Free Radicals and Aging of Anterior Segment Tissues of the Eye: A Hypothesis

Green, Keith

doi:10.1159/000267860

Cited by 76 publications

(46 citation statements)

References 23 publications

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“…Inúmeros estudos experimentais já sugeriram a relação entre as espécies ativas de oxigênio e a fisiopatologia de muitas doenças, incluindo o enfisema pulmonar, a doença de Parkinson, a doença de Alzheimer, o câncer, a hipertensão arterial sistêmica, a aterosclerose, a degeneração macular relacionada à idade e a catarata (6) . Substâncias químicas exógenas têm sido testadas para neutralizar esses efeitos e também para minimizar as reações degenerativas do envelhecimento (7)(8) . A doença e as estruturas oculares mais estudadas com relação ao estresse oxidativo, são respectivamente, o glaucoma, a córnea, o cristalino, a retina e a úvea.…”

Section: Potencial Antioxidativo Da Lágrima De Adultos Jovensunclassified

“…A doença e as estruturas oculares mais estudadas com relação ao estresse oxidativo, são respectivamente, o glaucoma, a córnea, o cristalino, a retina e a úvea. As publicações consistem, em sua maioria, em protocolos com animais, porém, alguns estudos já foram realizados em humanos (7,(9)(10) . A lágrima é estrutura vital para uma boa visão e, sendo ela de fácil acesso, este estudo preconiza estabelecer uma medida padrão de atividade antioxidante em adultos jovens, com risco muito baixo aos pacientes.…”

Section: Potencial Antioxidativo Da Lágrima De Adultos Jovensunclassified

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Potencial antioxidativo da lágrima de adultos jovens

Gus

Belló‐Klein

Llesuy

et al. 2006

Arq. Bras. Oftalmol.

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Section: Potencial Antioxidativo Da Lágrima De Adultos Jovensunclassified

Potencial antioxidativo da lágrima de adultos jovens

Gus

Belló‐Klein

Llesuy

et al. 2006

Arq. Bras. Oftalmol.

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“…La perte endothéliale spontanée est sans doute liée à l'exposition aux UV et au stress oxydatif par les radicaux libres (GREEN, 1995).…”

Section: Le Vieillissement De La Surface Oculaireunclassified

Le vieillissement de l’oeil chez l’animal

Rosolen¹

2005

bavf

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Ageing is the effect of time that predisposes beings to death. The study of the biology of ageing shows that certain molecular phenomenons are responsible for cellular and tissue modifications, including an increase in collagen rigidity, namely at the blood vessel level, in addition to an accumulation of “old” un-degraded molecules. In addition, oxygen, which is essential for life, gives rise to free radicals which attack different cellular molecules, DNA, lipids and proteins once it is metabolized. The brain is particularly susceptible to the mechanisms, given that it is a tissue that consumes high quantities of oxygen in order to carry out neuronal activity. Furthermore, the lack of neuronal renewal makes this tissue vulnerable to such injury. The eye is an example of such a vulnerable area, since retinal tissue is the highest consumer of oxygen and glucose. The choroid is responsible for supplying the retina with oxygen and glucose through numerous fenestrated blood vessels that allow photoreceptor oxygen concentrations to reach levels close to that found in the blood. The accumulation of glycation products in the lens and the irido-corneal angle favors the development of cataracts and a «thickening» of the trabeculum which results in a reduction of aqueous humor leakage that leads to an increase in intra-ocular pressure, and finally glaucoma. At the ocular surface, ageing of the extracellular stromal matrix is characterized by the increase in interfibrillary and intramolecular spacing of collagen which leaves room for the accumulation of glycation products. The eye is an organ which is particularly sensitive to the effects of ageing. An ophthalmic exam allows for the detection of various markers of ageing at the ocular surface, the irido-corneal angle, the lens and the fundus. These exams give information on the physiologic state of the ageing animal. Finally, it is interesting to note that, similar to man, the life expectancy of pets is increasing, thus revealing the same type of pathologies related to ageing. The eye is an «observation window» which is easily accesible in terms of not only the microcirculation, but also of the cerebral neurological state.

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“…A better understanding of the presence of progenitor cells in the TM and the dynamics of cell turnover in the TM may be important to help clarify the mechanisms involved in the functional failure of this tissue in glaucoma. The TM is exposed to chronic insults, such as oxidative, mechanical, and phagocytic stress, that can result in the death of TM cells (Spector and Garner, 1981;Johnson et al, 1989;Green, 1995;). A decline in the ability of the TM tissue to replace lost cells with new cells could be a contributing factor to the malfunction of this tissue in glaucoma.…”

Section: Introductionmentioning

confidence: 99%

Characterization of free-floating spheres from human trabecular meshwork (HTM) cell culture in vitro

González¹,

Epstein²,

Luna³

et al. 2006

Experimental Eye Research

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It has been observed in several tissues that direct isolation of cells in serum-free media and on nonadhesive substrates results in the formation of spherical clusters of cells known as free-floating spheres. Such free-floating spheres have been hypothesized to contain undifferentiated multipotent progenitor cells. Our goal was to isolate and characterize such free-floating spheres from HTM cell primary cultures.For this purpose, HTM cells were incubated in serum-free media and on a nonadhesive substrate. Individual free-floating spheres generated in these conditions were isolated in 96-well plates, and their proliferative capacity was evaluated by monitoring their size increase over time. The expression of the TM markers, MGP and CHI3L1, was examined using recombinant adenoviruses containing the respective promoters. Morphology of the free-floating spheres was analysed in semithin sections, and the gene expression profile was obtained using Human Genome U133 Plus 2.0 Affymetrix microarrays.HTM cells incubated in serum-free media and on nonadhesive substrate generated free-floating spheres that could be grown for more than 3 months. Addition of serum to the culture media promoted the attachment of the spheres to the substrate, migration of cells from the spheres, and differentiation into cells phenotypically similar to normal TM cells. Gene profiling analysis demonstrated strong similarities between the gene expression profiles of the spheres and HTM cell monolayers. Both infection with the recombinant adenoviruses and gene array analysis demonstrated the expression of CHI3L1 and MGP, indicating that free-floating spheres likely originate from HTM cells. Gene array analysis also showed expression of the marker for neural precursor cells nestin, as well as leukemia inhibitory factor, a gene involved in the maintenance of the undifferentiated state of progenitor cells. Analysis of semithin sections indicated that these TM free-floating spheres were highly dynamic structures demonstrating a distinct radial gradient of cell proliferation, survival, and apoptosis. Extensive up-and down-regulation of gene expression was associated with the processes of sphere attachment and cell migration after the addition of serum.These results suggest that HTM primary cultures might contain relatively undifferentiated or progenitor cells. The availability of TM progenitor cell cultures could constitute a useful tool to investigate cell therapy approaches targeting the TM in glaucoma.

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Free Radicals and Aging of Anterior Segment Tissues of the Eye: A Hypothesis

Cited by 76 publications

References 23 publications

Potencial antioxidativo da lágrima de adultos jovens

Potencial antioxidativo da lágrima de adultos jovens

Le vieillissement de l’oeil chez l’animal

Characterization of free-floating spheres from human trabecular meshwork (HTM) cell culture in vitro

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