gamma signals at approximately 2.5 μV/[Formula: see text] and 0.7 μV/[Formula: see text], respectively. The system architecture allowed for flexible recording configurations and algorithm triggered data recording. In the course of physiological analyses, sensing artifacts were observed (∼1 μVrms stationary tones at fixed frequency), which were mitigated either with post-processing or algorithm design and did not impact the scientific conclusions. Histological examination revealed no underlying tissue damage; however, a fibrous capsule had developed around the paddles, demonstrating a potential mechanism for the observed signal amplitude reduction. SIGNIFICANCE This study establishes the usefulness of this system in measuring chronic brain and muscle signals. Use of this system may potentially be valuable in human trials of chronic brain recording in movement disorders, a next step in the design of closed-loop neurostimulation paradigms.
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Affiliation(s)
- Elena Ryapolova-Webb
- Department of Neurological Surgery, University of California, 779 Moffitt, 505 Parnassus Ave, San Francisco, CA 94143, USA
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Douglas MR. Gene therapy for Parkinson's disease: state-of-the-art treatments for neurodegenerative disease. Expert Rev Neurother 2014; 13:695-705. [PMID: 23739006 DOI: 10.1586/ern.13.58] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Pharmacological and surgical treatments offer symptomatic benefits to patients with Parkinson's disease; however, as the condition progresses, patients experience gradual worsening in symptom control, with the development of a range of disabling complications. In addition, none of the currently available therapies have convincingly shown disease-modifying effects - either in slowing or reversing the disease. These problems have led to extensive research into the possible use of gene therapy as a treatment for Parkinson's disease. Several treatments have reached human clinical trial stages, providing important information on the risks and benefits of this novel therapeutic approach, and the tantalizing promise of improved control of this currently incurable neurodegenerative disorder.
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Affiliation(s)
- Michael R Douglas
- School of Clinical and Experimental Medicine, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK.
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59
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San Sebastian W, Kells AP, Bringas J, Samaranch L, Hadaczek P, Ciesielska A, Macayan M, Pivirotto PJ, Forsayeth J, Osborne S, Wright JF, Green F, Heller G, Bankiewicz KS. SAFETY AND TOLERABILITY OF MRI-GUIDED INFUSION OF AAV2-hAADC INTO THE MID-BRAIN OF NON-HUMAN PRIMATE. MOLECULAR THERAPY-METHODS & CLINICAL DEVELOPMENT 2014; 3:S2329-0501(16)30117-6. [PMID: 25541617 PMCID: PMC4274790 DOI: 10.1038/mtm.2014.49] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Aromatic L-amino acid decarboxylase (AADC) deficiency is a rare, autosomal-recessive neurological disorder caused by mutations in the DDC gene that leads to an inability to synthesize catecholamines and serotonin. As a result, patients suffer compromised development, particularly in motor function. A recent gene replacement clinical trial explored putaminal delivery of recombinant adeno-associated virus serotype 2 vector encoding human AADC (AAV2-hAADC) in AADC-deficient children. Unfortunately, patients presented only modest amelioration of motor symptoms, which authors acknowledged could be due to insufficient transduction of putamen. We hypothesize that, with the development of a highly accurate MRI-guided cannula placement technology, a more effective approach might be to target the affected mid-brain neurons directly. Transduction of AADC-deficient dopaminergic neurons in the substantia nigra and ventral tegmental area with locally infused AAV2-hAADC would be expected to lead to restoration of normal dopamine levels in affected children. The objective of this study was to assess the long-term safety and tolerability of bilateral AAV2-hAADC MRI-guided pressurized infusion into the mid-brain of nonhuman primates. Animals received either vehicle, low or high AAV2-hAADC vector dose and were euthanized 1, 3, or 9 months after surgery. Our data indicate that effective mid-brain transduction was achieved without untoward effects.
