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Blackiston DJ, Levin M. Ectopic eyes outside the head in Xenopus tadpoles provide sensory data for light-mediated learning. ACTA ACUST UNITED AC 2013; 216:1031-40. [PMID: 23447666 DOI: 10.1242/jeb.074963] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
A major roadblock in the biomedical treatment of human sensory disorders, including blindness, has been an incomplete understanding of the nervous system and its ability to adapt to changes in sensory modality. Likewise, fundamental insight into the evolvability of complex functional anatomies requires understanding brain plasticity and the interaction between the nervous system and body architecture. While advances have been made in the generation of artificial and biological replacement components, the brain's ability to interpret sensory information arising from ectopic locations is not well understood. We report the use of eye primordia grafts to create ectopic eyes along the body axis of Xenopus tadpoles. These eyes are morphologically identical to native eyes and can be induced at caudal locations. Cell labeling studies reveal that eyes created in the tail send projections to the stomach and trunk. To assess function we performed light-mediated learning assays using an automated machine vision and environmental control system. The results demonstrate that ectopic eyes in the tail of Xenopus tadpoles could confer vision to the host. Thus ectopic visual organs were functional even when present at posterior locations. These data and protocols demonstrate the ability of vertebrate brains to interpret sensory input from ectopic structures and incorporate them into adaptive behavioral programs. This tractable new model for understanding the robust plasticity of the central nervous system has significant implications for regenerative medicine and sensory augmentation technology.
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Affiliation(s)
- Douglas J Blackiston
- Center for Regenerative and Developmental Biology and Department of Biology, Tufts University, 200 Boston Avenue, Suite 4600, Medford, MA 02155, USA
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Gullapalli VK, Khodair MA, Wang H, Sugino IK, Madreperla S, Zarbin MA. Transplantation Frontiers. Retina 2013. [DOI: 10.1016/b978-1-4557-0737-9.00125-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Retinal Pigment Epithelium and Photoreceptor Transplantation Frontiers. Retina 2006. [DOI: 10.1016/b978-0-323-02598-0.50159-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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Lund RD, Ono SJ, Keegan DJ, Lawrence JM. Retinal transplantation: progress and problems in clinical application. J Leukoc Biol 2003; 74:151-60. [PMID: 12885930 DOI: 10.1189/jlb.0103041] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
There is currently no real treatment for blinding disorders that stem from the degeneration of cells in the retina and affect at least 50 million individuals worldwide. The excitement that accompanied the first studies showing the potential of retinal cell transplantation to alleviate the progress of blindness in such diseases as retinitis pigmentosa and age-related macular degeneration has lost some of its momentum, as attempts to apply research to the clinic have failed so far to provide effective treatments. What these studies have shown, however, is not that the approach is flawed but rather that the steps that need to be taken to achieve a viable, clinical treatment are many. This review summarizes the course of retinal transplant studies and points to obstacles that still need to be overcome to improve graft survival and efficacy and to develop a protocol that is effective in a clinical setting. Emphasis is given particularly to the consequences of introducing transplants to sites that have been considered immunologically privileged and to the role of the major histocompatibility complex classes I and II molecules in graft survival and rejection.
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Affiliation(s)
- R D Lund
- Moran Eye Center, University of Utah, Salt Lake City, UT 84132, USA.
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Coffey PJ, Whiteley SJ, Lund RD. Preservation and restoration of vision following transplantation. PROGRESS IN BRAIN RESEARCH 2001; 127:489-99. [PMID: 11142043 DOI: 10.1016/s0079-6123(00)27024-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/18/2023]
Affiliation(s)
- P J Coffey
- Visual Transplantation Research Group, Department of Psychology, University of Sheffield, Western Bank, Sheffield S10 2TP, UK.
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Kwan AS, Wang S, Lund RD. Photoreceptor layer reconstruction in a rodent model of retinal degeneration. Exp Neurol 1999; 159:21-33. [PMID: 10486172 DOI: 10.1006/exnr.1999.7157] [Citation(s) in RCA: 95] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
We have examined the potential of retinal cell transplantation to dystrophic retinal degeneration mice as a way of replacing photoreceptors lost because of an intrinsic genetic defect. Early postnatal retinae which had been gently dissociated survived for at least 6 weeks after transplantation to the subretinal space. Over a significant area of distribution, transplanted cells formed outer segments which lay in close apposition to the host retinal pigment epithelial cell layer. The grafts integrated with the remaining host retina, sufficient at least to mediate a simple light-dark preference. A new synaptic layer was seen at the graft-host interface, which contained substantial numbers of photoreceptor synapses. This and the fact that the behavior could be elicited at low luminance levels argue for functional circuit reconstruction between grafted cells and host retina.
