Human mesenchymal stem cells are regulated by specific microRNAs during the early stage of osteogenesis

Osteoblast and bone tissue differentiations are complex processes supported by human multipotent mesenchymal cells. Differentiation-specific microRNAs (miRNAs), which are involved and coordinate a broad range of biological processes, may play a key role in controlling human mesenchymal stem cells (hMSCs) fate. The characterization of miRNAs that operate through tissue-specific transcription factors is a fundamental step to obtain deeper insights about the signaling pathways and regulatory networks controlling bone formation and turnover. In regenerative medicine, to improve wound healing and tissue repair processes, miRNAs could be employed for biofunctionalization of last generation biomaterials. In this study, we investigated the microRNA regulative network inferred from the sequencing data, obtained by Next Generation Sequencing (NGS), during the early stage of osteogenic differentiation of bone marrow derived hMSCs. Then, functional studies were carried out with cultured hMSCs exposed to synthetic miRNA mimics and miRNA inhibitors. NGS-miR-expression profiling revealed a miRs signature able to distinguish osteogenic differentiation. Our Bayesian network showed that a group of well conserved miRNAs played a regulatory role in osteogenic differentiation of hMSCs. Interestingly, specific miRNAs overexpression or inhibition induced in hMSCs an osteogenic differentiation similar to the osteogenic medium in terms of matrix mineralization and osteogenic genes expression. The cellular epigenetic miRNAs regulatory network is critical to define the role played by these small RNA molecules during the osteogenic differentiation process. These insights could be exploited to control the cell fate in order to achieve a therapeutic advantage, reducing the post-intervention recovery time by osteogenesis stimulation