Currently,with the rapid development of drug delivery technologies,more and more efforts are taken into the efficient therapies for various diseases by delivering biologically-active macromolecules into the target cells directly.Although a certain number of positive treatment results were obtained from the therapies by using the biomacromolecules to cure some diseases,the microenvironment around the target cell still has a great influence on the final treatment effect.Since many diseases and injuries interfere the normal architecture of the extracellular matrix (ECM),the cell adhesion to ECM and the subsequent cellular activities,the normal microenvironment of the cell plays a critical role in maintaining body balance,tissue regeneration and repair.Given these points,this paper reviews the effects of the cellular microenvironment constructed by ECM on the efficacy of bioactive macromolecules,and provides a theoretical basis for future drug design and synthesis of pharmaceuticals.

Objective To investigate the preference of the postgraduates in school for work and their psychological changes based on the analysis of the employment status of postgraduates majoring in clinical science of stomatology in Anhui medical university in recent five years in an aim to provide preemployment counseling.Methods The employment status of postgraduates majoring in clinical science of stomatology in affiiated stomatological hospital of Anhui medical university in recent five years (2006 -2010) was summed up.Questionnaire of employment preference and the psychological pressure was conducted in 66 postgraduates majoring in clinical science of stomatology (2008 -2010 grade).Results The employment rate of provincial first-class hospitals was obviously decreased in the recent five years while that of municipal first-class hospitals was increased gradually.The number of postgraduates willing to work in the municipal first-class hospitals was reduced while that willing to future their study and work in the non first-class hospitals was increased.Psychological pressure was univcrsally existed in students and did not get released.Conelusion As the employment situation for postgraduates majoring in clinical science of stomatology changes,the preference for work and psychological pressure of the postgraduates also undergo corresponding changes.Targeted measures can be formulated to work out the problem based on the understanding of these changes.Meanwhile,adjustment should be made in the training methods and employment guidance for postgraduates majoring in clinieal science of stomatology.

Objective: To explore the feasibility of graphene oxide (GO)-chitosan (CS) guided bone regeneration composite membrane being used as a new guided bone regeneration (GBR) membrane by testing its tensile strength and its effect on the proliferation of human gingival fibroblasts (HGF). Methods: The CS solution and GO solution were mixed in following ratios, ultrasonically crushed and dispersed, and formed into membranes by self-evaporation. Composite membrane with 0.5%, 1.0%, 2.0%, 4.0%, 6.0%, 8.0% GO in CS was prepared. The tensile strength of the composite membranes was tested by mechanical universal testing machine (n=6). The microstructure of the composite membrane with the best tensile strength was observed by scanning electron microscopy and transmission electron microscopy. X-ray diffraction was used to characterize the ingredients of the material. A group of samples was prepared again with the proportion of the highest tensile strength composite membrane, and were immersed in a sodium hydroxide solution for acid removal. The tensile strength of the new group of samples was tested. The newly extracted impacted teeth were collected from the Department of Oral and Maxillofacial Surgery, Stomatologic Hospital and College, Anhui Medical University, and the gingival tissues remained on the teeth were taken for primary HGF and were cultured to P2 generation, which were identified by immunocytochemical staining methods. Cell counting kit-8 (CCK-8) was applied to detect cell counts in the blank control group, the pure CS membrane group, and the composite membrane group with the highest tensile strength (n=5) and all groups co-cultured with the HGF for 24 h and 48 h. Results: After adding GO, the cross-section of the composite membrane was in an ordered layer structure. X-ray diffraction analysis showed that GO could be found in the composite membrane. The tensile strength increased with the increase of GO ratio. When the mass fraction of GO in CS was 4.0%, the tensile strength reached (134.8±7.3) MPa and the tensile strength reached (144.6±8.1) MPa after deacidification of the composite membrane. The CCK-8 test of HGF showed that there was no significant difference in absorbance between the pure CS membrane group and the GO/CS composite membrane group when they were compared with the blank control group (P>0.05). Conclusions When the mass fraction of GO in CS is 4.0%, the composite membrane has the best tensile strength. The composite membrane showes good cytocompatibility, which lays a foundation for further in vivo experiments and the development of a new generation of GBR membrane.

BACKGROUND: Regenerative medicine by using stem cells from dental pulp is promising for treating patients with critical limb ischemic (CLI). Here, we investigated the difference in the angiogenetic ability of stem cells from human exfoliated deciduous teeth (SHED) and human dental pulp stem cells (DPSC). METHODS: SHED and DPSC were harvested from dental pulp and analyzed in flow- cytometry for detecting the expression of surface markers. Levels of angiogenetic marker were examined by RT-PCR and Western-blot. Eighteen immunodeficient mice of critical limb ischemic model were divided into three groups: SHED, DPSC and saline, which was administered with SHED, DPSC or saline intramuscularly. Histological examination was performed to detect the regenerative results. RESULTS: A highly expression of CD146 was detected in SHED. Moreover, cells with negative expression of both CD146 and CD31 in SHED were more in comparison with those in DPSC. Expression of angiogenesis factors including CXCL12, CXCR4, Hif-1a, CD31, VEGF and bFGF were significant higher in SHED than DPSC by the RT-PCR and Western-Blot results. SHED induced more CD31 expression and less fibrous tissue formation in the critical limb ischemic model as compare with DPSC and saline. CONCLUSION Both SHED and DPSC possessed the ability of repairing CLI. With expressing more proangiogenesis factors, SHED may have the advantage of repairing CLI.

