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Parwana KAK, Kaur Gill P, Njanike R, Yiu HHP, Adams CF, Chari DM, Jenkins SI. Investigating Internalization of Reporter-Protein-Functionalized Polyhedrin Particles by Brain Immune Cells. MATERIALS (BASEL, SWITZERLAND) 2024; 17:2330. [PMID: 38793398 PMCID: PMC11122724 DOI: 10.3390/ma17102330] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2024] [Revised: 04/11/2024] [Accepted: 04/26/2024] [Indexed: 05/26/2024]
Abstract
Achieving sustained drug delivery to the central nervous system (CNS) is a major challenge for neurological injury and disease, and various delivery vehicles are being developed to achieve this. Self-assembling polyhedrin crystals (POlyhedrin Delivery System; PODS) are being exploited for the delivery of therapeutic protein cargo, with demonstrated efficacy in vivo. However, to establish the utility of PODS for neural applications, their handling by neural immune cells (microglia) must be documented, as these cells process and degrade many biomaterials, often preventing therapeutic efficacy. Here, primary mouse cortical microglia were cultured with a GFP-functionalized PODS for 24 h. Cell counts, cell morphology and Iba1 expression were all unaltered in treated cultures, indicating a lack of acute toxicity or microglial activation. Microglia exhibited internalisation of the PODS, with both cytosolic and perinuclear localisation. No evidence of adverse effects on cellular morphology was observed. Overall, 20-40% of microglia exhibited uptake of the PODS, but extracellular/non-internalised PODS were routinely present after 24 h, suggesting that extracellular drug delivery may persist for at least 24 h.
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Affiliation(s)
| | | | - Runyararo Njanike
- School of Medicine, Keele University, Keele ST5 5BG, UK; (P.K.G.); (R.N.)
| | - Humphrey H. P. Yiu
- School of Engineering & Physical Sciences, University of Edinburgh, Edinburgh EH14 4AS, UK;
| | - Chris F. Adams
- School of Life Sciences, Keele University, Keele ST5 5BG, UK; (K.A.K.P.); (C.F.A.)
- Neural Tissue Engineering Keele (NTEK), Keele University, Keele ST5 5BG, UK
| | - Divya Maitreyi Chari
- School of Medicine, Keele University, Keele ST5 5BG, UK; (P.K.G.); (R.N.)
- Neural Tissue Engineering Keele (NTEK), Keele University, Keele ST5 5BG, UK
| | - Stuart Iain Jenkins
- School of Medicine, Keele University, Keele ST5 5BG, UK; (P.K.G.); (R.N.)
- Neural Tissue Engineering Keele (NTEK), Keele University, Keele ST5 5BG, UK
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Mitra S, Gera R, Linderoth B, Lind G, Wahlberg L, Almqvist P, Behbahani H, Eriksdotter M. A Review of Techniques for Biodelivery of Nerve Growth Factor (NGF) to the Brain in Relation to Alzheimer's Disease. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2021; 1331:167-191. [PMID: 34453298 DOI: 10.1007/978-3-030-74046-7_11] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/30/2023]
Abstract
Age-dependent progressive neurodegeneration and associated cognitive dysfunction represent a serious concern worldwide. Currently, dementia accounts for the fifth highest cause of death, among which Alzheimer's disease (AD) represents more than 60% of the cases. AD is associated with progressive cognitive dysfunction which affects daily life of the affected individual and associated family. The cognitive dysfunctions are at least partially due to the degeneration of a specific set of neurons (cholinergic neurons) whose cell bodies are situated in the basal forebrain region (basal forebrain cholinergic neurons, BFCNs) but innervate wide areas of the brain. It has been explicitly shown that the delivery of the neurotrophic protein nerve growth factor (NGF) can rescue BFCNs and restore cognitive dysfunction, making NGF interesting as a potential therapeutic substance for AD. Unfortunately, NGF cannot pass through the blood-brain barrier (BBB) and thus peripheral administration of NGF protein is not viable therapeutically. NGF must be delivered in a way which will allow its brain penetration and availability to the BFCNs to modulate BFCN activity and viability. Over the past few decades, various methodologies have been developed to deliver NGF to the brain tissue. In this chapter, NGF delivery methods are discussed in the context of AD.
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Affiliation(s)
- Sumonto Mitra
- Division of Clinical Geriatrics, NVS Department, Karolinska Institutet, Stockholm, Sweden.
| | - Ruchi Gera
- Division of Clinical Geriatrics, NVS Department, Karolinska Institutet, Stockholm, Sweden
| | - Bengt Linderoth
- Section of Neurosurgery, Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - Göran Lind
- Section of Neurosurgery, Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | | | - Per Almqvist
- Section of Neurosurgery, Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - Homira Behbahani
- Division of Clinical Geriatrics, NVS Department, Karolinska Institutet, Stockholm, Sweden.,Karolinska Universitets laboratoriet (LNP5), Karolinska University Hospital, Stockholm, Sweden
| | - Maria Eriksdotter
- Division of Clinical Geriatrics, NVS Department, Karolinska Institutet, Stockholm, Sweden.,Theme Aging, Karolinska University Hospital, Huddinge, Sweden
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Kanu LN, Ciolino JB. Nerve Growth Factor as an Ocular Therapy: Applications, Challenges, and Future Directions. Semin Ophthalmol 2021; 36:224-231. [PMID: 33641595 DOI: 10.1080/08820538.2021.1890793] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Nerve growth factor (NGF), the prototypical neurotrophin first discovered in the 1950s, has recently garnered increased interest as a therapeutic agent promoting neuronal health and regeneration. After gaining orphan drug status within the last decade, NGF-related research and drug development has accelerated. The purpose of this article is to review the preclinical and clinical evidence of NGF in various applications, including central and peripheral nervous system, skin, and ophthalmic disorders. We focus on the ophthalmic applications including not only the FDA-approved indication of neurotrophic keratitis but also retinal disease and glaucoma. NGF represents a promising therapy whose therapeutic profile is evolving. The challenges related to this therapy are reviewed, along with possible solutions and future directions.
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Affiliation(s)
- Levi N Kanu
- 1. Department of Ophthalmology, Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston, MA, USA
| | - Joseph B Ciolino
- 1. Department of Ophthalmology, Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston, MA, USA
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Shoji M, Ueda M, Nishioka M, Minato H, Seki M, Harada K, Kubo M, Fukuyama Y, Suzuki Y, Aoyama E, Takigawa M, Kuzuhara T. Jiadifenolide induces the expression of cellular communication network factor (CCN) genes, and CCN2 exhibits neurotrophic activity in neuronal precursor cells derived from human induced pluripotent stem cells. Biochem Biophys Res Commun 2019; 519:309-315. [PMID: 31506177 DOI: 10.1016/j.bbrc.2019.09.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2019] [Accepted: 09/02/2019] [Indexed: 01/27/2023]
Abstract
Jiadifenolide has been reported to have neurotrophin-like activity in primary rat cortical neurons, and also possesses neurotrophic effects in neuronal precursor cells derived from human induced pluripotent stem cells (hiPSCs), as we have previously reported. However, the molecular mechanisms by which jiadifenolide exerts its neurotrophic effects in rat and human neurons are unknown. Thus, we aimed to investigate the molecular mechanisms and pathways by which jiadifenolide promotes neurotrophic effects. Here, we found that jiadifenolide activated cellular communication network factor (CCN) signaling pathways by up-regulating mRNA level expression of CCN genes in human neuronal cells. We also found that CCN2 (also known as connective tissue growth factor, CTGF) protein promotes neurotrophic effects through activation of the p44/42 mitogen-activated protein kinase signaling pathway. This is the first discovery which links neurotrophic activity with CCN signaling.
