Copolymer cell/scaffold constructs for bone tissue engineering: co-culture of low ratios of human endothelial and osteoblast-like cells in a dynamic culture system.

The aim of this study was to compare the effect of different ratios of human umbilical vein endothelial cells (HUVECs) on osteogenic activity of human osteoblast-like cells (HOB) and capillary-like structure (CLS), seeded into copolymer scaffolds in a dynamic culture system. HOB and HUVEC were co-cultured into poly(L-lactide)-co-(1,5-dioxepan-2-one) [poly(LLA-co-DXO)] scaffolds at ratios of 5:1 (5:1 group) and 2:1 (2:1 group). Samples were collected after 5, 15, and 25 days. Cross-sections were processed and the CLS from HUVEC was disclosed in both groups. Cell viability was determined by dsDNA assay. Cells seeded at the ratio of 5:1 had good viability. Total RNA was isolated and the reverse transcription reaction was performed. The influences on the expression of several osteogenic genes were various with regarding to different ratios of HUVEC demonstrated by the PCR array. The RT-PCR results was in consistent with the PCR array results that several osteogenesis related genes had higher expression in the 5:1 group than in the 2:1 group, especially at day 25, such as alkaline phosphatase, insulin-like growth factor 1 (IGF1), and so forth. ELISA showed that the production of IGF1 after 25 days of incubation were higher in cells co-cultured at the 5:1 ratio than at the 2:1 ratio. The results show that under dynamic culture conditions, co-culture of HOB with a low ratio of HUVEC in copolymer scaffolds results in CLS formation and significantly influenced the expression of osteogenic markers.

Proteomic analysis of mitochondria from infantile hemangioma endothelial cells treated with sodium morrhuate and its liposomal formulation.

Hemangioma is the most common benign tumor of infancy. The aim of this study is to evaluate the biological effects of sodium morrhuate (SM) and its liposomal formulation on infantile hemangioma endothelial cells (IHECs). Morphological analysis revealed that exposure to liposomal sodium morrhuate (LSM) preferentially caused apoptotic death in IHECs, manifested as shrunken configuration and formation of apoptotic bodies. In contrast, necrotic death was prominent in IHECs treated with an equal concentration of SM. By means of proteomic analysis and confirmation experiments, we revealed that the apoptosis-inducing effects of LSM were associated with an upregulation of a set of genes involved in mitochondrial death pathway, including apoptosis-inducing factor, cytochrome c1, caspase-8, and lamin B1. In conclusion, our data highlight the proapoptotic activity of LSM in IHECs through the mitochondrial apoptotic pathway and may provide a promising avenue to treat hemangiomas of infancy.

Comparison of short-run cell seeding methods for poly(L-lactide-co-1,5-dioxepan-2-one) scaffold intended for bone tissue engineering.

Constructs intended for bone tissue engineering are influenced by the initial cell seeding procedure. The seeding method should be rapid, convenient, improve cell spatial distribution, and have no negative effects on cellular viability and differentiation. This study aimed to compare the effect of short-run seeding methods (centrifuge and vortex) with a static method on the scaffolds prepared from poly(L-lactide-co-1,5-dioxepan-2-one) by solvent-casting particulate-leaching (SCPL) technique. Human osteoblast-like cells (HOB) were seeded by the three methods described above. The seeding efficiency was determined by attached cell numbers. Cellular proliferation was analyzed by WST-1 and dsDNA assay. Cell distribution was examined by scanning electron (SEM) and fluorescence microscopy. Expression of alkaline phosphatase (ALP), collagen type I (Col I), osteocalcin (OC) and proliferating cell nuclear antigen (PCNA) were determined by real time RT-PCR. Results indicated that centrifuge and vortex increased seeding efficiency and had no negative effects on cellular viability. The data obtained by the fluorescence microscope confirmed the SEM results that the vortex method improved cell distribution through the scaffolds more than the other two methods (p<0.05). The RT-PCR results showed no significant differences on the expression of mRNA between the three methods of the above markers. The vortex method was found to be a simple and feasible seeding method for the poly(L-lactide-co-1,5-dioxepan-2-one) scaffolds.