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Affiliation(s)
- Waldy San Sebastian
- Department of Neurological Surgery, University of California San Francisco, San Francisco, CA, USA
| | - Adrian P Kells
- Department of Neurological Surgery, University of California San Francisco, San Francisco, CA, USA
| | - John Bringas
- Department of Neurological Surgery, University of California San Francisco, San Francisco, CA, USA
| | - Lluis Samaranch
- Department of Neurological Surgery, University of California San Francisco, San Francisco, CA, USA
| | - Piotr Hadaczek
- Department of Neurological Surgery, University of California San Francisco, San Francisco, CA, USA
| | - Agnieszka Ciesielska
- Department of Neurological Surgery, University of California San Francisco, San Francisco, CA, USA
| | - Michael Macayan
- Department of Neurological Surgery, University of California San Francisco, San Francisco, CA, USA
| | - Phillip J Pivirotto
- Department of Neurological Surgery, University of California San Francisco, San Francisco, CA, USA
| | - John Forsayeth
- Department of Neurological Surgery, University of California San Francisco, San Francisco, CA, USA
| | | | - J Fraser Wright
- Center for Cellular and Molecular Therapeutics, Children's Hospital of Philadelphia, Philadelphia, PA, USA ; Department of Pathology and Laboratory Medicine, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA
| | - Foad Green
- Department of Neurological Surgery, University of California San Francisco, San Francisco, CA, USA
| | - Gregory Heller
- Department of Neurological Surgery, University of California San Francisco, San Francisco, CA, USA
| | - Krystof S Bankiewicz
- Department of Neurological Surgery, University of California San Francisco, San Francisco, CA, USA
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San Sebastian W, Samaranch L, Kells AP, Forsayeth J, Bankiewicz KS. Gene therapy for misfolding protein diseases of the central nervous system. Neurotherapeutics 2013; 10:498-510. [PMID: 23700209 PMCID: PMC3701766 DOI: 10.1007/s13311-013-0191-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Protein aggregation as a result of misfolding is a common theme underlying neurodegenerative diseases. Accordingly, most recent studies aim to prevent protein misfolding and/or aggregation as a strategy to treat these pathologies. For instance, state-of-the-art approaches, such as silencing protein overexpression by means of RNA interference, are being tested with positive outcomes in preclinical models of animals overexpressing the corresponding protein. Therapies designed to treat central nervous system diseases should provide accurate delivery of the therapeutic agent and long-term or chronic expression by means of a nontoxic delivery vehicle. After several years of technical advances and optimization, gene therapy emerges as a promising approach able to fulfill those requirements. In this review we will summarize the latest improvements achieved in gene therapy for central nervous system diseases associated with protein misfolding (e.g., amyotrophic lateral sclerosis, Alzheimer's, Parkinson's, Huntington's, and prion diseases), as well as the most recent approaches in this field to treat these pathologies.
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Affiliation(s)
- Waldy San Sebastian
- Department of Neurological Surgery, University of California San Francisco, 1855 Folsom Street, San Francisco, CA USA
| | - Lluis Samaranch
- Department of Neurological Surgery, University of California San Francisco, 1855 Folsom Street, San Francisco, CA USA
| | - Adrian P. Kells
- Department of Neurological Surgery, University of California San Francisco, 1855 Folsom Street, San Francisco, CA USA
| | - John Forsayeth
- Department of Neurological Surgery, University of California San Francisco, 1855 Folsom Street, San Francisco, CA USA
| | - Krystof S. Bankiewicz
- Department of Neurological Surgery, University of California San Francisco, 1855 Folsom Street, San Francisco, CA USA
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Abstract
This study presents a computational tool for auto-segmenting the distribution of brain infusions observed by magnetic resonance imaging. Clinical usage of direct infusion is increasing as physicians recognize the need to attain high drug concentrations in the target structure with minimal off-target exposure. By co-infusing a Gadolinium-based contrast agent and visualizing the distribution using real-time using magnetic resonance imaging, physicians can make informed decisions about when to stop or adjust the infusion. However, manual segmentation of the images is tedious and affected by subjective preferences for window levels, image interpolation and personal biases about where to delineate the edge of the sloped shoulder of the infusion. This study presents a computational technique that uses a Gaussian Mixture Model to efficiently classify pixels as belonging to either the high-intensity infusate or low-intensity background. The algorithm was implemented as a distributable plug-in for the widely used imaging platform OsiriX®. Four independent operators segmented fourteen anonymized datasets to validate the tool’s performance. The datasets were intra-operative magnetic resonance images of infusions into the thalamus or putamen of non-human primates. The tool effectively reproduced the manual segmentation volumes, while significantly reducing intra-operator variability by 67±18%. The tool will be used to increase efficiency and reduce variability in upcoming clinical trials in neuro-oncology and gene therapy.
