Search

Fibroin‐hydrogel sponge and collagen gel were used as scaffold for in vitro cartilage regeneration. Fibroin‐hydrogel sponge was formed by phase separation from freezed fibroin solution. Chondrocytes were harvested from proximal humerus, distal femur and proximal tibia of 4‐week‐old Japanese white rabbits and inoculated in the fibroin–hydrogel sponge and collagen gel. Those constructs were cultured in DMEM supplemented with 10% FCS and 50 ml L‐ascorbate at 37°C. Histological observation, measurement of sulfated glycosaminoglycan and cell density were carried out at 3, 7, and 14 days after the cultivation. Well‐defined cartilage tissue can be seen both in the fibroin–hydrogel sponge and in the collagen gel. The matrix was intensely stained by safranin‐O and showed a metachromatic reaction in both group. However, the quantity of sulfated glycosaminoglycan and cell density of the fibroin–hydrogel sponge group were increased more rapidly than these of the collagen gel group. Thus, the chondrocytes proliferated in the fibroin sponge without losing their differentiated phenotype. It is possible that culture environment in the fibroin sponge was suitable for chondrocytes regeneration. [ABSTRACT FROM AUTHOR]

The dynamic visco‐elastic properties of regenerated cartilage tissue were measured to evaluate its mechanical function during cultivation. Harvested chondrocytes from 4‐week‐old Japanese white rabbits were inoculated into fibroin sponge at a cell concentration of about 5×10[sup 7] cells/ml. Dynamic visco‐elasticity measurements were performed under compressive loading to evaluate the load bearing function of the articular cartilage. The dynamic modulus and the dynamic loss of the regenerated cartilage increased and the peak value of tanδ, as well as the frequency at the peak, decreased with increasing cultivation time. The pores of the fibroin sponge became filled with newly formed tissue as cultivation time increased. These changes in the visco‐elastic properties of the regenerated cartilage were compared with those of a model system, ethylene propylene diene monomer sponge with interstitial fluid, and appear to be a result of increased fluid flow resistance and internal loss. We conclude that the changes in the dynamic visco‐elastic properties of the regenerated cartilage were caused because of narrowing of the fluid path by synthesized extracellular matrix. [ABSTRACT FROM AUTHOR]

The mechanical properties of regenerated cartilage tissue were measured to evaluate changes in their visco-elastic properties during cultivation. An indentation test and dynamic visco-elasticity measurements were carried out on cartilage tissue cultured with rabbit chondrocytes that had been inoculated into the fibroin sponge. A 1.5-mm-diameter porous indentor was used for the indentation test, in which time-dependent strain curves were derived from measurements taken under several loading conditions. Dynamic visco-elasticity measurements were performed under compressive loading to evaluate the loadbearing function of the articular cartilage. Although the amount of permanent deformation was not influenced by the duration of cartilage regeneration, the amount of creep deformation increased with longer cultivation. The E′ value of the regenerated cartilage increased and the peak value of tan &b.delta; and the frequency at the peak became lower with longer cultivation. It is suggested that the changes in the time-dependent strain curves and dynamic visco-elastic properties of the regenerated cartilage were caused by maturation of the cultured cartilage tissue. [ABSTRACT FROM AUTHOR]