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

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 plus or minus SEM, 81 plus or minus 5%, 88 plus or minus 7%, and 87 plus or minus 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 plus or minus 15%) or ICSI control embryos (46 plus or minus 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.