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Guo J, Wu Y, Gong Z, Chen X, Cao F, Kala S, Qiu Z, Zhao X, Chen J, He D, Chen T, Zeng R, Zhu J, Wong KF, Murugappan S, Zhu T, Xian Q, Hou X, Ruan YC, Li B, Li YC, Zhang Y, Sun L. Photonic Nanojet-Mediated Optogenetics. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2022; 9:e2104140. [PMID: 35187865 PMCID: PMC9036029 DOI: 10.1002/advs.202104140] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/2021] [Revised: 02/04/2022] [Indexed: 05/11/2023]
Abstract
Optogenetics has become a widely used technique in neuroscience research, capable of controlling neuronal activity with high spatiotemporal precision and cell-type specificity. Expressing exogenous opsins in the selected cells can induce neuronal activation upon light irradiation, and the activation depends on the power of incident light. However, high optical power can also lead to off-target neuronal activation or even cell damage. Limiting the incident power, but enhancing power distribution to the targeted neurons, can improve optogenetic efficiency and reduce off-target effects. Here, the use of optical lenses made of polystyrene microspheres is demonstrated to achieve effective focusing of the incident light of relatively low power to neighboring neurons via photonic jets. The presence of microspheres significantly localizes and enhances the power density to the target neurons both in vitro and ex vivo, resulting in increased inward current and evoked action potentials. In vivo results show optogenetic stimulation with microspheres that can evoke significantly more motor behavior and neuronal activation at lowered power density. In all, a proof-of-concept of a strategy is demonstrated to increase the efficacy of optogenetic neuromodulation using pulses of reduced optical power.
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Affiliation(s)
- Jinghui Guo
- Department of PhysiologySchool of MedicineJinan UniversityGuangzhou510632China
- Department of Biomedical EngineeringThe Hong Kong Polytechnic UniversityHong Kong SAR999077China
| | - Yong Wu
- Department of PhysiologySchool of MedicineJinan UniversityGuangzhou510632China
- Department of Biomedical EngineeringThe Hong Kong Polytechnic UniversityHong Kong SAR999077China
| | - Zhiyong Gong
- Institute of NanophotonicsJinan UniversityGuangzhou511443China
| | - Xixi Chen
- Institute of NanophotonicsJinan UniversityGuangzhou511443China
| | - Fei Cao
- Department of Biomedical EngineeringThe Hong Kong Polytechnic UniversityHong Kong SAR999077China
| | - Shashwati Kala
- Department of Biomedical EngineeringThe Hong Kong Polytechnic UniversityHong Kong SAR999077China
| | - Zhihai Qiu
- Department of Biomedical EngineeringThe Hong Kong Polytechnic UniversityHong Kong SAR999077China
| | - Xinyi Zhao
- Department of PhysiologySchool of MedicineJinan UniversityGuangzhou510632China
- Department of Biomedical EngineeringThe Hong Kong Polytechnic UniversityHong Kong SAR999077China
| | - Jun‐jiang Chen
- Department of PhysiologySchool of MedicineJinan UniversityGuangzhou510632China
| | - Dongming He
- Department of PhysiologySchool of MedicineJinan UniversityGuangzhou510632China
| | - Taiheng Chen
- Department of PhysiologySchool of MedicineJinan UniversityGuangzhou510632China
| | - Rui Zeng
- Department of PhysiologySchool of MedicineJinan UniversityGuangzhou510632China
| | - Jiejun Zhu
- Department of Biomedical EngineeringThe Hong Kong Polytechnic UniversityHong Kong SAR999077China
| | - Kin Fung Wong
- Department of Biomedical EngineeringThe Hong Kong Polytechnic UniversityHong Kong SAR999077China
| | - Suresh Murugappan
- Department of Biomedical EngineeringThe Hong Kong Polytechnic UniversityHong Kong SAR999077China
| | - Ting Zhu
- Department of Biomedical EngineeringThe Hong Kong Polytechnic UniversityHong Kong SAR999077China
| | - Quanxiang Xian
- Department of Biomedical EngineeringThe Hong Kong Polytechnic UniversityHong Kong SAR999077China
| | - Xuandi Hou
- Department of Biomedical EngineeringThe Hong Kong Polytechnic UniversityHong Kong SAR999077China
| | - Ye Chun Ruan
- Department of Biomedical EngineeringThe Hong Kong Polytechnic UniversityHong Kong SAR999077China
| | - Baojun Li
- Institute of NanophotonicsJinan UniversityGuangzhou511443China
| | - Yu Chao Li
- Institute of NanophotonicsJinan UniversityGuangzhou511443China
| | - Yao Zhang
- Institute of NanophotonicsJinan UniversityGuangzhou511443China
| | - Lei Sun
- Department of Biomedical EngineeringThe Hong Kong Polytechnic UniversityHong Kong SAR999077China
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Recent update of toxicity aspects of nanoparticulate systems for drug delivery. Eur J Pharm Biopharm 2021; 161:100-119. [DOI: 10.1016/j.ejpb.2021.02.010] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2020] [Revised: 01/07/2021] [Accepted: 02/20/2021] [Indexed: 12/18/2022]
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Sigurdsson SA, Yu Z, Lee J, Nurmikko A. A method for large-scale implantation of 3D microdevice ensembles into brain and soft tissue. MICROSYSTEMS & NANOENGINEERING 2020; 6:97. [PMID: 34567706 PMCID: PMC8433454 DOI: 10.1038/s41378-020-00210-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Revised: 07/11/2020] [Accepted: 08/07/2020] [Indexed: 05/16/2023]
Abstract
Wireless networks of implantable electronic sensors and actuators at the microscale (sub-mm) level are being explored for monitoring and modulation of physiological activity for medical diagnostics and therapeutic purposes. Beyond the requirement of integrating multiple electronic or chemical functions within small device volumes, a key challenge is the development of high-throughput methods for the implantation of large numbers of microdevices into soft tissues with minimal damage. To that end, we have developed a method for high-throughput implantation of ~100-200 µm size devices, which are here simulated by proxy microparticle ensembles. While generally applicable to subdermal tissue, our main focus and experimental testbed is the implantation of microparticles into the brain. The method deploys a scalable delivery tool composed of a 2-dimensional array of polyethylene glycol-tipped microneedles that confine the microparticle payloads. Upon dissolution of the bioresorbable polyethylene glycol, the supporting array structure is retrieved, and the microparticles remain embedded in the tissue, distributed spatially and geometrically according to the design of the microfabricated delivery tool. We first evaluated the method in an agarose testbed in terms of spatial precision and throughput for up to 1000 passive spherical and planar microparticles acting as proxy devices. We then performed the same evaluations by implanting particles into the rat cortex under acute conditions and assessed the tissue injury produced by our method of implantation under chronic conditions.
