O-008 The composition of commercially available human preimplantation embryo culture media
Authors: Zagers M , Laverde M , Schrauwen F , De Groot J , Vaz F , Mastenbroek S 
Published: June 2023

Abstract

Study question
What is the composition of currently available commercial human preimplantation embryo culture media from eleven different brands for each stage of preimplantation embryo development?

Summary answer
Besides similarities in embryo culture medium composition between brands, there were also differences in composition for which there does not seem to be a rationale.

What is known already
Although a lot remains uncertain, there seems to be some consensus in the scientific literature on the environmental and nutritional needs of preimplantation embryos in in vitro culture, at least for certain components. Since suppliers do not disclose the exact formulations of their media, it is unclear whether the embryo culture media currently used in IVF laboratories meet these suggested conditions. We previously published composition analyses of a limited number of culture media, but have now repeated this analysis and have included a larger number of media from eleven brands of human preimplantation embryo culture media.

Study design, size, duration
Forty-seven human embryo culture media and protein supplements were purchased between December 2019 and June 2020. Upon arrival, each complete medium (n = 23), unsupplemented medium (n = 14), and supplement (n = 10) was aliquotted in Eppendorf tubes, snap frozen in liquid nitrogen and stored in -80oC until composition analysis in November 2021. Additionally, unsupplemented media were supplemented with each available supplement from the same brand (n = 33 combinations) and then also aliquotted, snap frozen and stored in -80oC until analysis.

Participants/materials, setting, methods
The concentration of forty components was determined in all collected samples (n = 80). Seven ions, glucose, three immunoglobulins, uric acid, alanine aminotransferase (ASAT), aspartate aminotransferase (ALAT), albumin, and the total amount of proteins were determined in each sample using a Cobas 8000 Analyser (Roche Diagnostics). Analysis of pyruvate, lactate, carnitine and twenty-one amino acids was achieved with Ultra-high Performance Liquid Chromatography-Mass Spectometry (UPLC-MS/MS).

Main results and the role of chance
Our analysis of the concentration of 40 components in ready to use embryo culture media of most available brands on the market showed that in general the culture media follow generally accepted assumptions on the changing needs of an embryo during early development. However, there were clear differences between brands, and no two embryo culture media were the same. For example, pyruvate concentrations were higher in fertilization and cleavage stage media and lower in blastocyst stage media, whereas glucose was relatively high in fertilization media, lower in cleavage stage media, and higher again in blastocyst media. This follows previous findings that demonstrate that pyruvate is the main energy source until blastocyst stage and that glucose becomes the main energy source for blastocysts. Other components, like lactate for example, followed different patterns in the sequential media of different brands, and concentrations also differed between brands. The composition of continuous media resembled the composition of the other media of the same brand, but differed between brands. Interestingly, some of the culture media brands belong to the same parent company, but differ in their composition. The rationale of such differences is not clear. Research providing such rationale seems warranted.

Limitations, reasons for caution
The analysed embryo culture media may contain other components that were not investigated in this study.

Wider implications of the findings
Detailed information on human embryo culture medium composition, including the exact concentrations of each ingredient, is much needed to in the end be able to understand its effect on IVF outcomes, and to facilitate the scientific improvement of media for human preimplantation embryo culture.

Trial registration number
not applicable