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62
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Yin D, Zhai Y, Gruber HE, Ibanez CE, Robbins JM, Kells AP, Kasahara N, Forsayeth J, Jolly DJ, Bankiewicz KS. Convection-enhanced delivery improves distribution and efficacy of tumor-selective retroviral replicating vectors in a rodent brain tumor model. Cancer Gene Ther 2013; 20:336-41. [PMID: 23703472 PMCID: PMC3733370 DOI: 10.1038/cgt.2013.25] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
In the present study, we compared the therapeutic effect of tumor-selective retroviral replicating vectors (RRV) expressing the yeast cytosine deaminase (CD) delivered by CED or simple injection, followed by systemic administration of the pro-drug, 5-fluorocytosine (5-FC). Treatment with RRV-CD and systemic 5-FC significantly increased survival in rodent U87MG glioma model in comparison to controls (p<0.01). Interestingly, CED of RRV-CD followed by 5-FC further enhanced survival in this animal model in comparison to intra-tumoral injection of RRV-CD followed by systemic 5-FC (p<0.05). High expression levels of Ki-67 were found in untreated tumors compared to treated. Untreated tumors were also much larger than treated. CED resulted in excellent distribution of RRV while only partial distribution of RRV was obtained after injection. Furthermore, RRV-CD and cytosine deaminase were also found in tumors from treated rats at study end-points. These results demonstrated that RRV vectors may efficiently transduce and stably propagate in malignant human glioma, thereby achieving a significant in-situ amplification effect after initial administration. We conclude that delivery of RRV into the glioma by CED provides much wider vector distribution than simple, injection, and this correlated with better therapeutic outcomes.
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Affiliation(s)
- D Yin
- Department of Neurosurgery, University of California San Francisco, San Francisco, CA 94103, USA
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Potts MB, Silvestrini MT, Lim DA. Devices for cell transplantation into the central nervous system: Design considerations and emerging technologies. Surg Neurol Int 2013; 4:S22-30. [PMID: 23653887 PMCID: PMC3642746 DOI: 10.4103/2152-7806.109190] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2012] [Accepted: 11/04/2012] [Indexed: 12/14/2022] Open
Abstract
Successful use of cell-based therapies for the treatment of neurological diseases is dependent upon effective delivery to the central nervous system (CNS). The CNS poses several challenges to the delivery of cell-based therapeutics, including the blood-brain barrier, anatomic complexity, and regional specificity. Targeted delivery methods are therefore required for the selective treatment of specific CNS regions. In addition, CNS tissues are mechanically and physiologically delicate and even minor injury to normal brain or spinal cord can cause devastating neurological deficits. Targeted delivery methods must therefore minimize tissue trauma. At present, direct injection into brain or spinal cord parenchyma promises to be the most versatile and accurate method of targeted CNS therapeutic delivery. While direct injection methods have already been employed in clinical trials of cell transplantation for a wide variety of neurological diseases, there are many shortcomings with the devices and surgical approaches currently used. Some of these technical limitations may hinder the clinical development of cell transplantation therapies despite validity of the underlying biological mechanisms. In this review, we discuss some of the important technical considerations of CNS injection devices such as targeting accuracy, distribution of infused therapeutic, and overall safety to the patient. We also introduce and discuss an emerging technology - radially branched deployment - that may improve our ability to safely distribute cell-based therapies and other therapeutic agents to the CNS. Finally, we speculate on future technological developments that may further enhance the efficacy of CNS therapeutic delivery.
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Affiliation(s)
- Matthew B Potts
- Department of Neurological Surgery, University of California, San Francisco, CA, USA
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64
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Siegal T. Which drug or drug delivery system can change clinical practice for brain tumor therapy? Neuro Oncol 2013; 15:656-69. [PMID: 23502426 DOI: 10.1093/neuonc/not016] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The prognosis and treatment outcome for primary brain tumors have remained unchanged despite advances in anticancer drug discovery and development. In clinical trials, the majority of promising experimental agents for brain tumors have had limited impact on survival or time to recurrence. These disappointing results are partially explained by the inadequacy of effective drug delivery to the CNS. The impediments posed by the various specialized physiological barriers and active efflux mechanisms lead to drug failure because of inability to reach the desired target at a sufficient concentration. This perspective reviews the leading strategies that aim to improve drug delivery to brain tumors and their likelihood to change clinical practice. The English literature was searched for defined search items. Strategies that use systemic delivery and those that use local delivery are critically reviewed. In addition, challenges posed for drug delivery by combined treatment with anti-angiogenic therapy are outlined. To impact clinical practice and to achieve more than just a limited local control, new drugs and delivery systems must adhere to basic clinical expectations. These include, in addition to an antitumor effect, a verified favorable adverse effects profile, easy introduction into clinical practice, feasibility of repeated or continuous administration, and compatibility of the drug or delivery system with any tumor size and brain location.
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Affiliation(s)
- Tali Siegal
- Gaffin Center for Neuro-Oncology, Hadassah Hebrew-University Medical Center, Ein Kerem, P.O. Box 12000, Jerusalem 91120, Israel.
