Rhesus Monkey Embryos Produced by Nuclear Transfer from Embryonic Blastomeres or Somatic Cells1

Abstract

Production of genetically identical nonhuman primates would reduce the number of animals required for biomedical research and dramatically impact studies pertaining to immune system function, such as development of the human-immunodeficiency-virus vaccine. Our long-term goal is to develop robust somatic cell cloning and/or twinning protocols in the rhesus macaque. The objective of this study was to determine the developmental competence of nuclear transfer (NT) embryos derived from embryonic blastomeres (embryonic cell NT) or fetal fibroblasts (somatic cell NT) as a first step in the production of rhesus monkeys by somatic cell cloning. Development of cleaved embryos up to the 8-cell stage was similar among embryonic and somatic cell NT embryos and comparable to controls created by intracytoplasmic sperm injection (ICSI; mean +/- SEM, 81 +/- 5%, 88 +/- 7%, and 87 +/- 4%, respectively). However, significantly lower rates of development to the blastocyst stage were observed with somatic cell NT embryos (1%) in contrast to embryonic cell NT (34 +/- 15%) or ICSI control embryos (46 +/- 6%). Development of somatic cell NT embryos was not markedly affected by donor cell treatment, timing of activation, or chemical activation protocol. Transfer of embryonic, but not of somatic cell NT embryos, into recipients resulted in term pregnancy. Future efforts will focus on optimizing the production of somatic cell NT embryos that develop in high efficiency to the blastocyst stage in vitro.

Impairments in Embryonic Genome Activation in Rhesus Monkey Somatic Cell Nuclear Transfer Embryos

“…In general, major challenges and difficulties faced in SCNT are the low efficiency and high incidence of developmental abnormalities in the resultant cloned fetuses or neonates. In monkeys, embryonic cells have been used as nuclear donor cells to produce live offspring (Meng et al, 1997), but SCNT has not yet been achieved despite significant efforts investigating nuclear transfer techniques (Mitalipov et al, 2002;Ng et al, 2004;Simerly and Navara, 2003;Zhou et al, 2006). Failed attempts in nonhuman primates have been attributed to inadequate or inappropriate nuclear reprogramming (Simerly and Navara, 2003).…”

The first cell cycle after transfer of somatic cell nuclei in a non-human primate

“…In addition, although blastocysts have been developed from rhesus embryos after SCNT (Mitalipov et al, 2002), only nuclear transfer of embryonic cells in non-human primates has resulted in live-births (Meng et al, 1997).…”

Cloned blastocysts produced by nuclear transfer from somatic cells in cynomolgus monkeys (Macaca fascicularis)

“…Simerly et al (2003) performed electro fusion and activation simultaneously using DC pulses to produce NT blastocysts from skin fibroblast cells. In addition, Mitalipov et al (2002) reported success of SCNT blastocysts from fetal fibroblast cells using a combination of electro fusion and chemical activation in rhesus monkeys. They activated the reconstructed oocytes 3 h after electro fusion.…”