Effects of Intrauterine Infusion of G-CSF and HCG on Peripheral Blood Treg and Pregnancy Outcome in Patients with Thin Endometrium Undergoing Frozen-thawed Embryo Transfer

Background: Patients with thin endometrium undergoing frozen- thawed embryo transfer often encounter challenges with pregnancy outcomes. Enhancing endometrial receptivity and immune tolerance may improve these outcomes. Objective: To investigate the effects of intrauterine perfusion of granulocyte colony-stimulating factor (G-CSF) and human chorionic gonadotropin (HCG) on regulatory T cells (Tregs) and pregnancy outcomes in patients with thin endometrium undergoing frozen-thawed embryo transfer. Methods: 150 patients with thin endometrium were randomly assigned to three groups: a control group that received no intervention, an HCG group, and a G-CSF group. The effectiveness of the treatments was assessed by comparing uterine parameters, Treg levels, and pregnancy outcomes across the groups. Results: The HCG and G-CSF groups exhibited significant improvements compared to the control group, including increased endometrial thickness, enhanced blood flow, higher expression of endometrial receptivity markers (integrin alpha v beta 3, osteopontin), and elevated Treg levels. Notably, the G-CSF group demonstrated even greater enhancements compared to the HCG group, with significantly higher endometrial thickness, better blood flow, increased receptivity markers, and elevated Treg levels. Additionally, the G-CSF group achieved significantly higher biochemical and clinical pregnancy rates compared to both the HCG and control groups. This highlights the potential of G-CSF in improving pregnancy outcomes for patients with a thin endometrium. Conclusion: The intrauterine perfusion of G-CSF significantly enhanced pregnancy outcomes in patients with thin endometrium by improving endometrial blood flow, immune tolerance, thickness, Treg induction, and embryo implantation. These findings suggest that G-CSF could be a promising therapeutic option for this patient population.