Advances in the development of a noninvasive embryo model for the evaluation of the quality of cloned embryos subjected to different treatments
Total number of cells in cloned embryos is generally lower than that of in vivo derived embryos and in bovines cell allocation at the blastocyst stage, has been observed to be affected in a large proportion of cloned embryos. The current embryo staining procedures are toxic for mammalian cells and thus can not be used to determine the developmental potential of a stained embryo. Therefore, in the present study we sought to assess the feasibility to develop a noninvasive embryo model that would be suitable for the evaluation of cloned embryos subjected to different nuclear transfer and embryo culture procedures. For doing this, we stably transfected a bovine embryonic fibroblast cell line and generated a number of clones that constitutively expressed a red fluorescent protein (HcRed) in the nuclear compartment of the cell. Those clones with normal chromosomal content were further used as nuclear donor in nuclear transfer procedures (SCNT) to generate transgenic cloned embryos. These embryos expressed the red fluorescent protein in each blastomere, allowing their in vivo evaluation during development, thus demonstrating the potential of this model as a noninvasive tool for the assessment of the quality of cloned embryos.