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65
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Rapid inverse planning for pressure-driven drug infusions in the brain. PLoS One 2013; 8:e56397. [PMID: 23457563 PMCID: PMC3574124 DOI: 10.1371/journal.pone.0056397] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2012] [Accepted: 01/09/2013] [Indexed: 11/29/2022] Open
Abstract
Infusing drugs directly into the brain is advantageous to oral or intravenous delivery for large molecules or drugs requiring high local concentrations with low off-target exposure. However, surgeons manually planning the cannula position for drug delivery in the brain face a challenging three-dimensional visualization task. This study presents an intuitive inverse-planning technique to identify the optimal placement that maximizes coverage of the target structure while minimizing the potential for leakage outside the target. The technique was retrospectively validated using intraoperative magnetic resonance imaging of infusions into the striatum of non-human primates and into a tumor in a canine model and applied prospectively to upcoming human clinical trials.
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66
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Huo T, Barth RF, Yang W, Nakkula RJ, Koynova R, Tenchov B, Chaudhury AR, Agius L, Boulikas T, Elleaume H, Lee RJ. Preparation, biodistribution and neurotoxicity of liposomal cisplatin following convection enhanced delivery in normal and F98 glioma bearing rats. PLoS One 2012; 7:e48752. [PMID: 23152799 PMCID: PMC3496719 DOI: 10.1371/journal.pone.0048752] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2012] [Accepted: 10/01/2012] [Indexed: 11/18/2022] Open
Abstract
The purpose of this study was to evaluate two novel liposomal formulations of cisplatin as potential therapeutic agents for treatment of the F98 rat glioma. The first was a commercially produced agent, Lipoplatin™, which currently is in a Phase III clinical trial for treatment of non-small cell lung cancer (NSCLC). The second, produced in our laboratory, was based on the ability of cisplatin to form coordination complexes with lipid cholesteryl hemisuccinate (CHEMS). The in vitro tumoricidal activity of the former previously has been described in detail by other investigators. The CHEMS liposomal formulation had a Pt loading efficiency of 25% and showed more potent in vitro cytotoxicity against F98 glioma cells than free cisplatin at 24 h. In vivo CHEMS liposomes showed high retention at 24 h after intracerebral (i.c.) convection enhanced delivery (CED) to F98 glioma bearing rats. Neurotoxicologic studies were carried out in non-tumor bearing Fischer rats following i.c. CED of Lipoplatin™ or CHEMS liposomes or their "hollow" counterparts. Unexpectedly, Lipoplatin™ was highly neurotoxic when given i.c. by CED and resulted in death immediately following or within a few days after administration. Similarly "hollow" Lipoplatin™ liposomes showed similar neurotoxicity indicating that this was due to the liposomes themselves rather than the cisplatin. This was particularly surprising since Lipoplatin™ has been well tolerated when administered intravenously. In contrast, CHEMS liposomes and their "hollow" counterparts were clinically well tolerated. However, a variety of dose dependent neuropathologic changes from none to severe were seen at either 10 or 14 d following their administration. These findings suggest that further refinements in the design and formulation of cisplatin containing liposomes will be required before they can be administered i.c. by CED for the treatment of brain tumors and that a formulation that may be safe when given systemically may be highly neurotoxic when administered directly into the brain.