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Affiliation(s)
- Masaki Shoji
- Laboratory of Biochemistry, Faculty of Pharmaceutical Sciences, Tokushima Bunri University, Tokushima, Japan.
| | - Masako Ueda
- Laboratory of Biochemistry, Faculty of Pharmaceutical Sciences, Tokushima Bunri University, Tokushima, Japan
| | - Megumi Nishioka
- Laboratory of Biochemistry, Faculty of Pharmaceutical Sciences, Tokushima Bunri University, Tokushima, Japan
| | - Hiroki Minato
- Laboratory of Biochemistry, Faculty of Pharmaceutical Sciences, Tokushima Bunri University, Tokushima, Japan
| | - Masahide Seki
- Department of Computational Biology and Medical Sciences, Graduate School of Frontier Sciences, University of Tokyo, Chiba, Japan
| | - Kenichi Harada
- Laboratory of Biophysical Chemistry, Faculty of Pharmaceutical Sciences, Tokushima Bunri University, Tokushima, Japan
| | - Miwa Kubo
- Laboratory of Biophysical Chemistry, Faculty of Pharmaceutical Sciences, Tokushima Bunri University, Tokushima, Japan
| | - Yoshiyasu Fukuyama
- Laboratory of Biophysical Chemistry, Faculty of Pharmaceutical Sciences, Tokushima Bunri University, Tokushima, Japan
| | - Yutaka Suzuki
- Department of Computational Biology and Medical Sciences, Graduate School of Frontier Sciences, University of Tokyo, Chiba, Japan
| | - Eriko Aoyama
- Advanced Research Center for Oral and Craniofacial Sciences, Okayama University Dental School/Graduate School of Medicine Dentistry and Pharmaceutical Sciences, Okayama, Japan
| | - Masaharu Takigawa
- Advanced Research Center for Oral and Craniofacial Sciences, Okayama University Dental School/Graduate School of Medicine Dentistry and Pharmaceutical Sciences, Okayama, Japan
| | - Takashi Kuzuhara
- Laboratory of Biochemistry, Faculty of Pharmaceutical Sciences, Tokushima Bunri University, Tokushima, Japan.
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5
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Barnabas W. Drug targeting strategies into the brain for treating neurological diseases. J Neurosci Methods 2019; 311:133-146. [DOI: 10.1016/j.jneumeth.2018.10.015] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2018] [Revised: 10/08/2018] [Accepted: 10/10/2018] [Indexed: 12/17/2022]
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Cao J, Hou J, Ping J, Cai D. Advances in developing novel therapeutic strategies for Alzheimer's disease. Mol Neurodegener 2018; 13:64. [PMID: 30541602 PMCID: PMC6291983 DOI: 10.1186/s13024-018-0299-8] [Citation(s) in RCA: 142] [Impact Index Per Article: 23.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Accepted: 11/28/2018] [Indexed: 12/16/2022] Open
Abstract
Alzheimer's Disease (AD), the most prevalent neurodegenerative disease of aging, affects one in eight older Americans. Nearly all drug treatments tested for AD today have failed to show any efficacy. There is a great need for therapies to prevent and/or slow the progression of AD. The major challenge in AD drug development is lack of clarity about the mechanisms underlying AD pathogenesis and pathophysiology. Several studies support the notion that AD is a multifactorial disease. While there is abundant evidence that amyloid plays a role in AD pathogenesis, other mechanisms have been implicated in AD such as tangle formation and spread, dysregulated protein degradation pathways, neuroinflammation, and loss of support by neurotrophic factors. Therefore, current paradigms of AD drug design have been shifted from single target approach (primarily amyloid-centric) to developing drugs targeted at multiple disease aspects, and from treating AD at later stages of disease progression to focusing on preventive strategies at early stages of disease development. Here, we summarize current strategies and new trends of AD drug development, including pre-clinical and clinical trials that target different aspects of disease (mechanism-based versus non-mechanism based, e.g. symptomatic treatments, lifestyle modifications and risk factor management).
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Affiliation(s)
- Jiqing Cao
- James J Peters VA Medical Center, Research & Development, Bronx, NY 10468 USA
- Department of Neurology, Alzheimer Disease Research Center, Icahn School of Medicine at Mount Sinai, New York, NY 10029 USA
- The Central Hospital of The Hua Zhong University of Science and Technology, Wuhan, China
| | - Jianwei Hou
- James J Peters VA Medical Center, Research & Development, Bronx, NY 10468 USA
- Department of Neurology, Alzheimer Disease Research Center, Icahn School of Medicine at Mount Sinai, New York, NY 10029 USA
| | - Jing Ping
- The Central Hospital of The Hua Zhong University of Science and Technology, Wuhan, China
| | - Dongming Cai
- James J Peters VA Medical Center, Research & Development, Bronx, NY 10468 USA
- Department of Neurology, Alzheimer Disease Research Center, Icahn School of Medicine at Mount Sinai, New York, NY 10029 USA
- The Central Hospital of The Hua Zhong University of Science and Technology, Wuhan, China
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7
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Simmons DA. Modulating Neurotrophin Receptor Signaling as a Therapeutic Strategy for Huntington's Disease. J Huntingtons Dis 2018; 6:303-325. [PMID: 29254102 PMCID: PMC5757655 DOI: 10.3233/jhd-170275] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Huntington’s disease (HD) is an autosomal dominant neurodegenerative disorder caused by CAG repeat expansions in the IT15 gene which encodes the huntingtin (HTT) protein. Currently, no treatments capable of preventing or slowing disease progression exist. Disease modifying therapeutics for HD would be expected to target a comprehensive set of degenerative processes given the diverse mechanisms contributing to HD pathogenesis including neuroinflammation, excitotoxicity, and transcription dysregulation. A major contributor to HD-related degeneration is mutant HTT-induced loss of neurotrophic support. Thus, neurotrophin (NT) receptors have emerged as therapeutic targets in HD. The considerable overlap between NT signaling networks and those dysregulated by mutant HTT provides strong theoretical support for this approach. This review will focus on the contributions of disrupted NT signaling in HD-related neurodegeneration and how targeting NT receptors to augment pro-survival signaling and/or to inhibit degenerative signaling may combat HD pathologies. Therapeutic strategies involving NT delivery, peptidomimetics, and the targeting of specific NT receptors (e.g., Trks or p75NTR), particularly with small molecule ligands, are discussed.
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Affiliation(s)
- Danielle A Simmons
- Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Stanford, CA, USA
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Yang M, Yang T, Jia J, Lu T, Wang H, Yan X, Wang L, Yu L, Zhao Y. Fabrication and characterization of DDAB/PLA-alginate composite microcapsules as single-shot vaccine. RSC Adv 2018; 8:13612-13624. [PMID: 35542506 PMCID: PMC9079837 DOI: 10.1039/c8ra00013a] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2018] [Accepted: 03/09/2018] [Indexed: 11/21/2022] Open
Abstract
The most effective method to reduce chronic hepatitis B virus infection is the universal implementation of vaccination.
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Affiliation(s)
- Meiyang Yang
- State Key Laboratory of Biochemical Engineering
- Institute of Process Engineering
- Chinese Academy of Sciences
- Beijing
- PR China
| | - Tingyuan Yang
- State Key Laboratory of Biochemical Engineering
- Institute of Process Engineering
- Chinese Academy of Sciences
- Beijing
- PR China
| | - Jilei Jia
- State Key Laboratory of Biochemical Engineering
- Institute of Process Engineering
- Chinese Academy of Sciences
- Beijing
- PR China
| | - Ting Lu
- State Key Laboratory of Biochemical Engineering
- Institute of Process Engineering
- Chinese Academy of Sciences
- Beijing
- PR China
| | - Hailin Wang
- State Key Laboratory of Biochemical Engineering
- Institute of Process Engineering
- Chinese Academy of Sciences
- Beijing
- PR China
| | - Xueying Yan
- Heilongjiang University of Chinese Medicine
- PR China
| | - Lianyan Wang
- State Key Laboratory of Biochemical Engineering
- Institute of Process Engineering
- Chinese Academy of Sciences
- Beijing
- PR China
| | - Lian Yu
- College of Pharmacy
- Jiamusi University
- PR China
| | - Yue Zhao
- Epithelial Systems Biology Laboratory
- Systems Biology Center
- National Heart, Lung, and Blood Institute
- National Institutes of Health
- Bethesda
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Schneider C, Langer R, Loveday D, Hair D. Applications of ethylene vinyl acetate copolymers (EVA) in drug delivery systems. J Control Release 2017; 262:284-295. [DOI: 10.1016/j.jconrel.2017.08.004] [Citation(s) in RCA: 78] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2017] [Revised: 07/31/2017] [Accepted: 08/02/2017] [Indexed: 10/19/2022]
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10
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Nanotechnological strategies for nerve growth factor delivery: Therapeutic implications in Alzheimer’s disease. Pharmacol Res 2017; 120:68-87. [DOI: 10.1016/j.phrs.2017.03.020] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/23/2016] [Revised: 02/23/2017] [Accepted: 03/22/2017] [Indexed: 12/30/2022]
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11
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Nguyen XC, Herberger JD, Burke PA. Protein powders for encapsulation: a comparison of spray-freeze drying and spray drying of darbepoetin alfa. Pharm Res 2016; 21:507-14. [PMID: 15070103 DOI: 10.1023/b:pham.0000019306.89420.f0] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
PURPOSE To evaluate spray-freeze drying and spray drying processes for fabricating micron-sized particles of darbepoetin alfa (NESP, Aranesp) with uniform size distribution and retention of protein integrity, requirements for encapsulation. METHODS Darbepoetin alfa was spray-freeze dried using ultrasonic atomization at 120 kHz and 25 kHz and spray dried at bench-top and pilot scales. Reconstituted powders were evaluated by size exclusion chromatography and UV/VIS spectroscopy. Powder physical properties were also characterized. RESULTS Spray-freeze drying resulted in aggregation of darbepoetin alfa. Aggregates (primarily insoluble) formed on drying and/or reconstitution. Particle size distributions were broad (span > or = 3.6) at both nozzle frequencies. Annealing before drying reduced aggregate levels slightly but increased particle size over 5-fold. Spray drying at inlet temperatures up to 135 degrees C (and outlet temperatures up to 95 degrees C) showed little impact on integrity. Integrity at bench-top and pilot scales was identical, with 0.2% dimer and no high molecular weight or insoluble aggregates detected. Particle size was small (< or = 2.3 microm) with uniform distribution (span < or = 1.4) at both process scales. CONCLUSIONS Under the conditions tested spray drying, conducted at bench-top and pilot scales with commercially available equipment, was superior to spray-freeze drying for the fabrication of darbepoetin alfa particles for encapsulation.
