Development and regeneration in the central nervous system

As part of our attempts to understand principles that underly organism development, we have been studying the development of the rat optic nerve. This simple tissue is composed of three glial cell types derived from two distinct cellular lineages. Type-1 astrocytes appear to be derived from a monopotential neuroepithelial precursor, whereas type-2 astrocytes and oligodendrocytes are derived from a common oligodendrocyte-type-2 astrocyte (O-2A) progenitor cell. Type-1 astrocytes modulate division and differentiation of O-2A progenitor cells through secretion of platelet-derived growth factor, and can themselves be stimulated to divide by peptide mitogens and through stimulation of neurotransmitter receptors. In vitro analysis indicates that many dividing O-2A progenitors derived from optic nerves of perinatal rats differentiate symmetrically and clonally to give rise to oligodendrocytes, or can be induced to differentiate into type-2 astrocytes. O-2A perinatal progenitors can also differentiate to form a further O-2A lineage cell, the O-2A adult progenitor, which has properties specialized for the physiological requirements of the adult nervous system. In particular, O-2A adult progenitors have many of the features of stem cells, in that they divide slowly and asymmetrically and appear to have the capacity for extended self-renewal. The apparent derivation of a slowly and asymmetrically dividing cell, with properties appropriate for homeostatic maintenance of existing populations in the mature animal, from a rapidly dividing cell with properties suitable for the rapid population and myelination of central nervous system (CNS) axon tracts during early development, offers novel and unexpected insights into the possible origin of self-renewing stem cells and also into the role that generation of stem cells may play in helping to terminate the explosive growth of embryogenesis. Moreover, the properties of O-2A adult progenitor cells are consistent with, and may explain, the failure of successful myelin repair in conditions such as multiple sclerosis, and thus seem to provide a cellular biological basis for understanding one of the key features of an important human disease.

1995 ◽  
Vol 108 (8) ◽  
pp. 2747-2760 ◽  
Author(s):  
A. Webb ◽  
P. Clark ◽  
J. Skepper ◽  
A. Compston ◽  
A. Wood

Oligodendrocyte progenitors arise in subventricular zones and migrate extensively during development before differentiating into mature oligodendrocytes, which myelinate nerve tracts in the central nervous system. We have used microfabricated substrata, containing periodic patterns of contours similar to those of central nervous system axons to assess the influence in vitro of substratum topography on oligodendrocytes isolated from 7 day rat optic nerve. Antiganglioside antibody A2B5 positive oligodendrocyte-type 2 astrocyte progenitors, and galactocerebroside positive and myelin basic protein positive oligodendrocytes, were highly aligned by surface contours as small as 100 nm depth and 260 nm repeat spacing. Rat optic nerve astrocytes also aligned on surface contours, but rat hippocampal and cerebellar neurons were unresponsive. Oligodendrocytes demonstrated enhanced parallel extension of their processes on narrow repeating topography in an arrangement similar to that found in the intact optic nerve. This is in marked contrast to the phenotype displayed by this cell type on planar substrata. Neither oligodendrocytes nor oligodendrocyte-type 2 astrocyte progenitors showed high-order F-actin cytoskeletal networks; thus their alignment on gratings is unlikely to result from deformation of actin cables and focal contacts. In contrast, aligned astrocytes showed striking arrangements of actin stress fibres. These results establish glial cells as potentially the most topographically sensitive cell types within the central nervous system. Furthermore, the topographical pattern inducing maximal alignment of oligodendrocyte lineage cells corresponds to the diameters of single axons within the 7 day optic nerve. Thus the migration of oligodendrocyte-type 2 astrocyte progenitors and axonal ensheathment by oligodendrocytes may be guided by axonal topography within the developing nerve.


Author(s):  
Prithiv K R Kumar

Stem cells have the capacity to differentiate into any type of cell or organ. Stems cell originate from any part of the body, including the brain. Brain cells or rather neural stem cells have the capacitive advantage of differentiating into the central nervous system leading to the formation of neurons and glial cells. Neural stem cells should have a source by editing DNA, or by mixings chemical enzymes of iPSCs. By this method, a limitless number of neuron stem cells can be obtained. Increase in supply of NSCs help in repairing glial cells which in-turn heal the central nervous system. Generally, brain injuries cause motor and sensory deficits leading to stroke. With all trials from novel therapeutic methods to enhanced rehabilitation time, the economy and quality of life is suppressed. Only PSCs have proven effective for grafting cells into NSCs. Neurons derived from stem cells is the only challenge that limits in-vitro usage in the near future.


1973 ◽  
Vol 138 (3) ◽  
pp. 740-744 ◽  
Author(s):  
F. B. Knotts ◽  
M. L. Cook ◽  
J. G. Stevens

Herpes simplex virus (HSV) type 1 induces a long-standing latent infection in the central nervous system of mice and rabbits. The infection was extablished in the brain stems of rabbits after corneal inoculation of the virus, and in the spinal cords of mice after rear footpad infection. In these animals, infectious virus could not be recovered by direct isolation from tissues; it was detected only after the tissues were maintained as organ cultures in vitro.