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Affiliation(s)
| | - Zeyang Yu
- Department of Neurology, Massachusetts General Hospital, Boston, MA 02114 USA
| | - Joonhee Lee
- Department of Physics and Astronomy, West Virginia University, Morgantown, WV 26506 USA
- Department of Neuroscience, West Virginia University, Morgantown, WV 26506 USA
| | - Arto Nurmikko
- School of Engineering, Brown University, Providence, RI 02912 USA
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Enhanced detection of prion infectivity from blood by preanalytical enrichment with peptoid-conjugated beads. PLoS One 2019; 14:e0216013. [PMID: 31513666 PMCID: PMC6742390 DOI: 10.1371/journal.pone.0216013] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2019] [Accepted: 08/28/2019] [Indexed: 11/29/2022] Open
Abstract
Prions cause transmissible infectious diseases in humans and animals and have been found to be transmissible by blood transfusion even in the presymptomatic stage. However, the concentration of prions in body fluids such as blood and urine is extremely low; therefore, direct diagnostic tests on such specimens often yield false-negative results. Quantitative preanalytical prion enrichment may significantly improve the sensitivity of prion assays by concentrating trace amounts of prions from large volumes of body fluids. Here, we show that beads conjugated to positively charged peptoids not only captured PrP aggregates from plasma of prion-infected hamsters, but also adsorbed prion infectivity in both the symptomatic and preclinical stages of the disease. Bead absorbed prion infectivity efficiently transmitted disease to transgenic indicator mice. We found that the readout of the peptoid-based misfolded protein assay (MPA) correlates closely with prion infectivity in vivo, thereby validating the MPA as a simple, quantitative, and sensitive surrogate indicator of the presence of prions. The reliable and sensitive detection of prions in plasma will enable a wide variety of applications in basic prion research and diagnostics.
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Prodanov D, Delbeke J. Mechanical and Biological Interactions of Implants with the Brain and Their Impact on Implant Design. Front Neurosci 2016; 10:11. [PMID: 26903786 PMCID: PMC4746296 DOI: 10.3389/fnins.2016.00011] [Citation(s) in RCA: 78] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2015] [Accepted: 01/11/2016] [Indexed: 11/26/2022] Open
Abstract
Neural prostheses have already a long history and yet the cochlear implant remains the only success story about a longterm sensory function restoration. On the other hand, neural implants for deep brain stimulation are gaining acceptance for variety of disorders including Parkinsons disease and obsessive-compulsive disorder. It is anticipated that the progress in the field has been hampered by a combination of technological and biological factors, such as the limited understanding of the longterm behavior of implants, unreliability of devices, biocompatibility of the implants among others. While the field's understanding of the cell biology of interactions at the biotic-abiotic interface has improved, relatively little attention has been paid on the mechanical factors (stress, strain), and hence on the geometry that can modulate it. This focused review summarizes the recent progress in the understanding of the mechanisms of mechanical interaction between the implants and the brain. The review gives an overview of the factors by which the implants interact acutely and chronically with the tissue: blood-brain barrier (BBB) breach, vascular damage, micromotions, diffusion etc. We propose some design constraints to be considered in future studies. Aspects of the chronic cell-implant interaction will be discussed in view of the chronic local inflammation and the ways of modulating it.
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Affiliation(s)
- Dimiter Prodanov
- Department of Environment, Health and Safety, ImecLeuven, Belgium
- Neuroscience Research FlandersLeuven, Belgium
| | - Jean Delbeke
- LCEN3, Department of Neurology, Institute of Neuroscience, Ghent UniversityGhent, Belgium
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Musyanovych A, Dausend J, Dass M, Walther P, Mailänder V, Landfester K. Criteria impacting the cellular uptake of nanoparticles: a study emphasizing polymer type and surfactant effects. Acta Biomater 2011; 7:4160-8. [PMID: 21855659 DOI: 10.1016/j.actbio.2011.07.033] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2011] [Revised: 06/21/2011] [Accepted: 07/29/2011] [Indexed: 01/19/2023]
Abstract
A detailed understanding of the particle-cell interaction is essential and of immense interest in order to create a "specific carrier" for each particular application. In this paper, the effect of the surfactant type (non-ionic vs ionic) and polymer nature on the cellular uptake of fluorescent polystyrene and poly(L-lactide) nanoparticles was studied on HeLa cells. Nanoparticles in a size range from 100 to 160 nm were synthesized by the miniemulsion process. The particles were detected in cells by confocal laser scanning fluorescence microscopy and flow cytometry. It was found that the influence of the surface charge is greater than that of the polymer type itself. In fact, particles stabilized with cationic surfactant were incorporated in a large number irrespective of polymer type. Cellular pathways at ultrastructural level were studied by transmission electron microscopy in more detail to shed light on the particle-cell interaction based on the material properties. The criteria governing the cellular uptake of nanoparticles based on the polymer and surfactant types are finally established.
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7
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Mielczarski JA, Jeyachandran YL, Mielczarski E, Rai B. Modification of polystyrene surface in aqueous solutions. J Colloid Interface Sci 2011; 362:532-9. [PMID: 21802090 DOI: 10.1016/j.jcis.2011.05.068] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2011] [Revised: 05/18/2011] [Accepted: 05/22/2011] [Indexed: 10/18/2022]
Abstract
Herein, we report our analysis of the surface modification of polystyrene (PS) when treated under ambient conditions with a common biological buffer such as phosphate buffered saline (PBS) or aqueous solutions of the ionic constituents of PBS. Attenuated total reflection Fourier transform infrared spectroscopy was used for the analysis because the resultant spectra are very sensitive to minor changes in the chemical and structural properties of PS films. In addition, ultraviolet-visible spectroscopy was applied to characterize the surface modifications of PS. Treatment with PBS resulted in the most significant chemical and structural surface modifications of the PS films, as compared with each of the solutions of the constituents of PBS, which were tested separately. A multistep mechanism for the wet modification of PS is discussed. We postulate that the observed surface modifications are the result of photo-oxidation/reduction, swelling, and conformational changes and re-arrangement of the polymer chain. The resultant surface modifications could be similar to those produced by commonly used dry processes such as plasma treatments and electron, ion or ultraviolet irradiation. We found that the modifications that occurred in PBS were more stable than those initiated by dry processes. The formation of active groups on the surface of PS can be controlled by adsorption of bovine serum albumin or thermal annealing of PS before PBS treatment. This approach provides a simple and efficient method for the surface modification of PS for biomedical applications.
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Affiliation(s)
- J A Mielczarski
- LEM, Nancy-Université, CNRS, 15 Avenue du Charmois, B.P. 40, F-54501 Vandœuvre lès Nancy, France.
