The role of the ERK1/2 pathway in simvastatin-loaded nanomicelles and simvastatin in regulating the osteogenic effect in MG63 cells

Effects of Simvastatin-Loaded Nanomicelles on the Early Preservation of Tooth Extraction Sites

Object

The present study intended to evaluate the effect of simvastatin-loaded nanomicelles (SVNs) on promoting new bone formation and reducing alveolar ridge resorption at the tooth extraction sites at the early healing of the extraction sockets.

Methods

SVNs were synthesized using a dialysis method. The rabbit tooth extraction model was established, SVNs and simvastatin (SV) were loaded on gelatin sponge and inserted into the extraction socket. CBCT scans were performed at 0, 2, and 4 weeks postoperatively to evaluate bone formation and alveolar ridge absorption in the extraction sockets. And all the animals were sacrificed and the mandibles were harvested. And HE staining and Masson staining were used for histological evaluation of the bone formation in the extraction sockets.

Results

Radiographic evaluation showed that compared with the blank control group, at 2 and 4 weeks after extraction, SVNs increased the new bone density in the extraction sockets by 75.7% and 96.5%, and reduced the absorption rate of alveolar ridge length at the extraction sites by 60.8% and 49.1%, respectively. Histological evaluation showed that SVNs significantly improved the maturation of new bone tissue in the extraction sockets.

Conclusion

SVNs can significantly accelerate healing and effectively reduce the absorption of alveolar ridge at the extraction sites in the early stage of tooth extraction socket healing.

Recent advances on small molecules in osteogenic differentiation of stem cells and the underlying signaling pathways

Bone-related diseases are major contributors to morbidity and mortality in elderly people and the current treatments result in insufficient healing and several complications. One of the promising areas of research for healing bone fractures and skeletal defects is regenerative medicine using stem cells. Differentiating stem cells using agents that shift cell development towards the preferred lineage requires activation of certain intracellular signaling pathways, many of which are known to induce osteogenesis during embryological stages. Imitating embryological bone formation through activation of these signaling pathways has been the focus of many osteogenic studies. Activation of osteogenic signaling can be done by using small molecules. Several of these agents, e.g., statins, metformin, adenosine, and dexamethasone have other clinical uses but have also shown osteogenic capacities. On the other hand, some other molecules such as T63 and tetrahydroquinolines are not as well recognized in the clinic. Osteogenic small molecules exert their effects through the activation of signaling pathways known to be related to osteogenesis. These pathways include more well-known pathways including BMP/Smad, Wnt, and Hedgehog as well as ancillary pathways including estrogen signaling and neuropeptide signaling. In this paper, we review the recent data on small molecule-mediated osteogenic differentiation, possible adjunctive agents with these molecules, and the signaling pathways through which each small molecule exerts its effects.

Arylated gold nanoparticles have no effect on the adipogenic differentiation of MG-63 cells nor regulate any key signaling pathway during the differentiation

OBJECTIVE

MG-63 cells that have osteoblastic and adipogenic differentiation potential were evaluated for internalization, and adipogenic differentiation in the presence and absence of the covalently functionalized aryl gold nanoparticles (AuNPs-C6H4-4-COOH).

RESULTS

Inductively coupled plasma, flow cytometry and confocal microscopy analyses confirmed that gold nanoparticles were easily internalized by MG-63 cells. The MG-63 cells were differentiated into adipocytes without gold-aryl nanoparticles and with the gold-aryl nanoparticles at 5 µM concentration in both induction and maintenance media. The lipid content assay and the relative expressions of PPAR-γ, ADR1, GLUT1 and GLUT4 genes showed no significant variation with and without the gold nanoparticles treatment. Differential phosphorylation levels of 43 kinases phosphorylation sites were evaluated using the human phospho-kinase array to assess the effect of the gold nanoparticles on the signaling pathways during the differentiation. No kinase phosphorylation site was differentially phosphorylated with two or more folds after the nanoparticles treatment after the first day as well as at the end of MG-63 cells differentiation. The gold-aryl nanoparticles do not affect MG-63 cells differentiation into adipocytes neither do they affect any key signaling pathway. These properties make these gold nanoparticles suitable for future drug delivery and medical applications.

Functional identification of a rare vascular endothelial growth factor a (VEGFA) variant associating with the nonsyndromic cleft lip with/without cleft palate

Vascular endothelial growth factor A (VEGFA) is a crucial growth factor, which participates in multiple processes of human growth and development, such as angiogenesis and osteogenesis and is also necessary for development of palate. The purpose of this study was to investigate the effect of a rare VEGFA mutation (NM_001025366.2 773 T > C p.Val258Ala) on the cell functions and osteogenesis. Here, we found that the VEGFA mutation has adverse effects on the function of human embryonic palatal plate mesenchymal (HEPM) cells, and may affect the development of palate. The VEGFA mutation has adverse effects on promoting cell proliferation and migration and inhibiting apoptosis in HEPM and HEK–293 cells. In addition, the mutant VEGFA allele has a negative influence on osteogenesis. Taken together, the rare variant of the VEGFA gene had an adverse effect on cell functions and osteogenesis, which may impact the development of the palate. And these findings suggested that VEGFA mutation (c.773 T > C) may lead to nonsyndromic cleft lip with or without cleft palate and also provide a new insight into the mechanism of VEGFA gene in osteogenesis and palatogenesis.