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Affiliation(s)
- Xichdao C Nguyen
- Pharmaceutics and Drug Delivery, Amgen, Inc., One Amgen Center Drive, Thousand Oaks, California 91320, USA
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12
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Shoji M, Nishioka M, Minato H, Harada K, Kubo M, Fukuyama Y, Kuzuhara T. Neurotrophic activity of jiadifenolide on neuronal precursor cells derived from human induced pluripotent stem cells. Biochem Biophys Res Commun 2016; 470:798-803. [DOI: 10.1016/j.bbrc.2016.01.092] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Accepted: 01/15/2016] [Indexed: 01/05/2023]
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Abstract
The current experiment investigated the ability of coaxial electrospun poly(D,L-lactide-co-glycolide) (PLGA) biodegradable polymer implants loaded with the antiepileptic drugs (AED) lacosamide to reduce seizures following implantation above the motor cortex in the Genetic Absence Epilepsy Rat from Strasbourg (GAERS). In this prospective, randomized, masked experiments, GAERS underwent surgery for implantation of skull electrodes (n=6), skull electrodes and blank polymers (n=6), or skull electrodes and lacosamide loaded polymers (n=6). Thirty-minute electroencephalogram (EEG) recordings were started at day 7 after surgery and continued for eight weeks. The number of SWDs and mean duration of one SWD were compared week-by-week between the three groups. There was no difference in the number of SWDs between any of the groups. However, the mean duration of one SWD was significantly lower in the lacosamide polymer group for up to 7 weeks when compared to the control group (0.004<p<0.038). The mean duration of one seizure was also lower at weeks 3, 5, 6, and 7 when compared to the blank polymer group (p= 0.016, 0.037, 0.025, and 0.025, resp.). We have demonstrated that AED loaded PLGA polymer sheets implanted on the surface of the cortex could affect seizure activity in GAERS for a sustained period.
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Agile delivery of protein therapeutics to CNS. J Control Release 2014; 190:637-63. [PMID: 24956489 DOI: 10.1016/j.jconrel.2014.06.017] [Citation(s) in RCA: 72] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2014] [Revised: 06/10/2014] [Accepted: 06/13/2014] [Indexed: 12/11/2022]
Abstract
A variety of therapeutic proteins have shown potential to treat central nervous system (CNS) disorders. Challenge to deliver these protein molecules to the brain is well known. Proteins administered through parenteral routes are often excluded from the brain because of their poor bioavailability and the existence of the blood-brain barrier (BBB). Barriers also exist to proteins administered through non-parenteral routes that bypass the BBB. Several strategies have shown promise in delivering proteins to the brain. This review, first, describes the physiology and pathology of the BBB that underscore the rationale and needs of each strategy to be applied. Second, major classes of protein therapeutics along with some key factors that affect their delivery outcomes are presented. Third, different routes of protein administration (parenteral, central intracerebroventricular and intraparenchymal, intranasal and intrathecal) are discussed along with key barriers to CNS delivery associated with each route. Finally, current delivery strategies involving chemical modification of proteins and use of particle-based carriers are overviewed using examples from literature and our own work. Whereas most of these studies are in the early stage, some provide proof of mechanism of increased protein delivery to the brain in relevant models of CNS diseases, while in few cases proof of concept had been attained in clinical studies. This review will be useful to broad audience of students, academicians and industry professionals who consider critical issues of protein delivery to the brain and aim developing and studying effective brain delivery systems for protein therapeutics.
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Binan L, Ajji A, De Crescenzo G, Jolicoeur M. Approaches for Neural Tissue Regeneration. Stem Cell Rev Rep 2013; 10:44-59. [DOI: 10.1007/s12015-013-9474-z] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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16
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Small-molecule modulation of neurotrophin receptors: a strategy for the treatment of neurological disease. Nat Rev Drug Discov 2013; 12:507-25. [PMID: 23977697 DOI: 10.1038/nrd4024] [Citation(s) in RCA: 198] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Neurotrophins and their receptors modulate multiple signalling pathways to regulate neuronal survival and to maintain axonal and dendritic networks and synaptic plasticity. Neurotrophins have potential for the treatment of neurological diseases. However, their therapeutic application has been limited owing to their poor plasma stability, restricted nervous system penetration and, importantly, the pleiotropic actions that derive from their concomitant binding to multiple receptors. One strategy to overcome these limitations is to target individual neurotrophin receptors — such as tropomyosin receptor kinase A (TRKA), TRKB, TRKC, the p75 neurotrophin receptor or sortilin — with small-molecule ligands. Such small molecules might also modulate various aspects of these signalling pathways in ways that are distinct from the programmes triggered by native neurotrophins. By departing from conventional neurotrophin signalling, these ligands might provide novel therapeutic options for a broad range of neurological indications.
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Géral C, Angelova A, Lesieur S. From molecular to nanotechnology strategies for delivery of neurotrophins: emphasis on brain-derived neurotrophic factor (BDNF). Pharmaceutics 2013; 5:127-67. [PMID: 24300402 PMCID: PMC3834942 DOI: 10.3390/pharmaceutics5010127] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2012] [Revised: 01/30/2013] [Accepted: 02/05/2013] [Indexed: 01/01/2023] Open
Abstract
Neurodegenerative diseases represent a major public health problem, but beneficial clinical treatment with neurotrophic factors has not been established yet. The therapeutic use of neurotrophins has been restrained by their instability and rapid degradation in biological medium. A variety of strategies has been proposed for the administration of these leading therapeutic candidates, which are essential for the development, survival and function of human neurons. In this review, we describe the existing approaches for delivery of brain-derived neurotrophic factor (BDNF), which is the most abundant neurotrophin in the mammalian central nervous system (CNS). Biomimetic peptides of BDNF have emerged as a promising therapy against neurodegenerative disorders. Polymer-based carriers have provided sustained neurotrophin delivery, whereas lipid-based particles have contributed also to potentiation of the BDNF action. Nanotechnology offers new possibilities for the design of vehicles for neuroprotection and neuroregeneration. Recent developments in nanoscale carriers for encapsulation and transport of BDNF are highlighted.
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Affiliation(s)
- Claire Géral
- CNRS UMR8612 Institut Galien Paris-Sud, 5 rue J.-B. Clément, F-92296 Châtenay-Malabry, France; E-Mails: (C.G.); (S.L.)
- Univ Paris Sud 11, 5 rue J.-B. Clément, F-92296 Châtenay-Malabry, France
| | - Angelina Angelova
- CNRS UMR8612 Institut Galien Paris-Sud, 5 rue J.-B. Clément, F-92296 Châtenay-Malabry, France; E-Mails: (C.G.); (S.L.)
- Univ Paris Sud 11, 5 rue J.-B. Clément, F-92296 Châtenay-Malabry, France
| | - Sylviane Lesieur
- CNRS UMR8612 Institut Galien Paris-Sud, 5 rue J.-B. Clément, F-92296 Châtenay-Malabry, France; E-Mails: (C.G.); (S.L.)
