Osteogenesis is a complex multi-step process involving the differentiation of mesenchymal stem cells (MSCs) into osteoblast progenitor cells, preosteoblasts, osteoblasts and osteocytes, and the crosstalk between multiple cell types for the formation and remodeling of bone. The signaling regulatory networks during osteogenesis include various components, including growth factors, transcription factors, micro (mi)RNAs and effectors, a number of which form feedback loops controlling the balance of osteogenic differentiation by positive or negative regulation. miRNAs have been found to be important regulators of osteogenic signaling pathways in multiple aspects and multiple signaling pathways. The present review focusses on the progress in elucidating the role of miRNA in the osteogenesis signaling networks of MSCs as a substitute for bone implantation the the field of bone tissue engineering. In particular, the review classifies which miRNAs promote or suppress the osteogenic process, and summarizes which signaling pathway these miRNAs are involved in. Improvements in knowledge of the characteristics of miRNAs in osteogenesis provide an important step for their application in translational investigations of bone tissue engineering and bone disease.

A scaffold for bone tissue engineering should have highly interconnected porous structure, appropriate mechanical and biological properties. In this work, we fabricated well-interconnected porous β-tricalcium phosphate (β-TCP) scaffolds via selective laser sintering (SLS). We found that the mechanical and biological properties of the scaffolds were improved by doping of zinc oxide (ZnO). Our data showed that the fracture toughness increased from 1.09 to 1.40 MPam1/2, and the compressive strength increased from 3.01 to 17.89 MPa when the content of ZnO increased from 0 to 2.5 wt%. It is hypothesized that the increase of ZnO would lead to a reduction in grain size and an increase in density of the strut. However, the fracture toughness and compressive strength decreased with further increasing of ZnO content, which may be due to the sharp increase in grain size. The biocompatibility of the scaffolds was investigated by analyzing the adhesion and the morphology of human osteoblast-like MG-63 cells cultured on the surfaces of the scaffolds. The scaffolds exhibited better and better ability to support cell attachment and proliferation when the content of ZnO increased from 0 to 2.5 wt%. Moreover, a bone like apatite layer formed on the surfaces of the scaffolds after incubation in simulated body fluid (SBF), indicating an ability of osteoinduction and osteoconduction. In summary, interconnected porous β-TCP scaffolds doped with ZnO were successfully fabricated and revealed good mechanical and biological properties, which may be used for bone repair and replacement potentially.

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BackgroundNasopharyngeal carcinoma (NPC) is prevalent in South East Asia and Southern China particularly, despite the reported 5-year survival ratio is relative higher than other deadly cancers such as liver, renal, pancreas cancer, the lethality is characterized by high metastatic potential in the early stage and high recurrence rate after radiation treatment. MicroRNA-29c was found to be down-regulated in the serum as well as in the tissue of nasopharyngeal carcinoma tissue.MethodsIn this study, we found accidentally that the transfection of pre-miR-29c or miR-29c mimics significantly increases the expression level of miR-34c and miR-449a but doesn’t affect that of miR-222 using real-time quantitative PCR in nasopharyngeal carcinoma cell lines. To explore the molecular mechanism of the regulatory role, the cells are treated with 5-Aza-2-deoxycytidine (5-Aza-CdR) treatment and the level of miR-34c and miR-449a but not miR-222 accumulated by the treatment. DNA methyltransferase 3a, 3b were down-regulated by the 5-Aza-CdR treatment with western blot and real-time quantitative PCR.ResultsWe found that pre-miR-29c or miR-29c mimics significantly increases the expression level of miR-34c and miR-449a. We further found DNA methyltransferase 3a and 3b are the target gene of miR-29c. Restoration of miR-29c in NPC cells down-regulated DNA methyltransferase 3a, 3b, but not DNA methyltransferase T1.ConclusionsThe regulation of miR-29c/DNMTs/miR-34c\449a is an important molecular axis of NPC development and targeting DNMTs or restoring of miR-29c might be a promising therapy strategy for the prevention of NPC.