A polysaccharide from the traditional Chinese medicinal herb, Bletilla striata (Thunb.) Reichb. f., was isolated, purified and characterized. It induced the proliferation of human umbilical vascular endothelial cells and the expression of vascular endothelial growth factor up to 156% and 147% of control after 72 h, respectively.

Cartilage defects as a result of disease or injury have a very limited ability to heal spontaneously. Recently, tissue engineering and local therapeutic gene delivery systems have been paid much attention in the cartilage natural healing process. Gene-activated matrix (GAM) blends these two strategies, serving as local bioreactor with therapeutic agents expression and also providing a structural template to fill the lesion defects for cell adhesion, proliferation and synthesis of extracellular matrix (ECM). In the current study, we used chitosangelatin complex as biomaterials to fabricate three-dimensional scaffolds and plasmid DNA were entrapped in the scaffolds encoding transforming growth factor-β1 (TGF-β1), which has been proposed as a promoter of cartilage regeneration for its effect on the synthesis of matrix molecules and cell proliferation. The plasmid DNA incorporated in the scaffolds showed a burst release in the first week and a sustained release for the other 2 weeks. The gene transfectd into chondrocytes expresses TGF-β1 protein stably in 3 weeks. The histological and immunohistochemical results confirmed that the primary chondrocytes cultured into the chitosan-gelatin scaffold maintained round and owned characters of high secretion of specific ECM. From this study, it can be concluded that this gene-activated chitosan-gelatins matrix has a potential in the application of cartilage defects regeneration.

To study the electrostatic interaction between two ionic polymer surface, a polyester film surface was graft-polymerized with a cationic monomer, N,N-dimethylaminoethyl methacrylate and an anionic monomer, acrylic acid. When the oppositely charged film pair was brought into contact in the presence of water, they showed strong adhesion instantaneously in water. The adhesion interaction was studied with both shear strength method and atomic force microscopy. The interaction depended on the graft density and the ionic nature of the graft chains. The addition of salt to the medium of the measurement caused a remarkable reduction in the adhesive interaction. These interactions were attributed to the coulombic force between the grafted ionic polymer chains.

Chitosan has the potential for DNA complexation and is useful as a non-viral vector for gene delivery. Highly purified low molecular weight chitosan (LMWC) was prepared. Lactobionic acid (LA) bearing galactose group was coupled with LMWC for liver-specificity. A series of galactosylated-LMWC (gal-LMWC) samples covering a range of galactose group contents were prepared. The chitosan/DNA complexes were obtained using a complex coacervation process. Gal-LMWCs were used to transfer pSV-_-galactosidase reporter gene into human hepatocellular carcinoma cell (HepG2), L-02, SMMC-7721, and human cervix adenocarcinoma cell line (HeLa) cell lines in vitro. Transfection efficiency of gal-LMWCs was evaluated by _-galactosidase assay and compared with those of lipofectin, calcium phosphate (CaP), high molecular weigh chitosan (HMWC) and LMWC. Gal-LMWC/DNA complex shows a very efficient cell selective transfection to hepatocyte. The transfection efficiency of gal-LMWCs increased with the improvement of the galactosylation degree. Cytotoxicity of gal-LMWCwas determined by 3-(4,5-dimethylthiazd-2-yl)-2,5-diphenyltentrazolium bromide (MTT) assay and the results show that the modified chitosan has relatively low cytotoxicity, giving the evidence that the modified chitosan vector has the potential to be used as a safe gene-delivery system.

The chlorophenol chemicals(CPs) are a major class of widely distributed and frequently occurring persistent environmental pollutants. Pentachlorophenol (PCP) has been proposed to be procarcinogen in rodents and in possibly human beings. Human beings also easily expose to other chlorophenol chemicals, including 4-chlorophenol (CP), 2,4-dichlorophenol (DCP),2,3,4-trichlorophenol(TCP), prompting this investigation of their comparative cytotoxic effects and cell death mechanisms, assayed in fibroblast L929 cells, The effective concentration for half-maximal response (EC50) values at 24 h for CP, DCP, TCP, and PCP are 2.18, 0.83,0.46, and 0.11 mmol/L respectively and the EC50 values at 48 h are 1.18, 0.13, 0.08, and 0.06 mmol/L respectively by using 3-(4,5-dimethylthiazd-2-yl)-2, 5-diphenyltentrazolium bromide (MTT) reduction assay. A clear structure-activity relationship was observed between toxicity of CPs and their octanol-water partition coefficients. The further studies indicate that CP, DCP, and TCP induce apoptosis in L929 cells in a concentration or time-dependent manner, but PCP mediates cell death more characteristic of necrosis than apoptosis. These results not only demonstrate that L929 cell growth inhibition bioassay may be useful to provide the comparative evaluation of toxicity of CPs in vitro, but also implicate that CP, DCP, TCP, in comparison with PCP, can induce L929 cell death by apoptosis, resulting in lower procarcinogensis, which may help to elucidate the molecular basis for the adverse health effects associated with CPs exposure.