Dioxin,one of the persistent organic pollutants,persistently exists in the environment and does serious harm to the ecological environment as well as to the human body because of its reproductive toxicity,carcinogenicity,immune toxicity,skin toxicity and toxicity to other systems and organs.This paper reviewed the toxicities of dioxins to the human body,especially to the endocrine and immune systems.

BACKGROUND: Increasing evidences support that the physical properties, especially stiffness, can regulate the directional differentiation of stem cells.OBJECTIVE: To review the effects of extracellular matrix on stem cell behaviors, and the research progress concerning the influence of physical properties of biomaterials on stem cell differentiation.METHODS: The first author retrieved CNKI and Web of Science databases using the keywords of extracellular matrix, bioscaffolds materials, chemical property, physical property, substrate rigidity, stem cell differentiation in Chinese and English, respectively. Finally, a total of 31 literatures were included for analysis.RESULTS AND CONCLUSION: The physicochemical properties expose effects on the cell proliferation, migration and differentiation, and especially the regulatory effect of stiffness on the cell differentiation has a revelation for tissue engineering and regenerative medicine. Searching for more biochemical and physical factors interacting with the stiffness of extracellular matrix will enable us to control cell behaviors accurately and to prepare an ideal scaffold closely similar to in vivo environment.

Objective To determine the polymorphism in CXC chemokine SDF-1α transcript and its effects on HIV infection.Methods Three groups of study subjects lived in Hang Kong were recruited:278 HIV-heahhy donors of Chinese origin.49 HIV+Caucasians and 13 Chinese with high risk behavior to HIV but kept uninfected.Genomic DNA and RNA were extracted from eripheral blood mononucleal cell. The PCR and RT-PCR reaction were set up accordingly.Sequence of the SDF-1α promoter,the open reading frame(ORF)and the 3'untranslate region(3'UTR)were analyzed.Two steps PCR reaction using two reverseprimers with mismatched nucleic acid were employed to screen the frequency of a novel mutation. Results equencing analysis from 100 subjects indicated that non mutation happened in tlle promoter and ORF of SDF-1α.A novel mutation Was detected from 3'UTR of SDF-1α.It is a "GA" insertion in "G" rich region near the stop code of SDF-1α.The mutation Was named as SDF-1-3’GA+and submitted to GenBank (AY874118).The mutation happened in three roups.with allele frequency of 15.1% in the healthy Chinese.of 30.7% in the high risk Chinese group.Conclusions our results confirm that SDF-1 genes arerelatively conserved.None noteworthy mutation is identified in the promoter and ORF regions of SDF-1α However.a novel mutation is identified from the 3'UTR of SDF-1α. It would be worthwhile to etermine effect of the novel mutation on HIV infection.

[ABSTRACT]AIM:Toexploretheeffectoftheelasticmodulusandsizesofliquidcrystal(LC)phasesonosteo-genic differentiation based on OPC/PU composite substrate by mimicking the microenvironment in rat bone mesenchymal stem cells (rBMSCs).METHODS: A series of composite substrates with different elastic modulus were constructed via modulation of LC content in the composites .The surface phase structure was observed by polarized microscopy , and the mechanical property was measured by a universal material testing machine .Furthermore, the laser confocal microscope was employed to observe the spreading , polarization and the cytoskeleton arrangement of the rBMSCs .The proliferation of rBM-SCs was evaluated by CCK-8 assay.The specific mRNA expression of osteogenic differentiation such as collagen Ⅰ, and osteopontin on the composite membranes was detected by real-time PCR.RESULTS:The size and number of LC phase in-creased and the elastic modulus of the composite substrates decreased with the increase of the LC content .The rBMSCs ex-hibited better characteristics of initial adhesion , spreading and proliferation on the OPC 10-PU and OPC30-PU in the early and medium culturing .The rBMSCs displayed higher expression of collagen Ⅰ and osteopontin on the OPC10-PU in the early and medium osteogenic induction , while the high expression of these osteogenic genes occured on the OPC 30-PU and OPC50-PU in later osteogenic induction .The emphasis of genetic expression was switched from collagen Ⅰin the early and medium osteogenic induction to osteopontin in the later stage .CONCLUSION:When the content of LC remained low in the composite substrates , rBMSCs mainly responded to the mechanical stimuli induced by substrate stiffness and exhibited distinguished cellular behaviors;with the increase in the LC content , rBMSCs had strong interactions with LC by sensing the viscoelasticity of LC , probably resulted from the contribution of both substrate stiffness and the viscoelasticity of LC phase .