Lentivirus-mediated knockdown of aggrecanase-1 and -2 promotes chondrocyte-engineered cartilage formation in vitro.

Chondrocyte-based tissue engineering has emerged as a promising approach for repair of injured cartilage tissues that have a poor self-healing capacity. However, this technique faces a major limitation: dedifferentiation of chondrocytes occurs following several passages in culture. Aggrecan, a major component of cartilage extracellular matrix, plays an essential role in chondrocyte differentiation. The aim of this study is to determine whether inhibition of chondrocyte aggrecanases, key degradative enzymes for aggrecan in cartilage, could benefit chondrocyte differentiation and the preservation of chondrocyte phenotype within a long-term period. Lentivirus-mediated RNA interference (RNAi) was employed to target both aggrecanase-1 and -2 in primary rat chondrocytes, and the transduced cells were seeded into chitosan-gelatin three-dimensional scaffolds. Histological, morphological, and biochemical analyses were performed at 1-8 weeks post-implantation to study chondrocyte survival, differentiation, and function. We found that lentivirus-mediated RNAi notably decreased the abundance of aggrecanase transcripts in chondrocytes but did not affect cell viability. Most importantly, compared to the control constructs seeded with untransduced chondrocytes, the aggrecanase inhibition increased chondrocyte proliferation and reinforced the production of glycosaminoglycans and total collagen, indicative of chondrocyte differentiation. The mRNA expression of chondrocyte marker genes (collagen II and aggrecan) was enhanced by aggrecanase silencing relative to the control. Together our data demonstrate that inhibition of endogenous aggrecanases facilitates chondrocyte differentiation and chondrocyte-engineered cartilage formation in vitro. The combination of lentiviral delivery system and genetic manipulation techniques provides a useful tool for modulation of chondrocyte phenotype in cartilage engineering.

Cartilage tissue engineering with demineralized bone matrix gelatin and fibrin glue hybrid scaffold: an in vitro study.

To develop a cartilage-like tissue with hybrid scaffolds of demineralized bone matrix gelatin (BMG) and fibrin, rabbit chondrocytes were cultured on hybrid fibrin/BMG scaffolds in vitro. BMG scaffolds were carefully soaked in a chondrocyte-fibrin suspension, which was polymerized by submerging the constructs into thrombin-calcium chloride solution. Engineered cartilage-like tissue grown on the scaffolds was characterized by histology, immunolocalization, scanning electron microscopy, biochemical assays, and analysis of gene expression at different time points of the in vitro culture. The presence of proteoglycan in the fibrin/BMG hybrid constructs was confirmed by positive toluidine blue and alcian blue staining. Collagen type II exhibited intense immunopositivity at the pericellular matrices. Chondrogenic properties were further demonstrated by the expression of gene-encoded cartilage-specific markers, collagen type II, and aggrecan core protein. The glycosaminoglycan production and hydroxyproline content of tissue grown on the fibrin/BMG hybrid scaffolds were higher than that of the BMG group. In conclusion, the fibrin/BMG hybrid scaffolds may serve as a potential cell delivery vehicle and a structural basis for cartilage tissue engineering.

Fluorine-induced apoptosis and lipid peroxidation in human hair follicles in vitro.

Fluoride is an essential trace element for human body; however, exposure to high amounts of fluoride has been documented to be correlated with an increasing risk of hair loss. To date, little is known about the mechanism(s) of how fluoride affects hair follicles. Here, we demonstrated that middle (1.0 mmol/L) and high (10.0 mmol/L) concentrations of sodium fluoride (NaF) significantly inhibited hair follicle elongation in vitro, but low NaF (0.1 mmol/L) showed little influence. Moreover, treatment with high levels of NaF resulted in a marked increase in terminal dUTP nick end labeling-positive cells in the outer layer of the outer root sheath, the dermal sheath, and the lower bulb matrix surrounding dermal papilla. Furthermore, the enhanced apoptosis was coupled with an increased oxidative stress manifested as higher malondialdehyde content. Additionally, the presence of selenium considerably antagonized the effects of middle NaF on hair follicles, with regard to either the suppression of hair growth or the induction of oxidative stress and apoptosis. In conclusion, exposure to high levels of fluoride compromises hair follicle growth and accelerate cell apoptosis in vitro. The toxicity of fluoride can be reduced by selenium, at least partially via the suppression of intracellular oxidative stress.

