Portal de Pesquisa da BVS Veterinária

Tese em Português | VETTESES | ID: vtt-705

Resumo

Foram realizados quatro experimentos distintos. O experimento 1 avaliou a participação das células tronco mesenquimais da medula óssea (CTM-MO) na gênese das alterações ósseas induzidas pelo hipo e hipertireoidismo em ratas ovariectomizadas (OVX) e não OVX. O experimento 2 avaliou o efeito do tratamento in vitro com triiodotironina (T3) sob o potencial osteogênico reduzido das CTM-MO de ratas OVX com osteoporose, comparando-o ao das CTM-MO de ratas adultas e jovens sem osteoporose. O experimento 3 avaliou o efeito da T3 na diferenciação osteogênica das células tronco mesenquimais do tecido adiposo (CTM-TA) de ratas adultas OVX com osteoporose e comparou-o ao de ratas adultas e jovens sem osteoporose. E o experimento 4 comparou o potencial osteogênico das CTM-MO e das CTM-TA dentro dos grupos de ratas jovens, de ratas adultas e de ratas OVX com osteoporose. Concluiu-se no experimento 1 que a redução do potencial osteogênico das CTM-MO é um dos mecanismos envolvidos na gênese da osteopenia induzida pelo hipotireoidismo e que o aumento da diferenciação osteogênica das CTM de ratas OVX tratadas com tiroxina pode ser um dos mecanismos pelo qual esse hormônio aumenta a resistência óssea de ratas OVX. No experimento 2, concluiu-se que a T3 não somente melhora o potencial osteogênico reduzido das CTM-MO de ratas com osteoporose como aumenta esse potencial em relação ao das CTM-MO de ratas adultas sem osteoporose, sendo esse efeito dose-dependente. Mas, o tratamento com T3 não é capaz de igualar o potencial osteogênico das CTM de ratas com osteoporose ao de ratas jovens saudáveis. No experimento 3, concluiu-se as CTM-TA de ratas ovariectomizadas com osteoporose apresentaram redução da diferenciação osteogênica e que o tratamento com T3 apresenta efeitos negativos sobre alguns dos fatores envolvidos nessa diferenciação. No experimento 4, conclui-se que as CTM-TA de ratas jovens e de ratas OVX com osteoporose apresentam maior potencial osteogênico que as CTM-MO da mesma categoria de animais e que, no grupo de ratas adultas, o potencial osteogênico é semelhante entre as CTM-MO e as CTM-TA e que as CTM-TA de ratas OVX com osteoporose têm potencial osteogênico semelhante ao das CTM-MO de ratas jovens

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Four different experiments were performed. Experiment 1 evaluated the role of bone marrow mesenchymal stem cells (BMMSCs) on the genesis of bone alterations caused by hypo and hyperthyroidism in ovariectomized (OVX´d) or non-ovariectomized female rats. Experiment 2 evaluated the effect of in vitro treatment with triiodothyronine (T3) on the reduced osteogenic potential of BMMSCs of the OVX´d rats with osteoporosis, compared to that of BMMSCs of young and adult rats without osteoporosis. Experiment 3 evaluated the effect of T3 on osteogenic differentiation of adipose derived stem cells (ASCs) from adult OVX´d rats with osteoporosis, compared to that of ASCs of young and adult rats without osteoporosis. Finally, experiment 4 compared the osteogenic potential of BMMSCs and ASCs within groups of young rats, adult rats and OVX´d rats with osteoporosis. It was concluded in experiment 1 that the reduction of osteogenic differentiation of BMMSCs is one of the mechanisms involved in osteopenia genesis induced by hypothyroidism and that the increase of MSCs osteogenic differentiation may be one of the mechanisms by which thyroxine increases bone resistance of OVX´d female rats. In experiment 2 it was concluded that T3 improves reduced osteogenic potential of BMMSCs on rats with osteoporosis and it also increases the osteogenic potential with respect to the BMMSCs of adult rats without osteoporosis, where the effect was dose dependent. However, treatment with T3 was not able to reach the osteogenic potential of MSCs in rats with osteoporosis when compared to that of healthy young rats. In experiment 3 it was concluded that ASCs of OVX´d rats with osteoporosis showed reduced osteogenic differentiation and that treatment with T3 has negative effects on some of the factors involved in this differentiation. In experiment 4 it was concluded that ASCs of young rats and OVX´d rats with osteoporosis have higher osteogenic potential that BMMSCs of the same category of animals and that, in the group of adult rats, the osteogenic potential is similar between BMMSCs and ASCs. Furthermore ASCs of OVX´d rats with osteoporosis have an osteogenic potential similar to that of BMMSCs of young rats

Biblioteca responsável: BR68.1