Metaphase II karyoplast transfer from human in-vitro matured oocytes to enuclueated mature oocytes

Abstract

Metaphase II karyoplast transfer is believed to be a useful method to rescue aged oocytes. This study attempted karyoplast transfer of in-vitro matured metaphase II (MII) oocytes, as a model of aged oocytes, into enucleated freshly ovulated metaphase II oocytes with visualization of their chromosomes under an inverted microscope. Recipient karyoplasts derived from immature oocytes were cultured in-vitro until first polar body extrusion. After 1-2 days culture, 52.1% extruded a polar body, 95.5% had PSC, aneuploidy was very low (4.5%) and none had structural aberrations. Donor oocytes were obtained from IVF or intracytoplasmic sperm injection (ICSI) patients. Chromosomes were easily confirmed in 92.3% and 95.0% of in-vivo and in-vitro matured oocytes respectively. Thirty-one karyoplasts were placed in the perivitelline space of enucleated donor oocytes, and 25 (80.6%) fused to form a reconstituted oocyte. Fertilization, cleavage and blastocyst formation rates following ICSI were 76.0%, 64.0% and 28.0% respectively for reconstructed oocytes and 59.2%, 48.0% and 3.1% respectively for control (in-vitro matured) oocytes. Chromosomal analysis of five embryos developed after karyoplast transfer and ICSI showed normal diploid sets of 46 chromosomes. In conclusion, this metaphase II karyoplast transfer technique can be applied to the solution of chromosomal abnormalities related to oocyte ageing.

Mitochondrial DNA disease: new options for prevention

“…Evidence on the effect of metaphase II spindle transfer on embryo development is largely confined to studies in rhesus monkey with a report that the technique of spindle transfer is compatible with the birth of normal offspring (26). There has also been one report of blastocyst development following metaphase II spindle transfer in human oocytes (27).…”

Improvement of early developmental competence of postovulatory‐aged oocytes using metaphase II spindle injection in mice

“…Of these, the more widely used method is cellular membrane fusion, which is performed with electrostimulation, inactivated Sendai virus, or polyethylene glycol. Fusion methods are further grouped according to the oocyte stage: germinal vesicle (GV), [4][5][6][7][8][9] metaphase II (MII), [10][11][12] or pronuclear 13,14 (Figure 1). In particular, reconstructed oocytes generated by transferring GVs from oocytes of older patients into enucleated immature oocytes of young patients matured more successfully to meiosis II after an in vitro culture than the nonmanipulated control oocytes.…”

Mitochondrial enrichment in infertile patients: a review of different mitochondrial replacement therapies

“…This procedure significantly increased the number of embryos that developed to the blastocyst stage. 52 …”