Amino acids promote human blastocyst development in vitro

Supplementation of culture media with amino acids has been shown to benefit preimplantation embryo development in several species. This randomized stu dy analysed the in-vitro development of human embryos obtained after IVF in the presence or absence of a combination of amino acids from the 2- to 4-c ell stage to the blastocyst stage. A total of 129 human embryos was randoml y distributed between three serum-free chemically defined sequential media: (i) glucose-free Earle's balanced salt solution (EBSS) with glutamine (Gln ) prior to morula stage, supplemented with glucose for blastocyst formation ; (ii) glucose-free EBSS with glutamine and non-essential amino acids (AA) for cleavage stage development, and supplemented with all 20 AA for blastoc yst formation (Earle's + AA); and (iii) a sequential commercial medium cont aining amino acids (K-SCIM). Embryos were individually cultured for success ive periods of 24 h. On day 6 of development, blastocysts were differential ly labelled and the numbers of trophectoderm and inner cell mass cells, mit oses and dead cells were examined. Blastocyst development was similar for t he three sequential media. The mixture of AA significantly increased total blastocyst cell numbers from 61.8 +/- 4.2 with Earle's + Gln to 99.3 +/- 8. 4 with Earle's + AA and 100.2 +/- 9.4 with K-SCIM (P = 0.005). This increas e was present in both the trophectoderm and inner cell mass lineages (P < 0 .02). Furthermore, the dead cell index was significantly lower with Earle's + AA (P = 0.047).