[ ABSTRACT] AIM:To develop the cell model of polymer/liquid crystal and to study the effect of their elasticity on the adhesion of rat bone marrow mesenchymal stem cells (rBM-MSCs).METHODS: Using the method of solvent e-vaporation induced phase separation, the cell model of polymer/liquid crystal was constructed.The surface morphology and phase separation structure were determined by polarized optical microscopy ( POM) , scanning electron microscopy ( SEM) and small angle X-ray scattering ( SAXS ) .rBM-MSCs were separated and expanded by adherent culture.The surface markers of rBM-MSCs were detected by flow cytometry.The cells were induced to osteogenic differentiation and adipogenic differentiation for 2 weeks.After 3 passages, the cells were divided into 4 groups, including total PU control group, 10%membrane group, 30%membrane group and 50%membrane group.The cells were then incubated with rhodamine phalloi-din for cytoskeleton staining and were observed under the confocal laser scanning microscope after cultured for 24 h.RE-SULTS:The cell model of polymer/liquid crystal was constructed successfully using the method of solvent evaporation in-duced phase separation.Flow cytometry results showed that the rBM-MSCs positively expressed CD29, CD44 and CD90, and negatively expressed CD34 and CD45.After stained with alizarin red S and oil red O, the calcium nodule and lipid droplets in rBM-MSCs were observed obviously.The cytoskeleton staining result indicated that the area in total PU control group, 10%membrane group and 30%membrane group were greater, and the actin microfilaments were also clearer than
that in 50%membrane group.CONCLUSION:The cell model with suitable content of liquid crystal made a contribution to the rBM-MSCs’ adhesion, but too much liquid crystal inhibits cell adhesion.

AIM:To explore a novel method to isolate human nucleus pulposus mesenchymal stem cells (hNP-MSCs) in vitro and to identify their biological characteristics.METHODS:The explant culture method was employed to isolate hNP-MSCs from nucleus pulposus tissue obtained by percutaneous endoscopic lumbar discectomy (PELD).The isolated cells were passaged for purification and cultured in vitro followed by morphological observation.The cell proliferation ability was detected by CCK-8 assay.Growth curves of the cells were drawn and surface antigens were detected by flow cytometry.The cells at the 3rd~6th passages were induced for adipogenic, osteogenic and chondrogenic differentiation, and examined by oil red O staining, alizarin red staining and Alcian blue staining.RESULTS:The cells with self-renewal were obtained from nucleus pulposus tissue obtained by PELD.The results of flow cytometry analysis revealed that the cells were positive for CD29, CD44, CD90, CD73 and CD105, but negative for CD34 and CD45.The proliferative capacity was consistent with the growth characteristics of MSCs and multilineage differentiation potential was identified.CONCLUSION:A novel method to efficiently isolate and culture hNP-MSCs,PELD combined with explant culture method,was established, which would promote the study of regenerative medicine based on hNP-MSCs.

Nitrogen-doped carbon nanoparticles (N-CNPs) with a fluorescence quantum yield of 15.1％ were prepared from sucrose and urea in oleic acid medium by a one-pot solvothermal method.A new approach for quick,sensitive,and selective determination of free chlorine in water was developed based on fluorescence quenching of N-CNPs.There existed a good linear correlation between the fluorescence quenching and the concentration of ClO-in the range of 0.05-25.00 μmol/L.The limit of detection (LOD,S/N =3) was estimated to be 23 nmol/L.This method can be applied to the determination of free chlorine in real water samples.

