Birth of cloned mice from vaginal smear cells after somatic cell nuclear transfer

•Somatic cells in vaginal smear were used for somatic-cell cloning.•Through the estrous cycle, more than 60% nucleated cells exist in vaginal smear except at the estrus stage.•Birth of cloned mouse from these cells was demonstrated.

Less invasive methods for donor cell collection will facilitate reproduction of wild animals using somatic-cell nuclear transfer. Stages of the estrous cycle in mice have long been studies using somatic cells that can be collected from vaginal walls using cotton tipped swabs in a relatively non-invasive manner. In this study, we examined the feasibility of these cells as sources of nuclei for somatic-cell cloning using nuclear transfer. Estrous cycles generally comprise proestrus, estrus, metestrus, and diestrus stages. In the present experiments, more than 60% of cells were nucleated in vaginal smears from all but the estrus stage. However, after somatic-cell nuclear transfer of cells from proestrus, metestrus, and diestrus stages, 66%, 50%, and 72% of cloned embryos developed to the morula/blastocyst, and cloned female mouse birth rates after embryo transfer were 1.5%, 0.3%, and 1%, respectively. These results show that noninvasively collected vaginal smears contain somatic cells that can be used to clone female mice.