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Human embryos produce transforming growth factors alpha activity and insulin-like growth factors II
R Hemmings1, J Langlais, T Falcone
1Institut de Medecine de la Reproduction de Montreal, Quebec, Canada.
Objective:
To assess whether growth factors are produced by early human embryos in culture.
Design:
We studied various growth factors in the culture media of human embryos (n = 6) cultured from days 3 to 8 after fertilization.
Main Outcome Measures:
Four growth factors were measured: Insulin growth factors I and II (IGF-I and IGF-II), epidermal growth factor (EGF) and transforming growth factor alpha (TGF alpha) activity.
Results:
Nonconditioned INRA Menezo B2 (Biomerieux, S.A., Paris, France) culture medium contained significant levels of TGF alpha activity (5.2 ng/mL) and low levels of IGF-I (1.02 ng/mL) and IGF-II (2.8 ng/mL), whereas EGF was below detection of our assay. With human embryo, the culture media contained lower TGF alpha activity on days 3 and 4 after fertilization (2.5 ng/mL and 2.8 ng/mL, P less than 0.05). From days 5 to 8 after fertilization, a significant increase in TGF alpha activity and IGF-II was detected (TGF alpha activity: day 5: 3.7 ng/mL; day 6: 4.4 ng/mL; day 7: 6.4 ng/mL; day 8: 8.4 ng/mL) (IGF-II: day 5: 3.4 ng/mL; day 6: 3.1 ng/mL; day 7: 4.1 ng/mL; day 8: 4.2 ng/mL). Epidermal growth factor was undetectable, and IGF-I did not vary significantly.
Conclusion:
Transforming growth factor alpha activity and IGF-II are produced by human embryos in culture at a time when they could play a role in morula to blastocyst transformation.