Reply of the Authors: Choosing a culture medium: making informed choices

Abstract

We thank Ebert and Völklein for drawing our attention to Medium GM501 marketed by Gynemed (Lensahn, Germany). We were not aware at the time of writing our review of any peer-reviewed, journal papers describing the use of Medium GM501 for the extended culture of human preimplantation embryos. The omission of this medium from inclusion in Table 1 is thus understandable, not the flaw that they suggested in their letter. Moreover, the paper by Ebert et al. (1Ebert P. Szypajlo B. Tomalak K. Völklein K. Prospective comparison of two commercially available culture media under the provisions of the German embryo protection law.J Turkish-German Gynecol Assoc. 2009; 10: 10-13Google Scholar) was published after our review article appeared. Their paper focuses on the culture and the clinical outcome after the transfer of cleavage-stage human embryos, which is not germane to the principle focus of our review article on culturing human embryos from zygote to blastocyst. Reportedly, Medium GM501 has been successfully used for the culture of human zygotes to the blastocyst stage using a single-step protocol. These findings have not been published in a peer-review journal but rather appear, along with a detailed history of GM501 by Weiss and Schneider in Gynemedia, an undated company newsletter. This medium, like the Global medium marketed by IVFOnline, is a derivative of KSOMAA medium, designed originally for use in the mouse and used for the culture of human preimplantation embryos by Biggers and Racowsky (2Biggers J.D. Racowsky C. The development of fertilized human ova to the blastocyst stage in medium KSOMAA: is a two-step protocol necessary?.Reprod Biomed Online. 2002; 5: 133-140Abstract Full Text PDF PubMed Scopus (98) Google Scholar). The authors seem to have doubts about the scientific value of the summary of abstracts listed in our Table 2 because they are not peer reviewed. We felt that there was sufficient agreement between the abstracts to warrant the suggestion that serious consideration be given to the use of single-step protocols. It is indeed gratifying that our suggestions have been justified by the subsequent publication of two full-length, peer-reviewed papers supporting the efficaciousness of single-step protocols for the culture of human preimplantation embryos (3Sepúlveda S. Garcia J. Arriaga E. Diaz J. Noriega-Portella L. Noriega-Hoces L. In vitro development and pregnancy outcomes for human embryos in either a single medium or in a sequential media system.Fertil Steril. 2009; 91: 1765-1770Abstract Full Text Full Text PDF PubMed Scopus (64) Google Scholar, 4Reed M.L. Hamic A. Thompson D.J. Caperton C.L. Continuous uninterrupted single medium culture without medium renewal versus sequential media culture: a sibling embryo study.Fertil Steril. 2009; 92: 1783-1786Abstract Full Text Full Text PDF PubMed Scopus (57) Google Scholar). We wish to make a correction to a mistake made in our review with respect to the abstract by Sepúlveda et al. (5Sepúlveda S, Garcia J, Arriaga E., Noriega L, Wierner KE, Rieger D. Comparison of a single medium with sequential media for culture of sibling human embryos to the blastocyst stage. Proceedings of the 37th annual meeting of the Society for Reproductive Biology, Queensland, Australia, August 21, 2006.Google Scholar) and the paper by Sepúlveda et al. (3Sepúlveda S. Garcia J. Arriaga E. Diaz J. Noriega-Portella L. Noriega-Hoces L. In vitro development and pregnancy outcomes for human embryos in either a single medium or in a sequential media system.Fertil Steril. 2009; 91: 1765-1770Abstract Full Text Full Text PDF PubMed Scopus (64) Google Scholar) put online by Fertility and Sterility in 2008 and now in print in 2009. We mistakenly implied that the same data were used in these two studies; rather, the two contributions were based on independent sets of data. Thus, the sentence in which Ebert and Völklein question the validity of the work of Sepúlveda et al. is merely unjustified speculation. Ebert and Völklein quote part of the first sentence of the last paragraph of our review, “difficulties in the interpretation of clinical outcomes is the heterogeneous nature of the patient population …” (p. 478), and then say we ignored the many other variables that exist in the IVF laboratory. Their criticism is not justified. The last part of the paragraph quite plainly addresses the technical variables that occur in the IVF laboratory. Also, it is well-known that valid, unbiased evaluations of media are only obtained when the comparisons are made within clinics using the same culture conditions. Choosing a culture medium: making informed choicesFertility and SterilityVol. 93Issue 6PreviewTo the Editor: Full-Text PDF