Rhesus monkey placental transgene expression after lentiviral gene transfer into preimplantation embryos

Transgenic mice have provided invaluable information about gene function an d regulation. However, because of marked differences between rodents and pr imates, some areas of human biology such as early embryonic development, ag ing, and maternal-fetal interactions would be best studied in a nonhuman pr imate model. Here, we report that gene transfer into rhesus monkey (Macaca mulatta) preimplantation embryos gives rise to transgenic placentas that ex press a reporter transgene (eGFP). Blastocysts resulting from culture of in vitro fertilized ova were transduced with a self-inactivating lentiviral v ector and transferred into recipient females. One twin and one singleton pr egnancy were produced from a single stimulation cycle, and one live rhesus monkey was born from each pregnancy. Placentas from all conceptuses showed expression of the transgene as detected by reverse transcription-PCR, ribon uclease protection assay, direct epifluorescence, immunohistochemistry, and Western blot analysis. Integration in somatic tissues of the offspring was not detected. A maternal immune response to the xenogeneic placental antig en was shown by the presence of anti-GFP antibodies in peripheral blood of the recipient females by day 99 of gestation (term = 165 days). These resul ts demonstrate that transgene expression during gestation is compatible wit h successful pregnancy in nonhuman primates and provides an approach that c ould be broadly applicable to the development of novel models for primate b iomedical research.