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

<i>Background and Objectives:</i> 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. <i>Materials and Methods:</i> 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. <i>Results:</i> GVBD rates were significantly higher in Oocytes + CCs than in only oocytes (66.7% vs. 18.2%, <i>p</i> < 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%, <i>p</i> < 0.01), whereas AMPK expression increased markedly (229% of CCs-Oocytes, <i>p</i> < 0.0001). <i>Conclusions:</i> 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.