Evaluation of Endotoxin in Culture Medium for Human in vitro Fertilization

Objective To determine whether the presence of bacterial endotoxin in the commercial culture media utilized for human in vitro fertilization (IVF), and evaluate the difference in detecting endotoxin in culture medium between the human sperm motility assay and the 2-cell mouse embryo assay. Methods Thirty-six batches of culture media commonly used in IVF laboratories from 3 manufacturers were determined for the presence of endotoxin before using the medium for the assisted reproductive programs (group A). After being used, 25 specimens among above media were also tested (group B). The chromogenic limulus amoebocyte lysate (LAL) test was used for quantification the content of endotoxin. In addition, the human sperm motility assay was compared with the 2-cell mouse embryo assay to evaluate the difference in detecting endotoxin in culture medium. Results Endotoxin was not detected in group A. However, 2 samples were positive in group B. Sperm did not show significant change in motility in group A during 24 h of incubation when compared with the control (P>0.05). However, in group A the 2-cell embryo development to blastocyst was suppressed in 3 batches of media. Conclusions Regular screening of each batch of culture medium should be performed if possible although there was no evidence of endotoxin contamination in commercially prepared pre-tested media. Culture environment should be stringently controlled in case the medium is polluted. The sensitivity of the sperm motility assay was lower than that of the mouse embryo assay for detecting low levels of endotoxin or toxic compounds in the medium.