Comparison of globular albumin methacryloyl and random-coil gelatin methacryloyl: Preparation, hydrogel properties, cell behaviors, and mineralization.

Bovine serum albumin methacryloyl (BSAMA) is a newly emerging photocurable globular protein-based material whereas gelatin methacryloyl (GelMA) is one of the most popular photocurable fibrous protein-based materials. So far, the influence of their different structural conformations as building blocks on hydrogel properties and mineral deposition has not been investigated. Here, we compared their differences in structures, gelation kinetics, hydrogel properties, mineralization, and cell behaviors. BSAMA maintained a stable globular structure while GelMA exhibited temperature-sensitive conformations (4 - 37 °C). BSAMA displayed slower gelation kinetics and much more retarded enzymatic degradation compared to GelMA. Photocurable BSAMA (6.41 - 390.95 kPa) and GelMA hydrogels (36.09 - 199.70 kPa) exhibited tunable mechanical properties depending on their concentrations (10 - 20%). Interestingly, BSAMA hydrogels mineralized needle-like apatite (Ca/P: 1.409) with higher crystallinity compared to GelMA hydrogels (Ca/P: 1.344). BSAMA and GelMA supported satisfactory cell (MC3T3-L1) viability of 99.43 ± 0.57% and 97.14 ± 0.69%, respectively. However, BSAMA gels were less favorable to cell proliferation and migration than GelMA gels. In serum-free environments, cells on GelMA displayed a higher amount of attachment, a more elongated shape, and a longer protrusion compared to those on BSAMA (p < 0.01) during the early adhesion.

High-performance reversible aqueous zinc-ion battery based on iron-doped alpha-manganese dioxide coated by polypyrrole.

The development of zinc-ion storage cathode materials for aqueous zinc-ion batteries (AZIBs) is a necessary step for the construction of large-scale electrochemical energy conversion and storage devices. Iron-doped alpha-manganese dioxide (α-MnO2) nanocomposites were achieved in this study via pre-intercalation of Fe3+ during the formation of α-MnO2 crystals. A polypyrrole (PPy) granular layer was fabricated on the surface of α-MnO2 using acid-catalyzed polymerization of pyrroles. The pre-intercalation of Fe3+ effectively enlarges the lattice spacing of α-MnO2 and consequently decreases the hindrance for Zn2+ insertion/extraction in the iron-doped α-MnO2 coated by PPy (Fe/α-MnO2@PPy) composite. Meanwhile, the PPy buffer layer can ameliorate electron and ion conductivity and prevent dissolution of α-MnO2during the charge/discharge process. This unique structure makes the Fe/α-MnO2@PPy composite an efficient zinc-ion storage cathode for AZIBs. The targeted Fe/α-MnO2@PPy cathode achieves superior performance with reversible specific capacity (270 mA h g-1 at 100 mA g-1) and exhibits highdiffusioncoefficientof 10-10-10-14 cm-2 s-1. Therefore, a feasible approach is implemented on advanced electrode materials using in AZIBs for practical applications.

[Hypoxia regulates the expression of OPG/RANKL mRNA in rat bone marrow mesenchymal stem cells].

PURPOSE: To investigate the effects of hypoxia on the expression of osteoprotegerin (OPG) and receptor activator of nuclear factor kappa B ligand (RANKL) mRNA in rat bone marrow mesenchymal stem cells (rBMSCs). METHODS: rBMSCs were isolated and cultured by whole bone marrow cell adherent method, and an optimal hypoxic preconditioning model was established with CoCl2 (cobalt chloride). rBMSCs were incubated in cell culture mediums with different concentrations of CoCl2 (final concentrations of CoCl2 were 0, 50, 100, 200, 400 µmol/L) and incubated for different times. MTT assay was applied to detect the effect of CoCl2 on cell proliferation. mRNA and protein expression of HIF-1α of rBMSCs was detected by real-time PCR and Western blot. After treated with 100 µmol/L CoCl2 for 0, 12, 24, 48, 72, 96 h, the expression of rBMSCs OPG/RANKL mRNA were detected by real-time PCR. The differences in distribution of each genotype were analyzed with SPSS 18.0 software package. RESULTS: Compared with the control group, 200, 400 µmol/L CoCl2 inhibited the proliferation of rBMSCs (P<0.05). However, 50, 100 µmol/L CoCl2 had no significant impact on the proliferation of rBMSCs (P>0.05). Real-time PCR and Western blot showed that HIF-1α expression in 50 µmol/L and 100 µmol/L CoCl2 groups was significantly higher than the control group; the effect of 100 µmol/L CoCl2 was significantly greater than 50 µmol/L CoCl2. After cultivated in hypoxia condition for 12 h, the expression of OPG and RANKL mRNA in rBMSCs didn't change significantly (P>0.05). After cultured hypoxia condition for 24, 48, 72, 96 h, the expression of OPG mRNA in rBMSCs increased while the RANKL decreased, thus the ratio of OPG/RANKL increased and the difference was significant (P<0.05). CONCLUSIONS: Hypoxia can regulate the mRNA expression of OPG and RANKL mRNA in rBMSCs and significantly promote osteogenic differentiation.