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MESH Headings
- 3',5'-Cyclic-GMP Phosphodiesterases/genetics
- 3',5'-Cyclic-GMP Phosphodiesterases/metabolism
- Animals
- Behavior, Animal
- Cyclic Nucleotide Phosphodiesterases, Type 6
- Darkness
- Disease Models, Animal
- Genes, Recessive
- Graft Survival
- Lighting
- Mice
- Mice, Congenic
- Mice, Inbred C57BL
- Mice, Mutant Strains
- Microscopy, Electron
- Mutation
- Phosphoric Diester Hydrolases
- Retina/surgery
- Retinal Rod Photoreceptor Cells/enzymology
- Retinal Rod Photoreceptor Cells/transplantation
- Retinal Rod Photoreceptor Cells/ultrastructure
- Retinitis Pigmentosa/genetics
- Retinitis Pigmentosa/therapy
- Vision, Ocular
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Affiliation(s)
- A S Kwan
- Neural Transplant Program Department of Pathology, Institute of Ophthalmology, University College London, Bath Street, London, EC1V 9EL, United Kingdom
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Sollars PJ, Pickard GE. Restoration of circadian behavior by anterior hypothalamic grafts containing the suprachiasmatic nucleus: graft/host interconnections. Chronobiol Int 1998; 15:513-33. [PMID: 9787939 DOI: 10.3109/07420529808998705] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Destruction of the hypothalamic suprachiasmatic nucleus (SCN) disrupts circadian behavior. Transplanting SCN tissue from fetal donors into SCN-lesioned recipients can restore circadian behavior to the arrhythmic hosts. In the transplantation model employing fetal hamster donors and SCN-lesioned hamsters as hosts, the period of the restored circadian behavior is hamster-typical. However, when fetal rat anterior hypothalamic tissue containing the SCN is implanted into SCN-lesioned rats, the period of the restored circadian rhythm is only rarely typical of that of the intact rat. The use of an anterior hypothalamic heterograft model provides new approaches to donor specificity of restored circadian behavior and with the aid of species-specific markers, provides a means for assessing connectivity between the graft and the host. Using an antibody that stains rat and mouse neuronal tissue but not hamster neurons, it has been demonstrated that rat and mouse anterior hypothalamic heterografts containing the SCN send numerous processes into the host (hamster) neuropil surrounding the graft, consistent with graft efferents reported in other hypothalamic transplantation models in which graft and host tissue can be differentiated (i.e., Brattleboro rat and hypogonadal mouse). Moreover, SCN neurons within anterior hypothalamic grafts send an appropriately restricted set of efferent projections to the host brain which may participate in the functional recovery of circadian locomotor activity.
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Affiliation(s)
- P J Sollars
- Department of Psychiatry, University of Pennsylvania School of Medicine, Philadelphia 19104, USA
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MacLaren RE. Regeneration and transplantation of the optic nerve: developing a clinical strategy. Br J Ophthalmol 1998; 82:577-83. [PMID: 9713068 PMCID: PMC1722609 DOI: 10.1136/bjo.82.5.577] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Three separate experimental models of optic nerve regeneration have been presented--along the existing pathway in the presence of antibodies to neutralise inhibitory molecules, along peripheral nerve grafts and from retinal transplants. Each offers a theoretical clinical strategy for restoration of vision, if the mechanism of re-establishment of maps and reconnection to appropriate targets during regeneration can be determined. This is the process of axon guidance, and underlines the importance of our research into the molecular determinants that guide normal development of the visual system.
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Affiliation(s)
- R E MacLaren
- Division of Ophthalmology, Royal Berkshire Hospital, Reading
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Maclaren RE, Taylor JS. Regeneration in the developing optic nerve: correlating observations in the opossum to other mammalian systems. Prog Neurobiol 1997; 53:381-98. [PMID: 9364617 DOI: 10.1016/s0301-0082(97)00041-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Regeneration of severed axons within the central nervous system of adult mammals does not normally occur with any degree of success. During development, however, newly forming projections must send axons to distant sites and form appropriate connections with their targets: successful regeneration has been observed during this critical period. The opossum central nervous system develops during early postnatal life and has provided a useful experimental model to investigate this specialized mode of axonal regeneration in mammals. The presence of a clear decision point at the optic chiasm has also provided a useful site at which to investigate the navigational capacity of retinal ganglion cells regenerating along the optic nerve during this critical period. Regeneration failure occurs as the central nervous system progresses from this permissive, developing state to a mature, non-permissive adult state. Studies into the behaviour of glial and neuronal elements around this transition period can help elucidate some of the factors that need to be overcome if regeneration is ever to become successful in adult mammals. The regeneration characteristics of a lesioned projection are dependent upon its developmental stage and are also related to the proximity of axotomy along its pathway. A system of staging is proposed to correlate observations in the opossum optic nerve to other mammalian systems.
