The effect of radio-frequency glow discharge treatment of polystyrene on the behavior of porcine chondrocytes in vitro.

The aim of this study was to determine the effects of physicochemical surface properties of tissue-culture substrata on chondrocyte behavior. Polystyrene was modified by radio-frequency glow discharge (RFGD) plasma treatment with various monomers. The changes in surface properties of the modified polystyrene were verified by ESCA and water contact angle measurements. Porcine chondrocytes were seeded on these surfaces and cultured for 5 days. After 5 days of culture, the number of chondrocytes was highest on the N2 plasma-treated surface, followed by the CH2/N2 plasma-treated surface, untreated polystyrene and CF4 plasma-treated surface. The number of chondrocytes decreased with increasing water contact angle. The surface chemical properties influenced the morphology and gene expression of cultured chondrocytes. The cells cultured on the CF4 plasma-treated surface retained a round morphology characteristic of chondrocytes after day 1, while most of the cells grown on the N2 plasma-treated surface or the untreated polystyrene showed a flattened morphology. Using RT-PCR, expression of type-I collagen could not be detected in the chondrocytes cultured on the CF4 plasma-treated surface and the CH2/N2 plasma-treated surface. In contrast, the chondrocytes grown on the N2 plasma-treated surface or the untreated polystyrene surface expressed type-I collagen mRNA. This study shows that modification by RFGD treatment could modulate chondrocyte culture and gene expression.

Repair of porcine articular cartilage defect with autologous chondrocyte transplantation.

Articular cartilage is known to have poor healing capacity after injury. Autologous chondral grafting remains the mainstay to treat well-defined, full-thickness, symptomatic cartilage defects. We demonstrated the utilization of gelatin microbeads to deliver autologous chondrocytes for in vivo cartilage generation. Chondrocytes were harvested from the left forelimbs of 12 Lee-Sung pigs. The cells were expanded in monolayer culture and then seeded onto gelatin microbeads or left in monolayer. Shortly before implantation, the cell-laden beads were mixed with collagen type I gel, while the cells in monolayer culture were collected and re-suspended in culture medium. Full-thickness cartilage defects were surgically created in the weight-bearing surface of the femoral condyles of both knees, covered by periosteal patches taken from proximal tibia, and sealed with a porcine fibrin glue. In total, 48 condyles were equally allotted to experimental, control, and null groups that were filled beneath the patch with chondrocyte-laden beads in gel, chondrocytes in plain medium solution, or nothing, respectively. The repair was examined 6 months post-surgery on the basis of macroscopic appearance, histological scores based on the International Cartilage Repair Society Scale, and the proportion of characteristic chondrocytes. Tensile stress-relaxation behavior was determined from uniaxial indentation tests. The experimental group scored higher than the control group in the categories of matrix nature, cell distribution pattern, and absence of mineralization, with similar surface smoothness. Both the experimental and control groups were superior to the null group in the above-mentioned categories. Viable cell populations were equal in all groups, but the proportion of characteristic chondrocytes was highest in the experimental group. Matrix stiffness was ranked as null > native cartilage > control > experimental group. Transplanted autologous chondrocytes survive and could yield hyaline-like cartilage. The application of beads and gel for transplantation helped to retain the transferred cells in situ and maintain a better chondrocyte phenotype.

Fabrication of a novel porous PGA-chitosan hybrid matrix for tissue engineering.

Polyglycolide (PGA) and chitosan mixture solution was prepared using solvents of low toxicity to create novel, porous, biocompatible, degradable, and modifiable hybrid matrices for biomedical applications. The porosity of these PGA-chitosan hybrid matrices (P/C matrices) was created by a thermally induced phase separation method. Two types of the P/C hybrid matrices containing 70 wt% PGA (P/C-1 matrix) and 30 wt% PGA (P/C-2 matrix) were fabricated. Chitosan matrix was also prepared for comparison. A 35-day in vitro degradation revealed that the weight losses for the P/C-1 and P/C-2 matrices were similar ( approximately 61%), but the releases of glycolic acid from the P/C-1 and P/C-2 matrices were 95% and 60%, respectively. The P/C-1 matrix had higher porosity and higher mechanical strength than the P/C-2 and chitosan matrices. Fibroblast cells cultivated in these matrices proliferated well and the cell density was the highest in the P/C-1 matrix, followed by the chitosan and P/C-2 matrices, suggesting good biocompatibility for the P/C-1 matrix. We thereby concluded that the P/C-1 matrix, due to its high strength, porosity, biocompatibility and degradability, is a promising biomaterial. The presence of chitosan in the P/C matrices provides many amino groups for further modifications such as biomolecule conjugation and thus enhances the application potential of the P/C hybrid matrices in tissue engineering.