Reciprocal Interactions Between Human GV-Oocytes and Cumulus Cells: Effects on GVBD, ROS Production, and AMPK Expression

Background and Objectives: The quality of cumulus cells (CCs) is a major determinant of germinal vesicle (GV) oocyte maturation, yet the reciprocal effect of GV oocytes on cumulus cell function remains unclear. Materials and Methods: GV oocytes were cultured with or without cumulus cells (only oocytes or Oocytes–CCs), and GVBD rates were evaluated after 24 h. In parallel, cumulus cells were cultured either alone (only cumulus) or with oocytes (CCs + Oocytes). Cell morphology, growth, intracellular reactive oxygen species (ROS), and AMP-activated protein kinase (AMPK) expression were assessed by fluorescence and immunocytochemistry. Results: GVBD rates were significantly higher in Oocytes + CCs than in only oocytes (66.7% vs. 18.2%, p < 0.05). Cumulus cells co-cultured with oocytes exhibited improved growth, tighter cell connections, and greater extracellular matrix formation. ROS levels were reduced in CCs + Oocytes compared with only the cumulus group (12.1% vs. 21.9%, p < 0.01), whereas AMPK expression increased markedly (229% of CCs–Oocytes, p < 0.0001). Conclusions: In vitro co-culture underscores not only the supportive role of cumulus cells in oocyte maturation but also a reciprocal, beneficial effect of oocytes on cumulus cell viability and function, revealing the bidirectional nature of oocyte–cumulus interactions.