BACKGROUND: The role of sex hormones and their receptors has drawn much attention in the process of cartilage regeneration. This study aimed to investigate the effect of androgen receptor (AR) on the chondrogenic ability of articular chondrocytes and the related mechanism. METHODS: Articular chondrocytes were isolated, cultured, identified by toluidine blue staining and then transduced with lentivirus carrying the AR gene. The cell viability was determined using Cell Counting Kit-8, and cell apoptosis was assessed by flow cytometry analysis. The effects of AR overexpression on the expression of cartilage-specific proteins and some signalling molecules were evaluated by real-time PCR and Western blotting. Using 24 New Zealand rabbits, the regeneration of rabbit articular cartilage defects was further investigated in vivo and evaluated histologically. RESULTS: The overexpression of AR significantly reduced the apoptosis rate of chondrocytes but did not affect their proliferation. The overexpression of AR also promoted the expression of Sry-related HMG box 9, collagen II and aggrecan, decreased the expression of matrix metalloproteinase-13, and downregulated p-S6 and RICTOR. The experimental group with AR-overexpressing chondrocytes exhibited superior regeneration of cartilage defects. CONCLUSION AR overexpression can maintain the phenotype of chondrocytes and promote chondrogenesis in vitro and in vivo. mTOR-related signalling was inhibited.

BACKGROUND: The role of sex hormones and their receptors has drawn much attention in the process of cartilage regeneration. This study aimed to investigate the effect of androgen receptor (AR) on the chondrogenic ability of articular chondrocytes and the related mechanism. METHODS: Articular chondrocytes were isolated, cultured, identified by toluidine blue staining and then transduced with lentivirus carrying the AR gene. The cell viability was determined using Cell Counting Kit-8, and cell apoptosis was assessed by flow cytometry analysis. The effects of AR overexpression on the expression of cartilage-specific proteins and some signalling molecules were evaluated by real-time PCR and Western blotting. Using 24 New Zealand rabbits, the regeneration of rabbit articular cartilage defects was further investigated in vivo and evaluated histologically. RESULTS: The overexpression of AR significantly reduced the apoptosis rate of chondrocytes but did not affect their proliferation. The overexpression of AR also promoted the expression of Sry-related HMG box 9, collagen II and aggrecan, decreased the expression of matrix metalloproteinase-13, and downregulated p-S6 and RICTOR. The experimental group with AR-overexpressing chondrocytes exhibited superior regeneration of cartilage defects. CONCLUSION AR overexpression can maintain the phenotype of chondrocytes and promote chondrogenesis in vitro and in vivo. mTOR-related signalling was inhibited.

Objective : To explore the feasibility of the bilayer chitosan barrier membrane loaded with tannic acid (CS@ TA) for guided bone regeneration by exploring the reactive oxygen species (ROS) scavenging ability , bio- compatibility , and antibacterial properties . Methods : The single-layer chitosan (CS) film was prepared by self-evaporation , and the double-layer CS film was prepared by directional freezing and freeze-drying , and its microstruc- ture was ob served by scanning electron microscope . The prepared CS bilayer membrane was grafted with tannic acid (TA) in different proportions , and the interaction between TA and CS bilayer membrane was analyzed by Fourier infrared spectrometer (FITR) . The ROS scavenging ability was tested by 1 , 1 -diphenyl-2 -picrylhydrazyl (DPPH) , and the double-layer membrane of loading TA scavenging efficiency of more than 90% was selected to continue the follow-up experiment. CCK-8 assay and lived dead staining were used to evaluate the survival rate of cell in each groups . MC3T3 -E1 cells was adhesion the CS@ TA barrier film for studying by SEM . Colony counting was performed to test its antibacterial performance against Escherichia coli ( E. coli) and Staphylococcus aureus ( S. aureus ) . Results : One side was the smooth , dense while other side was rough , loose and porous , with a longitudinal ordered porous structure in cross-section of the double-layer membrane of CS@ TA . With the addition of TA , the ROS scavenging ability of the double-layer membrane first increased rapidly and then stabilized slowly. The results of CCK-8 and lived and dead cells staining showed that excessive TA addition significantly affected the biocompati- bility of the double-layer membrane . The counting results of bacterial dilution coating showed that compared with the double-layer membrane without TA loading , the double-layer membrane had certain antibacterial ability against E. coli and S. aureus when the appropriate amount of TA was added . Conclusion Thus the double-layer with ap- propriate TA loading has strong ROS scavenging ability , good biological performance , and certain antibacterial abil- ity for E. coli and S. aureus .