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8
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Harris CA, Resau JH, Hudson EA, West RA, Moon C, Black AD, McAllister JP. Effects of surface wettability, flow, and protein concentration on macrophage and astrocyte adhesion in an in vitro model of central nervous system catheter obstruction. J Biomed Mater Res A 2011; 97:433-40. [DOI: 10.1002/jbm.a.33078] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2010] [Revised: 01/21/2011] [Accepted: 01/31/2011] [Indexed: 11/07/2022]
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9
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Tao X, Fernandez B, Azucena O, Fu M, Garcia D, Zuo Y, Chen DC, Kubby J. Adaptive optics confocal microscopy using direct wavefront sensing. OPTICS LETTERS 2011; 36:1062-4. [PMID: 21478983 DOI: 10.1364/ol.36.001062] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Optical aberrations due to the inhomogeneous refractive index of tissue degrade the resolution and brightness of images in deep-tissue imaging. We introduce a confocal fluorescence microscope with adaptive optics, which can correct aberrations based on direct wavefront measurements using a Shack-Hartmann wavefront sensor with a fluorescent bead used as a point source reference beacon. The results show a 4.3× improvement in the Strehl ratio and a 240% improvement in the signal intensity for fixed mouse tissues at depths of up to 100 μm.
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Affiliation(s)
- Xiaodong Tao
- Jack Baskin School of Engineering, University of California, Santa Cruz, 1156 High Street MS:SOE2, Santa Cruz, California 95064, USA.
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10
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Direct local polymerization of poly(3,4-ethylenedioxythiophene) in rat cortex. PROGRESS IN BRAIN RESEARCH 2011; 194:263-71. [PMID: 21867810 DOI: 10.1016/b978-0-444-53815-4.00001-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Glial scar encapsulation is thought to be one of the major reasons for the failure of chronic brain-machine interfaces. Many strategies, including modification of the probe surface chemistry, delivery of anti-inflammatory drugs, and changes of probe geometry, have been employed to reduce glial scar formation. We have proposed that a possible means to establish long-term, reliable communication across the scar is the in situ polymerization of conjugated polymers such as PEDOT in neural tissue. Previously, we exposed entire brain slices to the EDOT monomer. Here, we demonstrate that PEDOT can be polymerized by the direct delivery of EDOT monomer to the reaction site. The monomer was delivered into rat cortex via microcannula and simultaneously electrochemically polymerized within the tissue using a microwire electrode. We found that the resulting PEDOT polymer cloud grew out from the working electrode tip and extended far out into the brain tissue, spanning distances more than 1mm. We also examined the morphology of resulting polymer cloud by optical microscopy.
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11
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12
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Harris CA, Resau JH, Hudson EA, West RA, Moon C, McAllister JP. Mechanical contributions to astrocyte adhesion using a novel in vitro model of catheter obstruction. Exp Neurol 2010; 222:204-10. [PMID: 20051241 DOI: 10.1016/j.expneurol.2009.12.027] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2009] [Revised: 12/22/2009] [Accepted: 12/23/2009] [Indexed: 02/06/2023]
Abstract
Drainage and diversion of cerebrospinal fluid (CSF) through shunt systems is the most common treatment for hydrocephalus, but complications due to tissue obstruction of the catheter occur in up to 61% of patients. Although shunt systems have undergone limited technological advancements to resist mammalian cell adhesion, there is a need to further reduce adhesion that can exacerbate obstruction. The high intrinsic variability in clinical studies and an inability to predict chronic adhesion of host cells in vitro while maintaining the environmental conditions observed in hydrocephalus have impeded progress. We designed the hydrocephalus shunt catheter bioreactor (HSCB) to measure inflammatory cell adhesion under experimentally manipulated conditions of CSF pressure, pulsation rate, and flow rates. For a 20-h period, astrocytes were perfused through the pulsatile flow system, and adhesion on silicone catheters was recorded. These results were compared with those obtained under static cell culture conditions. Astrocyte adhesion was significantly increased under conditions of increased flow rate (0.25 and 0.30 mL/min), and a trend toward increased adhesion was observed under conditions of elevated pressure and pulsation rate. Because the HSCB represents physiologic conditions more accurately than static cell culture, our results suggest that standard static cell culturing techniques are insufficient to model inflammatory cell adhesion on catheters used in the treatment of hydrocephalus and that changes to the ventricular microenvironment can alter the mechanisms of cellular adhesion. The HSCB represents a relevant test system and is an effective model system for the analysis of cellular adhesion and occlusion of shunt catheters.
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Affiliation(s)
- Carolyn A Harris
- Department of Bioengineering, University of Utah, Salt Lake City, UT 84112, USA.
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13
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Härtig W, Kacza J, Paulke BR, Grosche J, Bauer U, Hoffmann A, Elsinghorst PW, Gütschow M. In vivolabelling of hippocampal β-amyloid in triple-transgenic mice with a fluorescent acetylcholinesterase inhibitor released from nanoparticles. Eur J Neurosci 2010; 31:99-109. [DOI: 10.1111/j.1460-9568.2009.07038.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
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14
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Gong C, Shi S, Wang X, Wang Y, Fu S, Dong P, Chen L, Zhao X, Wei Y, Qian Z. Novel Composite Drug Delivery System for Honokiol Delivery: Self-Assembled Poly(ethylene glycol)−Poly(ε-caprolactone)−Poly(ethylene glycol) Micelles in Thermosensitive Poly(ethylene glycol)−Poly(ε-caprolactone)−Poly(ethylene glycol) Hydrogel. J Phys Chem B 2009; 113:10183-8. [PMID: 19572675 DOI: 10.1021/jp902697d] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Affiliation(s)
- ChangYang Gong
- State Key Laboratory of Biotherapy, West China Hospital, and School of Life Sciences, Sichuan University, Chengdu, 610041, P. R. China
| | - Shuai Shi
- State Key Laboratory of Biotherapy, West China Hospital, and School of Life Sciences, Sichuan University, Chengdu, 610041, P. R. China
| | - XiuHong Wang
- State Key Laboratory of Biotherapy, West China Hospital, and School of Life Sciences, Sichuan University, Chengdu, 610041, P. R. China
| | - YuJun Wang
- State Key Laboratory of Biotherapy, West China Hospital, and School of Life Sciences, Sichuan University, Chengdu, 610041, P. R. China
| | - ShaoZhi Fu
- State Key Laboratory of Biotherapy, West China Hospital, and School of Life Sciences, Sichuan University, Chengdu, 610041, P. R. China
| | - PengWei Dong
- State Key Laboratory of Biotherapy, West China Hospital, and School of Life Sciences, Sichuan University, Chengdu, 610041, P. R. China
| | - LiJuan Chen
- State Key Laboratory of Biotherapy, West China Hospital, and School of Life Sciences, Sichuan University, Chengdu, 610041, P. R. China
| | - Xia Zhao
- State Key Laboratory of Biotherapy, West China Hospital, and School of Life Sciences, Sichuan University, Chengdu, 610041, P. R. China
| | - YuQuan Wei
- State Key Laboratory of Biotherapy, West China Hospital, and School of Life Sciences, Sichuan University, Chengdu, 610041, P. R. China
| | - ZhiYong Qian
- State Key Laboratory of Biotherapy, West China Hospital, and School of Life Sciences, Sichuan University, Chengdu, 610041, P. R. China
