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.
2Department of Obstetrics and Gynecology, Sher Institutes for Reproductive Medicine, University of Nevada School of Medicine, Reno, NV 89109 , USA. gsher@sherinstitute.com
G
G
Sher
L
L
Keskintepe
T
T
Mukaida
M
M
Keskintepe
M
M
Ginsburg
Y
Y
Agca
G
G
Maassarani
A
A
Bayrak
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