Harnessing a Novel Inhibitory Role of miR-16 in Osteogenesis by Human Mesenchymal Stem Cells for Advanced Scaffold-Based Bone Tissue Engineering

MicroRNA (miRNA) therapeutics is increasingly being developed to either target bone-related diseases such as osteoporosis and osteoarthritis or as the basis for novel bone tissue engineering strategies. A number of miRNAs have been reported as potential osteo-therapeutics but no consensus has yet been established on the optimal target. miR-16 has been studied extensively in nonosteogenic functions and used as functionality reporter target in the development of nonviral miRNA delivery platforms. This study hypothesized that miR-16 may also play an inhibitory role in osteogenesis due to its ability to directly target Smad5 and AcvR2a. This study thus aimed to assess the potential of miR-16 inhibition to increase osteogenesis in human mesenchymal stem cells (hMSCs) using a previously established miRNA delivery platform composed of nanohydroxyapatite (nHA) particles as nonviral vectors in combination with collagen-nHA scaffolds designed specifically for bone repair. Initial results showed that antagomiR-16 delivery efficiently increased the relative levels of both putative targets and Runx2, the key transcription factor for osteogenesis, while also increasing osteocalcin levels. Furthermore, significant increases in mineral calcium deposition by hMSCs were found in both monolayer and most importantly in scaffold-based osteodifferentiation studies, ultimately demonstrating that miR-16 inhibition further enhances the therapeutic potential of a scaffold with known potential for bone repair applications and thus holds significant therapeutic potential as a novel bone tissue engineering strategy. Furthermore, we suggest that harnessing the additional functions known to miR-16 by incorporating either its enhancers or inhibitors to tissue-specific tailored scaffolds provides exciting opportunities for a diverse range of therapeutic indications.