- Univ Paris Sud 11, 5 rue J.-B. Clément, F-92296 Châtenay-Malabry, France
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Zhai P, Chen XB, Schreyer DJ. Preparation and characterization of alginate microspheres for sustained protein delivery within tissue scaffolds. Biofabrication 2013; 5:015009. [DOI: 10.1088/1758-5082/5/1/015009] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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20
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Levetiracetam-loaded biodegradable polymer implants in the tetanus toxin model of temporal lobe epilepsy in rats. J Clin Neurosci 2013; 20:148-52. [DOI: 10.1016/j.jocn.2012.05.017] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2012] [Revised: 04/25/2012] [Accepted: 05/02/2012] [Indexed: 11/18/2022]
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21
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Newland B, Dowd E, Pandit A. Biomaterial approaches to gene therapies for neurodegenerative disorders of the CNS. Biomater Sci 2013; 1:556-576. [DOI: 10.1039/c3bm60030k] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
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Ivirico JLE, Cruz DMG, Monrós MCA, Martínez-Ramos C, Pradas MM. Synthesis and properties of caprolactone and ethylene glycol copolymers for neural regeneration. JOURNAL OF MATERIALS SCIENCE. MATERIALS IN MEDICINE 2012; 23:1605-1617. [PMID: 22534765 DOI: 10.1007/s10856-012-4649-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2012] [Accepted: 04/14/2012] [Indexed: 05/31/2023]
Abstract
Copolymer networks from poly(ethylene glycol) methacrylate (PEGMA) and caprolactone 2-(methacryloyloxy) ethyl ester were synthesized and the resulting structure of the copolymer network was characterized by differential scanning calorimetry, thermogravimetry, Fourier transform infrared spectroscopy, equilibrium water gain and dynamic mechanical analysis, results which were employed to conclude about the network structure of the resulting copolymers. The new material is a random copolymer with a good miscibility and increasing hydrophilicity as the PEGMA content increases in the composition. Physical data suggest an excess free volume and synergistic interactions between the lateral chains of both comonomers. Olfactory ensheathing cells were cultured on the different networks, and cell viability and proliferation were assessed by MTS assay. The copolymers with a 30 wt% of PEGMA showed the best results compared with the other compositions in this respect, indicating the relevance for biological performance of a balance of hydrophilic and hydrophobic functionalities in the polymer chain.
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Affiliation(s)
- Jorge Luis Escobar Ivirico
- Center for Biomaterials and Tissue Engineering, Universitat Politècnica de València, 46022, Valencia, Spain.
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23
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Casalini T, Masi M, Perale G. Drug eluting sutures: A model for in vivo estimations. Int J Pharm 2012; 429:148-57. [DOI: 10.1016/j.ijpharm.2012.03.024] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2012] [Revised: 03/12/2012] [Accepted: 03/13/2012] [Indexed: 10/28/2022]
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24
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Patel T, Zhou J, Piepmeier JM, Saltzman WM. Polymeric nanoparticles for drug delivery to the central nervous system. Adv Drug Deliv Rev 2012; 64:701-5. [PMID: 22210134 DOI: 10.1016/j.addr.2011.12.006] [Citation(s) in RCA: 298] [Impact Index Per Article: 24.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2011] [Revised: 12/02/2011] [Accepted: 12/12/2011] [Indexed: 01/31/2023]
Abstract
The central nervous system (CNS) poses a unique challenge for drug delivery. The blood-brain barrier significantly hinders the passage of systemically delivered therapeutics and the brain extracellular matrix limits the distribution and longevity of locally delivered agents. Polymeric nanoparticles represent a promising solution to these problems. Over the past 40years, substantial research efforts have demonstrated that polymeric nanoparticles can be engineered for effective systemic and local delivery of therapeutics to the CNS. Moreover, many of the polymers used in nanoparticle fabrication are both biodegradable and biocompatible, thereby increasing the clinical utility of this strategy. Here, we review the major advances in the development of polymeric nanoparticles for drug delivery to the CNS.
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Affiliation(s)
- Toral Patel
- Department of Neurosurgery, Yale University School of Medicine, New Haven, CT 06511 USA
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25
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Cooke MJ, Wang Y, Morshead CM, Shoichet MS. Controlled epi-cortical delivery of epidermal growth factor for the stimulation of endogenous neural stem cell proliferation in stroke-injured brain. Biomaterials 2011; 32:5688-97. [PMID: 21550655 DOI: 10.1016/j.biomaterials.2011.04.032] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2011] [Accepted: 04/12/2011] [Indexed: 01/06/2023]
Abstract
One of the challenges in treating central nervous system (CNS) disorders with biomolecules is achieving local delivery while minimizing invasiveness. For the treatment of stroke, stimulation of endogenous neural stem/progenitor cells (NSPCs) by growth factors is a promising strategy for tissue regeneration. Epidermal growth factor (EGF) enhances proliferation of endogenous NSPCs in the subventricular zone (SVZ) when delivered directly to the ventricles of the brain; however, this strategy is highly invasive. We designed a biomaterials-based strategy to deliver molecules directly to the brain without tissue damage. EGF or poly(ethylene glycol)-modified EGF (PEG-EGF) was dispersed in a hyaluronan and methylcellulose (HAMC) hydrogel and placed epi-cortically on both uninjured and stroke-injured mouse brains. PEG-modification decreased the rate of EGF degradation by proteases, leading to a significant increase in protein accumulation at greater tissue depths than previously shown. Consequently, EGF and PEG-EGF increased NSPC proliferation in uninjured and stroke-injured brains; and in stroke-injured brains, PEG-EGF significantly increased NSPC stimulation. Our epi-cortical delivery system is a minimally-invasive method for local delivery to the brain, providing a new paradigm for local delivery to the brain.
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Affiliation(s)
- Michael J Cooke
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, 200 College Street, Toronto, ON, Canada M5S 3E5
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26
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Paolino D, Cosco D, Molinaro R, Celia C, Fresta M. Supramolecular devices to improve the treatment of brain diseases. Drug Discov Today 2011; 16:311-24. [DOI: 10.1016/j.drudis.2011.02.006] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2010] [Revised: 01/05/2011] [Accepted: 02/08/2011] [Indexed: 01/03/2023]
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27
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Liu Y, Paliwal S, Bankiewicz KS, Bringas JR, Heart G, Mitragotri S, Prausnitz MR. Ultrasound-enhanced drug transport and distribution in the brain. AAPS PharmSciTech 2010; 11:1005-17. [PMID: 20532711 PMCID: PMC2974134 DOI: 10.1208/s12249-010-9458-0] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2009] [Accepted: 05/13/2010] [Indexed: 11/30/2022] Open
Abstract
Drug delivery in the brain is limited by slow drug diffusion in the brain tissue. This study tested the hypothesis that ultrasound can safely enhance the permeation of drugs in the brain. In vitro exposure to ultrasound at various frequencies (85 kHz, 174 kHz, and 1 MHz) enhanced the permeation of tritium-labeled molecules with molecular weight up to 70 kDa across porcine brain tissue. A maximum enhancement of 24-fold was observed at 85 kHz and 1,200 J/cm2. In vivo exposure to 1-MHz ultrasound further demonstrated the ability of ultrasound to facilitate molecule distribution in the brain of a non-human primate. Finally, ultrasound under conditions similar to those used in vivo was shown to cause no damage to plasmid DNA, siRNA, adeno-associated virus, and fetal rat cortical neurons over a range of conditions. Altogether, these studies demonstrate that ultrasound can increase drug permeation in the brain in vitro and in vivo under conditions that did not cause detectable damage.
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Sirianni RW, Olausson P, Chiu AS, Taylor JR, Saltzman WM. The behavioral and biochemical effects of BDNF containing polymers implanted in the hippocampus of rats. Brain Res 2010; 1321:40-50. [PMID: 20096671 DOI: 10.1016/j.brainres.2010.01.041] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2009] [Revised: 12/25/2009] [Accepted: 01/14/2010] [Indexed: 01/29/2023]
Abstract
Brain-derived neurotrophic factor (BDNF) is closely linked with neuronal survival and plasticity in psychiatric disorders. In this work, we engineered degradable, injectable alginate microspheres and non-degradable, implantable poly(ethylene vinyl acetate) matrices to continuously deliver BDNF to the dorsal hippocampus of rats for two days or more than a week, respectively. The antidepressant-like behavioral effects of BDNF delivery were examined in the Porsolt forced swim test. Rats were sacrificed 10days after surgery and tissue samples were analyzed by western blot. A small dose of BDNF delivered in a single infusion, or from a two-day sustained-release alginate implant, produced an antidepressant-like behavior, whereas the same dose delivered over a longer period of time to a larger tissue region did not produce antidepressant-like effects. Prolonged delivery of BDNF resulted in a dysregulation of plasticity-related functions: increased dose and duration of BDNF delivery produced increased levels of TrkB, ERK, CREB, and phosphorylated ERK, while also producing decreased phosphorylated CREB. It is evident from this work that both duration and magnitude of BDNF dosing are of critical importance in achieving functional outcome.
