Pluripotent stem cells proliferation is associated with placentation in dogs.

Pluripotent stem cells have been studied as source of cells for regenerative medicine and acquire or genetic diseases, as an innovative therapy. Most tissues have stem cells populations, however in few quantities or impossible to be used during adult life, which lead to scientists look for new sources. Thus, this study aimed to analyze the presence of pluripotent cells in the uterus and placenta, following up non-pregnant, pregnant (begin, middle, and final), and postpartum periods in dogs. The uteri were obtained from social castration programs for population control in Pirassununga, Sao Paulo, Brazil. It was collected 20 uteri at different stages. The samples were fixed and processed for immunohistochemical analysis of NANOG, OCT4 and SOX2 expression, knowing as pluripotent stem cells makers. Our results showed positive expression for NANOG, OCT4 and SOX2 in all stages of gestation and nonpregnant uterus; however, we highlight some quantitative different between stages. OCT4 showed more expression in non-pregnant uterus than NANOG and SOX2, and its expression increased in pregnant uterus. In pregnant uterus there was more expression of NANOG than OCT4 and SOX2. Interesting, no difference was found between these markers in the other periods. In conclusion, it was possible to identify pluripotent stem cells in all periods in dog placenta and uterus, however during the early stage of pregnancy we observed more pluripotent stem cells than in all the others periods confirming the high plasticity and regeneration capacity of the uterine tissue.