Cytochrome C in in vitro fertilization: a promising tool for distinguishing spent embryo culture fluids of normoresponder, diminished ovarian reserve, and polycystic ovarian syndrome

Aims: Cytochrome C (Cyt C) is a small heme protein located in the mitochondria, playing a dual and crucial role in cellular physiology as cellular respiration and apoptosis. This study aimed to investigate Cyt C gene expression in spent embryo culture fluid (SECF) as a non-invasive biomarker for distinguishing between Normoresponder (NOR), Early-Diminished Ovarian Reserve (E-DOR), Advanced-Diminished Ovarian Reserve (A-DOR), and polycystic ovarian syndrome (PCOS) patients undergoing in vitro fertilization (IVF). Methods: SECF samples were collected from patients at Bahçeci Health Group Umut IVF Laboratory, İstanbul, with informed consent and ethical approval (2023/19-22). Forty-eight samples from each group (NOR, E-DOR, A-DOR, PCOS) were analyzed. Ovarian stimulation followed an antagonist protocol, and embryos were cultured individually. On day 3, embryos were morphologically graded. Total RNA was isolated from SECF, converted to cDNA, and Cyt C gene expression was quantified using RT-PCR, with GAPDH as an internal control. Statistical analyses included the Kolmogorov-Smirnov and Shapiro-Wilk tests for normality, Sidak for multiple comparisons, and the Pearson correlation test for group relationships. Results: Compared to NOR samples, Cyt C gene expression was significantly upregulated in A-DOR samples, while E-DOR samples showed downregulation (p0.05). Pearson correlation revealed a significant relationship only between NOR and A-DOR SECF samples (r