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Affiliation(s)
- Rachael W Sirianni
- Department of Biomedical Engineering, Yale University, New Haven, CT 06511, USA
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29
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MacKinnon N, Guérin G, Liu B, Gradinaru CC, Macdonald PM. Liposome-hydrogel bead complexes prepared via biotin-avidin conjugation. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2009; 25:9413-9423. [PMID: 19603800 DOI: 10.1021/la900163r] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Liposomes immobilized onto polymeric hydrogel microbeads have potential advantages both in tissue engineering applications and as drug delivery vehicles. Here we demonstrate, quantify, and optimize lipid vesicle binding to polymeric hydrogel microbeads via the avidin-biotin conjugation system and characterize the stability of the resulting microgel-bound liposomes. Microgels consisting of a copolymer of N-isopropylacrylamide (NIPAM) and acrylic acid (AA), cross-linked with bis-acrylamide, that is, p(NIPAM-co-AA), were biotinylated using aqueous carbodiimide chemistry. Extruded liposomes consisting of 1-palmitoyl-2-oleoyl-phosphatidylcholine (POPC) plus a small fraction of a biotin-derivatized phosphatidylethanolamine (B-PE) were saturated with avidin and allowed to bind to biotinylated hydrogel beads. Using a combination of fluorescence spectroscopy, quenching, and microscopy and 31P NMR static and magic angle spinning (MAS) spectroscopies, we demonstrate conditions for near-quantitative liposome binding to p(NIPAM-co-AA) microbeads and show that liposome fusion does not occur under such conditions, that the liposomes remain intact and impermeable when so bound, and that they can function as slow release vehicles for entrapped aqueous species.
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Affiliation(s)
- Neil MacKinnon
- Department of Chemistry, University of Toronto, 80 St. George St., Toronto, Ontario, Canada, M5S 3H6
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Valmikinathan CM, Defroda S, Yu X. Polycaprolactone and bovine serum albumin based nanofibers for controlled release of nerve growth factor. Biomacromolecules 2009; 10:1084-9. [PMID: 19323510 DOI: 10.1021/bm8012499] [Citation(s) in RCA: 111] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Tissue engineering approaches for peripheral nerve regeneration employ biodegradable scaffolds coupled with growth factors for improved performance in regeneration of large nerve injuries. Electrospun nanofibers provide a versatile platform for fabrication of scaffolds with extracellular matrix like architecture and increased surface area. Incorporation of growth factors in nanofibers have been previously demonstrated using oil in water emulsion techniques but are associated with burst release and loss of valuable growth factor. Here, we show a novel blend of polycaprolactone and bovine serum albumin (BSA) to form nanofibers containing nerve growth factors. The BSA helps in overcoming the most common drawbacks associated with hydrophobic polymers such as reduced loading efficiency, long degradation periods, and burst release. The controlled release of nerve growth factor (NGF) from the nanofibers was evaluated using enzyme linked immune sorbent assay (ELISA) and PC12 based bioassay over a 28 day time period. A sustained release of NGF was obtained for at least 28 days. PC12 bioassays confirmed the bioactivity of the NGF, and showed that the released NGF was sufficient to induce neurite outgrowth from PC12 cells throughout the period of release, therefore, demonstrating the successful incorporation and controlled release potential of PCL BSA scaffolds.
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Affiliation(s)
- Chandra M Valmikinathan
- Department of Chemistry, Chemical Biology, and Biomedical Engineering, Stevens Institute of Technology, Hoboken, New Jersey 07030, USA
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31
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Adenosine augmentation therapies (AATs) for epilepsy: prospect of cell and gene therapies. Epilepsy Res 2009; 85:131-41. [PMID: 19428218 DOI: 10.1016/j.eplepsyres.2009.03.019] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2008] [Revised: 03/24/2009] [Accepted: 03/26/2009] [Indexed: 12/17/2022]
Abstract
Deficiencies in the brain's own adenosine-based seizure control system contribute to seizure generation. Consequently, reconstitution of adenosinergic neuromodulation constitutes a rational approach for seizure control. This review will critically discuss focal adenosine augmentation strategies and their potential for antiepileptic and disease modifying therapy. Due to systemic side effects of adenosine focal adenosine augmentation--ideally targeted to an epileptic focus--becomes a therapeutic necessity. This has experimentally been achieved in kindled seizure models as well as in post-status epilepticus models of spontaneous recurrent seizures using three different therapeutic strategies that will be discussed here: (i) polymer-based brain implants that were loaded with adenosine; (ii) brain implants comprised of cells engineered to release adenosine and embedded in a cell-encapsulation device; (iii) direct transplantation of stem cells engineered to release adenosine. To meet the therapeutic goal of focal adenosine augmentation, genetic disruption of the adenosine metabolizing enzyme adenosine kinase (ADK) in rodent and human cells was used as a molecular strategy to induce adenosine release from cellular brain implants, which demonstrated antiepileptic and neuroprotective properties. New developments and therapeutic challenges in using AATs for epilepsy therapy will critically be evaluated.
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Klose D, Laprais M, Leroux V, Siepmann F, Deprez B, Bordet R, Siepmann J. Fenofibrate-loaded PLGA microparticles: effects on ischemic stroke. Eur J Pharm Sci 2009; 37:43-52. [PMID: 19168134 DOI: 10.1016/j.ejps.2008.12.016] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2008] [Revised: 12/09/2008] [Accepted: 12/27/2008] [Indexed: 11/18/2022]
Abstract
Many drugs are not able to cross the Blood Brain Barrier (BBB) and, thus, cannot reach a target site within the Central Nervous System (CNS). Local controlled drug delivery can help to overcome this restriction. However, this is a highly challenging approach and only one product is yet available on the market: Gliadel, which is used to reduce the risk of local tumor recurrence upon resection of malignant glioma. The aim of this study was to evaluate the potential of local controlled drug delivery to the CNS to reduce the consequences of ischemic stroke. Fenofibrate as well as its active metabolite fenofibric acid were encapsulated within PLGA microparticles. Importantly, fenofibrate-loaded microparticles effectively reduced the consequences of ischemic stroke in Wistar rats: the total, cortical and striatal infarct volumes decreased from 257 to 197, 193 to 139, and 64 to 58 mm(3), respectively. Interestingly, fenofibric acid-loaded microparticles did not show significant in vivo efficacy, which might be attributable to a potentially limited distribution pattern within the brain and/or limited cell uptake. Thus, local controlled drug delivery to the CNS also has a significant potential for the treatment/prevention of other types of diseases than cancer. Furthermore, this approach can help to provide proof of concept in vivo in the early drug discovery phase, if the drug candidate cannot cross the BBB.
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Affiliation(s)
- D Klose
- College of Pharmacy, JE 2491, University of Lille, 3 Rue du Professeur Laguesse, 59006 Lille, France
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33
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Quaglia F. Bioinspired tissue engineering: The great promise of protein delivery technologies. Int J Pharm 2008; 364:281-97. [DOI: 10.1016/j.ijpharm.2008.04.030] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2008] [Revised: 04/11/2008] [Accepted: 04/15/2008] [Indexed: 01/27/2023]
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34
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Ghahremankhani AA, Dorkoosh F, Dinarvand R. PLGA-PEG-PLGA Tri-Block Copolymers as In Situ Gel-Forming Peptide Delivery System: Effect of Formulation Properties on Peptide Release. Pharm Dev Technol 2008; 13:49-55. [DOI: 10.1080/10837450701702842] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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35
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Hendricks JL, Chikar JA, Crumling MA, Raphael Y, Martin DC. Localized cell and drug delivery for auditory prostheses. Hear Res 2008; 242:117-31. [PMID: 18573323 DOI: 10.1016/j.heares.2008.06.003] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/19/2007] [Revised: 05/09/2008] [Accepted: 06/02/2008] [Indexed: 12/20/2022]
Abstract
Localized cell and drug delivery to the cochlea and central auditory pathway can improve the safety and performance of implanted auditory prostheses (APs). While generally successful, these devices have a number of limitations and adverse effects including limited tonal and dynamic ranges, channel interactions, unwanted stimulation of non-auditory nerves, immune rejection, and infections including meningitis. Many of these limitations are associated with the tissue reactions to implanted auditory prosthetic devices and the gradual degeneration of the auditory system following deafness. Strategies to reduce the insertion trauma, degeneration of target neurons, fibrous and bony tissue encapsulation, and immune activation can improve the viability of tissue required for AP function as well as improve the resolution of stimulation for reduced channel interaction and improved place-pitch and level discrimination. Many pharmaceutical compounds have been identified that promote the viability of auditory tissue and prevent inflammation and infection. Cell delivery and gene therapy have provided promising results for treating hearing loss and reversing degeneration. Currently, many clinical and experimental methods can produce extremely localized and sustained drug delivery to address AP limitations. These methods provide better control over drug concentrations while eliminating the adverse effects of systemic delivery. Many of these drug delivery techniques can be integrated into modern auditory prosthetic devices to optimize the tissue response to the implanted device and reduce the risk of infection or rejection. Together, these methods and pharmaceutical agents can be used to optimize the tissue-device interface for improved AP safety and effectiveness.
