Selective vitrification of euploid oocytes markedly improves survival, fertilization and pregnancy-generating potential.
Enthusiasm for oocyte cryopreservation has been limited by poor pregnancy rates per thawed metaphase II (MII) oocytes (<4%) and low implantation rates per embryos. The reasons relate to technical limitations in the freezing process, and the fact that <40% of oocytes are euploid and unable to produce 'competent' embryos. Comparative genomic hybridization was performed on the first polar body (PB-1) of 323 MII oocytes retrieved from 16 donors. Of these, 111 were euploid, and were vitrified. Seventy-five of 78 vitrified oocytes (96%) survived warming and were fertilized using intracytoplasmic sperm injection. Thirty-one (41%) subsequently developed into expanded blastocysts, of which no more than two were subsequently transferred per uterus to 16 out of 19 prospective embryo recipients. Twelve of 19 (63%) recipients produced 17 healthy babies (eight singletons, three twins, and one set of triplets) One twin pregnancy miscarried in the late first trimester The birth rate per transfer of a maximum of two blastocysts to 16 recipients was 75%. The implantation rate per vitrified euploid oocyte was 27%. This study showed a six-fold improvement in pregnancy rate per cryopreserved oocyte over previous reports and a marked improvement in implantation rate. If independently validated, this approach could open the door to commercial egg cryobanking, significantly expanding women's reproductive choices.
Sher
G
G
2Department of Obstetrics and Gynecology, Sher Institutes for Reproductive Medicine, University of Nevada School of Medicine, Reno, NV 89109 , USA. gsher@sherinstitute.com
Keskintepe
L
L
Mukaida
T
T
Keskintepe
M
M
Ginsburg
M
M
Agca
Y
Y
Maassarani
G
G
Bayrak
A
A
D000328:Adult; D002470:Cell Survival; D015925:Cryopreservation / Q000379:methods*; D004624:Embryo Transfer; D005260:Female; D005306:Fertilization / Q000502:physiology*; D006801:Humans; D008875:Middle Aged; D009865:Oocytes; D011003:Ploidies; D011247:Pregnancy; D018873:Pregnancy Rate; D011272:Pregnancy, Multiple / Q000706:statistics & numerical data; D014427:Twins; D055815:Young Adult