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Affiliation(s)
- Tianyao Huo
- Department of Pathology, The Ohio State University, Columbus, Ohio, United States of America
| | - Rolf F. Barth
- Department of Pathology, The Ohio State University, Columbus, Ohio, United States of America
- * E-mail:
| | - Weilian Yang
- Department of Pathology, The Ohio State University, Columbus, Ohio, United States of America
| | - Robin J. Nakkula
- Department of Pathology, The Ohio State University, Columbus, Ohio, United States of America
| | - Rumiana Koynova
- Division of Pharmaceutics, College of Pharmacy, The Ohio State University, Columbus, Ohio, United States of America
| | - Boris Tenchov
- Division of Pharmaceutics, College of Pharmacy, The Ohio State University, Columbus, Ohio, United States of America
| | - Abhik Ray Chaudhury
- Department of Pathology, The Ohio State University, Columbus, Ohio, United States of America
| | - Lawrence Agius
- Department of Pathology, Mater Dei Hospital and University of Malta Medical School, Msida, Malta
| | - Teni Boulikas
- Regulon Inc., Mountain View, California, United States of America
| | | | - Robert J. Lee
- Division of Pharmaceutics, College of Pharmacy, The Ohio State University, Columbus, Ohio, United States of America
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Miranpuri GS, Kumbier L, Hinchman A, Schomberg D, Wang A, Marshall H, Kubota K, Ross C, Sillay K. Gene-based therapy of Parkinson's Disease: Translation from animal model to human clinical trial employing convection enhanced delivery. Ann Neurosci 2012; 19:133-46. [PMID: 25205986 PMCID: PMC4117084 DOI: 10.5214/ans.0972.7531.190310] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2012] [Revised: 07/02/2012] [Accepted: 07/02/2012] [Indexed: 11/17/2022] Open
Abstract
The existing treatment of Parkinson's disease (PD) is directed towards substituting dopamine loss with either dopamine replacement therapy or pharmacological therapies aimed at increasing dopamine at the synapse level. Emerging viable alternatives include the use of cell-based and gene-based therapeutics. In this review, we discuss efforts in developing in vitro and in vivo models and their translation to human clinical trials for gene-based therapy of this distressing and prevalent neurodegenerative disorder. Given the mismatch between expectations from preclinical data and results of human pivotal trials, drug delivery has been identified as the key emerging area for translational research due to limitation of limited efficacy. The chief highlights of the current topic include use of improved delivery methods of gene-based therapeutic agents. Convection-enhanced delivery (CED), an advanced infusion technique with demonstrated utility in ex vivo and in vivo animal models has recently been adopted for PD gene-based therapy trials. Several preclinical studies suggest that magnetic resonance imaging (MRI)-guided navigation for accurately targeting and real time monitoring viral vector delivery (rCED) in future clinical trials involving detection of gene expression and restoration of dopaminergic function loss using pro-drug approach will greatly enhance these PD treatments.
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Affiliation(s)
- Gurwattan S. Miranpuri
- Department of Neurological Surgery, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin 53792, USA
| | - Lauren Kumbier
- Department of Neurological Surgery, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin 53792, USA
| | - Angelica Hinchman
- Department of Neurological Surgery, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin 53792, USA
| | - Dominic Schomberg
- Department of Neurological Surgery, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin 53792, USA
| | - Anyi Wang
- Department of Neurological Surgery, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin 53792, USA
| | - Hope Marshall
- Department of Neurological Surgery, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin 53792, USA
| | - Ken Kubota
- Kinetic Foundation, Los Altos, CA, 94023, USA
| | - Chris Ross
- Engineering Resources Group Inc, Pembroke Pines, FL, 33029, USA
| | - Karl Sillay
- Department of Neurological Surgery, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin 53792, USA
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68
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Fiandaca MS, Bankiewicz KS, Federoff HJ. Gene therapy for the treatment of Parkinson's disease: the nature of the biologics expands the future indications. Pharmaceuticals (Basel) 2012; 5:553-90. [PMID: 24281662 PMCID: PMC3763661 DOI: 10.3390/ph5060553] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2012] [Revised: 05/18/2012] [Accepted: 05/23/2012] [Indexed: 12/20/2022] Open
Abstract
The pharmaceutical industry's development of therapeutic medications for the treatment of Parkinson's disease (PD) endures, as a result of the continuing need for better agents, and the increased clinical demand due to the aging population. Each new drug offers advantages and disadvantages to patients when compared to other medical offerings or surgical options. Deep brain stimulation (DBS) has become a standard surgical remedy for the effective treatment of select patients with PD, for whom most drug regimens have failed or become refractory. Similar to DBS as a surgical option, gene therapy for the treatment of PD is evolving as a future option. In the four different PD gene therapy approaches that have reached clinical trials investigators have documented an excellent safety profile associated with the stereotactic delivery, viral vectors and doses utilized, and transgenes expressed. In this article, we review the clinically relevant gene therapy strategies for the treatment of PD, concentrating on the published preclinical and clinical results, and the likely mechanisms involved. Based on these presentations, we advance an analysis of how the nature of the gene therapy used may eventually expand the scope and utility for the management of PD.
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Affiliation(s)
- Massimo S. Fiandaca
- Translational NeuroTherapy Center, Department of Neurological Surgery, University of California San Francisco, 1855 Folsom Street, Mission Center Building, San Francisco, CA 94103, USA; (K.S.B.)
| | - Krystof S. Bankiewicz
- Translational NeuroTherapy Center, Department of Neurological Surgery, University of California San Francisco, 1855 Folsom Street, Mission Center Building, San Francisco, CA 94103, USA; (K.S.B.)
| | - Howard J. Federoff
- Departments of Neurology and Neuroscience, Georgetown University Medical Center, 4000 Reservoir Road, Washington, DC 20007, USA; (H.J.F.)