Objective: To explore the feasibility of silk fibron ( SF) - phlorotannins( PT) double layer membranes as barrier membrane for guided bone regeneration ( GBR) by exploring the mechanical property，biocompatibility， and the effect on osteogenic differentiation of SF-PT double layer membranes． Methods : The SF solution treated with different degumming time was prepared into SF bilayer by solution cast technique，ice template method and lyophilization．The tensile strength of the membranes under hydration were measured via mechanical universal machine (n = 5) ．The microstructures of the composite membranes with the highest tensile strength under hydration condition were observed by scanning electron microscopy．Then the rough surfaces of SF double layer membranes was loaded with PT to prepare SF-PT double layer membranes ，Fourier transformed infrared spectroscopy was carried out to characterize the interaction between PT and SF double layer membranes，and the bone marrow mesenchymal stem cells of human alveolar origins (hABMSCs) adhesion was studied by SEM．CCK-8 assay and live dead staining were used to evaluated the biocompatibility of SF-PT double layer membranes． qRT-PCR , ALP staining and alizarin red stain were carried out to measure the osteogenic differentiation of hABMSCs in different groups. Results: The SF membranes prepared from SF solution with a degumming time of 30 min has the highest tensile strength，reaching (3. 293 ± 0. 122 8 ) MPa． The smooth surface of SF double layer membrane was dense and smooth，while the rough surface was longitudinally ordered loose porous structure．PT was loaded onto the rough surface of the SF double layer membranes by hydrogen bond，hydrophobic interaction and other forces．There was no significant difference in the results of CCK-8 and live dead staining between blank group，SF group and PT-SF group．Compared with blank group and SF group，PT-SF double layer membranes promoted osteogenic differentiation of hABMSCs． Conclusion Thus，the PT-SF double layer membranes expressed desired mechanical，biological properties and can promote the osteogenic differentiation of hABMSCs to a certain extent．These results indicate that PT-SF double layer membranes is successfully fabricated，providing a solid foundation for future in vivo experiments.

Objective : To compare the osteogenic differentiation ability of human apical papilla stem cells (SCAPs) , dental pulp mesenchymal stem cells (DPSCs) and alveolar bone mesenchymal stem cells (ABMMSCs) in vitro. Methods : The apical papilla stem cells , dental pulp mesenchymal stem cells and alveolar bone mesenchy⁃ mal stem cells isolated from the third molars and alveolar bone tissues were cultured and passaged. The morphology of primary and P3 generation cells was observed under a microscope. Flow cytometry was used to detect cell immunophenotype. Real⁃time fluorescent quantitative PCR (qRT⁃PCR) and cell counting kit⁃8 were used to analyze cell senescence and proliferation ability. After osteogenic induction , alkaline phosphatase (ALP) and alizarin red staining and qRT⁃PCR were used to detect osteogenic related genes to compare osteogenic ability. Results: There was no significant difference in the morphology of the three cells , which showed the morphology of fibroblasts , long spindle⁃shaped , smooth and uniform after passage. There were no senescence differences among the 3 types of cells , all of which maintained stable proliferative capacity ; the proliferation capacity of SCAPs was significantly higher than that of the other 2 types of cells , and the proliferation capacity of ABMMSCs was weaker; ALP staining and alizarin red staining after 7 and 14 d osteogenesis induction showed that the osteogenic ability of ABMMSCs was significantly stronger than that of SCAPs and DPSCs ; qRT⁃PCR showed that ABMMSCs had the most significant inrease in osteogenesis⁃related genes. Conclusion SCAPs , DPSCs and ABMMSCs have stable biological properti and can undergo osteogenic differentiation , and ABMMSCs have stronger osteogenic ability than DPSCs and SCAPs in vitro.

Objective : To develop a high modulus and high strength biodegradable silk fibroin GBR membrane to address the issue of maintaining the space for bone regeneration in the repair of osseous defects . Methods : After purifying silk fibroin protein , membrane materials were prepared using evaporation-hot pressing method . The physi- cal and chemical properties and biological performance of the membranes were evaluated using stretching tests , in vitro simulations , and cell co-culturing methods . Results : A silk fibroin GBR membrane was successfully fabrica- ted , resulting in a simulated degradation rate of 35 . 3% after 12 h in vitro . The wet-state elastic modulus reached 45 MPa , while the tensile strength reached 8. 39 MPa. Furthermore , the cell survival rate was nearly 100% after 7 days . Conclusion The biodegradable GBR membrane produced in this study possesses high modulus and strength , as well as excellent biocompatibility , offering a promise as a foundation for addressing the bone defect re- pair and bone space maintenance .