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Affiliation(s)
- Jeffrey L Hendricks
- Department of Biomedical Engineering, The University of Michigan, 1107 Gerstacker Building, 2200 Bonisteel Boulevard, Ann Arbor, MI 48109-2099, USA.
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36
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Emerging restorative treatments for Parkinson's disease. Prog Neurobiol 2008; 85:407-32. [PMID: 18586376 DOI: 10.1016/j.pneurobio.2008.05.001] [Citation(s) in RCA: 110] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2007] [Revised: 04/03/2008] [Accepted: 05/06/2008] [Indexed: 01/18/2023]
Abstract
Several exciting approaches for restorative therapy in Parkinson's disease have emerged over the past two decades. This review initially describes experimental and clinical data regarding growth factor administration. We focus on glial cell line-derived neurotrophic factor (GDNF), particularly its role in neuroprotection and in regeneration in Parkinson's disease. Thereafter, we discuss the challenges currently facing cell transplantation in Parkinson's disease and briefly consider the possibility to continue testing intrastriatal transplantation of fetal dopaminergic progenitors clinically. We also give a more detailed overview of the developmental biology of dopaminergic neurons and the potential of certain stem cells, i.e. neural and embryonic stem cells, to differentiate into dopaminergic neurons. Finally, we discuss adult neurogenesis as a potential tool for restoring lost dopamine neurons in patients suffering from Parkinson's disease.
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37
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Jay SM, Shepherd BR, Bertram JP, Pober JS, Saltzman WM. Engineering of multifunctional gels integrating highly efficient growth factor delivery with endothelial cell transplantation. FASEB J 2008; 22:2949-56. [PMID: 18450813 DOI: 10.1096/fj.08-108803] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Transplantation of Bcl-2-transduced human umbilical vein endothelial cells (ECs) in protein gels into the gastrocnemius muscle improves local reperfusion in immunodeficient mouse hosts with induced hind limb ischemia. We tested the hypothesis that incorporation of local, sustained growth factor delivery could enhance and accelerate this effect. Tissue engineering scaffolds often use synthetic polymers to enable controlled release of proteins, but most synthetic delivery systems have major limitations, most notably hydrophobicity and inefficient protein loading. Here, we report the development of a novel alginate-based delivery system for vascular endothelial growth factor-A(165) (VEGF) that exhibits superior loading efficiency and physical properties to previous systems in vitro. In vivo, VEGF released from alginate microparticles within protein gels was biologically active and, when combined with EC transplantation, led to increased survival of transplanted cells at 28 days. The composite graft described also improved early (14 days) tissue perfusion and late (28 days) muscle myoglobin expression, a sign of recovery from ischemia, compared with EC transplantation and VEGF delivery separately. We conclude that our improved approach to sustained VEGF delivery in tissue engineering is useful in vivo and that the integration of high efficiency protein delivery enhances the therapeutic effect of protein gel-based EC transplantation.
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Affiliation(s)
- Steven M Jay
- Yale University, Department of Biomedical Engineering, 55 Prospect St., New Haven, CT 06511, USA
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Fong P, Goyal A, Brennan M, Park J, Moss L, Saltzman WM, Breuer CK. Development of PTH Eluting Microspheres for the Treatment of Hypoparathyroidism. J Surg Res 2007; 143:195-9. [PMID: 17720197 DOI: 10.1016/j.jss.2006.04.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2005] [Revised: 03/01/2006] [Accepted: 04/11/2006] [Indexed: 11/17/2022]
Abstract
BACKGROUND Parathyroid hormone (PTH) replacement has been demonstrated to be superior to conventional treatment with calcium supplementation and vitamin D analogs for the treatment of hypoparathyroidism. In this investigation we evaluated the feasibility of using PTH microsphere encapsulation as a potential delivery system for PTH. MATERIALS AND METHODS Using the spontaneous emulsion technique, PTH microspheres were created by encapsulating PTH (1-34) in a copolymer of polyglycolic and polylactic acid (PLGA). Additional microspheres were constructed by coencapsulating calmodulin with PTH (1-34) in the PLGA microspheres. Microsphere production was confirmed using electron microscopy. PTH release was measured in vitro using an enzyme-linked immunosorbent assay. The bioactivity of PTH released from the microspheres was confirmed in vivo using a hypoparathyroid rat model by measuring serum calcium concentrations before and 3 h after subcutaneous injection of PTH microspheres. RESULTS PTH microsphere and PTH/calmodulin microspheres could be created using the spontaneous emulsion technique. Physiologically significant PTH release was measured in vitro for 20 days. PTH release was calcium sensitive and exhibited negative feedback. This effect was augmented by coencapsulation with calmodulin. PTH released from the microspheres caused a significant rise in serum calcium levels from an average of 6.35 (6.19-6.48 mg/dL) to 8.55 mg/dL (8.22-8.73). PTH released from the PTH/calmodulin microspheres resulted in an increase in serum calcium from a mean of 6.8 (6.7-6.9 mg/dL) to 8.1 mg/dL (7.8-8.2). CONCLUSIONS The PLGA microspheres can be used to provide calcium sensitive controlled release of biologically active PTH and offer a potential mean of providing biomimetic hormone replacement therapy.
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Affiliation(s)
- Peter Fong
- Department of Surgery, Yale University School of Medicine, New Haven, Connecticut 06520, USA
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39
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Benny O, Kim SK, Gvili K, Radzishevsky IS, Mor A, Verduzco L, Menon LG, Black PM, Machluf M, Carroll RS. In vivo
fate and therapeutic efficacy of PF‐4/CTF microspheres in an orthotopic human glioblastoma model. FASEB J 2007; 22:488-99. [PMID: 17873103 DOI: 10.1096/fj.07-8801com] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The correlation between glioma grade and angiogenesis suggests that antiangiogenic therapies are potentially therapeutically effective for these tumors. However, to achieve tumor suppression, antiangiogenic therapies need to be administered daily using high systemic quantities. We designed a biodegradable polymeric device that overcomes those barriers by providing sustained local delivery of a C-terminal fragment of platelet factor 4 (PF-4/CTF), an antiangiogenic agent. Fluorescent-labeled microspheres composed of poly lactic-coglycolic acid (PLGA) were loaded with rhodamine-labeled PF-4/CTF and formulated to release their contents over time. Fluorescent labeling enabled the correlation between the in vitro to the in vivo kinetic and release studies. PF-4/CTF microspheres were injected into established intracranial human glioma tumors in nude mice. Noninvasive magnetic resonance imaging (MRI) was used to assess the therapeutic response. Tumor size, microvessel density, proliferation, and apoptosis rate were measured by histological analysis. Intracranially, the microspheres were located throughout the tumor bed and continuously released PF-4/CTF during the entire experimental period. MRI and histological studies showed that a single injection of microspheres containing PF-4/CTF caused a 65.2% and 72% reduction in tumor volume, respectively, with a significant decrease in angiogenesis and an increase in apoptosis. Our data demonstrate that polymeric microspheres are an effective therapeutic approach for delivering antiangiogenic agents that result in the inhibition of glioma tumor growth.
