ABSTRACT
OBJECTIVES: Erythropoietin may have neuroprotective potential after ischemia of the central nervous system. Here, we conducted a study to characterize the protective effects of erythropoietin on retinal ganglion cells and gliotic reactions in an experimentally induced oligemia model. METHODS: Rats were subjected to global oligemia by bilateral common carotid artery occlusion and then received either vehicle or erythropoietin via intravitreal injection after 48 h; they were euthanized one week after the injection. The densities of retinal ganglion cells and contents of glial fibrillary acidic protein (astrocytes/Müller cells) and cluster of differentiation 68 clone ED1 (microglia/macrophages), assessed by fluorescence intensity, were evaluated in frozen retinal sections by immunofluorescence and epifluorescence microscopy. RESULTS: Retinal ganglion cells were nearly undetectable one week after oligemia compared with the sham controls; however, these cells were partially preserved in erythropoietin-treated retinas. The contents of glial fibrillary acidic protein and cluster of differentiation 68 clone ED1, markers for reactive gliosis, were significantly higher in retinas after bilateral common carotid artery occlusion than those in both sham and erythropoietin-treated retinas. CONCLUSIONS: The number of partially preserved retinal ganglion cells in the erythropoietin-treated group suggests that erythropoietin exerts a neuroprotective effect on oligemic/ischemic retinas. This effect could be related to the down-modulation of glial reactivity, usually observed in hypoxic conditions, clinically observed during glaucoma or retinal artery occlusion conditions. Therefore, glial reactivity may enhance neurodegeneration in hypoxic conditions, like normal-tension glaucoma and retinal ischemia, and erythropoietin is thus a candidate to be clinically applied after the detection of decreased retinal blood flow.
Subject(s)
Animals , Male , Retinal Ganglion Cells/drug effects , Erythropoietin/pharmacology , Neuroprotective Agents/pharmacology , Glial Fibrillary Acidic Protein/drug effects , Retinal Diseases/pathology , Cell Count , Hematopoietic Cell Growth Factors/pharmacology , Rats, Wistar , Carotid Artery, Common/surgery , Carotid Artery Injuries/surgery , Disease Models, Animal , Ectodysplasins/drug effectsABSTRACT
O propósito do presente trabalho foi investigar a participação da proliferação celular e da expressão dos componentes da matriz extracelular na cascata de eventos do processo de reparo da fratura óssea, empregando as técnicas histológica, imunohistoquímica e morfométrica, em um modelo experimental padronizado para a indução da lesão na tíbia de ratos a partir do método empregado por Yuehuei e Friedman. É importante padronizar um modelo de indução da fratura, para posterior investigação da participação das células e dos componentes da matriz extracelular no processo de reparo da fratura, considerando que o tempo de consolidação depende significantemente da natureza e do tipo da lesão produzida. Quarenta (n=40) ratos Wistar foram submetidos a fratura. Os animais foram avaliados em oito (n=8) grupos de cinco (n=5) animais, cada grupo experimental com 12, 24, 48, 72, 96, 144, 192 e 240 horas após a fratura (12h até 10 dias). As fraturas foram classificadas de acordo com o sistema de classificação internacional de fratura de Muller, AO (Associação para Osteosíntese). Foram encontradas fraturas simples em 86% do total, sendo 68% de fraturas transversas e 18% de fraturas obliquas, 14% do total de fraturas foram complexas, sendo 8% de fraturas irregulares e 6% de fraturas segmentares. Esses resultados demonstram que o aparelho permite padronizar radiológicamente o tipo de fratura, caracterizado pela linha que separa os fragmentos ósseos. Os resultados qualitativos dos componentes da matriz extracelular para TGF-B, VEGF, colágeno I e II, osteopontina, proteoglicanos, fibras do sistema elástico com a coloração de resorcina funcsina de Weigert, e para proliferação celular pelo PCNA, assim como os resultados morfométricos, surgerem que a modulação da expressão dos componentes da matriz extracelular e a proliferação celular durante o processo de reparo da fratura não é homogênea para todos os componentes teciduais, dependendo significantemente das tensões locais geradas...
The purpose of this study was to investigate the role of cells proliferation and extracellular matrix components expression in the process of bone fracture repair. To do so it used histological techniques, immunohistochemistry and morphometric analysis as well as a standardized experimental model for the induction of injury to the tibia of rats as proposed by Yuehuei and Friedman. It is important to standardize a model of fracture induction for further investigation of the involvement of cells and extracellular matrix components in the fracture repair process, whereas the healing time depends significantly on the nature and type of lesion produced. Forty (n=40) Wistar rats were subjected to fracture. The animals were divided into eight (n=8) groups of five (n=5). Each subgroup was observed after 12, 24, 48, 72, 96, 144, 192 and 240 hours of fracture (12 to 10 days). Immediately afterwards, the fractures were classified according to the system of international classification of fracture by Muller, AO (Association for Osteosynthesis). Simple fractures were found in 86% of the total, among them, 68% were transverse and 18% were oblique. Complex fractures were found in 14% of the cases, among them 8% were irregular and 6% were segmental. These results demonstrated that the device enables researchers to standardize the type of fracture by X-ray, marked by the line separating the bone fragments. The qualitative results of the cells and extracellular matrix components of TGF-B, VEGF, PCNA, collagen I and II, osteopontin, proteoglycans, elastic fibers system with resorcin funcsin of Weigert, as well as the morphometric results suggest that the repair process of the fracture is not homogeneous for all components. Expression of the extracellular matrix components and cell proliferation modulation significantly depends on the local stresses generated by the type of the fracture. Such type can be decisive in determining time duration for bone regeneration...