[Effects of RNA interference against aggrecanase 1 gene on extracellular matrix metabolism of cultured chondrocytes in vitro].

OBJECTIVE: To study the effect of RNA interference (RNAi)-mediated aggrecanase-1 gene silencing on extracellular matrix metabolism of cultured rat costochondral chondrocytes. METHODS: Rat costochondral chondrocyte monolayers were obtained by microdissection and digestion. The growth and morphological changes of the chondrocytes were observed after RNAi of aggrecanase-1 gene. The mRNA expression of aggrecanase-1 was detected by RT-PCR method, and aggrecan content was determined by Western blotting. RESULTS: The specific inhibition of aggrecanase-1 by RNAi produced no adverse effect on the morphology and growth of the chondrocytes. The mRNA of aggrecanase-1 decreased and aggrecan content increased significantly after transfection of the chondrocytes. CONCLUSION: Inhibition of aggrecanase-1 decreases aggrecan degradation in cultured rat chondrocytes. RNAi technique can be a useful means for studying extracellular matrix metabolism in the cartilage.

Effects of RNAi-mediated inhibition of aggrecanase-1 and aggrecanase-2 on rat costochondral chondrocytes in vitro.

AIM: Failure of transplanted cartilage or allogenic chondrocytes is attributed mainly to immunological rejection and cartilage degradation. A major feature is the loss of aggrecan from the cartilage matrix, primarily due to the action of the specific proteinases aggrecanase-1 and aggrecanase-2. The aim of this in vitro study was to determine whether the specific inhibition of aggrecanase-1 and aggrecanase-2 by RNAi would mitigate aggrecan loss from cultured chondrocytes. METHODS: Expression plasmid vectors of shRNA targeting aggrecanase-1 and aggrecanase-2 were constructed and transfected into cultured rattus costochondral chondrocytes. The transfected cells were induced with interleukin-1beta (IL-1beta). Gene mRNA levels were analyzed by RT-PCR. Aggrecan and collagen II content were measured by immunohistochemistry and Western blotting. RESULTS: As the chondrocytes underwent dedifferentiation, aggrecanase-1 increased significantly. The specific inhibition of aggrecanase-1 and aggrecanase-2 by RNAi had no negative effect on the morphology and growth velocity of the chondrocytes. The mRNA of aggrecanase-1 and aggrecanase-2 decreased significantly. The alpha-2-macroglobulin expression level was increased by the shRNA specific for aggrecanase-1. Other genes of the chondrocytic extracellular matrix were not affected. RNAi significantly increased the aggrecan and collagen II content of chondrocytes treated with IL-1beta. CONCLUSION: The results suggest that inhibition of aggrecanase-1 and aggrecanase-2 by RNAi can mitigate aggrecan degradation, without interfering with chondrocytic gene phenotype recovery. RNAi technology can be a useful tool for studying degenerative processes in cartilage.

[Study of immunolipo-sodium morrhuate applied on human hemangioma endothelial cells in vitro].

PURPOSE: To explore the method of preparing immunolipo-sodium morrhuate and evaluate its effect on human hemangioma endothelial cells in vitro. METHODS: Using SPDP((N-Succinimidyl-3-(2-pyridyldithio)) propionate) as cross-linker, anti-VEGFR2/KDR monoclone antibody was combined to the liposome surface to prepare immunolipo-sodium morrhuate by extruding method, and then its effect on human hemangioma endothelial cells in vitro was observed by laser scanning confocal microscope, inverted microscope, Gimsa staining, transmission electron microscope, MTT and flow cytometry. RESULTS: The average diameter of the immunoliposome was 122.9 nm, which had a very good stability when compared with normal liposome, it had stronger and faster combining ability, its potential to induce apoptosis was much more prominent, and its toxic effect on human hemangioma endothelial cells was gentle, which was similar to normal liposome. CONCLUSION: We have prepared immunolipo-sodium morrhuate successfully, which has very good specific initiative targetting ability in vitro and can induce pervasive apoptosis of human hemangioma endothelial cells.