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Affiliation(s)
- Ofra Benny
- M.M., Department of Biotechnology and Food Engineering, Technion-Israel Institute of Technology, Haifa, Israel
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Abstract
Neurodegenerative and infectious disorders including Alzheimer's and Parkinson's diseases, amyotrophic lateral sclerosis, and stroke are rapidly increasing as population's age. Alzheimer's disease alone currently affects 4.5 million Americans, and more than $100 billion is spent per year on medical and institutional care for affected people. Such numbers will double in the ensuing decades. Currently disease diagnosis for all disorders is made, in large measure, on clinical grounds as laboratory and neuroimaging tests confirm what is seen by more routine examination. Achieving early diagnosis would enable improved disease outcomes. Drugs, vaccines or regenerative proteins present "real" possibilities for positively affecting disease outcomes, but are limited in that their entry into the brain is commonly restricted across the blood-brain barrier. This review highlights how these obstacles can be overcome by polymer science and nanotechnology. Such approaches may improve diagnostic and therapeutic outcomes. New developments in polymer science coupled with cell-based delivery strategies support the notion that diseases that now have limited therapeutic options can show improved outcomes by advances in nanomedicine.
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Willerth SM, Sakiyama-Elbert SE. Approaches to neural tissue engineering using scaffolds for drug delivery. Adv Drug Deliv Rev 2007; 59:325-38. [PMID: 17482308 PMCID: PMC1976339 DOI: 10.1016/j.addr.2007.03.014] [Citation(s) in RCA: 211] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2006] [Accepted: 03/28/2007] [Indexed: 02/07/2023]
Abstract
This review seeks to give an overview of the current approaches to drug delivery from scaffolds for neural tissue engineering applications. The challenges presented by attempting to replicate the three types of nervous tissue (brain, spinal cord, and peripheral nerve) are summarized. Potential scaffold materials (both synthetic and natural) and target drugs are discussed with the benefits and drawbacks given. Finally, common methods of drug delivery, including degradable/diffusion-based delivery systems, affinity-based delivery systems, immobilized drug delivery systems, and electrically controlled drug delivery systems, are examined and critiqued. Based on the current body of work, suggestions for future directions of research in the field of neural tissue engineering are presented.
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Affiliation(s)
| | - Shelly E. Sakiyama-Elbert
- Department of Biomedical Engineering, Washington University in St. Louis
- Center for Materials Innovation, Washington University in St. Louis
- * To whom correspondence should be addressed: Shelly Sakiyama-Elbert, Department of Biomedical Engineering, Washington University, Campus Box 1097, One Brookings Drive, St. Louis, MO 63130,
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Gu H, Song C, Long D, Mei L, Sun H. Controlled release of recombinant human nerve growth factor (rhNGF) from poly[(lactic acid)-co-(glycolic acid)] microspheres for the treatment of neurodegenerative disorders. POLYM INT 2007. [DOI: 10.1002/pi.2272] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Taylor SJ, Rosenzweig ES, McDonald JW, Sakiyama-Elbert SE. Delivery of neurotrophin-3 from fibrin enhances neuronal fiber sprouting after spinal cord injury. J Control Release 2006; 113:226-35. [PMID: 16797770 PMCID: PMC1615967 DOI: 10.1016/j.jconrel.2006.05.005] [Citation(s) in RCA: 92] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2006] [Revised: 04/24/2006] [Accepted: 05/01/2006] [Indexed: 10/24/2022]
Abstract
Neurotrophins have been shown to promote axonal growth and regeneration after spinal cord injury. The therapeutic utility of neurotrophins may be enhanced by using a controlled delivery system to increase the duration of neurotrophin availability following injury. Such a delivery system can be incorporated into a bioactive scaffold to serve as a physical bridge for regeneration. This study assessed the effect of controlled delivery of neurotrophin-3 (NT-3) from fibrin scaffolds implanted in spinal cord lesions immediately following 2-mm ablation injury in adult rats. Nine days after injury, fibrin scaffolds containing the delivery system and NT-3 (1000 ng/mL) elicited more robust neuronal fiber growth into the lesion than did control scaffolds or saline (1.5- to 3-fold increase). Implantation of fibrin scaffolds resulted in a dramatic reduction of glial scar formation at the white matter border of the lesion. Hindlimb motor function of treated animals did not improve relative to controls at 12 weeks post-injury. Thus, controlled delivery of NT-3 from fibrin scaffolds enhanced the initial regenerative response by increasing neuronal fiber sprouting and cell migration into the lesion, while functional motor recovery was not observed in this model.
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Affiliation(s)
- Sara J Taylor
- Department of Biomedical Engineering, Washington University, St. Louis, MO 63130, USA
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44
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Siepmann J, Siepmann F, Florence AT. Local controlled drug delivery to the brain: mathematical modeling of the underlying mass transport mechanisms. Int J Pharm 2006; 314:101-19. [PMID: 16647231 DOI: 10.1016/j.ijpharm.2005.07.027] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2005] [Accepted: 07/12/2005] [Indexed: 10/24/2022]
Abstract
The mass transport mechanisms involved in the controlled delivery of drugs to living brain tissue are complex and yet not fully understood. Often the drug is embedded within a polymeric or lipidic matrix, which is directly administered into the brain tissue, that is, intracranially. Different types of systems, including microparticles and disc- or rod-shaped implants are used to control the release rate and, thus, to optimize the drug concentrations at the site of action in the brain over prolonged periods of time. Most of these dosage forms are biodegradable to avoid the need for the removal of empty remnants after drug exhaustion. Various physical and chemical processes are involved in the control of drug release from these systems, including water penetration, drug dissolution, degradation of the matrix and drug diffusion. Once the drug has been released from the delivery system, it has to be transported through the living brain tissue to the target site(s). Again, a variety of phenomena, including diffusion, drug metabolism and degradation, passive or active uptake into CNS tissue and convection can be of importance for the fate of the drug. An overview is given of the current knowledge of the nature of barriers to free access of drug to tumour sites within the brain and the state of the art of: (i) mathematical modeling approaches describing the physical transport processes and chemical reactions which can occur in different types of intracranially administered drug delivery systems, and of (ii) theories quantifying the mass transport phenomena occurring after drug release in the living tissue. Both, simplified as well as complex mathematical models are presented and their major advantages and shortcomings discussed. Interestingly, there is a significant lack of mechanistically realistic, comprehensive theories describing both parts in detail, namely, drug transport in the dosage form and in the living brain tissue. High quality experimental data on drug concentrations in the brain tissue are difficult to obtain, hence this is itself an issue in testing mathematical approaches. As a future perspective, the potential benefits and limitations of these mathematical theories aiming to facilitate the design of advanced intracranial drug delivery systems and to improve the efficiency of the respective pharmacotherapies are discussed.
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Affiliation(s)
- J Siepmann
- College of Pharmacy, Freie Universitaet Berlin, Kelchstr. 31, 12169 Berlin, Germany.
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45
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Schöll I, Kopp T, Bohle B, Jensen-Jarolim E. Biodegradable PLGA Particles for Improved Systemic and Mucosal Treatment of Type I Allergy. Immunol Allergy Clin North Am 2006; 26:349-64, ix. [PMID: 16701149 DOI: 10.1016/j.iac.2006.02.007] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Although allergen immunotherapy is basically a story of success, it still needs improvement. The goal of this study was to optimize parenteral and oral allergen formulations through using the biocompatible polymer of lactic and glycolic acid (PLGA). Subcutaneous application of birch pollen allergen Bet v 1 encapsulated in nanoparticles biased the immune response toward Th1 in allergic mice and did not elicit granuloma formation in mice and in human volunteers. When oral immunotherapy of mice was tried with birch pollen-filled PLGA microparticles, mucosal targeting was indispensable for achieving any immune response, and targeting of M-cells was necessary for modulating an ongoing allergic response toward Th1. The authors suggest that biocompatible PLGA nano- or microparticles can be useful tools for upgrading therapy of type I allergy.
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Affiliation(s)
- Isabella Schöll
- Medical University of Vienna, Währinger Gürtel 18-20, 1090 Vienna, Austria
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46
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Popovic N, Brundin P. Therapeutic potential of controlled drug delivery systems in neurodegenerative diseases. Int J Pharm 2006; 314:120-6. [PMID: 16529886 DOI: 10.1016/j.ijpharm.2005.09.040] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2005] [Accepted: 09/09/2005] [Indexed: 12/28/2022]
Abstract
Several compounds that exhibit a therapeutic effect in experimental models of neurodegenerative diseases have been identified over recent years. Safe and effective drug delivery to the central nervous system is still one of the main obstacles in translating these experimental strategies into clinical therapies. Different approaches have been developed to enable drug delivery in close proximity to the desired site of action. In this review, we describe biodegradable polymeric systems as drug carriers in models of neurodegenerative diseases. Biomaterials described for intracerebral drug delivery are well tolerated by the host tissue and do not exhibit cytotoxic, immunologic, carcinogenic or teratogenic effects even after chronic exposure. Behavioral improvement and normalization of brain morphology have been observed following treatment using such biomaterials in animal models of Parkinson's, Alzheimer's and Huntington's diseases. Application of these devices for neuroactive drugs is still restricted due to the relatively small volume of tissue exposed to active compound. Further development of polymeric drug delivery systems will require that larger volumes of brain tissue are targeted, with a controlled and sustained drug release that is carefully controlled so it does not cause damage to the surrounding tissue.