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69
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Salegio EA, Samaranch L, Kells AP, Forsayeth J, Bankiewicz K. Guided delivery of adeno-associated viral vectors into the primate brain. Adv Drug Deliv Rev 2012; 64:598-604. [PMID: 22036906 DOI: 10.1016/j.addr.2011.10.005] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2011] [Accepted: 10/13/2011] [Indexed: 11/17/2022]
Abstract
In this review, we discuss recent developments in the delivery of adeno-associated virus-based vectors (AAV), particularly with respect to the role of axonal transport in vector distribution in the brain. The use of MRI-guidance and new stereotactic aiming devices have now established a strong foundation for neurological gene therapy to become an accepted procedure in interventional neurology.
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Affiliation(s)
- Ernesto A Salegio
- Department of Neurological Surgery, University of California San Francisco, San Francisco, CA 94103–0555, USA
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Mittermeyer G, Christine CW, Rosenbluth KH, Baker SL, Starr P, Larson P, Kaplan PL, Forsayeth J, Aminoff MJ, Bankiewicz KS. Long-term evaluation of a phase 1 study of AADC gene therapy for Parkinson's disease. Hum Gene Ther 2012; 23:377-81. [PMID: 22424171 DOI: 10.1089/hum.2011.220] [Citation(s) in RCA: 188] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
We report the results of a long-term follow-up of subjects in a phase 1 study of AAV2-hAADC (adeno-associated virus type 2-human aromatic L-amino acid decarboxylase) gene therapy for the treatment of Parkinson's disease (PD). Ten patients with moderately advanced PD received bilateral putaminal infusions of either a low or a high dose of AAV2-hAADC vector. An annual positron emission tomography (PET) imaging with [(18)F]fluoro-L-m-tyrosine tracer was used for evaluation of AADC expression, and a standard clinical rating scale [Unified Parkinson's Disease Rating Scale (UPDRS)] was used to assess effect. Our previous analysis of the 6-month data suggested that this treatment was acutely safe and well tolerated. We found that the elevated PET signal observed in the first 12 months persisted over 4 years in both dose groups. A significantly increased PET value compared with the presurgery baseline was maintained over the 4-year monitoring period. The UPDRS in all patients off medication for 12 hr improved in the first 12 months, but displayed a slow deterioration in subsequent years. This analysis demonstrates that apparent efficacy continues through later years with an acceptable safety profile. These data indicate stable transgene expression over 4 years after vector delivery and continued safety, but emphasize the need for a controlled efficacy trial and the use of a higher vector dose.
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Affiliation(s)
- Gabriele Mittermeyer
- Department of Neurological Surgery, University of California San Francisco, San Francisco, CA 94143, USA
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71
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San Sebastian W, Richardson RM, Kells AP, Lamarre C, Bringas J, Pivirotto P, Salegio EA, Dearmond SJ, Forsayeth J, Bankiewicz KS. Safety and tolerability of magnetic resonance imaging-guided convection-enhanced delivery of AAV2-hAADC with a novel delivery platform in nonhuman primate striatum. Hum Gene Ther 2012; 23:210-7. [PMID: 22017504 DOI: 10.1089/hum.2011.162] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Degeneration of nigrostriatal neurons in Parkinson's disease (PD) causes progressive loss of aromatic l-amino acid decarboxylase (AADC), the enzyme that converts levodopa (l-DOPA) into dopamine in the striatum. Because loss of this enzyme appears to be a major driver of progressive impairment of response to the mainstay drug, l-DOPA, one promising approach has been to use gene therapy to restore AADC activity in the human putamen and thereby restore normal l-DOPA response in patients with PD. An open-label phase I clinical trial of this approach in patients with PD provided encouraging signs of improvement in Unified Parkinson's Disease Rating Scale scores and reductions in antiparkinsonian medications. However, such improvement was modest compared with the results previously reported in parkinsonian rhesus macaques. The reason for this discrepancy may have been that the relatively small volume of vector infused in the clinical study restricted the distribution of AADC expression, such that only about 20% of the postcommissural putamen was covered, as revealed by l-[3-(18)F]-α-methyltyrosine-positron emission tomography. To achieve more quantitative distribution of vector, we have developed a visual guidance system for parenchymal infusion of AAV2. The purpose of the present study was to evaluate the combined magnetic resonance imaging-guided delivery system with AAV2-hAADC under conditions that approximate the intended clinical protocol. Our data indicate that this approach directed accurate cannula placement and effective vector distribution without inducing any untoward effects in nonhuman primates infused with a high dose of AAV2-hAADC.
