Reconstruction of the glial environment of a photochemically induced lesion in the rat spinal cord by transplantation of mixed glial cells (original) (raw)
Related papers
2011
S pinal cord injury often results in permanent neurological impairment due to glial activation, oxidative stress, inflammation, cell death, and axon fiber disruption. 9,28 Severed axons are unable to regenerate for many reasons. First of all, regeneration is made difficult by progressive tissue cavitation (formation of a glial cyst, in which macrophage and microglial infiltration occurs). In addition, astrocytes become hypertrophic through increased production of intermediate filaments, giving rise to reactive astrogliosis, and finally surrounding the lesion site and producing a glial scar. 29,45 The role of the glial scar is still unclear, but it represents a physical and biological barrier for axonal regeneration. 13,45 However, recent evidence indicates that it might play several beneficial roles in protecting tissue and preserving function after neurotrauma; in fact, astrocytes can support axonal regrowth, limit neuronal degeneration and inflammation, and repair the blood-brain barrier through production of antiinflammatory cytokines and neurotrophic factors such as LIF (leukemia inhibitory factor), IGF (insulinlike growth factor), EGF (epidermal growth factor), NGF, FGF, and CNTF. 12,33,41,42 One of the most promising strategies for spinal cord repair is transplantation of stem cells into the lesion site. 2,14,44 Different types of stem cells have been used, 7,14,43,52 but to date none has been found to result in a full repair. The greatest regenerative capacity and potential to repair the spinal cord were obtained with cells collected from the immature CNS. In particular, the mouse neural tube at embryonic Day 9 contains multipotent neuroepithelial stem cells that at embryonic Day 12 give rise to lineage-restricted self-renewing NPs, including neuronal-and glial-restricted precursor cells. 31 Neural precursor cells injected into injured rats showed great survival, Early graft of neural precursors in spinal cord compression reduces glial cyst and improves function Laboratory investigation
Astrocytes derived from glial-restricted precursors promote spinal cord repair
Journal of biology, 2006
Transplantation of embryonic stem or neural progenitor cells is an attractive strategy for repair of the injured central nervous system. Transplantation of these cells alone to acute spinal cord injuries has not, however, resulted in robust axon regeneration beyond the sites of injury. This may be due to progenitors differentiating to cell types that support axon growth poorly and/or their inability to modify the inhibitory environment of adult central nervous system (CNS) injuries. We reasoned therefore that pre-differentiation of embryonic neural precursors to astrocytes, which are thought to support axon growth in the injured immature CNS, would be more beneficial for CNS repair. Transplantation of astrocytes derived from embryonic glial-restricted precursors (GRPs) promoted robust axon growth and restoration of locomotor function after acute transection injuries of the adult rat spinal cord. Transplantation of GRP-derived astrocytes (GDAs) into dorsal column injuries promoted gr...
Experimental Neurology, 2004
Transplantation of stem cells and immature cells has been reported to ameliorate tissue damage, induce axonal regeneration, and improve locomotion following spinal cord injury. However, unless these cells are pushed down a neuronal lineage, the majority of cells become glia, suggesting that the alterations observed may be potentially glially mediated. Transplantation of glial-restricted precursor (GRP) cells—a precursor cell population restricted to oligodendrocyte and astrocyte lineages—offers a novel way to examine the effects of glial cells on injury processes and repair. This study examines the survival and differentiation of GRP cells, and their ability to modulate the development of the lesion when transplanted immediately after a moderate contusion injury of the rat spinal cord. GRP cells isolated from a transgenic rat that ubiquitously expresses heat-stable human placental alkaline phosphatase (PLAP) were used to unambiguously detect transplanted GRP cells. Following transplantation, some GRP cells differentiated into oligodendrocytes and astrocytes, retaining their differentiation potential after injury. Transplanted GRP cells altered the lesion environment, reducing astrocytic scarring and the expression of inhibitory proteoglycans. Transplanted GRP cells did not induce long-distance regeneration from corticospinal tract (CST) and raphe-spinal axons when compared to control animals. However, GRP cell transplants did alter the morphology of CST axons toward that of growth cones, and CST fibers were found within GRP cell transplants, suggesting that GRP cells may be able to support axonal growth in vivo after injury.
