Influência da interação entre o oócito e as células da granulosa nos resultados dos procedimentos de reprodução assistida / The influence of interaction between oocyte and granulosa cells on the results of procedures in assisted reproduction

A interação oócito-células da granulosa in vivo e sua influência na qualidade oocitária e embrionária tem sido alvo de inúmeros estudos, mas muitas questões ainda necessitam ser esclarecidas. O objetivo deste trabalho foi revisar a importância dessa comunicação, estabelecendo uma relação com a questão da maturação in vitro de oócitos imaturos humanos aplicando esses conhecimentos para definir possíveis marcadores moleculares que poderiam melhorar a seleção de oócitos e, consequentemente, selecionar embriões de boa qualidade para posterior transferência e sucesso de gravidez de pacientes submetidas ao tratamento da infertilidade conjugal. As células da granulosa têm um importante papel na maturação oocitária in vitro e os benefícios da presença dessas células durante essa etapa podem ser atribuídos à formação de um microambiente favorável (bioquímico e metabólico) ao redor do oócito. Foram identificados nesta revisão vários marcadores em potencial nas células do cumulus de oócitos competentes, incluindo vários genes que poderiam ser usados como preditores da competência oocitária, o que pode contribuir para a formulação de critérios mais objetivos e confiáveis para a seleção de oócitos e embriões, e consequente aprimoramento e otimização das técnicas em reprodução humana assistida que são aplicadas nos procedimentos clínicos atuais de fertilização in vitro.

The interaction of oocyte-granulosa cells in vivo and in vitro and its influence on oocyte and embryo quality has been the subject of numerous studies, but many issues still need to be clarified. The objective of this study was to promote a review about the importance of this communication establishing a connection with the issue of in vitro maturation of immature human oocytes by applying this knowledge to define potential molecular markers that could improve the selection of oocytes and consequently select good quality embryos for later transfer and success of pregnancy in patients undergoing treatment of infertility. The granulosa cells also have an important role in oocyte maturation in vitro and the venefits from the presence of these cells during this process can be atributed to the formation of a favorable micro-environment (biochemical and metabolic) around the oocyte. In this review, we identified several potential markers in the cumulus cells of competent oocytes, including several genes that could be used as predictors of oocyte competence, which contributes for more objective and reliable criteria for the selection of oocytes and embryos, thus improving and optimizing techniques in assisted human reproduction that are applied in current clinical in vitro fertilization.

Autologous somatic cell nuclear transfer in pigs using recipient oocytes and donor cells from the same animal

The objective of the present study was to examine the feasibility of the production of autologous porcine somatic cell nuclear transfer (SCNT) blastocysts using oocytes and donor cells from slaughtered ovaries. Therefore, we attempted to optimize autologous SCNT by examining the effects of electrical fusion conditions and donor cell type on cell fusion and the development of SCNT embryos. Four types of donor cells were used: 1) denuded cumulus cells (DCCs) collected from in vitro-matured (IVM) oocytes; 2) cumulus cells collected from oocytes after 22 h of IVM and cultured for 18 h (CCCs); 3) follicular cells obtained from follicular contents and cultured for 40 h (CFCs); and 4) adult skin fibroblasts. The DCCs showed a significantly (p > 0.01) lower rate of fusion than the CCCs when two pulses of 170 V/mm DC were applied for 50 microsec (19 +/- 2% vs. 77 +/- 3%). The rate of DCC fusion with oocytes was increased by the application of two DC pulses of 190 V/mm for 30 microsec, although this was still lower than the rate of fusion in the CCCs (33 +/- 1% vs. 80 +/- 2%). The rates of cleavage (57 +/- 5%) and blastocyst formation (1 +/- 1%) in the DCC-derived embryos did not differ from those (55 +/- 6% and 3 +/- 1%, respectively) in the CCC-derived SCNT embryos. Autologous SCNT embryos derived from CFCs (5 +/- 2%) showed higher levels of blastocyst formation (p > 0.01) than CCC-derived autologous SCNT embryos (1 +/- 0%). In conclusion, the results of the present study show that culturing cumulus and follicular cells before SCNT enhances cell fusion with oocytes and that CFCs are superior to CCCs in the production of higher numbers of autologous SCNT blastocysts.