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Affiliation(s)
- Waldy San Sebastian
- Department of Neurological Surgery, University of California San Francisco , San Francisco, CA 94103, USA
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72
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van der Bom IMJ, Moser RP, Gao G, Sena-Esteves M, Aronin N, Gounis MJ. Frameless multimodal image guidance of localized convection-enhanced delivery of therapeutics in the brain. J Neurointerv Surg 2011; 5:69-72. [PMID: 22193239 PMCID: PMC3533401 DOI: 10.1136/neurintsurg-2011-010170] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
INTRODUCTION Convection-enhanced delivery (CED) has been shown to be an effective method of administering macromolecular compounds into the brain that are unable to cross the blood-brain barrier. Because the administration is highly localized, accurate cannula placement by minimally invasive surgery is an important requisite. This paper reports on the use of an angiographic c-arm system which enables truly frameless multimodal image guidance during CED surgery. METHODS A microcannula was placed into the striatum of five sheep under real-time fluoroscopic guidance using imaging data previously acquired by cone beam computed tomography (CBCT) and MRI, enabling three-dimensional navigation. After introduction of the cannula, high resolution CBCT was performed and registered with MRI to confirm the position of the cannula tip and to make adjustments as necessary. Adeno-associated viral vector-10, designed to deliver small-hairpin micro RNA (shRNAmir), was mixed with 2.0 mM gadolinium (Gd) and infused at a rate of 3 μl/min for a total of 100 μl. Upon completion, the animals were transferred to an MR scanner to assess the approximate distribution by measuring the volume of spread of Gd. RESULTS The cannula was successfully introduced under multimodal image guidance. High resolution CBCT enabled validation of the cannula position and Gd-enhanced MRI after CED confirmed localized administration of the therapy. CONCLUSION A microcannula for CED was introduced into the striatum of five sheep under multimodal image guidance. The non-alloy 300 μm diameter cannula tip was well visualized using CBCT, enabling confirmation of the position of the end of the tip in the area of interest.
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73
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Elias WJ, Zheng ZA, Domer P, Quigg M, Pouratian N. Validation of connectivity-based thalamic segmentation with direct electrophysiologic recordings from human sensory thalamus. Neuroimage 2011; 59:2025-34. [PMID: 22036683 DOI: 10.1016/j.neuroimage.2011.10.049] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2011] [Revised: 09/18/2011] [Accepted: 10/12/2011] [Indexed: 11/17/2022] Open
Abstract
Connectivity-based segmentation has been used to identify functional gray matter subregions that are not discernable on conventional magnetic resonance imaging. However, the accuracy and reliability of this technique has only been validated using indirect means. In order to provide direct electrophysiologic validation of connectivity-based thalamic segmentations within human subjects, we assess the correlation of atlas-based thalamic anatomy, connectivity-based thalamic maps, and somatosensory evoked thalamic potentials in two adults with medication-refractory epilepsy who were undergoing intracranial EEG monitoring with intrathalamic depth and subdural cortical strip electrodes. MRI with atlas-derived localization was used to delineate the anatomic boundaries of the ventral posterolateral (VPL) nucleus of the thalamus. Somatosensory evoked potentials with intrathalamic electrodes physiologically identified a discrete region of phase reversal in the ventrolateral thalamus. Finally, DTI was obtained so that probabilistic tractography and connectivity-based segmentation could be performed to correlate the region of thalamus linked to sensory areas of the cortex, namely the postcentral gyrus. We independently utilized these three different methods in a blinded fashion to localize the "sensory" thalamus, demonstrating a high-degree of reproducible correlation between electrophysiologic and connectivity-based maps of the thalamus. This study provides direct electrophysiologic validation of probabilistic tractography-based thalamic segmentation. Importantly, this study provides an electrophysiological basis for using connectivity-based segmentation to further study subcortical anatomy and physiology while also providing the clinical basis for targeting deep brain nuclei with therapeutic stimulation. Finally, these direct recordings from human thalamus confirm early inferences of a sensory thalamic component of the N18 waveform in somatosensory evoked potentials.
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Affiliation(s)
- W Jeffrey Elias
- Department of Neurosurgery, University of Virginia Health Sciences Center, Box 800212, Charlottesville, Virginia 22903, USA.