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15
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Sintzel MB, Merkli A, Tabatabay C, Gurny R. Influence of Irradiation Sterilization on Polymers Used as Drug Carriers—A Review. Drug Dev Ind Pharm 2008. [DOI: 10.3109/03639049709148693] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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16
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Petit S, Garcion E, Benoit JP, Menei P. Chimiothérapie locale dans les gliomes malins : de l’injection à la seringue aux nanotechnologies. Rev Neurol (Paris) 2008; 164:547-53. [DOI: 10.1016/j.neurol.2008.03.015] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2007] [Accepted: 03/13/2008] [Indexed: 10/22/2022]
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17
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Wong DY, Hollister SJ, Krebsbach PH, Nosrat C. Poly(ɛ-Caprolactone) and Poly (L-Lactic-Co-Glycolic Acid) Degradable Polymer Sponges Attenuate Astrocyte Response and Lesion Growth in Acute Traumatic Brain Injury. ACTA ACUST UNITED AC 2007; 13:2515-23. [PMID: 17655492 DOI: 10.1089/ten.2006.0440] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
This study evaluated the response of rat brain to 2 degradable polymers (poly (L-lactic-co-glycolic acid) (PLGA), and poly(epsilon-caprolactone) (PCL)), two common materials in tissue engineering. PLGA has been extensively studied in the brain for controlled drug release as injectable microspheres and is generally accepted as biocompatible in that capacity. Biocompatibility in other forms and for different functions in the brain has not been widely studied. PCL was chosen as an alternative to PLGA for its slower degradation and less-acidic pH upon degradation. Porous scaffolds were made from both polymers and implanted into rat cerebral cortex for 1 and 4 weeks. Morphology, defect size, activation of microglia (OX-42) and astrocytes (glial fibrillary acidic protein (GFAP)), infiltration of activated macrophages (major histocompatibility complex (MHC)-II), and ingrowth of neurons (beta-tubulin type III (Tuj-1)) and progenitor cells (nestin) were analyzed using hematoxylin and eosin staining and immunofluorescence. PCL induced a lower inflammatory response than PLGA, as demonstrated by lower MHC-II and GFAP expression and greater ingrowth. Both polymers alleviated astrocytic activation and prevented enlargement of the defect. Tuj-1-, nestin-, and GFAP-positive cells were observed growing on both polymers at the peripheries of the sponge implants, demonstrating their permissiveness to neural ingrowth. These findings suggest that both polymers attenuate secondary death and scarring and that PCL might have advantages over PLGA.
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Affiliation(s)
- Darice Y Wong
- Department of Biomedical Engineering, University of Michigan at Ann Arbor, Ann Arbor, MI 48109, USA.
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Schwartz AB, Cui XT, Weber DJ, Moran DW. Brain-Controlled Interfaces: Movement Restoration with Neural Prosthetics. Neuron 2006; 52:205-20. [PMID: 17015237 DOI: 10.1016/j.neuron.2006.09.019] [Citation(s) in RCA: 412] [Impact Index Per Article: 22.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Brain-controlled interfaces are devices that capture brain transmissions involved in a subject's intention to act, with the potential to restore communication and movement to those who are immobilized. Current devices record electrical activity from the scalp, on the surface of the brain, and within the cerebral cortex. These signals are being translated to command signals driving prosthetic limbs and computer displays. Somatosensory feedback is being added to this control as generated behaviors become more complex. New technology to engineer the tissue-electrode interface, electrode design, and extraction algorithms to transform the recorded signal to movement will help translate exciting laboratory demonstrations to patient practice in the near future.
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Affiliation(s)
- Andrew B Schwartz
- Department of Neurobiology, Center for the Neural Basis of Cognition, McGowan Institute for Regenerative Medicine, Pittsburgh, Pennsylvania 15213, USA.
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Fournier E, Passirani C, Colin N, Sagodira S, Menei P, Benoit JP, Montero-Menei CN. The brain tissue response to biodegradable poly(methylidene malonate 2.1.2)-based microspheres in the rat. Biomaterials 2006; 27:4963-74. [PMID: 16759690 DOI: 10.1016/j.biomaterials.2006.04.045] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2006] [Accepted: 04/28/2006] [Indexed: 11/29/2022]
Abstract
The aim of this study was to follow the in vivo biodegradation as well as to appreciate the brain tissue response to poly(methylidene malonate 2.1.2) (PMM 2.1.2)-based microspheres implanted into the rat brain. Ninety-three adult Sprague-Dawley female rats were engaged in the study in which 54 underwent stereotactic implantation of blank gamma-sterilized PMM 2.1.2-based microspheres, prepared by an emulsion-extraction method. Twelve rats were implanted with the same 5-fluorouracil (5-FU)-loaded microspheres. Seventeen controls received the suspension medium alone (carboxymethylcellulose aqueous solution). The animals were sacrificed on post-operative days 1, 2, 8 and months 1, 2, 3, 6, 9, 12, 15 and 18. The brains were dissected, frozen, cut in a freezing microtome, and the slides were processed for immunohistological evaluation and scanning electron microscopy. During the first few days, the moderate inflammatory response to blank or loaded PMM 2.1.2 microspheres was largely a consequence of the mechanical trauma that occurs during surgery. The macrophagous-microglial reaction was similar to the one typically found following any damage in the CNS. There were also no differences in GFAP reactivity between the implanted animals and the controls. Blank microspheres began to degrade between 3 and 6 months, while 5-FU microspheres degraded between 8 days and 1 month. The polymer degradation generated in both cases a pronounced inflammatory and immunological reaction, leading to an important cell loss, a cerebral atrophy and to the death of several animals. PMM 2.1.2 was thus shown to be inadequate for intracerebral drug delivery.
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Affiliation(s)
- Elvire Fournier
- Inserm U646 (Ingénierie de la vectorisation particulaire), 10 rue André Bocquel, 49 100 Angers, France.
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20
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Polikov VS, Tresco PA, Reichert WM. Response of brain tissue to chronically implanted neural electrodes. J Neurosci Methods 2005; 148:1-18. [PMID: 16198003 DOI: 10.1016/j.jneumeth.2005.08.015] [Citation(s) in RCA: 1102] [Impact Index Per Article: 58.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2005] [Revised: 08/06/2005] [Accepted: 08/08/2005] [Indexed: 11/16/2022]
Abstract
Chronically implanted recording electrode arrays linked to prosthetics have the potential to make positive impacts on patients suffering from full or partial paralysis. Such arrays are implanted into the patient's cortical tissue and record extracellular potentials from nearby neurons, allowing the information encoded by the neuronal discharges to control external devices. While such systems perform well during acute recordings, they often fail to function reliably in clinically relevant chronic settings. Available evidence suggests that a major failure mode of electrode arrays is the brain tissue reaction against these implants, making the biocompatibility of implanted electrodes a primary concern in device design. This review presents the biological components and time course of the acute and chronic tissue reaction in brain tissue, analyses the brain tissue response of current electrode systems, and comments on the various material science and bioactive strategies undertaken by electrode designers to enhance electrode performance.
