FGF2, LIF, and IGF1 (FLI) supplementation during human in vitro maturation enhances markers of gamete competence.

This article investigates whether supplementation of in vitro maturation (IVM) medium with a cocktail of fibroblast growth factor 2 (FGF2), leukemia inhibitory factor (LIF), and insulin-like growth factor 1 (IGF1)—collectively termed FLI—improves the maturation of cumulus–oocyte complexes (COCs) obtained from children, adolescents, and young adults undergoing ovarian tissue cryopreservation (OTC). The study found that while FLI supplementation did not increase the rate of oocyte meiotic maturation to metaphase II, it significantly enhanced markers of oocyte quality, including cumulus cell expansion, transzonal projection retraction, and mitogen-activated protein kinase (MAPK) expression in cumulus cells. These findings suggest that FLI may improve the developmental potential of immature oocytes recovered during OTC, particularly in a pediatric population where fertility preservation options are limited and IVM success rates are low. Further research is needed to assess the clinical translation of these quality improvements and to optimize IVM protocols for this demographic.