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Abbott CJ, Allen PJ, Williams CE, Williams RA, Epp SB, Burns O, Thomas R, Harrison M, Thien PC, Saunders A, McGowan C, Sloan C, Luu CD, Nayagam DAX. Chronic electrical stimulation with a peripheral suprachoroidal retinal implant: a preclinical safety study of neuroprotective stimulation. Front Cell Dev Biol 2024; 12:1422764. [PMID: 38966426 PMCID: PMC11222648 DOI: 10.3389/fcell.2024.1422764] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2024] [Accepted: 06/05/2024] [Indexed: 07/06/2024] Open
Abstract
Purpose Extraocular electrical stimulation is known to provide neuroprotection for retinal cells in retinal and optic nerve diseases. Currently, the treatment approach requires patients to set up extraocular electrodes and stimulate potentially weekly due to the lack of an implantable stimulation device. Hence, a minimally-invasive implant was developed to provide chronic electrical stimulation to the retina, potentially improving patient compliance for long-term use. The aim of the present study was to determine the surgical and stimulation safety of this novel device designed for neuroprotective stimulation. Methods Eight normally sighted adult feline subjects were monocularly implanted in the suprachoroidal space in the peripheral retina for 9-39 weeks. Charge balanced, biphasic, current pulses (100 μA, 500 µs pulse width and 50 pulses/s) were delivered continuously to platinum electrodes for 3-34 weeks. Electrode impedances were measured hourly. Retinal structure and function were assessed at 1-, 2-, 4-, 6- and 8-month using electroretinography, optical coherence tomography and fundus photography. Retina and fibrotic thickness were measured from histological sections. Randomized, blinded histopathological assessments of stimulated and non-stimulated retina were performed. Results All subjects tolerated the surgical and stimulation procedure with no evidence of discomfort or unexpected adverse outcomes. The device position was stable after a post-surgery settling period. Median electrode impedance remained within a consistent range (5-10 kΩ) over time. There was no change in retinal thickness or function relative to baseline and fellow eyes. Fibrotic capsule thickness was equivalent between stimulated and non-stimulated tissue and helps to hold the device in place. There was no scarring, insertion trauma, necrosis, retinal damage or fibroblastic response in any retinal samples from implanted eyes, whilst 19% had a minimal histiocytic response, 19% had minimal to mild acute inflammation and 28% had minimal to mild chronic inflammation. Conclusion Chronic suprathreshold electrical stimulation of the retina using a minimally invasive device evoked a mild tissue response and no adverse clinical findings. Peripheral suprachoroidal electrical stimulation with an implanted device could potentially be an alternative approach to transcorneal electrical stimulation for delivering neuroprotective stimulation.
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Affiliation(s)
- Carla J. Abbott
- Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, East Melbourne, VIC, Australia
- Department of Surgery (Ophthalmology), University of Melbourne, East Melbourne, VIC, Australia
| | - Penelope J. Allen
- Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, East Melbourne, VIC, Australia
- Department of Surgery (Ophthalmology), University of Melbourne, East Melbourne, VIC, Australia
- Vitreoretinal Unit, Royal Victorian Eye and Ear Hospital, East Melbourne, VIC, Australia
| | - Chris E. Williams
- Bionics Institute, East Melbourne, VIC, Australia
- Medical Bionics Department, University of Melbourne, Fitzroy, VIC, Australia
| | - Richard A. Williams
- Department of Clinical Pathology, University of Melbourne, Parkville, VIC, Australia
- Dorevitch Pathology, Heidelberg, VIC, Australia
| | | | - Owen Burns
- Bionics Institute, East Melbourne, VIC, Australia
| | - Ross Thomas
- Bionics Institute, East Melbourne, VIC, Australia
| | | | - Patrick C. Thien
- Bionics Institute, East Melbourne, VIC, Australia
- Medical Bionics Department, University of Melbourne, Fitzroy, VIC, Australia
| | | | | | | | - Chi D. Luu
- Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, East Melbourne, VIC, Australia
- Department of Surgery (Ophthalmology), University of Melbourne, East Melbourne, VIC, Australia
| | - David A. X. Nayagam
- Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, East Melbourne, VIC, Australia
- Department of Clinical Pathology, University of Melbourne, Parkville, VIC, Australia
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Rabesandratana O, Goureau O, Orieux G. Pluripotent Stem Cell-Based Approaches to Explore and Treat Optic Neuropathies. Front Neurosci 2018; 12:651. [PMID: 30294255 PMCID: PMC6158340 DOI: 10.3389/fnins.2018.00651] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2018] [Accepted: 08/30/2018] [Indexed: 12/15/2022] Open
Abstract