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Affiliation(s)
- Vadim S Polikov
- Department of Biomedical Engineering, Duke University, Durham, NC 27708, USA
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Le Ray AM, Gautier H, Laty MK, Daculsi G, Merle C, Jacqueline C, Hamel A, Caillon J. In vitro and in vivo bactericidal activities of vancomycin dispersed in porous biodegradable poly(epsilon-caprolactone) microparticles. Antimicrob Agents Chemother 2005; 49:3025-7. [PMID: 15980391 PMCID: PMC1168678 DOI: 10.1128/aac.49.7.3025-3027.2005] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2004] [Revised: 11/15/2004] [Accepted: 03/23/2005] [Indexed: 11/20/2022] Open
Abstract
Treatment of methicillin-resistant Staphylococcus aureus osteomyelitis requires a prolonged antibiotic therapy with vancomycin. Because of its weak diffusion, the in situ implantation of vancomycin could be interesting. The activity of vancomycin encapsulated in microparticles was evaluated in vitro and in vivo on rabbit osteomyelitis and showed a good activity compared to intravenous administration.
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Affiliation(s)
- Anne-Marie Le Ray
- Centre de Recherche sur les Matériaux d'Intérêt Biologique, Equipe INSERM 99-03, UFR Odontologie, University of Nantes, 1 rue Gaston Veil, 44035 Nantes, France
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22
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Sinha VR, Bansal K, Kaushik R, Kumria R, Trehan A. Poly-epsilon-caprolactone microspheres and nanospheres: an overview. Int J Pharm 2004; 278:1-23. [PMID: 15158945 DOI: 10.1016/j.ijpharm.2004.01.044] [Citation(s) in RCA: 672] [Impact Index Per Article: 33.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2002] [Revised: 01/19/2004] [Accepted: 01/27/2004] [Indexed: 11/29/2022]
Abstract
Poly-epsilon-caprolactone (PCL) is a biodegradable, biocompatible and semicrystalline polymer having a very low glass transition temperature. Due to its slow degradation, PCL is ideally suitable for long-term delivery extending over a period of more than one year. This has led to its application in the preparation of different delivery systems in the form of microspheres, nanospheres and implants. Various categories of drugs have been encapsulated in PCL for targeted drug delivery and for controlled drug release. Microspheres of PCL either alone or of PCL copolymers have been prepared to obtain the drug release characteristics. This article reviews the advancements made in PCL-based microspheres and nanospheres with special reference to the method of preparation of these and their suitability in developing effective delivery systems.
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Affiliation(s)
- V R Sinha
- University Institute of Pharmaceutical Sciences, Panjab University, Chandigarh 160014, India.
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23
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Menei P, Jadaud E, Faisant N, Boisdron-Celle M, Michalak S, Fournier D, Delhaye M, Benoit JP. Stereotaxic implantation of 5-fluorouracil-releasing microspheres in malignant glioma. Cancer 2004; 100:405-10. [PMID: 14716778 DOI: 10.1002/cncr.11922] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
BACKGROUND The authors developed a new method of drug delivery into the brain using implantable, biodegradable microspheres. The strategy was evaluated initially to provide localized and sustained delivery of the radiosensitizer 5-fluorouracil (5-FU) after patients underwent surgical resection of malignant glioma. In this study, the microspheres were implanted by stereotaxy into deeply situated and inoperable brain tumors. METHODS Ten patients with newly diagnosed, inoperable, malignant gliomas were included in the study, and 1 dose of 5-FU was studied (132 mg). After histologic confirmation, a suspension of poly(D-L lactide-co-glycolide) 5-FU-loaded microspheres was implanted by stereotaxy into the tumor in one or several trajectories with one to seven deposits per trajectory. External beam radiation (59.4 grays) was started before postoperative Day 7. Patients were followed by clinical examination, computed tomography scanning, magnetic resonance imaging, and 5-FU assays in blood and cerebrospinal fluid (CSF). RESULTS The number of trajectories was adapted to the size and shape of the tumor. Microsphere implantation was tolerated well, except in four patients who received a single trajectory and experienced a transitory worsening of preexisting neurologic symptoms. There were no episodes of edema or hematologic complications. 5-FU was detected in CSF and blood in some patients at very low concentrations. The median overall survival was 40 weeks, with 2 patients who had longer survival (71 weeks and 89 weeks, respectively). CONCLUSIONS In this study, the authors demonstrated that biodegradable microspheres could be implanted by stereotaxy and were efficient systems for drug delivery into brain tumors. This method may have future applications in the treatment of patients other malignancies.
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Affiliation(s)
- Philippe Menei
- Department of Neurosurgery, Centre Hospitalo-Universitaire d'Angers, 49033 Angers Cedex 01, France.
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Fournier E, Passirani C, Montero-Menei CN, Benoit JP. Biocompatibility of implantable synthetic polymeric drug carriers: focus on brain biocompatibility. Biomaterials 2003; 24:3311-31. [PMID: 12763459 DOI: 10.1016/s0142-9612(03)00161-3] [Citation(s) in RCA: 254] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Numerous polymeric biomaterials are implanted each year in human bodies. Among them, drug delivery devices are potent novel powerful therapeutics for diseases which lack efficient treatments. Controlled release systems are in direct and sustained contact with the tissues, and some of them degrade in situ. Thus, both the material itself and its degradation products must be devoid of toxicity. The knowledge and understanding of the criteria and mechanisms determining the biocompatibility of biomaterials are therefore of great importance. The classical tissue response to a foreign material leads to the encapsulation of the implant, which may impair the drug diffusion in the surrounding tissue and/or cause implant failure. This tissue response depends on different factors, especially on the implantation site. Indeed, several organs possess a particular immunological status, which may reduce the inflammatory and immune reactions. Among them, the central nervous system is of particular interest, since many pathologies still need curative treatments. This review describes the classical foreign body reaction and exposes the particularities of the central nervous system response. The recent in vivo biocompatibility studies of implanted synthetic polymeric drug carriers are summarized in order to illustrate the behavior of different classes of polymers and the methodologies used to evaluate their tolerance.