[The effect of aloesin on melanocytes in the pigmented skin equivalent model].

OBJECTIVE: To observe the effect of aloesin, tea polyphenols, arbutin on melanocytes in the pigmented skin equivalent model. METHODS: First, we constructed the pigmented skin equivalent model in vitro. And then we detected the effect of aloesin, tea polyphenols and arbutin on the cells' shape, tyrosinase activity and formation of melanin in the constructed pigmented skin equivalent. RESULTS: Three depigmenting agents showed an inhibition effect on the tyrosinase activity of melanocytes and reduced significantly melanin content in the pigmented skin equivalent model, in which the tea polyphenols had the strongest effect, and then was the aloesin. But the tea polyphenols showed the strongest toxicity, while the aloesin and arbutin had a much lower toxicity. CONCLUSIONS: All the three depigmenting agents showed a concentration dependent suppression effect on the tyrosinase activity and formation of melanin, in which the tea polyphenols was the strongest effect( P <0.05). Aoesin has a good suppression effect on the tyrosinase activity and formation of melanin, but has a much lower toxicity, which could be used as a safe depigmenting agent.

[Construction of an in vitro equivalent of the pigmented skin].

OBJECTIVE: To construct an in vitro equivalent of the pigmented skin using tissue engineering methods. METHODS: Surgically removed foreskins was used as the source of keratinocytes and melanocytes harvested by routine tissue digestion. The fibroblasts were enriched by tissue block culture and seeded into the scaffold constructed using mouse tail collagens to construct the pigmented skin equivalent model. The general structure and the melanocyte distribution and growth status in this model were observed with HE staining and Fontana Masson staining. The ultrastructure of the constructed pigmented skin equivalent was observed by transmission electron microscope. RESULTS AND CONCLUSION: The pigmented skin equivalent model was structurally intact, and allowed optimal cell growth. Fontana Masson staining identified in the basal layer numerous melanocytes in normal growth, and the constructed model was structurally similar to normal skin tissue, suggesting successful construction of the pigmented skin equivalent model.

[Three-dimensional finite element analysis of three conjunctive methods of free iliac bone graft for established mandibular body defects].

OBJECTIVE: To analyze the stress and displacement distribution of 3D-FE models in three conjunctive methods of vascularized iliac bone graft for established mandibular body defects. METHODS: Using computer image process technique, a series of spiral CT images were put into Ansys preprocess programe to establish three 3D-FE models of different conjunctions. RESULTS: The three 3D-FE models of established mandibular body defects by vascularized iliac bone graft were built up. The distribution of Von Mises stress and displacement around mandibular segment, grafted ilium, plates and screws was obtained. CONCLUSION: It may be determined successfully that the optimal conjunctive shape be the on-lay conjunction.

[The experimental study of lipo-sodium morrhuate promoting apoptosis of ECV-304 cells].

OBJECTIVE: To evaluate the effect of lipo-sodium morrhuate on ECV-304 cell line. METHODS: The effect lipo-sodium morrhuate was evaluated by toxicology trial (MTT), electron microscope, DNA electrophoresis and flow cytometer. RESULTS: The toxicology results showed, that the number of vital cells in lipo-sodium morrhuate group decreased slowly. The electron microscope exhibited apoptosis in the lipo-sodium morrhuate group. And there were typical DNA ladder in DNA electrophoresis and typical apoptosis peak in flow cytometer. The apoptosis rate was 22.23%. CONCLUSIONS: Unlike the normal preparation of sodium morrhuate, lipo-sodium morrhuate could induce apoptosis of ECV-304 cell line.

[Apoptotic study on the effect of fluorine and selenium on the human hair follicle in vitro].

