Low-intensity pulsed ultrasound enhances immunomodulation and facilitates osteogenesis of human periodontal ligament stem cells by inhibiting the NF-κB pathway.

Human periodontal ligament stem cells (hPDLSCs) are vital in cellular regeneration and tissue repair due to their multilineage differentiation potential. Low intensity pulsed ultrasound (LIPUS) has been applied for treating bone and cartilage defects. This study explored the role of LIPUS in the immunomodulation and osteogenesis of hPDLSCs. hPDLSCs were cultured in vitro, and the effect of different intensities of LIPUS (30, 60, and 90 mW/cm2) on hPDLSC viability was measured. hPDLSCs irradiated by LIPUS and stimulated by lipopolysaccharide (LPS) and LIPUS (90 mW/cm2) were co-cultured with peripheral blood mononuclear cells (PBMCs). Levels of immunomodulatory factors in hPDLSCs and inflammatory factors in PBMCs were estimated, along with determination of osteogenesis-related gene expression in LIPUS-irradiated hPDLSCs. The mineralized nodules and alkaline phosphatase (ALP) activity of hPDLSCs and levels of IκBα, p-IκBα, and p65 subunits of NF-κB were determined. hPDLSC viability was increased as LIPUS intensity increased. Immunomodulatory factors were elevated in LIPUS-irradiated hPDLSCs, and inflammatory factors were reduced in PBMCs. Osteogenesis-related genes, mineralized nodules, and ALP activity were promoted in LIPUS-irradiated hPDLSCs. The cytoplasm of hPDLSCs showed increased IκBα and p65 and decreased p-IκBα at increased LIPUS intensity. After LPS and LIPUS treatment, the inhibitory effect of LIPUS irradiation on the NF-κB pathway was partially reversed, and the immunoregulation and osteogenic differentiation of hPDLSCs were decreased. LIPUS irradiation enhanced immunomodulation and osteogenic differentiation abilities of hPDLSCs by inhibiting the NF-κB pathway, and the effect is dose-dependent. This study may offer novel insights relevant to periodontal tissue engineering.

miR-200a-3p represses osteogenesis of human periodontal ligament stem cells by targeting ZEB2 and activating the NF-κB pathway.

OBJECTIVES: Human periodontal ligament stem cells (hPDLSCs) bear multilineage differentiation potential and represent the cytological basis of periodontal tissue regeneration. microRNA (miR) is accepted as a critical regulator of cell differentiation. This study explored the molecular mechanism of miR-200a-3p in osteogenesis of hPDLSCs. MATERIAL AND METHODS: hPDLSCs were cultured and identified in vitro. miR-200a-3p expression during osteogenic differentiation of hPDLSCs was detected. hPDLSCs were transfected with miR-200a-3p mimic or miR-200a-3p inhibitor. Alkaline phosphatase (ALP) activity, calcified nodules and osteogenesis-related genes of hPDLSCs were measured. The binding relationship between miR-200a-3p and ZEB2 was predicted and verified. hPDLSCs were infected with sh-ZEB2, and then the osteogenic capacity was examined. miR-200a-3p inhibitor-transfected hPDLSCs were infected with sh-ZEB2. The key proteins of the NF-κB pathway were measured. RESULTS: miR-200a-3p expression was downregulated during osteogenic differentiation of hPDLSCs. Upregulation of miR-200a-3p reduced ALP activity, calcified nodules and osteogenesis-related genes of hPDLSCs, while downregulation of miR-200a-3p facilitated the osteogenesis of hPDLSCs. miR-200a-3p targeted ZEB2. ZEB2 silencing repressed osteogenesis of hPDLSCs. ZEB2 silencing attenuated the promoting effect of miR-200a-3p inhibitor on osteogenesis of hPDLSCs. miR-200a-3p activated the NF-κB pathway by targeting ZEB2. CONCLUSION: miR-200a-3p repressed osteogenesis of hPDLSCs by targeting ZEB2 and activating the NF-κB pathway. This study may offer insights for periodontal tissue regeneration engineering.

Coexistence and Sudden Entrapment between Two Dissimilar, Miscible Oil Lenses.

The property of substrates is one of the important factors determining the interaction between two lenses (droplets). There likely exist different interactions between two dissimilar oil lenses (droplets) floating on the surface of a liquid phase from the interaction between two dissimilar oil droplets on a rigid substrate, for example, coalescence or coexistence. The interaction between two dissimilar oil lenses (droplets) is dependent on the intrinsic properties of both oil lenses (droplets) and external environmental factors. In this work, we investigate the contact interaction between two dissimilar, miscible oil lenses (toluene and silicone oil) on the surface of deionized water (DI water). The morphological evolution of two dissimilar, miscible oil lenses during the interaction under different experimental conditions is recorded and analyzed. The effects of the volume ratio of two dissimilar, miscible oil lenses, temperature of DI water, and viscosity of silicone oil on characteristic parameters are systematically studied. A sudden "entrapment" of a toluene lens into a silicone oil lens occurs after a period of the "mass exchange" (coexistence) between these two oil lenses. Several characteristic parameters, including the duration of the "mass exchange" and critical sizes of the toluene lens at the onset of the entrapment and after the entrapment, are found to be dependent on experimental conditions.

Strain Dependence of Energetics and Kinetics of Vacancy in Tungsten.

We investigate the influence of hydrostatic/biaxial strain on the formation, migration, and clustering of vacancy in tungsten (W) using a first-principles method, and show that the vacancy behaviors are strongly dependent on the strain. Both a monovacancy formation energy and a divacancy binding energy decrease with the increasing of compressive hydrostatic/biaxial strain, but increase with the increasing of tensile strain. Specifically, the binding energy of divacancy changes from negative to positive when the hydrostatic (biaxial) tensile strain is larger than 1.5% (2%). These results indicate that the compressive strain will facilitate the formation of monovacancy in W, while the tensile strain will enhance the attraction between vacancies. This can be attributed to the redistribution of electronic states of W atoms surrounding vacancy. Furthermore, although the migration energy of the monovacancy also exhibits a monotonic linear dependence on the hydrostatic strain, it shows a parabola with an opening down under the biaxial strain. Namely, the vacancy mobility will always be promoted by biaxial strain in W, almost independent of the sign of strain. Such unexpected anisotropic strain-enhanced vacancy mobility originates from the Poisson effect. On the basis of the first-principles results, the nucleation of vacancy clusters in strained W is further determined with the object kinetic Monte Carlo simulations. It is found that the formation time of tri-vacancy decrease significantly with the increasing of tensile strain, while the vacancy clusters are not observed in compressively strained W, indicating that the tensile strain can enhance the formation of voids. Our results provide a good reference for understanding the vacancy behaviors in W.