The optic nerve is responsible for transmitting the electrical impulses it receives from the photoreceptors of the retina to the brain, enabling us to see. If this nerve becomes damaged, as a result of disease (such as, for example, glaucoma) or from trauma, impairment or loss of vision will result. Damage to this nerve is normally irreversible; however, researchers have recently found a way to regenerate its growth (in a rat) by using embryonic stem cells derived from the neural tube of chickens (NTSCs) at stage 10 of embryological development.
The optic nerve consists of the axons of the ganglion cells of the retina. When the nerve is damaged, these axons cannot pass within its interior because of a lack of myelin or build-up of scar tissue from glial cells. NTSCs have been found to promote the regeneration of these axons by producing neurotrophic factors which stimulate axonal growth. The NTSCs were also found to create a microenvironment which enabled axon elongation. This is thought to be due to the workings of two metallopeptidases (MMP2 and MMP14) – genes involved in the degradation of extracellular matrix (in this case, the glial scar tissue). There was found to be an up-regulation of these genes in the grafting site, possibly directly due to the NTSCs (although this is still under investigation). The time taken for the axons to reach the brain was approximately six to eight weeks after the surgery. These findings have important implications for the future of repairing neural injuries in other species. However, there still exists the ethical problem of using animals for these experiments.
Written by: s4140034
Primary source:
1.) Charalambous, P., Hurst, L.A., Thanos, S., 2008. “Engrafted chicken neural tube derived stem cells support the innate propensity for axonal regeneration within the rat optic nerve”, Investigative Ophthalmology and Visual Science, April 11 [EPub ahead of print], viewed 29 May 2008, <http://www.iovs.org/cgi/rapidpdf/iovs.07-1473v1>.
Secondary sources:
2.) Barnard, S., ‘An introduction to diseases of the optic nerve’, American Academy of Optometry, viewed 29 May, 2008, <http://www.academy.org.uk/lectures/barnard3.htm>.
3.) ‘Neurotrophic factors’, Ceregene, viewed 29 May 2008, <http://www.ceregene.com/neurotrophic.asp>.
4.) Hill, M., 2007. ‘Chicken Development Stages’, University of NSW Embryology, viewed 29 May, 2008, <http://embryology.med.unsw.edu.au/OtherEmb/chick2.htm>.
Image source:
Rural Ramblings <http://www.ruralramblings.com/blog/2007_07_01_archive.html>
The optic nerve consists of the axons of the ganglion cells of the retina. When the nerve is damaged, these axons cannot pass within its interior because of a lack of myelin or build-up of scar tissue from glial cells. NTSCs have been found to promote the regeneration of these axons by producing neurotrophic factors which stimulate axonal growth. The NTSCs were also found to create a microenvironment which enabled axon elongation. This is thought to be due to the workings of two metallopeptidases (MMP2 and MMP14) – genes involved in the degradation of extracellular matrix (in this case, the glial scar tissue). There was found to be an up-regulation of these genes in the grafting site, possibly directly due to the NTSCs (although this is still under investigation). The time taken for the axons to reach the brain was approximately six to eight weeks after the surgery. These findings have important implications for the future of repairing neural injuries in other species. However, there still exists the ethical problem of using animals for these experiments.
Written by: s4140034
Primary source:
1.) Charalambous, P., Hurst, L.A., Thanos, S., 2008. “Engrafted chicken neural tube derived stem cells support the innate propensity for axonal regeneration within the rat optic nerve”, Investigative Ophthalmology and Visual Science, April 11 [EPub ahead of print], viewed 29 May 2008, <http://www.iovs.org/cgi/rapidpdf/iovs.07-1473v1>.
Secondary sources:
2.) Barnard, S., ‘An introduction to diseases of the optic nerve’, American Academy of Optometry, viewed 29 May, 2008, <http://www.academy.org.uk/lectures/barnard3.htm>.
3.) ‘Neurotrophic factors’, Ceregene, viewed 29 May 2008, <http://www.ceregene.com/neurotrophic.asp>.
4.) Hill, M., 2007. ‘Chicken Development Stages’, University of NSW Embryology, viewed 29 May, 2008, <http://embryology.med.unsw.edu.au/OtherEmb/chick2.htm>.
Image source:
Rural Ramblings <http://www.ruralramblings.com/blog/2007_07_01_archive.html>
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