BACKGROUND: Though there were many experiments addressing repairing osteochondral defects before, faulty restoration occurred at coupling interfaces. OBJECTIVE: To investigate the feasibility of repairing of osteochondral composite defects in rabbit knees with animal-origin osteochondral scaffold combined with bone marrow mesenchymal stem cells (BMSCs)/chondrocytes.METHODS: New Zealand white rabbits were randomly divided into the experimental, control and blank groups and prepared for unilateral knee joint osteochondral defects. Animal-origin osteochondral scaffold combined with BMSCs/chondrocytes, animal-origin osteochondral scaffold and no material was implanted to repair the defects in the experimental, control and blank groups, respectively. Healing condition was evaluated by gross observation, hematoxylin-eosin staining, and toluidine blue staining at 4, 8, and 12 weeks after operation. RESULTS AND CONCLUSION: At 12 weeks after operation, gross observation showed the defects were repaired completely without local depression and the regenerated tissues were fused with surrounding tissues in the experimental group. Hematoxylin-eosin staining and toluidine blue staining revealed that there were many new hyaline cartilages in the cartilage defects in which columnar cells were lined well and cartilage lacuna was obviously, also, there were many bony tissues in the bone defects. The regeneration cartilage, the underlying subchondral bone and host bone were coupled completely. The toluidine blue positive rate and histologic scores of the experimental group were superior to those of the control and blank groups (P < 0.05). It is demonstrated that animal-origin osteochondral scaffold combined with BMSCs/chondrocytes is an ideal method to repair defects between cartilage and the underlying subchondral bone.

BACKGROUND: The development of cartilage tissue engineering provides novel ideas for treatment of articular cartilage defects and implements construction of tissue-engineered cartilage in vivo.OBJECTIVE: To investigate the feasibility of constructing tissue-engineered osteochondral composite through bone marrow stem cells(BMSCs) cultured on the poly(lactide-co-glycolic acid) (PLGA), which was modified with collagen and cellular growth factors.METHODS: PLGA was made by phase separation technique, composited with collagen Ⅱ, basic fibroblast growth factor, and transforming growth factor-β1. The BMSCs of passage 3 were cultured on the above scaffolds. Thirty-six SD rats were randomly divided into experimental, control, and blank groups. These three groups received implantation of BMSCs composited with growth factors and collagen-PLGA, implantation of BMSCs composited with collagen-PLGA, and implantation of collagen-PLGA into the muscle, respectively. At 4, 8, and 12 weeks after surgery, cell directional differentiation and growth were examined by gross observation, hematoxylin-eosin staining, toluidine blue staining, collagen Ⅱ staining, and scanning electron microscope.RESULTS AND CONCLUSION: Gross observation showed that there were many chondroid tissues in the experimental group and fibrous tissues in the control and black groups. Stainings and electron microscope revealed that many chondroblasts and a few osteoclasts appeared in the composite of the experimental group. Toluidine blue and collagen Ⅱ stainings were positive in the experimental group and negative in the control and blank groups. These findings demonstrate that PLGA modified with collagen had a good cellular compatibility. BMSCs cultured on PLGA, which was modified with collagen and cellular growth factors, can construct the tissue-angineered osteochondral composite in rats.

Background and Objectives: Mesenchymal stromal cells (MSCs)-based treatment for degeneration of intervertebral disc (IVD) has been proposed recently. We here addressed whether MSC secreted factors can rejuvenate nucleus pulposus- derived stem/progenitor cells from degenerated disc (D-NPSCs) in vitro. Methods: and Results: We analyzed the expression of MSCs and NP cell specific surface markers, pluripotency related genes, multilineage potential and cell proliferative capacity of D-NPSCs upon incubation with the conditioned medium which was collected from the umbilical cord derived MSCs (UCMSCs). Our results indicated that the conditioned medium restore the stemness of D-NPSCs by up-regulating the expression level of CD29 and CD105, pluripotency related genes OCT4 and Nanog, and NP progenitor marker Tie2. The increased stemness was accompanied by promoted cell proliferative capacity and improved osteogenic and chondrogenic differentiation potential. Conclusions Our findings suggested that the UCMSCs derived conditioned medium might be used to rejuvenate the degenerated NP stem/progenitor cells.