Universität zu Köln

Ban, Zhaoqiao (2026). Comparative Analysis of Human GV-Oocyte Maturation Under Cumulus-Supported and Denuded Culture Conditions. PhD thesis, Universität zu Köln.

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Abstract

Background: In-vitro maturation (IVM) of human oocytes provides a safer, hormone-sparing alternative to conventional in-vitro fertilization (IVF), particularly for patients at risk of ovarian hyperstimulation syndrome (OHSS) or with contraindications to gonadotropin use. Despite its clinical appeal, IVM efficiency remains limited, which is thought to result partly from disruption of the somatic microenvironment normally maintained by cumulus cells. This study examined whether preserving the cumulus-oocyte complex (COC) during culture improves meiotic resumption and modulates oxidative and metabolic states in surrounding cumulus cells. Methods: Primary cumulus cells and GV-stage oocytes were obtained from follicular aspirates collected during ultrasound-guided ovarian puncture at the Women’s Clinic, University of Cologne. For the oocyte experiments, immature GV oocytes were allocated to two culture conditions: (i) only oocytes, where oocytes were cultured without cumulus cells; and (ii) oocyte with cumulus, where oocytes were cultured together with primary cumulus cells. After 48 hours, germinal vesicle breakdown (GVBD) was evaluated as an indicator of nuclear maturation. For the cumulus-cell experiments, intracellular reactive oxygen species (ROS) levels were quantified using the H2DCFDA fluorescence probe, and AMP-activated protein kinase (AMPKalpha1) expression was evaluated by immunocytochemistry. Results: Oocytes cultured together with cumulus cells showed a significantly higher rate of GVBD than oocytes cultured without cumulus cells. Cumulus-oocyte co-culture exhibited markedly lower intracellular ROS levels and significantly higher AMPK expression. Morphologically, co-cultured cumulus cells displayed enhanced expansion and tighter intercellular connections. Conclusions: Maintaining oocytes with cumulus during culture establishes a low-oxidative, energy-efficient microenvironment that promotes meiotic resumption in human GV-stage oocytes. These findings highlight the critical role of somatic-germ cell communication and provide a mechanistic basis for microenvironment-centered refinements in human IVM protocols, particularly in patients with PCOS or undergoing fertility preservation.

Item Type:	Thesis (PhD thesis)
Translated abstract:	Abstract Language UNSPECIFIED English
Creators:	Creators Email ORCID ORCID Put Code Ban, Zhaoqiao banzhaoqiao@gmail.com UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-805426
Date:	2026
Publisher:	Universität zu Köln
Place of Publication:	Köln
Language:	English
Faculty:	Faculty of Medicine
Divisions:	Faculty of Medicine > Frauenheilkunde > Klinik und Poliklinik für Frauenheilkunde und Geburtshilfe
Subjects:	Medical sciences Medicine
Uncontrolled Keywords:	Keywords Language oocyte maturation; cumulus cells; cumulus-oocyte complex; in vitro maturation; GVBD English oxidative stress; reactive oxygen species; ROS; AMPK; assisted reproduction English
Date of oral exam:	12 May 2026
Referee:	Name Academic Title Rahimi, Gohar Prof. Dr. med.
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/80542