One of the main reasons for limiting the widespread clinical use of mesenchymal stem cells (MSCs) is a low speed of their proliferation in vitro. In this regard, the search for new safe and effective growth stimulants is an urgent task. In this study, we investigated the effect of nanocrystalline cerium oxide doped with gadolinium (Ce1-х Gdх Oy), on the morphofunctional characteristics and proliferative activity of MSCs derived from dental pulp. It was shown that the introduction of Ce1-х Gdх Oy nanoparticles into the culture of dental MSCs provides the activation of proliferation of the cells in a dose-dependent manner. High concentrations of Ce1-х Gdх Oy nanoparticles inhibit the proliferation of the cells; however, this does not lead to further development of apoptosis and cell death. The obtained results indicate that the nanocrystalline cerium oxide can be considered as a basis for the development of highly efficient and low-cost supplements for culturing MSCs.