Baicalein enhances the osteogenic differentiation of human periodontal ligament cells by activating the Wnt/ß-catenin signaling pathway.

OBJECTIVE: Periodontium regeneration is one of the most important processes for periodontitis therapy. Human periodontal ligament cells (hPDLCs) play a vital role in the repair and regeneration of periodontal tissues. Our study aimed to investigated the mechanisms underlying the promotion of hPLDCs osteogenic differentiation by baicalein. DESIGN: hPDLCs were obtained from periodontal ligament (PDL) tissues by primary culture. The MTT assay was used to determine the growth curves of hPDLCs treated with different concentrations of baicalein (1.25, 2.5, 5, or 10µM). Alkaline phosphatase (ALP) staining and Alizarin red S staining were performed to assess osteogenic differentiation of hPDLCs administered baicalein. Osteogenic differentiation-related gene and protein expression levels and Wnt/ß-catenin pathway signal changes were assessed by qRT-PCR and Western blotting analysis. RESULTS: The results showed that baicalein decreased the growth of hPDLCs slightly and increased ALP activity and calcium deposition in a dose-dependent manner. The expression of runt-related transcription factor 2 (RUNX2), bone morphogenetic protein 2 (BMP2), Osterix (OSX) and osteocalcin (OCN) were elevated after baicalein administration. Moreover, baicalein strongly activated the Wnt/ß-catenin pathway and up-regulated the expression of ß-catenin, lymphoid enhancer factor 1 (LEF1) and Cyclin D1. Dickkopf-related protein 1 (DKK-1) significantly reversed the effects of baicalein on hPDLCs. CONCLUSIONS: Our findings indicated that baicalein enhanced the osteogenic differentiation of hPDLCs via the activation of the Wnt/ß-catenin signaling pathway, which may represent a potential candidate for periodontitis therapy.

Endogenous hydrogen sulfide is involved in osteogenic differentiation in human periodontal ligament cells.

OBJECTIVE: Endogenous hydrogen sulfide (H2S) has recently emerged as an important intracellular gaseous signaling molecule within cellular systems. Endogenous H2S is synthesized from l-cysteine via cystathionine ß-synthase and cystathionine γ-lyase and it regulates multiple signaling pathways in mammalian cells. Indeed, aberrant H2S levels have been linked to defects in bone formation in experimental mice. The aim of this study was to examine the potential production mechanism and function of endogenous H2S within primary human periodontal ligament cells (PDLCs). DESIGN: Primary human PDLCs were obtained from donor molars with volunteer permission. Immunofluorescent labeling determined expression of the H2S synthetase enzymes. These enzymes were inhibited with D,L-propargylglycine or hydroxylamine to examine the effects of H2S signaling upon the osteogenic differentiation of PDLCs. Gene and protein expression levels of osteogenic markers in conjunction with ALP staining and activity and alizarin red S staining of calcium deposition were used to assay the progression of osteogenesis under different treatment conditions. Cultures were exposed to Wnt3a treatment to assess downstream signaling mechanisms. RESULTS: In this study, we show that H2S is produced by human PDLCs via the cystathionine ß-synthase/cystathionine γ-lyase pathway to promote their osteogenic differentiation. These levels must be carefully maintained as excessive or deficient H2S levels temper the observed osteogenic effect by inhibiting Wnt/ß-catenin signaling. CONCLUSIONS: These results demonstrate that optimal concentrations of endogenous H2S must be maintained within PDLCs to promote osteogenic differentiation by activating the Wnt/ß-catenin signaling cascade.