The Effect of Nano-apatite on the Expression of Telomerase Gene of Human Hepatocellular Carcinoma Cells

To investigate the effect of nano-apatite on the expression of the telomerase gene of human hepatocellular carcinoma cell lines and further explore the mechanism of the nano-apatite inhibiting cancer cells. Using the hybridization in situ method to detect the expression of the telomerase gene of human hepatocellular carcinoma cells treated with the nano-apatite for 4 h at 37 ℃ . The hybridization in situ showed that the cytoplasm of the positive cells was stained in nigger- brown. The positive cell rate of the control group was 88.49% , the cisplatin group was 25.6% , the nano-apatite group was 63.6% . The activity of telomerase gene was both obviously dedined comparing with the control group and the difference had significance （ p 〈 0. 05, p 〈 0.01 ）. The nanoapatite obviously inhabit the expression of the telomerase gene of human hepatocellular carcinoma cells.

Preparation of Bone-like Hydroxyapatite via a Reverse Microemulsion

Bone-like hydroxyapatite （ HAp ） powders were synthesized using a reverse microemulsion method without further calcine processing. Synthesis conditions had significant effects on the formation of HAp. According to the results of XRD patterns and FFIR spectra, the obtained needle shape HAp powder with poorly crystallized and carbonate substitution was chemically and structurally similar to the human bone powders. The alkaline of emulsion was responsible for the obtained HAp without calcine route, and carbonate came from CO2 in air during preparation. By ultrasonic treatment, the morphology of HAp particles changed from spherical to needle shape for the reverse micelles broke up due to the high energy of ultrasonic.

Material and regenerative properties of an osteon-mimetic cortical bone-like scaffold

The objective of this work was to fabricate a rigid,resorbable and osteoconductive scaffold by mimicking the hierarchical structure of the cortical bone.Aligned peptide-functionalize nanofiber microsheets were generated with calcium phosphate(CaP)content similar to that of the natural cortical bone.Next,the CaP-rich fibrous microsheets were wrapped around a microneedle to form a laminated microtube mimicking the structure of an osteon.Then,a set of the osteon-mimetic microtubes were assembled around a solid rod and the assembly was annealed to fuse the microtubes and form a shell.Next,an array of circular microholes were drilled on the outer surface of the shell to generate a cortical bone-like scaffold with an interconnected network of Haversian-and Volkmann-like microcanals.The CaP content,porosity and density of the bone-mimetic microsheets were 240 wt%,8%and 1.9 g/ml,respectively,which were close to that of natural cortical bone.The interconnected network of microcanals in the fused microtubes increased permeability of a model protein in the scaffold.The cortical scaffold induced osteogenesis and vasculogenesis in the absence of bone morphogenetic proteins upon seeding with human mesenchymal stem cells and endothelial colony-forming cells.The localized and timed-release of morphogenetic factors significantly increased the extent of osteogenic and vasculogenic differentiation of human mesenchymal stem cells and endothelial colony-forming cells in the cortical scaffold.The cortical bonemimetic nature of the cellular construct provided balanced rigidity,resorption rate,osteoconductivity and nutrient diffusivity to support vascularization and osteogenesis.

Biosafety of the Novel Vancomycin-loaded Bone-like Hydroxyapatite/Poly-amino Acid Bony Scaffold

