Análise do dano de DNA em produtos de abortamento

• Autor(a) principal: Magalhães, Mariana Filipa Leite
• Data de Publicação: 2020
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10348/11122
• topic: Miscarriage; chromosomal abnormalities

Infertility and miscarriage are common events in the failure of human reproduction. About 50% of women who experience bleeding during the first trimester of pregnancy ends up having spontaneous pregnancy loss. Most of miscarriage are caused by chromosomal abnormalities such as trisomy’s and polyploidies that are more common with increasing of maternal age. However, there are other factors such as genetics, uterus abnormalities, hormonal disorders, sperm quality and lifestyle. Human body cells are constantly exposed to factors that can cause DNA damage. The occurrence of such damage and the failure of repair mechanisms are related to various health problems, including male infertility. In this sense, this study aimed to evaluate DNA damage in abortion products in order to understand if there is a correlation with the occurrence of spontaneous abortions. This work consists of assessing DNA damage and cytogenetic analysis. 47 samples of anonymized abortion products were analyzed by cytogenetic. Through GTL banding it was possible obtain a diagnosis in 41 cases. It was necessary to resort the FISH technique in 5 cases, where there was cell growth, but no quality metaphases were obtained. In 6 cases that there was no cell growth and in 2 cases in which maternal contamination was suspected, the TOUCH-FISH technique was used. Through these techniques it was possible to exclude the most common aneuploidies in 76.9% of the analyzed cases. DNA damage was analyzed by comet assay. In this experimental analysis three types of assays were performed in 43 of the 47 samples analyzed by cytogenetics. In the first, DNA damage was evaluated in previously cryopreserved samples in liquid nitrogen. This test was applied to 33 samples and it was found that all had a very high damage, and it was not possible to extrapolate any relationship between abortion and damage. A second assay was then performed, where the damage was analyzed in 13 fresh samples and after freezing in liquid nitrogen to assess whether the freezing process induced damage as described in the literature for other cell types. 12 of 13 samples showed superior damage after freezing. In the third assay, performed on 10 samples, the damage recovery capacity of cultured cells was analyzed. This analysis compared the damage of fresh samples and at 24, 48 and 72 hours of culture. In this group we considered the age and clinical history of the pregnant woman. In fresh samples the damage ranged from 14 to 375 AU, being higher in cases where the maternal age was higher. The highest damage value (375 UA) was observed in a case where the pregnant woman suffered from epilepsy. In all cases there was a high repair rate, which was most evident after 48h in culture, in which 50% of the cases had repair greater than 90% compared to the initial damage. This conclusion allows us to speculate that the origin of the damage in some cases may have been induced by external factors such as the conditions for sampling. The study of DNA damage in abortion products was an innovative approach and there is no data in the literature on damage assessment in this type of samples. In this work it was corroborated the information that cryopreservation increases the damage in DNA and an increase in damage to cells was observed after this process. DNA repair ability was not equal for all samples and was not associated with cytogenetic abnormalities, which raises new research perspectives. The persistence of DNA damage in some samples indicates that the role of DNA damage in the source of abortion should be investigated.