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Affiliation(s)
- N Popovic
- Neuronal Survival Unit, Department of Experimental Medical Science, BMC A10, 22 184 Lund, Sweden.
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47
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Shen H, Ackerman AL, Cody V, Giodini A, Hinson ER, Cresswell P, Edelson RL, Saltzman WM, Hanlon DJ. Enhanced and prolonged cross-presentation following endosomal escape of exogenous antigens encapsulated in biodegradable nanoparticles. Immunology 2006; 117:78-88. [PMID: 16423043 PMCID: PMC1782199 DOI: 10.1111/j.1365-2567.2005.02268.x] [Citation(s) in RCA: 293] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
CD8(+) T-cell responses are critical in the immunological control of tumours and infectious diseases. To prime CD8(+) T cells against these cell-associated antigens, exogenous antigens must be cross-presented by professional antigen-presenting cells (APCs). While cross-presentation of soluble antigens by dendritic cells is detectable in vivo, the efficiency is low, limiting the clinical utility of protein-based vaccinations. To enhance the efficiency of presentation, we generated nanoparticles from a biodegradable polymer, poly(D,L-lactide-co-glycolide) (PLGA), to deliver antigen into the major histocompatibility complex (MHC) class I antigen presentation pathway. In primary mouse bone marrow-derived dendritic cells (BMDCs), the MHC class I presentation of PLGA-encapsulated ovalbumin (OVA) stimulated T cell interleukin-2 secretion at 1000-fold lower concentration than soluble antigen and 10-fold lower than antigen-coated latex beads. The microparticles also served as an intracellular antigen reservoir, leading to sustained MHC class I presentation of OVA for 72 hr, decreasing by only 20% after 96 hr, a time at which the presentation of soluble and latex bead-associated antigens was undetectable. Cytosol extraction demonstrated that antigen delivery via PLGA particles increased the amount of protein that escaped from endosomes into the cytoplasm, thereby increasing the access of exogenous antigen to the classic MHC class I loading pathway. These data indicate that the unique properties of PLGA particle-mediated antigen delivery dramatically enhance and sustain exogenous antigen presentation by MHC class I, potentially facilitating the clinical use of these particles in vaccination.
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Affiliation(s)
- Hong Shen
- Department of Biomedical Engineering, Yale University, New Haven, CT 06520, USA
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48
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Huynh GH, Deen DF, Szoka FC. Barriers to carrier mediated drug and gene delivery to brain tumors. J Control Release 2006; 110:236-259. [PMID: 16318895 DOI: 10.1016/j.jconrel.2005.09.053] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2005] [Accepted: 09/29/2005] [Indexed: 01/18/2023]
Abstract
Brain tumor patients face a poor prognosis despite significant advances in tumor imaging, neurosurgery and radiation therapy. Potent chemotherapeutic drugs fail when used to treat brain tumors because biochemical and physiological barriers limit drug delivery into the brain. In the past decade a number of strategies have been introduced to increase drug delivery into the brain parenchyma. In particular, direct drug administration into the brain tumor has shown promising results in both animal models and clinical trials. This technique is well suited for the delivery of liposome and polymer drug carriers, which have the potential to provide a sustained level of drug and to reach cellular targets with improved specificity. We will discuss the current approaches that have been used to increase drug delivery into the brain parenchyma in the context of fluid and solute transport into, through and from the brain, with a focus on liposome and polymer drug carriers.
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Affiliation(s)
- Grace H Huynh
- Joint Graduate Group in Bioengineering, University of California at San Francisco and Berkeley San Francisco, CA 94143-0446, United States
| | - Dennis F Deen
- Brain Tumor Research Center of the Department of Neurological Surgery, University of California at San Francisco, San Francisco, CA 94143-0520, United States
| | - Francis C Szoka
- Joint Graduate Group in Bioengineering, University of California at San Francisco and Berkeley San Francisco, CA 94143-0446, United States; Departments of Pharmaceutical Chemistry and Biopharmaceutical Sciences, University of California at San Francisco, San Francisco, CA 94143-0446, United States.
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49
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Aschkenasy C, Kost J. On-demand release by ultrasound from osmotically swollen hydrophobic matrices. J Control Release 2005; 110:58-66. [PMID: 16257468 DOI: 10.1016/j.jconrel.2005.09.025] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2005] [Revised: 09/07/2005] [Accepted: 09/13/2005] [Indexed: 10/25/2022]
Abstract
Ethylene-vinyl acetate copolymer (EVAc) based controlled release systems are composed of a continuous hydrophobic polymer phase and of dispersed solid drug particles. In matrices with high drug loadings (> or =50%) most drug particles are interconnected. Thus, when these matrices are immersed in water, release rates are relatively high. In matrices with low drug loadings (<40%) most drug particles are isolated within the continuous hydrophobic polymer matrix. Thus, release rates are very low. Matrices containing water soluble particles at a low loading swell intensely after immersion in water; this is caused by the osmotic force of the isolated particles which causes the water to permeate into the hydrophobic polymer. The enclosed drug particles absorb water, and at the end of the swelling process the matrices consist of an immense number of fluid pockets containing dissolved drugs. In attempt to develop on-demand release systems, we studied the effect of ultrasound (US) on the release rates of these swollen matrices. We found that low-frequency ultrasound (20 kHz) reversibly increased the release rates from these swollen matrices by a factor of 30-500, in contrast to the unswollen matrices, where the release rates increased only by a factor of 2-3. Unswollen and swollen matrices react differently to US, as unswollen matrices contain drug particles which absorb ultrasound on the surface of the matrices, causing ultrasound attenuation. On the other hand, swollen matrices contain a compact arrangement of fluid pockets separated from each other by thin membranes containing a solution of the dissolved drug, therefore ultrasound penetrates through the matrix volume. Ultrasound penetration causes tearing of these membranes within the matrices. As a result, the fluid pockets interconnect, and drug molecules diffuse out through these interconnected pockets.
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Affiliation(s)
- Chaim Aschkenasy
- Department of Biomedical Engineering, Ben Gurion University of the Negev, Beer Sheva, Israel
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50
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Salvay DM, Shea LD. Inductive tissue engineering with protein and DNA-releasing scaffolds. MOLECULAR BIOSYSTEMS 2005; 2:36-48. [PMID: 16880921 PMCID: PMC2657198 DOI: 10.1039/b514174p] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Cellular differentiation, organization, proliferation and apoptosis are determined by a combination of an intrinsic genetic program, matrix/substrate interactions, and extracellular cues received from the local microenvironment. These molecular cues come in the form of soluble (e.g. cytokines) and insoluble (e.g. ECM proteins) factors, as well as signals from surrounding cells that can promote specific cellular processes leading to tissue formation or regeneration. Recent developments in the field of tissue engineering have employed biomaterials to present these cues, providing powerful tools to investigate the cellular processes involved in tissue development, or to devise therapeutic strategies based on cell replacement or tissue regeneration. These inductive scaffolds utilize natural and/or synthetic biomaterials fabricated into three-dimensional structures. This review summarizes the use of scaffolds in the dual role of structural support for cell growth and vehicle for controlled release of tissue inductive factors, or DNA encoding for these factors. The confluence of molecular and cell biology, materials science and engineering provides the tools to create controllable microenvironments that mimic natural developmental processes and direct tissue formation for experimental and therapeutic applications.
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Affiliation(s)
- David M. Salvay
- Department of Chemical and Biological Engineering, 2145 Sheridan Rd E156 Evanston, IL 60208-3120. E-mail: ; Fax: 847-491-3728; Tel: 847-491-7043
| | - Lonnie D. Shea
- Department of Chemical and Biological Engineering, 2145 Sheridan Rd E156 Evanston, IL 60208-3120. E-mail: ; Fax: 847-491-3728; Tel: 847-491-7043
- Department of Biomedical Engineering, Northwestern University, 2145 Sheridan Rd E156 Evanston, IL 60208-3120
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