L. Keskintepe

Genetic analysis of human embryos by metaphase comparative genomic hybridization (mCGH) improves efficiency of IVF by increasing embryo implantation rate and reducing multiple pregnancies and spontaneous miscarriages

OBJECTIVE To assess the benefit of selecting blastocysts for cryotransfer based upon prior comparative genomic hybridization (CGH) karyotyping of blastomeres derived from their cleaved embryos of origin. Implantation and birth rates per transfer of previtrified CGH-tested blastocysts were compared with those following the transfer of nonCGH-tested fresh and warmed embryos. DESIGN In vitro studies. SETTING Private infertility clinic. PATIENT(S) Women undergoing infertility treatment. INTERVENTION(S) Three groups of women with similar clinical and demographic characteristics were compared. Group A underwent transfer of warmed blastocysts derived from CGH-normal day 3 embryos. Group B underwent embryo transfer of warmed blastocysts derived from nonkaryotyped vitrified embryos. Group C underwent fresh transfers with non-CGH-tested blastocysts. MAIN OUTCOME MEASURE(S) Implantation and birth rates per embryo after the cryotransfer of CGH-tested blastocysts. RESULT(S) The birth rate per transferred blastocyst in group A was 48%, versus 15% for group B and 19% for group C. The birth rate per embryo transfer was 60% for group A, and 33% for group B and 36% for group C. The miscarriage rate was 4% in group A, 8% in group B, and 12% in group C. CONCLUSION(S) The transfer of previously vitrified blastocysts derived from CGH-normal embryos significantly improves implantation and birth rates per embryo transferred and reduces the miscarriage rate. Vitrification does not compromise this enhancement.

Vitrification of human embryos subjected to blastomere biopsy for pre-implantation genetic screening produces higher survival and pregnancy rates than slow freezing

PurposeCryopreservation of blastocysts, especially those subjected to the trauma due to blastomere biopsy for the purposes of pre-implantation genetic screening (PGS), requires significant optimization. Laboratory and clinical outcomes were compared to determine the effect of two different cryopreservation techniques on the development of human pre-implantation embryos that underwent blastomere biopsy and blastocoel drainage prior to cryopreservation.DesignRetrospective clinical study.Patient(s)Women who requested cryotransfer of supernumerary blastocysts were analyzed by FISH.ResultsThe main outcome measures were post-thaw survival (SR), pregnancy (PR), and implantation (IR). The SR of slowly frozen blastocysts was 83% compared to 97% for vitrified blastocysts. In 160 cases where biopsied embryos were cryotransferred, the results for slowly frozen versus vitrified blastocysts were: SR (71% vs. 95%), PR (23% vs. 37%), and IR (26% vs. 36%, P < 0.05), respectively.ConclusionThe results revealed that vitrified blastocysts provided higher SR, PR and IR as compared to slowly frozen counterparts.

High survival rate of metaphase II human oocytes after first polar body biopsy and vitrification: determining the effect of previtrification conditions

OBJECTIVE To use metaphase II (MII) bovine oocytes as a model for MII human oocyte cryopreservation and to determine the effect of different previtrification equilibration temperatures, vitrification solutions, zona slitting, and first polar body biopsy on in vitro and in vivo developmental competence of MII human oocytes after the CryoLoop vitrification method. DESIGN In vitro and in vivo studies. SETTING A private infertility clinic. PATIENT(S) Women undergoing infertility treatment. INTERVENTION(S) Metaphase II stage bovine and MII human oocytes underwent first polar body biopsy before cryopreservation in different vitrification conditions, and human oocytes were fertilized by intracytoplasmic sperm injection after warming. The resulting embryos were transferred into women undergoing infertility treatment. MAIN OUTCOME MEASURE(S) Postvitrification morphologic survival, in vitro blastocyst development, and clinical outcome after ET. RESULT(S) The equilibration temperature had a significant effect on cryosurvival of both bovine and human oocytes. High (97%-99%) postvitrification survival was achieved for both MII bovine and human oocytes, and high fertilization (90%-97%) at 35 degrees C to 37 degrees C, blastocyst development (18%-45%), and pregnancy (50%) rates were achieved at 35 degrees C with 5.0 mol/L ethylene glycol + 1.3 mol/L dimethyl sulfoxide for MII human oocytes that underwent first polar body biopsy. CONCLUSION(S) Previtrification equilibration temperature had a profound effect on the postthaw developmental competence of MII human oocytes in vitro and in vivo. The CryoLoop vitrification of first polar body-biopsied MII human oocytes in the presence of 5 mol/L ethylene glycol plus 1.3 mol/L dimethyl sulfoxide gave the best results in terms of fertilization, embryo development, and implantation rates.

FREEZE-DRYING OF MAMMALIAN SPERM

Long-term preservation of mammalian sperm at suprazero temperatures is desired to save storage and space costs as well as to facilitate transport of preserved samples. This can be accomplished by the freeze-drying of sperm samples. Although freeze-drying results in immotile and membrane-compromised sperm, intracytoplasmic sperm injection (ICSI) can be used to introduce such an immotile sperm into an oocyte and thus start the fertilization process. So far, it has been shown that improved freeze-drying protocols preserve chromosomal integrity and oocyte-activating factor(s) at 4 °C for several years and at ambient temperature for approximately 1 month, which permits shipping freeze-dried samples at ambient temperature. This chapter concisely reviews freeze-drying of mammalian sperm first and then presents a simple freeze-drying protocol.

sHLA-G expression: is it really worth measuring?

HLA-G is believed to play a pivotal role in the immunoprotection of the semiallogenic embryo. Its expression during pre- and early implantation is correlated with the cleavage rate of the embryo. Studies in congenic mice have revealed that mRNA of both the maternal and paternal haplotypes are present in zygotes and in embryos at all stages of development.