Background： Recently, local sustained-release antibiotics systems have been developed because they can increase local loci of concentrated antibiotics without increasing the plasma concentration, and thereby effectively decrease any systemic toxicity and side effects. A vancomycin-loaded bone-like hydroxyapatite/poly-amino acid （V-BHA/PAA） bony scaffold was successfully fabricated with vancomycin-loaded poly lactic-co-glycolic acid microspheres and BHA/PAA, which was demonstrated to exhibit both porosity and perfect biodegradability. The aim of this study was to systematically evaluate the biosafety of this novel scaffold by conducting toxicity tests in vitro and in vivo. Methods： According to the ISO rules for medical implant biosafety, for in vitro tests, the scaffold was incubated with L929 fibroblasts or rabbit noncoagulant blood, with simultaneous creation of positive control and negative control groups. The growth condition ofL929 cells and hemolytic ratio were respectively evaluated after various incubation periods. For in vivo tests, a chronic osteomyelitis model involving the right proximal tibia of New Zealand white rabbits was established. After bacterial identification, the drug-loaded scaffold, drug-unloaded BHA/PAA, and poly （methyl methacrylate） were implanted, and a blank control group was also set up. Subsequently, the in vivo blood drug concentrations were measured, and the kidney and liver functions were evaluated. Results： In the in vitro tests, the cytotoxicity grades of V-BHA/PAA and BHA/PAA-based on the relative growth rate were all below 1. The hemolysis ratios of V-BHA/PAA and BHA/PAA were 2.27% and 1.42%, respectively, both below 5%. In the in vivo tests, the blood concentration of vancomycin after implantation of V-BHA/PAA was measured at far below its toxic concentration （60 mg/L）, and the function and histomorphology of the liver and kidney were all normal. Conclusion： According to ISO standards, the V-BHA/PAA scaffold is considered to have sufficient safety for clinical utilization.

In vitro study of iron doped hydroxyapatite

The effect of iron substitution on the bioactivity of hydroxyapatite (HAp) under the physiological conditions was investigated. Five samples of iron doped hydroxyapatite (FeHAp) with different iron concentrations (0, 0.05, 0.1, 0.2, and 0.3 mol%) were synthesized by wet chemical method. The formation of bone-like apatite layer on the surface of the samples was detected using X-ray diffraction (XRD), Fourier transforms infrared (FTIR) and scanning electron microscope techniques. The changes of the pH of SBF medium were measured at pre-determined time intervals using a pH meter. The dissolution of calcium, phosphorus and iron ions in SBF medium was determined by single beam scanning spectrophotometer. XRD and FTIR results exhibit the formation of carbonate apatite layer on the surface of the immersed samples, which increase with the increase of iron content. SEM results showed agglomeration of small crystals on the surface of the immersed samples. The solubility and dissolution tests revealed that iron doped HAp samples had a higher solubility and dissolution rate than pure sample, which indicated that iron increased the bioactivity of HAp in vitro.

A novel mutation in COL1A2 leads to osteogenesis imperfecta/Ehlers-Danlos overlap syndrome with brachydactyly

Osteogenesis imperfecta(OI)is mainly characterized by bone fragility and Ehlers-Danlos syndrome(EDS)by connective tissue defects.Mutations in COL1A1 or COL1A2 can lead to both syndromes.OI/EDS overlap syndrome is mostly caused by helical mutations near the amino-proteinase cleavage site of type Ⅰ procollagen.In this study,we identified a Thai patient having OI type Ⅲ,EDS,brachydactyly,and dentinogenesis imperfecta.His dentition showed delayed eruption,early exfoliation,and severe malocclusion.For the first time,ultrastructural analysis of the tooth affected with OI/EDS showed that the tooth had enamel inversion,bonelike dentin,loss of dentinal tubules,and reduction in hardness and elasticity,suggesting severe developmental disturbance.These severe dental defects have never been reported in OI or EDS.Exome sequencing identified a novel de novo heterozygous glycine substitution,c.3296G>A,p.Gly1099Glu,in exon 49 of COL1A2.Three patients with mutations in the exon 49 of COL1A2 were previously reported to have OI with brachydactyly and intracranial hemorrhage.Notably,two of these three patients did not show hyperextensible joints and hypermobile skin,while our patient at the age of 5 years had not developed intracranial hemorrhage.Here,we demonstrate that the novel glycine substitution in the carboxyl region of alpha2(Ⅰ)collagen triple helix leads to OI/EDS with brachydactyly and severe tooth defects,expanding the genotypic and phenotypic spectra of OI/EDS overlap syndrome.