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Affiliation(s)
- E Fournier
- Inserm ERIT-M 0104, Ingénierie de la Vectorisation Particulaire, 10, rue André Bocquel, 49100 Angers, France
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25
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Härtig W, Paulke BR, Varga C, Seeger J, Harkany T, Kacza J. Electron microscopic analysis of nanoparticles delivering thioflavin-T after intrahippocampal injection in mouse: implications for targeting beta-amyloid in Alzheimer's disease. Neurosci Lett 2003; 338:174-6. [PMID: 12566180 DOI: 10.1016/s0304-3940(02)01399-x] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Prevention of beta-amyloid (Abeta) production, aggregation and formation of Abeta deposits is a key pharmacological target in Alzheimer's disease. The passage of Abeta-binding compounds through the blood-brain barrier is often hampered for free ligands, whereas it is enhanced by drug encapsulation in nanoparticles. Here, we describe the preparation and characterization of polymeric carriers containing thioflavin-T as a marker for fibrillar Abeta. This study is then focused on electron microscopic analyses of thioflavin-T after injection of thioflavin-T-containing nanoparticles into the mouse hippocampus. Therefore, the photoconversion of fluorescent thioflavin-T as model drug was performed in tissues fixed 3 days post-injection. Thioflavin-T delivered from nanospheres was predominantly found in neurons and microglia. Our data suggest that drugs delivered by nanoparticles might target Abeta in the brain.
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Affiliation(s)
- Wolfgang Härtig
- Department of Neurochemistry, Paul Flechsig Institute for Brain Research, University of Leipzig, Jahnallee 59, 04109, Leipzig, Germany
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26
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Menei P, Benoit JP. Implantable drug-releasing biodegradable microspheres for local treatment of brain glioma. ACTA NEUROCHIRURGICA. SUPPLEMENT 2003; 88:51-5. [PMID: 14531561 DOI: 10.1007/978-3-7091-6090-9_9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/27/2023]
Abstract
Our group have developed a new method of drug delivery into the brain using implantable biodegradable microspheres. In this mini-review, we describe the development, preclinical studies and clinical trials involving 5-fluorouracil-releasing microspheres for interstitial radiosensitization of malignant glioma. Future developments concerning these microspheres for treatment of brain tumors are presented.
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Affiliation(s)
- P Menei
- Department of Neurosurgery, Universitaire d'Angers, Angers Cedex, France.
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27
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Pang SW, Park HY, Jang YS, Kim WS, Kim JH. Effects of charge density and particle size of poly(styrene/(dimethylamino)ethyl methacrylate) nanoparticle for gene delivery in 293 cells. Colloids Surf B Biointerfaces 2002. [DOI: 10.1016/s0927-7765(01)00335-6] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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28
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Nicholas AP, McInnis C, Gupta KB, Snow WW, Love DF, Mason DW, Ferrell TM, Staas JK, Tice TR. The fate of biodegradable microspheres injected into rat brain. Neurosci Lett 2002; 323:85-8. [PMID: 11950499 DOI: 10.1016/s0304-3940(01)02534-4] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Biodegradable microspheres made with poly-[D,L-lactide-co-glycolide] represent an evolving technology for drug delivery into the central nervous system. Even though these microspheres have been shown to be engulfed by astrocytes in vitro, the purpose of the present study was to track the fate of biodegradable microspheres in vivo. This was accomplished using microspheres containing the fluorescent dye coumarin-6 followed 1 day, 1 week and 1 month after intracerebral injections of this material were made into the rat brain. Using dual color immunohistochemistry and antisera against glial fibrillary acidic protein for astrocytes versus phosphotyrosine for microglia, results demonstrate that phagocytosis of small coumarin-containing microspheres <7.5 microm in diameter was primarily by microglia in vivo during the first week post-injection. In contrast, only a small minority of these microspheres appeared to be engulfed by astrocytes.
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Affiliation(s)
- Anthony P Nicholas
- Department of Neurology, University of Alabama at Birmingham and the Birmingham Veterans Administration Medical Center, 619 19th Street South, Birmingham, AL 35249-7340, USA.
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29
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Iooss P, Le Ray AM, Grimandi G, Daculsi G, Merle C. A new injectable bone substitute combining poly(epsilon-caprolactone) microparticles with biphasic calcium phosphate granules. Biomaterials 2001; 22:2785-94. [PMID: 11545313 DOI: 10.1016/s0142-9612(01)00022-9] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Previous studies have shown the effectiveness of an injectable bone substitute (IBS) composed of biphasic calcium phosphate in 2% hydroxypropyl methylcellulose gel (50/50 w/w). A therapeutic agent in the form of a drug can be added to the biomaterial by encapsulation into microparticles to protect the active agent, control its release and preserve the material rheological properties. Poly(epsilon-caprolactone) was used in this study because of its biocompatibility and resorbability, as tested in orthopaedic implants and surgical sutures. Particles (80-200 microm) were manufactured by a solvent evaporation-extraction process (1 g of polymer, 11-15 ml methylene chloride, with a stirring speed of 400-600 rpm) and introduced into the IBS in a 5-50% (V/V) range. Injectability was evaluated by texture analysis. With less than 45% of particles, the material had rheological properties similar to those of the reference IBS, whereas injectability decreased markedly with more than 45% of particles. A preliminary in vitro release study showed that this type of triphasic IBS could be efficient for drug delivery systems with osteoconduction properties.
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Affiliation(s)
- P Iooss
- Laboratoire de Pharmacie Galénique, Faculté de Pharmacie de Nantes, France
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30
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Olivera ER, Carnicero D, Jodra R, Miñambres B, García B, Abraham GA, Gallardo A, Román JS, García JL, Naharro G, Luengo JM. Genetically engineered Pseudomonas: a factory of new bioplastics with broad applications. Environ Microbiol 2001; 3:612-8. [PMID: 11722541 DOI: 10.1046/j.1462-2920.2001.00224.x] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
New bioplastics containing aromatic or mixtures of aliphatic and aromatic monomers have been obtained using genetically engineered strains of Pseudomonas putida. The mutation (-) or deletion (Delta) of some of the genes involved in the beta-oxidation pathway (fadA(-), fadB(-) Delta fadA or Delta fad BA mutants) elicits a strong intracellular accumulation of unusual homo- or co-polymers that dramatically alter the morphology of these bacteria, as more than 90% of the cytoplasm is occupied by these macromolecules. The introduction of a blockade in the beta-oxidation pathway, or in other related catabolic routes, has allowed the synthesis of polymers other than those accumulated in the wild type (with regard to both monomer size and relative percentage), the accumulation of certain intermediates that are rapidly catabolized in the wild type and the accumulation in the culture broths of end catabolites that, as in the case of phenylacetic acid, phenylbutyric acid, trans-cinnamic acid or their derivatives, have important medical or pharmaceutical applications (antitumoral, analgesic, radiopotentiators, chemopreventive or antihelmintic). Furthermore, using one of these polyesters (poly 3-hydroxy-6-phenylhexanoate), we obtained polymeric microspheres that could be used as drug vehicles.