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74
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Kells AP, Forsayeth J, Bankiewicz KS. Glial-derived neurotrophic factor gene transfer for Parkinson's disease: anterograde distribution of AAV2 vectors in the primate brain. Neurobiol Dis 2011; 48:228-35. [PMID: 22019719 DOI: 10.1016/j.nbd.2011.10.004] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2011] [Revised: 08/26/2011] [Accepted: 10/06/2011] [Indexed: 01/08/2023] Open
Abstract
Delivery of neurotrophic factors to treat neurodegenerative diseases has not been efficacious in clinical trials despite their known potency for promoting neuronal growth and survival. Direct gene delivery to the brain offers an approach for establishing sustained expression of neurotrophic factors but is dependent on accurate surgical procedures to target specific anatomical regions of the brain. Serotype-2 adeno-associated viral (AAV2) vectors have been investigated in multiple clinical studies for neurological diseases without adverse effects; however the absence of significant clinical efficacy after neurotrophic factor gene transfer has been largely attributed to insufficient coverage of the target region. Our pre-clinical development of AAV2-glial-derived neurotrophic factor (GDNF) for Parkinson's disease involved real-time image guided delivery and optimization of delivery techniques to maximize gene transfer in the putamen. We have demonstrated that AAV2 vectors are anterogradely transported in the primate brain with GDNF expression observed in the substantia nigra after putaminal delivery in both intact and nigrostriatal lesioned primates. Direct midbrain delivery of AAV2-GDNF resulted in extensive anterograde transport to multiple brain regions and significant weight loss.
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Affiliation(s)
- Adrian P Kells
- University of California San Francisco, Department of Neurological Surgery, Box 0555, San Francisco, CA 94143, USA
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Rosenbluth KH, Eschermann JF, Mittermeyer G, Thomson R, Mittermeyer S, Bankiewicz KS. Analysis of a simulation algorithm for direct brain drug delivery. Neuroimage 2011; 59:2423-9. [PMID: 21945468 DOI: 10.1016/j.neuroimage.2011.08.107] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2011] [Revised: 08/16/2011] [Accepted: 08/30/2011] [Indexed: 11/15/2022] Open
Abstract
Convection enhanced delivery (CED) achieves targeted delivery of drugs with a pressure-driven infusion through a cannula placed stereotactically in the brain. This technique bypasses the blood brain barrier and gives precise distributions of drugs, minimizing off-target effects of compounds such as viral vectors for gene therapy or toxic chemotherapy agents. The exact distribution is affected by the cannula positioning, flow rate and underlying tissue structure. This study presents an analysis of a simulation algorithm for predicting the distribution using baseline MRI images acquired prior to inserting the cannula. The MRI images included diffusion tensor imaging (DTI) to estimate the tissue properties. The algorithm was adapted for the devices and protocols identified for upcoming trials and validated with direct MRI visualization of gadoinium in 20 infusions in non-human primates. We found strong agreement between the size and location of the simulated and gadolinium volumes, demonstrating the clinical utility of this surgical planning algorithm.
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Affiliation(s)
- Kathryn Hammond Rosenbluth
- Department of Neurosurgery, University of California San Francisco (UCSF), San Francisco, CA 94103-0555, USA.
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Interventional MRI-guided putaminal delivery of AAV2-GDNF for a planned clinical trial in Parkinson's disease. Mol Ther 2011; 19:1048-57. [PMID: 21343917 DOI: 10.1038/mt.2011.11] [Citation(s) in RCA: 98] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Clinical trials involving direct infusion of neurotrophic therapies for Parkinson's disease (PD) have suffered from poor coverage of the putamen. The planned use of a novel interventional-magnetic resonance imaging (iMRI) targeting system for achieving precise, real-time convection-enhanced delivery in a planned clinical trial of adeno-associated virus serotype 2 (AAV2)-glial-derived neurotrophic factor (GDNF) in PD patients was modeled in nonhuman primates (NHP). NHP received bilateral coinfusions of gadoteridol (Gd)/AAV2-GDNF into two sites in each putamen, and three NHP received larger infusion volumes in the thalamus. The average targeting error for cannula tip placement in the putamen was <1 mm, and adjacent putamenal infusions were distributed in a uniform manner. GDNF expression patterns in the putamen were highly correlated with areas of Gd distribution seen on MRI. The distribution volume to infusion volume ratio in the putamen was similar to that in the thalamus, where larger infusions were achieved. Modeling the placement of adjacent 150 and 300 µl thalamic infusions into the three-dimensional space of the human putamen demonstrated coverage of the postcommissural putamen, containment within the striatum and expected anterograde transport to globus pallidus and substantia nigra pars reticulata. The results elucidate the necessary parameters for achieving widespread GDNF expression in the putamenal motor area and afferent substantia nigra of PD patients.
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