Introduction
Synthetic embryo culture medium may be deficient in iron. There is a need to determine optimum iron concentration in embryo culture medium.
Objective
To determine: whether iron is present in sufficient amounts for development of embryos in embryo culture media?; the optimal concentrations of iron needed for embryo development; and examine the need for/impact of supplemented iron on embryo development in vitro.
Materials and methods
Quakenbush sibling mouse zygotes were randomly apportioned to individual treatments. Suboptimal media (EBSS) was supplemented with 5mg/ml of bovine serum albumin (BSA), antibiotics penicillin/ streptomycin sulfate, and pyruvate/lactate. Treatments consisted of culture media supplemented with (i) Desferrioxamine, (ii) graded amounts of ferric iron without EDTA or (iii) with 0.11mM EDTA. End point: day 6 (expanded, hatching, hatched embryos).
Results
Desferrioxamine >1000nM (but not 200 to 800nM) and ferric iron without EDTA >8uM (but not 400 to 1600nM) were toxic. Iron supplementation 2 to 10uM and embryo death is significantly correlated, r = 0.9432 (p<0.01). In the presence of 0.11mM EDTA development of days 5 and 6 embryos was significantly higher in groups supplemented with 5uM to 20uM treatment versus control group (p<0.05).
0>Conclusion
Iron is essential for embryo development but the amount present in culture medium as contaminant appears just barely sufficient to meet the metabolic needs of the embryo. Supplementation of iron in very minute quantities in the culture medium devoid of EDTA elicited insignificant positive embryonic development, insufficient to attain significant improvement while levels beyond 8uM are toxic. 5 to 20uM of iron +0.11mM EDTA proved beneficial for embryo development indicating the need for iron supplementation in embryo culture media. EDTA ameliorates deleterious effects of iron while making sufficient iron available for improved embryonic development. Subsequent work shall examine impact of iron in synthetic protein-free medium (Ali et al.Hum Reprod.15:145,2000)
References.
Ali J, Shahata MAM, Al-Natsha SD. Formulation of a protein-free medium for human assisted reproduction. Hum Reprod. 2000;15(1)145-156