OBJECTIVE: The aim of this study was to observe the human hair follicle apoptosis status affected by fluorine and the antagonism effect by selenium in vitro. METHODS: The single hair follicles were separated and cultured, then they were added in different concentrations of sodium fluoride and sodium selenite. Chosen the appropriate concentrations, they were divided into 7 groups. The TUNEL was used to investigate the apoptotic cells of different parts. The morphous of hair follicles was observed consecutively and electron microscope was used. RESULTS: We found that in 1 mmol/L and 10 mmol/L sodium fluoride groups, when the human hair follicles in vitro were cultured on the 5th day, the apoptotic cells of outer root sheath (ORS), dermal sheath and hair papilla, hair bulb were obviously increased. But 0.01 mmol/L sodium selenite weakened the toxicity of 1 mmol/L sodium fluoride at the outer root sheath and hair bulb (P < 0.05). CONCLUSIONS: Different concentrations of sodium fluoride had different effect on the growth of human hair follicle in vitro which were cultured on 5th day. Sodium fluoride of certain concentration could accelerate the apoptosis of human hair follicle in vitro. Sodium selenite of certain concentration could act antagonism to the toxicity of sodium fluoride.

[Mechanical force distribution on cleft maxillary finite-element models after alveolar and hard palate bone graft].

OBJECTIVE: To investigate the biomechanical force distribution of three different cleft maxillary finite-element models pre- and post-bone graft with specified load to certain area of the models. METHODS: Developing a cleft palate bony model from a 15-year cleft palate male CT scan DICOM data and generating alveolar bone-grafted, alveolopalatal bone-grafted cleft maxillary finite-element model was set up through gluing the graft model. Also the pre-grafted model as compared, vector lip force on the anterior and anteriolateral face of the alveolar ridge was applied, and studied the press distribution properties and localized area. RESULTS: The press principal spread along the alveolar ridge and focused on anterior wall of maxillary prior to graft. But the press tended to be evenly distributed after bone grafted, whether alveolar or/and hard palate bone grafted. The grafted bone could resisted the medially deformation of alveolar crest and decreased the shear press to the nasal base bony structure. The map showed no significant differences along with alveolar or/and hard palate bone graft. CONCLUSION: The postoperative lip pressure plays an important role for the deformation and deviation of alveolar ridge. Alveolar bone graft could even the distribution of the stresses and should be emphasized. But the grafted bony palatal appears superior to but no significant mapping and anti-deformation difference with alveolar bone graft.

[Compare the effect of lipo- and normal prepared Sodium Morrhuate on ECV-304 cell line].

OBJECTIVE: To compare the effect of Sodium Morrhuate on ECV-304 between its lipo- and normal preparation. METHODS: The ECV-304 cell line was supplemented with Sodium Morrhuate and lipo-Sodium Morrhuate in order, and the result on morphology (microscope, Giemsa Staining and electron microscope), cell activity (MTT), and flow cytometer between the two preparation were compared. RESULTS: In normal preparation group, cell's edema occurred. Chromatin was like catkins. Tumefaction and degeneration of mitochondrion and endoplasmic reticulum appeared. In lipo-Sodium Morrhuate group, the membrane was creased and processus appeared. Chromatin aggregates to the membrane of nucleus was like crescent, and then broken. The apoptotic body was formed. MTT changes showed that the curve of the normal preparation group was steep and the change time was short relatively, which cues the vital cells decreased sharply. The curve of lipo-Sodium Morrhuate group was gentle and the change time was long relatively, which cues the vital cells decreased slowly. The flow cytometer showed that typical apoptosis peak appeared. CONCLUSION: The normal preparation group shows an acute toxic effect on ECV-304 cell line, which result in a necrosis course, while lipo-Sodium Morrhuate shows a gradual releasing process, which may indicate a apoptosis course.

[Experimental study on induction of the normal human melanocytes apoptosis in vitro by cycloheximide and TNF-alpha].

