Mesenchymal stem cells (MSCs), also referred to as multipotent stromal cells, have been isolated from various adult tissue sources because of their capabilities of differentiating into multiple cell lineages including osteoblasts, thus providing a novel approach for treating bone diseases and metabolic disorders. Despite extensive potential in cell therapy and widespread interest in clinical applications of MSCs, the molecular mechanisms with regard to the regulation of their therapeutic properties and osteoblast differentiation remain to be fully elucidated. MicroRNAs (miRNAs), a novel class of endogenous small noncoding RNAs, regulate gene expressions by translational repression or degradation of their targets. Recently, emerging evidence has shown that miRNAs are closely involved in controlling the key steps of osteoblast differentiation in MSCs. This review focuses on miRNAs and their roles in regulating osteogenic differentiation of MSCs.

Despite extensive research on osteoblast differentiation and proliferation in mesenchymal stem cells (MSCs), the accurate mechanism remains to be further elucidated. MicroRNAs have been reported to be key regulators of osteoblast differentiation and proliferation. Here, we found that miR‐144‐3p is down‐regulated during osteoblast differentiation of C3H10T1/2 cells. Overexpression of miR‐144‐3p inhibited osteogenic differentiation, whereas inhibition of miR‐144‐3p reversed this process. Furthermore, miR‐144‐3p inhibited the proliferation of C3H10T1/2 cells by arresting cells at the G0/G1 phase. Results from bioinformatics analysis, luciferase assay and western blotting demonstrated that miR‐144‐3p directly targeted Smad4. Additionally, Smad4 knockdown blocks the effects of miR‐144‐3p inhibitor. Therefore, we conclude that miR‐144‐3p negatively regulates osteogenic differentiation and proliferation of C3H10T1/2 cells by targeting Smad4.

SUMMARYSignificant tissue destruction, repair, and remodeling are involved in parturition, which involves fetal membrane rupture, cervical ripening, and uterine contraction and its subsequent involution. Extracellular matrix degradation and remodeling by proteolytic enzymes, such as matrix metalloproteinases (MMPs), are required for the final steps of parturition. MMPs participate in physiological degradation and remodeling through their proteolytic activities on specific substrates, and are balanced by the action of their inhibitors. Disruption to this balance can result in pathological stress that ends with preterm or post-term birth or pre-eclampsia. In this review, we examine the roles and regulation of the MMP system in physiological and pathological labor, and propose a model that illustrates the mechanisms by which the MMP system contributes to these processes.Mol. Reprod. Dev. 83: 276À286,