Sight is a major sense for human and visual impairment profoundly affects quality of life, especially retinal degenerative diseases which are the leading cause of irreversible blindness worldwide. As for other neurodegenerative disorders, almost all retinal dystrophies are characterized by the specific loss of one or two cell types, such as retinal ganglion cells, photoreceptor cells, or retinal pigmented epithelial cells. This feature is a critical point when dealing with cell replacement strategies considering that the preservation of other cell types and retinal circuitry is a prerequisite. Retinal ganglion cells are particularly vulnerable to degenerative process and glaucoma, the most common optic neuropathy, is a frequent retinal dystrophy. Cell replacement has been proposed as a potential approach to take on the challenge of visual restoration, but its application to optic neuropathies is particularly challenging. Many obstacles need to be overcome before any clinical application. Beyond their survival and differentiation, engrafted cells have to reconnect with both upstream synaptic retinal cell partners and specific targets in the brain. To date, reconnection of retinal ganglion cells with distal central targets appears unrealistic since central nervous system is refractory to regenerative processes. Significant progress on the understanding of molecular mechanisms that prevent central nervous system regeneration offer hope to overcome this obstacle in the future. At the same time, emergence of reprogramming of human somatic cells into pluripotent stem cells has facilitated both the generation of new source of cells with therapeutic potential and the development of innovative methods for the generation of transplantable cells. In this review, we discuss the feasibility of stem cell-based strategies applied to retinal ganglion cells and optic nerve impairment. We present the different strategies for the generation, characterization and the delivery of transplantable retinal ganglion cells derived from pluripotent stem cells. The relevance of pluripotent stem cell-derived retinal organoid and retinal ganglion cells for disease modeling or drug screening will be also introduced in the context of optic neuropathies.
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Affiliation(s)
| | - Olivier Goureau
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, Paris, France
| | - Gaël Orieux
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, Paris, France
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Ievins A, Moritz CT. Therapeutic Stimulation for Restoration of Function After Spinal Cord Injury. Physiology (Bethesda) 2018; 32:391-398. [PMID: 28814499 DOI: 10.1152/physiol.00010.2017] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2017] [Revised: 07/11/2017] [Accepted: 07/11/2017] [Indexed: 12/19/2022] Open
Abstract
Paralysis due to spinal cord injury can severely limit motor function and independence. This review summarizes different approaches to electrical stimulation of the spinal cord designed to restore motor function, with a brief discussion of their origins and the current understanding of their mechanisms of action. Spinal stimulation leads to impressive improvements in motor function along with some benefits to autonomic functions such as bladder control. Nonetheless, the precise mechanisms underlying these improvements and the optimal spinal stimulation approaches for restoration of motor function are largely unknown. Finally, spinal stimulation may augment other therapies that address the molecular and cellular environment of the injured spinal cord. The fact that several stimulation approaches are now leading to substantial and durable improvements in function following spinal cord injury provides a new perspectives on the previously "incurable" condition of paralysis.
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Affiliation(s)
- Aiva Ievins
- Department of Rehabilitation Medicine, University of Washington, Seattle, Washington.,Graduate Program in Neuroscience, University of Washington, Seattle, Washington.,Center for Sensorimotor Neural Engineering, Seattle, Washington
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Zhang C, Rong W, Zhang GH, Wang AH, Wu CZ, Huo XL. Early electrical field stimulation prevents the loss of spinal cord anterior horn motoneurons and muscle atrophy following spinal cord injury. Neural Regen Res 2018; 13:869-876. [PMID: 29863018 PMCID: PMC5998640 DOI: 10.4103/1673-5374.232483] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Our previous study revealed that early application of electrical field stimulation (EFS) with the anode at the lesion and the cathode distal to the lesion reduced injury potential, inhibited secondary injury and was neuroprotective in the dorsal corticospinal tract after spinal cord injury (SCI). The objective of this study was to further evaluate the effect of EFS on protection of anterior horn motoneurons and their target musculature after SCI and its mechanism. Rats were randomized into three equal groups. The EFS group received EFS for 30 minutes immediately after injury at T10. SCI group rats were only subjected to SCI and sham group rats were only subjected to laminectomy. Luxol fast blue staining demonstrated that spinal cord tissue in the injury center was better protected; cross-sectional area and perimeter of injured tissue were significantly smaller in the EFS group than in the SCI group. Immunofluorescence and transmission electron microscopy showed that the number of spinal cord anterior horn motoneurons was greater and the number of abnormal neurons reduced in the EFS group compared with the SCI group. Wet weight and cross-sectional area of vastus lateralis muscles were smaller in the SCI group to in the sham group. However, EFS improved muscle atrophy and behavioral examination showed that EFS significantly increased the angle in the inclined plane test and Tarlov's motor grading score. The above results confirm that early EFS can effectively impede spinal cord anterior horn motoneuron loss, promote motor function recovery and reduce muscle atrophy in rats after SCI.
