Biomedical subjects

Zhiming Yang

Publications and source records attributed to Zhiming Yang.

65 records · Page 4Linked to original sources

PubMed2002

Surface modification of poly (D,L-lactic acid) with chitosan and its effects on the culture of osteoblasts in vitro.

Chitosan is a good biodegradable natural polymer, widely used in biomedical fields. In this study, chitosan was used to modify the surface of poly (D,L-lactic acid) (PDLLA) in order to enhance its cell affinity. The properties of a modified PDLLA surface and control were investigated by contact angle and electron spectroscopy for chemical analysis (ESCA), which indicated the changes in surface energy and chemical structure. Scanning electron microscopy (SEM) observation displayed differences in surface morphology between the chitosan-modified film and the control. These data reflected that PDLLA films could be modified with chitosan and in turn may affect the biocompatibility of the modified films. Therefore, adhesion and growth of osteoblasts on modified PDLLA films as well as control were studied. Cell morphologies on the films were examined by SEM and cell viability was evaluated using an MTT assay; the differentiated cell function was assessed by measuring alkaline phosphatase (ALP) activity. The ALP activity of modified PDLLA films was significantly higher than that found on the control (p < 0.01). The proliferation of osteoblasts on modified films was also found to be higher than that on the control (p < 0.05), suggesting that chitosan could be used to modify PDLLA and then enhance its cell biocompatibility.

Alkaline Phosphatase↗

PubMed2002

Improvement of the functions of osteoblasts seeded on modified poly(D,L-lactic acid) with poly(aspartic acid).

One of the challenges in the field of tissue engineering is the development of biomaterial/cell interactions. For the purposes of the present study, two molecular weights of poly(aspartic acid) (PASP) were used to modify poly(D,L-lactic acid) (PDLLA) films in order to enhance their cell affinity. The properties of the PDLLA-modified surfaces and the controls were investigated by water contact angle measurement and electron spectroscopy for chemical analysis (ESCA). These data reflect the change in the biocompatibility of modified PDLLA surfaces. Then rat osteoblasts were seeded onto these modified surfaces and on controls to examine their effects on cell adhesion and proliferation. Cell morphologies on these surfaces were studied by scanning electron microscopy (SEM), and cell viability was evaluated with a MTT assay. In addition, differentiated cell function was assessed by measuring alkaline phosphatase (ALP) activity. The results suggest that PASP-modified surfaces may enhance the interactions between osteoblasts and PDLLA films.

Alkaline Phosphatase↗

PubMed2002

Poly(D,L-lactic acid) surfaces modified by silk fibroin: effects on the culture of osteoblast in vitro.

The objective of this study was to modify the surface of poly(D,L-lactic acid) (PDLLA) with different molecular weight of silk fibroins, and assess the effects of the modified surfaces on the functions of rat osteoblasts cultured in vitro. The properties of the modified PDLLA surface and the control one were investigated by contact angle and electron spectroscopy for chemical analysis (ESCA). The former indicated the variation of hydrophilicity and the latter suggested that the modified PDLLA film using silk fibroin is enriched with nitrogen atoms. The biocompatibility of the PDLLA film may be altered and in turn affects the seeded cell functions. Therefore, attachment and proliferation of osteoblasts seeded on the modified PDLLA films and the control one were examined. Cell morphologies on these films were studied by scanning electron microscopy (SEM) and cell viability was evaluated by MTT assay. In addition, differentiated cell function was assessed by measuring the alkaline phosphatase (ALP) activity. These results suggest that the silk fibroin-modified PDLLA surface can improve the interaction between osteoblasts and the PDLLA films.

Alkaline Phosphatase↗

PubMed2002

Influence of different surface modification treatments on poly(D,L-lactic acid) with silk fibroin and their effects on the culture of osteoblast in vitro.

The objective of this study was to investigate the efficiency of two treatments for poly(D,L-lactic acid) (PDLLA) surface modification using silk fibroin. one chemical treatment and one physical treatment: 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide (WSC) and entrapment. The properties of control films, WSC-modified and entrapment-treated PDLLA films were investigated by water contact angle measurement and electron spectroscopy for chemical analysis (ESCA). The water-contact angle measurement indicated the change of hydrophilicity and the ESCA analysis suggested that the modified PDLLA film using silk fibroin became enriched with nitrogen atoms. The biocompatibility of PDLLA film might be altered, which in turn would affect the functions of cells that were seeded on it. Therefore, attachment and proliferation of osteoblasts that were seeded on modified PDLLA films and control films were examined. Cell viability was evaluated by the MTT assay and differentiated cell function was assessed by measuring alkaline phosphatase activity. These results suggested that silk fibroin was used to modify PDLLA surface via WSC and that entrapment could improve the interactions between osteoblasts and PDLLA films. The entrapment treatment was more effective thin WSC treatment to accomplish the goal of surface modification.

