Recombinant amelogenin regulates the bioactivity of mouse cementoblasts in vitro

Amelogenin（AMG） is a cell adhesion molecule that has an important role in the mineralization of enamel and regulates events during dental development and root formation. The purpose of the present study was to investigate the effects of recombinant human AMG（rhAMG） on mineralized tissue-associated genes in cementoblasts. Immortalized mouse cementoblasts（OCCM-30）were treated with different concentrations（0.1, 1, 10, 100, 1 000, 10 000, 100 000 ng · mL^-1） of recombinant human AMG（rhAMG）and analyzed for proliferation, mineralization and mRNA expression of bone sialoprotein（BSP）, osteocalcin（OCN）, collagen type I（COL I）, osteopontin（OPN）, runt-related transcription factor 2（Runx2）, cementum attachment protein（CAP）, and alkaline phosphatase（ALP） genes using quantitative RT-PCR. The dose response of rhAMG was evaluated using a real-time cell analyzer.Total RNA was isolated on day 3, and cell mineralization was assessed using von Kossa staining on day 8. COL I, OPN and lysosomalassociated membrane protein-1（LAMP-1）, which is a cell surface binding site for amelogenin, were evaluated using immunocytochemistry. F-actin bundles were imaged using confocal microscopy. rhAMG at a concentration of 100 000 ng · mL^-1 increased cell proliferation after 72 h compared to the other concentrations and the untreated control group. rhAMG（100 000 ng · mL^-1） upregulated BSP and OCN mRNA expression levels eightfold and fivefold, respectively. rhAMG at a concentration of 100 000 ng · mL^-1 remarkably enhanced LAMP-1 staining in cementoblasts. Increased numbers of mineralized nodules were observed at concentrations of 10 000 and 100 000 ng · mL^-1 rhAMG. The present data suggest that rhAMG is a potent regulator of gene expression in cementoblasts and support the potential application of rhAMG in therapies aimed at fast regeneration of damaged periodontal tissue.

Preparation and bioactivity of sol-gel macroporous bioactive glass

Bioactive glass is well known for its ability of bone regeneration, and sol-gel bioactive glass has many advantages compared with melt-derived bioactive glass. 3-D scaffold prepared by the sol-gel method is a promising substrate material for bone tissue engineering and large-scale bone repair. Porous sol-gel glass in the CaO-SiO2-P205 system with macropores larger than 100 μm was prepared by the addition of stearic acid as a pore former. The diameter of the pore created by the pore former varied from 100 to 300 μm. The formation of a hydroxyapatite layer on the glass was analyzed by studying the surface of the porous glass by scanning electron microscopy, energy dispersive spectroscopy, X-ray diffraction, and Raman spectra after they had been immersed in simulated body fluid （SBF） for some time, and the porous glass shows good bioactivity.

Ultra-lightweight ceramic scaffolds with simultaneous improvement of pore interconnectivity and mechanical strength

The high porosity and interconnectivity of scaffolds are critical for nutrient transmission in bone tis-sue engineering but usually lead to poor mechanical properties.Herein,a novel method that combines acid etching(AE)with selective laser sintering(SLS)and reaction bonding(RB)of Al particles is pro-posed to realize highly improved porosity,interconnectivity,mechanical strength,and in vitro bioactivity in 3D Al_(2)O_(3) scaffolds.By controlling the oxidation and etching behaviors of Al particles,a tunable hol-low spherical feature can be obtained,which brings about the distinction in compressive response and fracture path.The prevention of microcrack propagation on the in situ formed hollow spheres results in unique near elastic buckling rather than traditional brittle fracture,allowing an unparalleled compressive strength of 3.72±0.17 MPa at a high porosity of 87.7%±0.4%and pore interconnectivity of 94.7%±0.4%.Furthermore,scaffolds with an optimized pore structure and superhydrophilic surface show excellent cell proliferation and adhesion properties.Our findings offer a promising strategy for the coexistence of out-standing mechanical and biological properties,with great potential for tissue engineering applications.