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Affiliation(s)
- Cheng Zhang
- Beijing Key Laboratory of Bioelectromagnetism, Institute of Electrical Engineering, Chinese Academy of Sciences, Beijing, China
| | - Wei Rong
- Department of Orthopedics, Beijing Tsinghua Changgung Hospital, Medical Center, Tsinghua University, Beijing, China
| | - Guang-Hao Zhang
- Beijing Key Laboratory of Bioelectromagnetism, Institute of Electrical Engineering, Chinese Academy of Sciences, Beijing, China
| | - Ai-Hua Wang
- Beijing Key Laboratory of Bioelectromagnetism, Institute of Electrical Engineering, Chinese Academy of Sciences, Beijing, China
| | - Chang-Zhe Wu
- Beijing Key Laboratory of Bioelectromagnetism, Institute of Electrical Engineering, Chinese Academy of Sciences, Beijing, China
| | - Xiao-Lin Huo
- Beijing Key Laboratory of Bioelectromagnetism, Institute of Electrical Engineering, Chinese Academy of Sciences; University of Chinese Academy of Sciences, Beijing, China
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Abstract
The number of clinical trials in regenerative medicine is burgeoning, and stem cell/tissue engineering technologies hold the possibility of becoming the standard of care for a multitude of diseases and injuries. Advances in regenerative biology reveal novel molecular and cellular targets, with potential to optimize tissue healing and functional recovery, thereby refining rehabilitation clinical practice. The purpose of this review is to (1) highlight the potential for synergy between the fields of regenerative medicine and rehabilitation, a convergence of disciplines known as regenerative rehabilitation; (2) provide translational examples of regenerative rehabilitation within the context of neuromuscular injuries and diseases; and (3) offer recommendations for ways to leverage activity dependence via combined therapy and technology, with the goal of enhancing long-term recovery. The potential clinical benefits of regenerative rehabilitation will likely become a critical aspect in the standard of care for many neurological and musculoskeletal disorders.
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Neuronal Atrophy Early in Degenerative Ataxia Is a Compensatory Mechanism to Regulate Membrane Excitability. J Neurosci 2015; 35:11292-307. [PMID: 26269637 DOI: 10.1523/jneurosci.1357-15.2015] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
UNLABELLED Neuronal atrophy in neurodegenerative diseases is commonly viewed as an early event in a continuum that ultimately results in neuronal loss. In a mouse model of the polyglutamine disorder spinocerebellar ataxia type 1 (SCA1), we tested the hypothesis that cerebellar Purkinje neuron atrophy serves an adaptive role rather than being simply a nonspecific response to injury. In acute cerebellar slices from SCA1 mice, we find that Purkinje neuron pacemaker firing is initially normal but, with the onset of motor dysfunction, becomes disrupted, accompanied by abnormal depolarization. Remarkably, subsequent Purkinje cell atrophy is associated with a restoration of pacemaker firing. The early inability of Purkinje neurons to support repetitive spiking is due to unopposed calcium currents resulting from a reduction in large-conductance calcium-activated potassium (BK) and subthreshold-activated potassium channels. The subsequent restoration of SCA1 Purkinje neuron firing correlates with the recovery of the density of these potassium channels that accompanies cell atrophy. Supporting a critical role for BK channels, viral-mediated increases in BK channel expression in SCA1 Purkinje neurons improves motor dysfunction and partially restores Purkinje neuron morphology. Cerebellar perfusion of flufenamic acid, an agent that restores the depolarized membrane potential of SCA1 Purkinje neurons by activating potassium channels, prevents Purkinje neuron dendritic atrophy. These results suggest that Purkinje neuron dendritic remodeling in ataxia is an adaptive response to increases in intrinsic membrane excitability. Similar adaptive remodeling could apply to other vulnerable neuronal populations in neurodegenerative disease. SIGNIFICANCE STATEMENT In neurodegenerative disease, neuronal atrophy has long been assumed to be an early nonspecific event preceding neuronal loss. However, in a mouse model of spinocerebellar ataxia type 1 (SCA1), we identify a previously unappreciated compensatory role for neuronal shrinkage. Purkinje neuron firing in these mice is initially normal, but is followed by abnormal membrane depolarization resulting from a reduction in potassium channels. Subsequently, these electrophysiological effects are counteracted by cell atrophy, which by restoring normal potassium channel membrane density, re-establishes pacemaker firing. Reversing the initial membrane depolarization improved motor function and Purkinje neuron morphology in the SCA1 mice. These results suggest that Purkinje neuron remodeling in ataxia is an active compensatory response that serves to normalize intrinsic membrane excitability.