Alkaline Phosphatase↗

PubMed2002

Modulation of osteoblast function using poly(D,L-lactic acid) surfaces modified with alkylation derivative of chitosan.

Poly(D,L-lactic acid) (PDLLA) was modified with alkylated chitosan (N-butyl chitosan and N-cetyl chitosan), and the effects of modified films on the functions of rat osteoblasts were investigated. The characteristics of surfaces (both modified and control) were examined by water contact angle measurement and electron spectroscopy for chemical analysis (ESCA). Cell morphologies on these surfaces were taken using scanning electron microscopy (SEM). Cell attachment and proliferation were used to assess cell behavior on modified surface and control. MTT assay was used to determined cell viability, and alkaline phosphatase (ALP) activity was taken to evaluate differentiated cell function. Compared with the untreated films, no significant difference in cell attachment of osteoblasts was found on the modified films at a period of 8 h (p > 0.05). However, cell proliferation of N-butyl chitosan rather than N-cetyl chitosan modified PDLLA films was significantly higher than that found on control one (p < 0.05) at the end of the 4th and 7th days. The cell viability of osteoblasts on N-butyl chitosan modified PDLLA films were found higher than that on control (p < 0.05). These results suggested that N-butyl chitosan contributed greater than N-cetyl chitosan when used to modify PDLLA films for improving its biocompatibility.

Alkaline Phosphatase↗

PubMed2002

[Experimental studies on procedures and properties of natural derived scaffold materials of tissue engineered bone].

To detect the properties of natural xenogeneic bone derived materials which were processed with different physical and chemical treatments, we made fully deproteinized bone(FDB), partially deproteinized bone (PDPB), partially decalcified bone(PDCB) from pig ribs. Their morphological features, constitute components and mechanical properties were examined by scanning electron microscopy, x-rays diffraction analysis, mechanical assay and so on. The results showed that FDB, PDPB and PDCB maintained natural network pore system. The ratios of calcium to phosphorus were 1.81, 1.74 and 1.50, and the protein contents were 0.01% +/- 0.02%, 22.41% +/- 0.83% and 35.75% +/- 2.12% respectively. The sequence of their mechanic strength was PDCB > PDPB > FDB. These data indicate that FDB, PDPB and PDCB possess natural network pore system. Their organic and inorganic component ratios and contents are different, so their mechanic properties are not alike. Additionally, more investigations will be necessary to detect the biocompatibility of the three different scaffold materials of natural derived bone.

Animals↗

PubMed2002

[A tissue-engineered strain scaffold for three-dimensional cell cultures].

This article introduces a three-dimensional scaffold which is used to perform three-dimensional cell culture under mechanical stretch from the point of construction of tissue-engineered tissue. The composition, structure, surface characteristics, mechanical property, and cell compatibility of the scaffold have been studied by using surface chemistry and material mechanics testing methods. The results indicate that the polyvinyl alcohol (PVA) sponge, which is water-tolerant, coated with Poly-DL-lactic-co-glycolic acid (PLGA) possesses a good nature in appropriate surface feature, porosity, elastic recoil, and cell compatibility. These features provide wide options for using this scaffold to study the effects of mechanical stretch on cells maintained in three-dimensional culture to provide a three-dimensional matrix.

Biocompatible Materials↗

PubMed2002

[Experimental studies on histocompatibility of three bio-derived bones].

OBJECTIVE: To study the histocompatibility of three bio-derived bones. METHODS: After treatment with different physical and chemical method, three bio-derived bones, the composite fully deproteinized bone (CFDB), partially deproteinized bone (PDPB) and partially decalcified bone (PDCB) were implanted into rabbits. The toxicity, immune response and subperiosteum osteogenesis of CFDB, PDPB and PDCB were studied through gross observation, serum antibody measurement, evaluation of local cellular immune response and HE staining. RESULTS: The study showed that CFDB, PDPB and PDCB had no toxicity. They could conduct peripheral tissue to grow into them and had no harmful effect on subperiosteum osteogenesis. They could also promote cartilage and osteoid tissue derived from periosteum to calcify to new bone, and combine with the peripheral bone. The degree of immune response caused by them was in the sequence of PDCB > PDPB > CFDB. CONCLUSIONS: The three bio-derived bones, CFDB, PDPB and PDCB have good histocompatibility.