1990 ◽  
Vol 111 (1) ◽  
pp. 209-215 ◽  
Author(s):  
A da Cunha ◽  
L Vitković

Growth-associated protein 43 (GAP-43) is an abundant, intensely investigated membrane phosphoprotein of the nervous system (Benowitz, L.I., and A. Routtenberg. 1987. Trends Neurosci. 10:527-532; Skene, J. H. P. 1989. Annu. Rev. Neurosci. 12:127-156), with a hitherto unknown function. We have previously demonstrated that astrocytes, brain macroglial cells, contain GAP-43 (Steisslinger, H. W., V. J. Aloyo, and L. Vitković, 1987. Brain Res. 415:375-379; Vitković, L., H. W. Steisslinger, V. J. Aloyo, and M. Mersel. 1988. Proc. Natl. Acad. Sci. USA. 85:8296-8300; Vitković L., and M. Mersel. 1989. Metab. Brain Dis. 4:47-53). Results from double immunofluorescent labeling experiments presented here show that oligodendrocytes also contain GAP-43 immunoreactivity (GAP-43ir). Thus, all three macroglial cell types of the central nervous system (type I and type 2 astrocytes and oligodendrocytes) contain GAP-43. Whereas immunoreactive GAP-43 is expressed by progenitors of all macroglial cell types, the developmental regulation of its expression is cell type specific. Immunoreactive GAP-43 is downregulated in type 1 astrocytes, and constitutively expressed in both type 2 astrocytes and oligodendrocytes. These results may be relevant to potential function(s) of GAP-43.


Development ◽  
1989 ◽  
Vol 105 (3) ◽  
pp. 595-603 ◽  
Author(s):  
I.K. Hart ◽  
W.D. Richardson ◽  
C.H. Heldin ◽  
B. Westermark ◽  
M.C. Raff

It has been shown previously that cultures of rat optic nerve contain three types of macroglial cells—oligodendrocytes and two types of astrocytes. Type-1 astrocytes develop from their own precursor cells beginning before birth, while oligodendrocytes and type-2 astrocytes develop postnatally from a common bipotential precursor called the O-2A progenitor cell. Proliferating O-2A progenitor cells give rise to postmitotic oligodendrocytes beginning around birth, and to type-2 astrocytes beginning in the second postnatal week. Studies in vitro have suggested that platelet-derived growth factor (PDGF), secreted by type-1 astrocytes, plays an important part in timing oligodendrocyte development: PDGF seems to keep O-2A progenitor cells proliferating until an intrinsic clock in the progenitor cells initiates the process leading to oligodendrocyte differentiation. The clock apparently determines when a progenitor cell becomes unresponsive to PDGF, at which point the cell stops dividing and, as a consequence, automatically differentiates into an oligodendrocyte. Here we have used radiolabelled PDGF to show that O-2A progenitor cells have PDGF receptors, suggesting that these cells respond directly to PDGF. The receptors resemble the type A PDGF receptor previously described on human fibroblasts and are initially retained when progenitor cells stop dividing and develop in vitro into oligodendrocytes. The latter finding indicates that receptor loss is not the reason that progenitor cells initially become mitotically unresponsive to PDGF.


2021 ◽  
Vol 22 (8) ◽  
pp. 4085
Author(s):  
Hanadi Ananbeh ◽  
Petr Vodicka ◽  
Helena Kupcova Skalnikova

Huntington’s disease (HD) is a rare hereditary autosomal dominant neurodegenerative disorder, which is caused by expression of mutant huntingtin protein (mHTT) with an abnormal number of glutamine repeats in its N terminus, and characterized by intracellular mHTT aggregates (inclusions) in the brain. Exosomes are small extracellular vesicles that are secreted generally by all cell types and can be isolated from almost all body fluids such as blood, urine, saliva, and cerebrospinal fluid. Exosomes may participate in the spreading of toxic misfolded proteins across the central nervous system in neurodegenerative diseases. In HD, such propagation of mHTT was observed both in vitro and in vivo. On the other hand, exosomes might carry molecules with neuroprotective effects. In addition, due to their capability to cross blood-brain barrier, exosomes hold great potential as sources of biomarkers available from periphery or carriers of therapeutics into the central nervous system. In this review, we discuss the emerging roles of exosomes in HD pathogenesis, diagnosis, and therapy.


1999 ◽  
Vol 73 (10) ◽  
pp. 8640-8646 ◽  
Author(s):  
Angela N. Cauthen ◽  
Corrie C. Brown ◽  
Katherine R. Spindler

ABSTRACT Previous attempts to construct a mouse adenovirus type 1 early region 3 (E3) null mutant by initiator codon mutagenesis were unsuccessful because one of the E3 proteins, gp11K, is synthesized as a fusion protein from a late viral mRNA (A. N. Cauthen and K. R. Spindler, Virology 259:119–128, 1999). Therefore, a different mutagenesis strategy was employed that inserted termination codons into all three reading frames of the E3 proteins. This strategy produced a mutant, pmE314, that was null for the expression of E3 proteins as determined by immunoprecipitation with E3-specific antisera. This mutant grew as well as wild-type (wt) virus in both 3T6 mouse fibroblasts and mouse brain microvascular endothelial cells. However, the 50% lethal dose for pmE314 in adult NIH Swiss outbred mice was approximately 6 log units higher than that of wt virus, indicating that pmE314 was less virulent in mice. In situ hybridization experiments revealed that the absence of the E3 proteins did not alter the tropism of the mutant virus from that of wt virus. When the histopathology was evaluated, the characteristics of the pmE314 infection at both doses administered were strikingly different from those exhibited by wt virus. The central nervous system of wt-infected mice exhibited damage to the endothelium and recruitment of inflammatory cells, whereas the central nervous system of pmE314-infected mice showed no inflammatory response and only mild signs of endothelial damage.


1997 ◽  
Vol 19 (1) ◽  
pp. 1-12 ◽  
Author(s):  
Yuichi Inoue ◽  
Yutaka Nemoto ◽  
Takahiko Tashiro ◽  
Keiko Nakayama ◽  
Tetsuo Nakayama ◽  
...  

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