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Affiliation(s)
- E R Olivera
- Departamento de Bioquímica y Biología Molecular, Facultad de Veterinaria, Universidad de León, 24007 León, Spain
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Benoit JP, Faisant N, Venier-Julienne MC, Menei P. Development of microspheres for neurological disorders: from basics to clinical applications. J Control Release 2000; 65:285-96. [PMID: 10699288 DOI: 10.1016/s0168-3659(99)00250-3] [Citation(s) in RCA: 121] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Drug delivery to the central nervous system remains a challenging area of investigation for both basic and clinical neuroscientists. Numerous drugs are generally excluded from blood to brain transfer due to the negligible permeability of the brain capillary endothelial wall, which makes up the blood brain barrier in vivo. For several years, we have explored the potential applications of the microencapsulation of therapeutic agents to provide local controlled drug release in the central nervous system. Due to their size, these microparticles can be easily implanted by stereotaxy in discreet, precise and functional areas of the brain without damaging the surrounding tissue. This type of implantation avoids the inconvenient insertion of large implants by open surgery and can be repeated if necessary. We have established the compatibility of poly(lactide-co-glycolide) microspheres with brain tissues. Presently, the most developed applications concern Neurology and Neuro-oncology, with local delivery of neurotrophic factors and antimitotic drugs into neurodegenerative lesions and brain tumours, respectively. The drugs that had been encapsulated by our group included nerve growth factor (NGF), 5-fluorouracil (5-FU), idoxuridine and BCNU. Preclinical studies have been performed with each drug. Studies with NGF are reported as an example. A phase I/II clinical trial has been carried out in patients with newly diagnosed glioblastomas to assess the potentialities of 5-FU-loaded microspheres when intracranially implanted.
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Affiliation(s)
- J P Benoit
- UPRES EA 2169, Faculté de Pharmacie, Université d'Angers, Angers, France.
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Abstract
The blood brain barrier (BBB) and the systemic toxicity of conventional chemotherapy present obstacles to the success of future blood-borne drug therapies of brain tumors. The work with polymer-encapsulated cancer drugs suggests an alternative and more focused treatment approach. Our experimental strategy integrates direct intracerebral drug delivery, sustained drug release from liposomes or polymer implants, and increased targeting of the drug either by chemically modifying the drug or by using tumor-specific carriers. This review will present some of the recent work on targeted drug delivery for brain cancer treatment.
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Affiliation(s)
- R L Gutman
- Department of Pharmaceutical and Biomedical Sciences, College of Pharmacy, University of Georgia, Athens, GA 30602, USA
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Menei P, Pean JM, Nerrière-Daguin V, Jollivet C, Brachet P, Benoit JP. Intracerebral implantation of NGF-releasing biodegradable microspheres protects striatum against excitotoxic damage. Exp Neurol 2000; 161:259-72. [PMID: 10683292 DOI: 10.1006/exnr.1999.7253] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Intrastriatal implantation of genetically modified cells synthesizing nerve growth factor (NGF) constitutes one way to obtain a long-term supply of this neurotrophic factor and a neuronal protection against an excitotoxic lesion. We have investigated if NGF-loaded poly(d,l-lactide-co-glycolide) microspheres could represent an alternative to cell transplantations. These microspheres can be implanted stereotaxically and locally release the protein in a controlled and sustained way. In order to test this paradigm, the NGF release kinetics were characterized in vitro using radiolabeled NGF, immunoenzymatic assay, and PC-12 cells bioassay and then in vivo after implantation in the intact rat striatum. These microspheres were thus implanted into the rat striatum 7 days prior to infusing quinolinic acid. Control animals were either not treated or implanted with blank microspheres. The extent of the lesion and the survival of ChAT-, NADPH-d-, and DARPP-32-containing neurons were analyzed. In vitro studies showed that microspheres allowed a sustained release of bioactive NGF for at least 1 month. Microspheres implanted in the intact striatum still contained NGF after 2.5 months and they were totally degraded after 3 months. After quinolinic acid infusion, the lesion size in the group treated with NGF-releasing microspheres was reduced by 40% when compared with the control groups. A marked neuronal sparing was noted, principally concerning the cholinergic interneurons, but also neuropeptide Y/somatostatin interneurons and GABAergic striatofuge neurons. These results indicate that implantation of biodegradable NGF-releasing microspheres can be used to protect neurons from a local excitotoxic lesion and that this strategy may ultimately prove to be relevant for the treatment of various neurological diseases.
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Affiliation(s)
- P Menei
- Department of Neurosurgery, University Hospital, Angers, France
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Menei P, Venier MC, Gamelin E, Saint-Andr� JP, Hayek G, Jadaud E, Fournier D, Mercier P, Guy G, Benoit JP. Local and sustained delivery of 5-fluorouracil from biodegradable microspheres for the radiosensitization of glioblastoma. Cancer 1999. [DOI: 10.1002/(sici)1097-0142(19990715)86:2<325::aid-cncr17>3.0.co;2-s] [Citation(s) in RCA: 90] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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Gallardo A, Eguiburu JL, Fernandez Berridi MJ, San Román J. Preparation and in vitro release studies of ibuprofen-loaded films and microspheres made from graft copolymers of poly(L-lactic acid) on acrylic backbones. J Control Release 1998; 55:171-9. [PMID: 9795046 DOI: 10.1016/s0168-3659(98)00047-9] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The present article describes the preparation of films of various thickness and microspheres from new resorbable graft copolymers of polyacrylic (methyl methacrylate, MMA, or methyl acrylate, MA), or polyvinylic (vinyl pyrrolidone, VP) chains and poly(l-lactic acid) (PLLA) side blocks charged with 15-20% of ibuprofen (IBU) (a non-steroidic antiinflammatory agent). In the case of MMA-LLA and MA-LLA graft copolymers the release of IBU in buffered solution is modulated by the flexibility of the copolymer chains in a first step of one to two days and in a second step by the diffusive properties of the system as well as by the biodegradation of the polymers. The VP-PLLA graft copolymers are highly hydrophilic and the release of IBU is modulated by the diffusion of the drug through the swollen system. Specific interactions between the IBU molecules and the pyrrolidone rings also participate in the kinetic behaviour of the release process.
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Affiliation(s)
- A Gallardo
- Instituto de Ciencia y Tecnología de Polímeros, CSIC, Juan de la Cierva 3, 28006 Madrid, Spain
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36
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Del Bigio MR. Biological reactions to cerebrospinal fluid shunt devices: a review of the cellular pathology. Neurosurgery 1998; 42:319-25; discussion 325-6. [PMID: 9482182 DOI: 10.1097/00006123-199802000-00064] [Citation(s) in RCA: 74] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
OBJECTIVE To understand the interaction between cerebrospinal fluid shunt components and the brain and other tissues. METHODS A systematic review of the medical literature directly pertaining to shunt complications, and that dealing with tissues' reactions to implants in general, was conducted. RESULTS Vascularized pedicles of glial tissue or choroid plexus grow into ventricular catheters, primarily as a mechanical phenomenon. Cellular debris or blood can cause dysfunction of valve components. Chronic inflammation, which is nonspecific, might contribute to degradation of the components. CONCLUSION Care must be taken to prevent early entry of debris or blood into the shunt system. Ventricular collapse onto the shunt must be avoided. Refinement of manufacturing methods or modification of shunt materials could reduce the susceptibility of shunts to infection and improve longevity of the apparatus.