Animals↗

PubMed2002

[Characteristics of tenocyte adhesion to biologically-modified surface of polymer].

In this study we examined the in vitro characteristics of tenocyte adhesion to biologically-modified surface of polymer. Polylactic-co-glycolic acid (PLGA) 85/15 films were prepared by a solvent-casting technique. Each film was adhered onto the bottom of a chamber. The film was precoated with poly-D-lysine (PDL), and then coated with serum-free F12 medium containing various concentrations of fibronectin (FN), type I collagen (CN I), and insulin-like growth factor1 (IGF-1). The monoclonal antibodies (to FN and to CN I) with various dilutions were used to inhibit attachment of tenocytes to surface precoated with FN or CN I. Human embryonic tendon cells (HETCs) and transformed human embryonic tendon cells (THETCs) were used as the seeding cells. The system used for the measurement of adhesion force was the micropipette aspiration experiment system. The micropipette was manipulated to aspirate a small portion of the tenocyte body by using a small aspiration pressure. Then the pipette was pulled away from the adhesion area by micromanipulation. The minimum force required to detach the tenocyte from the substrate was defined as the adhesion force. The results showed that modification of FN or CN I by precoating significantly enhanced attachment of tenocytes to surface of polymer (P < 0.05). As antibodies to FN or CN I were added to a polymer film precoated with FN or CN I, the adhesion force decreased significantly (P < 0.05). We concluded that the specific adhesion forces of tenocytes to extracellular matrix adhesion proteins (FN and CN I) had coordinated action and showed good dependence on their precoating concentrations, and were inhibited by the antibodies to these adhesion proteins. Films precoated with IGF-1 strongly accelerated the adhesion of tenocytes to polymer. These results indicate that the specific adhesion of tenocytes to polymer can be promoted by coating extracellular matrix adhesive proteins and insulin-like growth factor1. It is of great importance to construct tissue-engineered tendon.

Biocompatible Materials↗

PubMed2002

[Initial study on three-dimensional culture of tenocytes under cyclic mechanical stretch].

OBJECTIVE: To detect the effect of mechanical stretch on shape, alignment, proliferation, and metabolism of tendon cells maintained in three-dimensional culture. METHODS: A cyclic mechanical strain apparatus for three-dimensional cell cultures was developed. Based on the apparatus, a specific stretch pattern (10% elongation, 12 stretches/min for 15 min of each hour) was applied to tenocytes-scaffolding composites. RESULTS: Initial studies demonstrated that the stretch-mediated effects on cell division, DNA synthesis, and metabolism in such cultures were influenced by the amplitude, frequency, periodicity, and duration of the applied stretch. After 48 hours' exposure to the stretch, the cell number and [3H] thymidine incorporation into DNA were increased, compared with those of the nonstretched controls(P < 0.05). Under the stretch pattern, the shape of cells changed to oblate and spread to the direction of the stretch. The cyclic stretch also caused an increase in collagen synthesis by tendon cells (P < 0.05), which was predominant in type I. CONCLUSION: Cyclic mechanical stretches act directly to stimulate tendon cell growth and these results are compatible with a significant role for stretch in tissue-engineered tendon construction.

Cell Division↗

PubMed2002

[Tissue-engineered auricled cartilage: an experimental study].

OBJECTIVE: To study the feasibility of engineering auricled neocartilage with chitosan/polylacticacid-polycrylactone (PLA-PCL) network scaffolds and to search the difference between dynamic and silent chondrocytal culture techniques. METHODS: Chondrocytes from auricled cartilage of 4 weeks old New Zealand White rabbit were seeded onto chitosan/PLA-PCL network. Ten cell-polymer scaffolds were divided into two groups: dynamic group (n1 = 5) with rotating bioreactors and silent group (n2 = 5) with ordinary dishes to culture. Using scan electroscope, grossly histological and immunohistological techniques, the morphological evaluation was done individually at 1st week in vitro, 4th and 8th week in vivo. RESULTS: Chondrocytes adhered and grew up well on the network, but more quantities of chondrocytes, Glycoaminoglygan (GAG) and type II collagen were found in dynamic group. There was an obvious difference between dynamic and silent group (P < 0.05). CONCLUSION: Chitosan/PLA-PCL network scaffold is good for adhesions and growth of chondrocytes. Furthermore, dynamic cell culture method is better than silent method for formation of neocartilage.

Animals↗