Blastocyst formation, karyotype, and mitochondrial DNA of interspecies embryos derived from nuclear transfer of human cord fibroblasts into enucleated bovine oocytes

Fertil Steril. 2003 Dec;80(6):1380-7. doi: 10.1016/j.fertnstert.2003.07.006.


Objective: To establish an interspecies somatic cell nuclear transfer (iSCNT) technique for deriving blastocysts having human chromosome complements without sacrificing human oocytes.

Design: Prospective, randomized study undertaken in vitro.

Setting: University-affiliated hospital and laboratory, Seoul National University.

Patient(s): Postpartum women with natural spontaneous vaginal delivery.

Intervention(s): Human cord fibroblasts were retrieved from five postpartum women from whom informed consent was obtained. After subculture and cryopreservation, serum-starved cells were transferred into enucleated bovine oocytes.

Main outcome measure(s): Embryo development, karyotype, and the presence of mitochondrial DNA (mtDNA).

Result(s): A total 1,742 oocytes were provided for iSCNT and results showed that both fibroblast batch and reconstruction method significantly affected iSCNT outcome. An iSCNT using a single DC pulse of 1.9-2.1 kV/cm for 20 microseconds yielded better rates of fusion (30%-56%) and cleavage (36%) than the other iSCNT protocols. Four to 9% interspecies embryos produced with the optimized method developed to morulae or blastocysts after cultured in a serum-free medium. Results from karyotyping demonstrated that 56% of interspecies embryos evaluated had human chromosome complements. In polymerase chain reaction (PCR) analysis of a single embryo, both human and bovine mtDNAs were detected until the 16-cell stage, whereas only the bovine mtDNA was found beyond the morula stage.

Conclusion(s): An iSCNT using human cord fibroblasts and bovine oocytes can yield blastocysts and the results of karyotyping and mtDNA analysis confirmed the feasibility of the iSCNT technique.

MeSH terms

  • Adult
  • Animals
  • Base Sequence
  • Blastocyst / cytology
  • Blastocyst / physiology*
  • Cattle
  • Chromosome Mapping
  • DNA Primers
  • DNA, Mitochondrial / genetics*
  • Female
  • Fetal Blood / cytology*
  • Fibroblasts / transplantation
  • Humans
  • Infant, Newborn
  • Karyotyping
  • Male
  • Nuclear Transfer Techniques*
  • Oocytes / physiology*
  • Pregnancy
  • Reproductive Techniques, Assisted


  • DNA Primers
  • DNA, Mitochondrial