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Affiliation(s)
- R E Maclaren
- Division of Ophthalmology, Royal Berkshire Hospital, London, Reading, U.K
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Sharma RK, Ehinger B. Retinal cell transplants: how close to clinical application? ACTA OPHTHALMOLOGICA SCANDINAVICA 1997; 75:355-63. [PMID: 9374240 DOI: 10.1111/j.1600-0420.1997.tb00390.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Affiliation(s)
- R K Sharma
- Department of Ophthalmology, Lund University Hospital, Sweden
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Abstract
Neural grafts can reverse many functional deficits associated with brain damage, whether of traumatic, toxic, neurodegenerative or genetic origin. In some model systems recovery can be partial or complete; whereas in others the grafts have limited effects or may actually cause further dysfunction. In order to devise rational and effective transplantation strategies it is necessary to understand the mechanisms by which grafts exert their functional effects. Several alternatives have been proposed, and these include non-specific consequences of surgery, acute diffuse neurotrophic and growth mechanisms, chronic diffuse release of deficient neurochemicals, bridging tissues for host regeneration, diffuse reinnervation of the host brain, and reciprocal graft-host reconnection. These alternative mechanisms are not necessarily exclusive in any particular situation, and all have been seen to apply in different model systems.
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Affiliation(s)
- S B Dunnett
- Cambridge Centre for Brain Repair, University of Cambridge, UK
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12
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Lau KC, So KF, Campbell G, Lieberman AR. Pupillary constriction in response to light in rodents, which does not depend on central neural pathways. J Neurol Sci 1992; 113:70-9. [PMID: 1469457 DOI: 10.1016/0022-510x(92)90267-o] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
We show here that the widely held belief that reflex constriction of the mammalian pupil in response to light depends exclusively upon neural pathways between eye and brain is in need of revision. We investigated the response of the pupil to light in dark-adapted rodents (golden hamsters; hooded rats; albino rats) subjected to a variety of surgical and pharmacological interventions designed to destroy or block all of the neural pathways and structures through which the reflex could be mediated. The interventions included bilateral intraorbital optic nerve section, or unilateral intracranial optic nerve section with enucleation of the contralateral eye, combined in some cases with bilateral removal of the superior cervical ganglia and/or pinealectomy; topical application of atropine; intraocular injection of tetrodotoxin (TTX). Golden hamsters and hooded rats, but not albino rats, retained an effective constriction of the pupil in response to light after all of these interventions, although the constriction was less and slower than in normal animals. These findings show that hamsters and hooded rats have both a neurally mediated fast light reflex that can be eliminated by severing connections between eye and brain, by blockade of cholinergic transmission to iris smooth muscle, and by blockade of action potentials by TTX; and a local, slower constriction in response to light, which remains after all these procedures. We have also confirmed previous observations of Bito and Turansky (1975) that pupillary constriction in response to light occurs in isolated in vitro anterior chamber preparations of hamster and hooded rat eyes.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- K C Lau
- Department of Anatomy, University of Hong Kong
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Banerjee R, Lund RD. A role for microglia in the maintenance of photoreceptors in retinal transplants lacking pigment epithelium. JOURNAL OF NEUROCYTOLOGY 1992; 21:235-43. [PMID: 1588345 DOI: 10.1007/bf01224758] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Studies on intact retina have pointed to a necessary role for retinal pigment epithelium in the maintenance of photoreceptor outer segments and for regeneration of visual pigment. However, it has been shown that when embryonic retinae are separated from the pigment epithelium and transplanted into the brain of neonatal rats, the transplanted photoreceptors develop outer segments and the retina responds to light in the apparent absence of pigment epithelial cells. We confirm that there are no retinal pigment epithelium cells associated with transplanted retinae in the present series of experiments and show that a row of cells, composed predominantly of microglia of host origin, border the graft. These cells can be seen to contain engulfed outer segments when they are apposed to the outer retina, suggesting that the microglia have assumed, at the least, the phagocytic function normally associated with retinal pigment epithelium. Microglial cells and their processes are also found within the transplant, but these cells are typically devoid of phagosomes, indicating an absence of phagocytic activity. The close physical association of these resting microglia with the transplant may facilitate their role in antigen presentation under specific conditions of immune provocation.
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Affiliation(s)
- R Banerjee
- Department of Anatomy, University of Cambridge, UK
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