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Moldovan M, Alvarez S, Rosberg MR, Krarup C. Persistent alterations in active and passive electrical membrane properties of regenerated nerve fibers of man and mice. Eur J Neurosci 2015; 43:388-403. [DOI: 10.1111/ejn.13047] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2015] [Revised: 07/31/2015] [Accepted: 08/13/2015] [Indexed: 12/12/2022]
Affiliation(s)
- Mihai Moldovan
- Department of Neuroscience and Pharmacology; University of Copenhagen; Copenhagen Denmark
- Department of Clinical Neurophysiology; NF3063 Rigshospitalet 9 Blegdamsvej 2100 Copenhagen Denmark
| | - Susana Alvarez
- Department of Neuroscience and Pharmacology; University of Copenhagen; Copenhagen Denmark
- Department of Clinical Neurophysiology; NF3063 Rigshospitalet 9 Blegdamsvej 2100 Copenhagen Denmark
| | - Mette R. Rosberg
- Department of Neuroscience and Pharmacology; University of Copenhagen; Copenhagen Denmark
- Department of Clinical Neurophysiology; NF3063 Rigshospitalet 9 Blegdamsvej 2100 Copenhagen Denmark
| | - Christian Krarup
- Department of Neuroscience and Pharmacology; University of Copenhagen; Copenhagen Denmark
- Department of Clinical Neurophysiology; NF3063 Rigshospitalet 9 Blegdamsvej 2100 Copenhagen Denmark
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Mondello SE, Kasten MR, Horner PJ, Moritz CT. Therapeutic intraspinal stimulation to generate activity and promote long-term recovery. Front Neurosci 2014; 8:21. [PMID: 24578680 PMCID: PMC3936503 DOI: 10.3389/fnins.2014.00021] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2013] [Accepted: 01/24/2014] [Indexed: 11/13/2022] Open
Abstract
Neuroprosthetic approaches have tremendous potential for the treatment of injuries to the brain and spinal cord by inducing appropriate neural activity in otherwise disordered circuits. Substantial work has demonstrated that stimulation applied to both the central and peripheral nervous system leads to immediate and in some cases sustained benefits after injury. Here we focus on cervical intraspinal microstimulation (ISMS) as a promising method of activating the spinal cord distal to an injury site, either to directly produce movements or more intriguingly to improve subsequent volitional control of the paretic extremities. Incomplete injuries to the spinal cord are the most commonly observed in human patients, and these injuries spare neural tissue bypassing the lesion that could be influenced by neural devices to promote recovery of function. In fact, recent results have demonstrated that therapeutic ISMS leads to modest but sustained improvements in forelimb function after an incomplete spinal cord injury (SCI). This therapeutic spinal stimulation may promote long-term recovery of function by providing the necessary electrical activity needed for neuron survival, axon growth, and synaptic stability.
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Affiliation(s)
- Sarah E Mondello
- Department of Rehabilitation Medicine, University of Washington Seattle, WA, USA ; Department of Neurological Surgery, University of Washington Seattle, WA, USA ; Center for Sensorimotor Neural Engineering, University of Washington Seattle, WA, USA
| | - Michael R Kasten
- Department of Rehabilitation Medicine, University of Washington Seattle, WA, USA
| | - Philip J Horner
- Department of Neurological Surgery, University of Washington Seattle, WA, USA ; Graduate Program in Neurobiology and Behavior, University of Washington Seattle, WA, USA
| | - Chet T Moritz
- Department of Rehabilitation Medicine, University of Washington Seattle, WA, USA ; Center for Sensorimotor Neural Engineering, University of Washington Seattle, WA, USA ; Graduate Program in Neurobiology and Behavior, University of Washington Seattle, WA, USA ; Department of Physiology and Biophysics, University of Washington Seattle, WA, USA
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