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Affiliation(s)
- M R Del Bigio
- Department of Pathology, Health Sciences Centre and University of Manitoba, Winnipeg, Canada
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Fritz H, Maier M, Bayer E. Cationic Polystyrene Nanoparticles: Preparation and Characterization of a Model Drug Carrier System for Antisense Oligonucleotides. J Colloid Interface Sci 1997; 195:272-88. [PMID: 9441629 DOI: 10.1006/jcis.1997.5172] [Citation(s) in RCA: 52] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Polystyrene nanoparticles were prepared by surfactant-free emulsion polymerization using water-soluble cationic initiators to induce a positive surface charge. Reaction conditions were optimized to obtain monodisperse polymeric particles with mean diameters of 150-200 nm. The nanospheres were characterized by scanning electron microscopy, photocorrelation spectroscopy, conductometric titrations, zeta potential measurements, and investigations of their colloidal stability in different media. Sterically stabilized polymeric latexes, showing a low cytotoxicity in the concentrations required for antisense experiments, are capable of binding negatively charged oligonucleotides. The influence of pH, type of latex, and oligonucleotide modification on the adsorption characteristics was investigated. The results indicate that high attractive forces in terms of multiple electrostatic interactions are predominantly responsible for oligonucleotide binding. Comparing the experimental data with calculations based on the random sequential adsorption (RSA) model, it appears that the surface coverage at the saturation level can be considered as a monolayer of "side-on" adsorbed molecules. Oligonucleotide release can be induced by the addition of anionic surfactants or by increasing the pH of the dispersion medium. Investigations of the enzymatic degradation by micellar electrokinetic capillary chromatography (MECC) indicate a significantly enhanced stability of adsorbed oligonucleotides against nuclease attack. Copyright 1997 Academic Press. Copyright 1997Academic Press
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Affiliation(s)
- H Fritz
- Institute of Organic Chemistry, University of Tubingen, Auf der Morgenstelle 18, Tubingen, D-72076, Germany
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García-Contreras L, Abu-Izza K, Lu DR. Biodegradable cisplatin microspheres for direct brain injection: preparation and characterization. Pharm Dev Technol 1997; 2:53-65. [PMID: 9552431 DOI: 10.3109/10837459709022609] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The objectives of the present study were to prepare cisplatin loaded-PLGA microspheres that are suitable for direct brain injection and to characterize them in terms of their physicochemical properties, in vitro drug release, and self-removal mechanism. The microspheres were prepared by emulsification/solvent evaporation method using PLGA (50:50) as the biodegradable matrix forming polymer. The physicochemical characterization encompassed the following: surface morphology, particle size, entrapment efficiency, surface area, and density. The in vitro release and in vitro degradation studies were performed in phosphate buffer and in 10% rat brain preparation. SEM micrographs revealed that the microspheres have a rough porous surface and a smooth interior. Particle size typically ranged from 180 to 250 microns with an average of 230 T microns. Entrapment efficiency was approximately 70% and was found to be dependent on the particle size. Surface area and density ranged from 0.038 to 0.025 m2/g and from 1.44 to 1.39 g/cm3, respectively. Both were also dependent on particle size. In the in vitro release study in phosphate buffer, approximately 80% of cisplatin was released over 30 days, after which the release rate plateaued. The release profile in 10% rat brain preparation was comparable in shape to that obtained in phosphate buffer. However, the release rate was lower and the total amount released by the end of the study was only 55% of the total cisplatin content. The degradation of PLGA microspheres in phosphate buffer and in rat brain homogenate correlated well with the respective release profiles. Based on the evidence of self-removal and the sustained release of cisplatin for over a month, cisplatin-loaded PLGA microspheres may be useful for local delivery to brain tumors.
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Affiliation(s)
- L García-Contreras
- Department of Pharmaceutics, College of Pharmacy, University of Georgia, Athens 30602, USA
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39
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Menei P, Boisdron-Celle M, Croué A, Guy G, Benoit JP. Effect of stereotactic implantation of biodegradable 5-fluorouracil-loaded microspheres in healthy and C6 glioma-bearing rats. Neurosurgery 1996; 39:117-23; discussion 123-4. [PMID: 8805147 DOI: 10.1097/00006123-199607000-00023] [Citation(s) in RCA: 90] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
OBJECTIVE Poly(lactic acid-co-glycolic acid) (PLAGA) microspheres are promising systems for interstitial chemotherapy of brain tumors. They can be readily implanted by stereotaxy and are biocompatible with the brain, in which they are totally biodegraded within 2 months. 5-Fluorouracil (5-FU) was selected for encapsulation, because this hydrophilic and antimetabolic drug is not directly neurotoxic and does not readily cross the blood-brain barrier. Also, its anticancer activity may be improved by sustained administration. Furthermore, it is a potent radiosensitizer. METHODS To study their fate and toxicity, two types of 5-FU-loaded PLAGA microspheres were implanted in healthy rats by stereotaxy. One type presented a fast in vitro release profile (FR), and the second exhibited a slow in vitro release pattern (SR) (100% of the encapsulated 5-FU is released within 72 hours and 18 days, respectively). Periodically, rats were killed for microscopic examination. The efficacy of these microspheres on rat glioma was then evaluated. Seven days after stereotactic implantation of C6 malignant glioma cells in the brain, the rats were treated by intratumoral injection of 5-FU solution, blank microspheres, or 5-FU-loaded microspheres (FR and SR types). The mortality of these treated groups was compared by the log-rank test with that of an untreated group. RESULTS After implantation of two types of 5-FU-loaded PLAGA microspheres, no sign of clinical or histological toxicity was observed. Entrapped 5-FU crystals were observed until Days 12 and 20 postimplantation within FR and SR microspheres, respectively, which suggests a longer releasing period in vivo than in vitro. In the therapeutic evaluation, only intratumoral implantation of SR-type 5-FU-loaded microspheres significantly decreased the mortality (P = 0.017). CONCLUSION 5-FU-loaded PLAGA microspheres were implanted in rat brains without evident toxicity. Histological examination suggested a longer sustained delivery period in vivo than in vitro. Intratumoral implantation of SR-type 5-FU-loaded microspheres decreased the mortality of C6 tumor-bearing rats. This effect can be related to the local and the sustained delivery of the drug, because 5-FU administered systemically is ineffective against brain tumors.
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Affiliation(s)
- P Menei
- Service de Neurochirurgie, Centre Hospitalo-Universitaire, Angers, France
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