Rapid visualization of metaphase chromosomes in single human blastomeres after fusion with in-vitro matured bovine eggs

Steen Willadsen, Jacob Levron, Santiago Munné, Tim Schimmel, Carmen Márquez, Richard Scott, Jacques Cohen

Research output: Contribution to journalArticlepeer-review

Abstract

The present study was aimed to facilitate karyotyping of human blastomeres using the metaphase-inducing factors present in unfertilized eggs. A rapid technique for karyotyping would have wide application in the field of preimplantation genetic diagnosis. When cryopreserved in-vitro matured bovine oocytes were fused with human blastomeres, the transferred human nuclei were forced into metaphase within a few hours. Eighty-seven human blastomeres from abnormal or arrested embryos were fused with bovine oocytes in a preclinical study. Fusion efficiency was 100%. In 21 of the hybrid cells, no trace of human chromatin was found. Of the remaining 66, 64 (97%) yielded chromosomes suitable for analysis. The method was used to karyotype embryos from two patients with maternal translocations. One embryo which was judged to be karyotypically normal was replaced in the first patient, resulting in one pregnancy with a normal fetus. None of the second patient's embryos was diagnosed as normal, and hence none was transferred. The results of the present study demonstrated that the ooplasmic factors which induce and maintain metaphase in bovine oocytes can force transferred human blastomere nuclei into premature metaphase, providing the basis for a rapid method of karyotyping blastomeres from preimplantation embryos and, by implication, cells from other sources.

Original languageEnglish
Pages (from-to)470-475
Number of pages6
JournalHuman Reproduction
Volume14
Issue number2
DOIs
StatePublished - 1999
Externally publishedYes

Keywords

  • Electrofusion
  • FISH
  • Nuclear transplantation
  • Spectral karyotyping
  • Translocation

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