Serum-derived human serum albumin as a source of undeclared proteins and compositional variability in commercially available IVF media

This project explores the origin of undeclared proteins in commercially available IVF culture media using untargeted proteomic analysis (nanoLC-TIMS-TOF-MS/MS). Although human serum albumin (HSA) is the only declared protein component, we detected hundreds of additional proteins in unused media, indicating a non-standardized background that may affect embryo development and confound spent culture media (SCM) biomarker studies. We analyzed SCM samples from both successful and unsuccessful IVF embryo cultures, along with corresponding controls and blank media from multiple production lots and IVF cycles. Supplementation experiments demonstrated that adding plasma-derived HSA introduces variable protein contaminants, likely originating from human serum. These findings underscore the need for greater transparency and standardization in IVF media composition and highlight the sensitivity of proteomic workflows to background variability in embryo culture systems.