OBJECTIVE: To investigate the effects of cycloheximide and TNF-alpha on melanocyte (MC). METHODS: Melanocyte apoptosis was studied with MTT, transmitting electron microscopy and fluorescence labeling of alive cells. RESULTS: We added TNF-alpha and cycloheximide in melanocytes, and the typical apoptosis appeared 24 hours later, with chromatin condensation, nuclear pyknosis and apoptotic bodies formation. The results of cytometry showed the typical apoptotic peak. CONCLUSION: TNF-alpha and cycloheximide together could inhibit MC proliferation and induce MC apoptosis.

[Stress distribution analysis of the surface of condyle during simulated fracture healing of the neck of condyle by miniplate osteosynthesis].

OBJECTIVE: To find the reasons why patients always have temporomandibular disorders (TMD) after condylar fracture by analyzing the stress distribution change of the condylar surface whose subcondylar fracture ware fixed by miniplate during the whole healing process. METHODS: Analyzing the stress distribution change of the condylar surface whose subcondylar fracture were fixed by miniplate during the whole healing process by three-dimension finite element method (3D FEM). RESULTS: During the whole healing process of the fracture, the miniplate osteosynthesis was helpful to the biomechanics environment rehabilitation of the condylar local, but it still had difference with normal after fixing 12 weeks long. CONCLUSION: The difference of stress distribution of condylar surface that fractured and fixed by miniplate with normal may be part of the reason of TMD after the subcondylar fracture miniplate osteosynthesis.

Dental fluorosis and dental caries in permanent teeth: rural schoolchildren in high-fluoride areas in the Shaanxi province, China.

OBJECTIVES: To study the dental fluorosis and caries in the permanent teeth of 12 to 13-year-old children in fluorosis-endemic areas; to assess the relationship between fluorosis and the fluoride content of the drinking water and the relationship between caries and the fluoride content of the water; finally, to analyze the effect of fluoride intake and water stored in clay pots on dental fluorosis. MATERIAL AND METHODS: 477 children were divided into 5 groups (A to E) according to the fluoride concentration of the waters, i.e. by 0.4, 1.0, 1.8, 3.5, and 5.6 mg F/l, respectively. Dental fluorosis was assessed by TF score and caries by the DMF-T index. A questionnaire was used to obtain information about water storage and other information relevant to children's fluoride intake. RESULTS: A positive relationship was found between the mean TF scores and the water fluoride concentration. In groups B and D, the TF score was higher in 13-year-olds than in 12-year-olds. Caries prevalence and mean DMF-T ranged from 2.6% and 0.03 (group E) to 22.1% and 0.38 (group A). Storage of water in clay pots seemed to increase the severity of fluorosis slightly, and to decrease the caries prevalence. CONCLUSIONS: Defluoridation of drinking water, or--alternatively--the provision of low-fluoride water sources, should be given high priority in the examined Shaanxi rural areas. Fluoride concentration of drinking water should be maximum 0.6 mg/l. Storage of water in the local clay pots may increase the severity of dental fluorosis.

[The effects of aloesin and arbutin on cultured melanocytes in a synergetic method].

OBJECTIVE: To study the effects of aloesin and arbutin on normal cultured human melanocytes in synergetic method. METHODS: Building up the system of cultured human melanocytes. The cultured melanocytes in vitro were treated with the mixture of aloesin and arbutin. The cell viability and tyrosinase activity was measured by MTT assay, utilization of L-Dopa as the substrate respectively; melanin content was measured by image analysis system. Furthermore, the effects of the mixture on melanocytes were compared with that of aloesin and arbutin. RESULTS: The mixture of aloesin and arbutin showed an inhibition on tyrosinase activity of human melanocytes and reduced significantly melanin content. Between the mixture and the single use of aloesin or arbutin, there is significant difference (P < 0.05). On the other hand, the mixture has little influence on melanocytes viability and there is negative significance. CONCLUSION: The mixture of aloesin and arbutin can significantly inhibit the tyrosinase activity and melanogenesis of cultured human melanocytes. It showed the effects of aloesin and arbutin in a synergistic manner. It is worth to give farther study later.