Neurotherapeutics, 2011
This review summarizes current progress on development of astrocyte transplantation therapies for repair of the damaged central nervous system. Replacement of neurons in the injured or diseased central nervous system is currently one of the most popular therapeutic goals, but if neuronal replacement is attempted in the absence of appropriate supporting cells (astrocytes and oligodendrocytes), then the chances of restoring neurological functional are greatly reduced. Although the past 20 years have offered great progress on oligodendrocyte replacement therapies, astrocyte transplantation therapies have been both less explored and comparatively less successful. We have now developed successful astrocyte transplantation therapies by pre-differentiating glial restricted precursor (GRP) cells into a specific population of GRP cell-derived astrocytes (GDAs) by exposing the GRP cells to bone morphogenetic protein-4 (BMP) prior to transplantation. When transplanted into transected rat spinal cord, rat and human GDAs BMP promote extensive axonal regeneration, rescue neuronal cell survival, realign tissue structure, and restore behavior to pre-injury levels on a grid-walk analysis of volitional foot placement. Such benefits are not provided by GRP cells themselves, demonstrating that the lesion environment does not direct differentiation in a manner optimally beneficial for the restoration of function. Such benefits also are not provided by transplantation of a different population of astrocytes generated from GRP cells exposed to ciliary neurotrophic factor (GDAs CNTF), thus providing the first transplantation-based evidence of functional heterogeneity in astrocyte populations. Moreover, lessons learned from the study of rat cells are strongly predictive of outcomes using human cells. Thus, these studies provide successful strategies for the use of astrocyte transplantation therapies for restoration of function following spinal cord injury. Keywords Glial-restricted precursor cells. Glial precursor cell-derived astrocyte. Spinal cord injury. Regeneration. Astrocyte transplantation therapy. Astrocyte heterogeneity Abbreviations AMPA a-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid AQP4 aquaporin 4 BMP bone morphogenetic protein-4 CNS central nervous system CNTF ciliary neurotrophic factor CSPG chondroitin sulfate proteoglycan DFL dorsolateral funiculus ESC embryonic stem cell FGF fibroblast growth factor GDA GRP-derived astrocyte GDNF glial-derived neurotrophic factor GFAP glial fibrillary acidic protein GLT-1 glutamate transporter 1 Christoph Pröschel and Stephen J. E. Davies contributed equally to this review.
Experimental Neurology, 2012
Although astrocytes are involved in the production of an inhibitory glial scar following injury, they are also capable of providing neuroprotection and supporting axonal growth. There is growing appreciation for a diverse and dynamic population of astrocytes, specified by a variety of glial precursors, whose function is regulated regionally and temporally. Consequently, the therapeutic application of glial precursors and astrocytes by effective transplantation protocols requires a better understanding of their phenotypic and functional properties and effective protocols for their preparation. We present a systematic analysis of astrocyte differentiation using multiple preparations of glial-restricted precursors (GRP), evaluating their morphological and phenotypic properties following treatment with fetal bovine serum (FBS), bone morphogenetic protein 4 (BMP-4), or ciliary neurotrophic factor (CNTF) in comparison to controls treated with basic fibroblast growth factor (bFGF), which maintains undifferentiated GRP. We found that treatments with FBS or BMP-4 generated similar profiles of highly differentiated astrocytes that were A2B5−/GFAP+. Treatment with FBS generated the most mature astrocytes, with a distinct and nearhomogeneous morphology of fibroblast-like flat cells, whereas BMP-4 derived astrocytes had a stellate, but heterogeneous morphology. Treatment with CNTF induced differentiation of GRP to an intermediate state of GFAP+ cells that maintained immature markers and had relatively long processes. Furthermore, astrocytes generated by BMP-4 or CNTF showed considerable experimental plasticity, and their morphology and phenotypes could be reversed with complementary treatments along a wide range of mature-immature states. Importantly, when GRP or GRP treated with BMP-4 or CNTF were transplanted acutely into a dorsal column lesion of the spinal cord, cells from all 3 groups survived and generated permissive astrocytes that supported axon growth and regeneration of host sensory axons into, but not out of the lesion. Our study underscores the dynamic nature of astrocytes prepared from GRP and their permissive properties, and suggest that future therapeutic applications in restoring connectivity following CNS injury are likely to require a combination of treatments.
Integration of genetically modified adult astrocytes into the lesioned rat spinal cord
Journal of Neuroscience Research, 2006
Combination of ex vivo gene transfer and cell transplantation is now considered as a potentially useful strategy for the treatment of spinal cord injury. In a perspective of clinical application, autologous transplantation could be an option of choice. We analyzed the fate of adult rat cortical astrocytes genetically engineered with a lentiviral vector transplanted into a lesioned rat spinal cord. Cultures of adult rat cortical astrocytes were infected with an HIV-1-derived vector (TRIP-CMV-GFP) and labeled with the fluorescent dye Hoechst. Transfected and labeled astrocyte suspension was injected at T11 in rats in which spinal cord transection at T7-T8 levels had been carried out 1 week earlier. Six weeks after grafting, the animals were sacrificed and transplants were retrieved either by Hoechst fluorescence or by immunohistochemistry for detection of glial fibrillary acidic protein (GFAP) and vimentin. Grafted astrocytes expressing green fluorescent protein (GFP) were found both at the injection and transection sites. Genetically modified astrocytes thus survived, integrated, and migrated within the host parenchyma when grafted into the completely transected rat spinal cord. In addition, they retained some ability to express the GFP transgene for at least 6 weeks after transplantation. Adult astrocytes infected with lentiviral vectors can therefore be a valuable tool for the delivery of therapeutic factors into the lesioned spinal cord. V V C 2005 Wiley-Liss, Inc.
Development, regeneration, and neoplasia of glial cells in the central nervous system
Annals of the New …, 1991
Our studies on glial cell biology are concerned with three related goals: (1) the elucidation of basic principles involved in the control of glial cell division and differentiation; (2) the development of cellular and molecular biological approaches to understanding diseases of the human central nervous system (CNS) that involve glial cells; and (3) the development of precursor cell transplantation as an approach to the repair of damaged tissues. In this review we summarize our present knowledge about glial precursors, oligodendrocytic differentiation, and the relationship between glial cells and human gliomas. We also discuss a new approach to the isolation of precursors and novel cell lines that we believe will dramatically enhance our abilities to identify new precursors and study their properties.