Embryo Development Following Single Blastomere Biopsy: Sage vs. G-PGD Medium

Authors: N. Buehlera,B. Reggioa,M. Surreya, H. Danzera and D.L. Hill, ART Reproductive Center, 450 N. Roxbury Dr. Beverly Hills, CA P-15. 

Objective: To determine if there is any difference in human embryo development when performing single blastomere biopsy using either Ca/Mg++ free biopsy medium (Sage) or G-PGD medium (Vitrolife).

Study Design: Embryos were evaluated at biopsy (D3) and again on D5. Embryo quality on D3 was scored on a fragmentation scale of A–D (A = 0%, B ≤ 10%, C = up to 50%, and D > 50%). Chromosomal status of the biopsied embryos was determined by FISH to diagnose aneuploidy.

Materials and Methods: Embryos were biopsied in either Ca/Mg++-free biopsy medium (Sage) supplemented on-site with 0.5 g sucrose (Sigma), 5% HSA (Irvine Scientific) and 20 μL 100X non-essential amino acids (NEaa; Irvine Scientific) or a commercially supplemented Ca/Mg++-free biopsy medium containing sucrose and NEaa (G-PGD medium, Vitrolife). Except during micromanipulation, all embryos were cultured in the G series medium (Vitrolife). Embryos were biopsied the morning of D3, then placed into G2.3 medium and incubated for an additional 2 days. Only grade A or B embryos with ≥6 blastomeres (high-quality embryos) at biopsy were analyzed for development to the morula/blastocyst stage.

Results: There was no difference in euploid, high-quality embryo development following treatment. However, there was a significant difference (Fisher's exact test, p<.025) in the number of high-quality aneuploid embryos that developed to the morula/blastocyst stage following treatment. Aneuploid, high-quality embryos biopsied in the G-PGD medium (n = 208) had a higher developmental rate (78%) to the morula/blastocyst stage (n = 163) compared to those embryos (n = 240) biopsied in Sage medium (68%, n = 163).

*Determined via FISH; number of euploid plus number of aneuploid embryos ≠total number embryos biopsied (not all blastomeres returned a useable signal).

**Only high-quality (grade A or B) embryos with at least 6 cells at biopsy were analyzed with respect to development to the morula/blastocyst stage.

a,b Values within columns with different superscripts are different (Fisher's exact test, p<.025).

Conclusion: The choice of biopsy medium does not influence embryo development to the morula/blastocyst stage when analyzing euploid embryos. However, aneuploid embryos had a higher development rate when biopsied in G-PGD medium compared to Sage medium. Although aneuploid embryos are not transferred, they may have value in stem cell research and other investigations. Therefore, G-PGD medium appears to be a logical choice, as aneuploid embryos have a higher developmental potential when biopsied in this medium.