Tissue-engineered cartilage by in vivo culturing of chondrocytes in PLGA-collagen hybrid sponge

Bovine chondrocytes were isolated from the shoulder articular joints of a c alf, seeded in biodegradable porous polymer scaffolds, and implanted subcut aneously in the dorsum of athymic nude mice to tissue engineer articular ca rtilage in vivo. Hybrid sponge of poly(DL-lactic-co-glycolic acid) (PLGA) a nd collagen was used as the porous scaffold with PLGA sponge and collagen s ponge used as the controls. Chondrocytes were seeded in low (1 X 10(7) cell s/ml) and high (5 X 10(7) cells/ml) densities. Before implantation, the sca ffold-cell constructs were cultured in vitro for I week. The implants were harvested after in vivo incubation of 2, 4, 6, and 8 weeks. The PLGA-collag en hybrid sponge implants maintained their original shapes, as did the PLGA sponge, whereas the collagen sponge collapsed. The mechanically strong PLG A sponge functioned as a skeleton and prevented the embedded collagen spong e from collapsing. The implants were examined histochemically by haematoxyl in and eosin staining, by safranin O/fast green staining, and immunohistoch emically by anti-collagen type H antibody. The percent of cartilaginous ext racellular matrices increased, while neovascularization decreased with an i ncreased implantation period. A greater amount of homogeneous cartilaginous tissue formed when chondrocytes were seeded at a hi-her density. The morph ology of chondrocytes, the expression of cartilaginous matrices in the PLGA -collagen hybrid sponge, was similar to those in collagen sponge, The carti laginous matrices were more homogeneously distributed in the PLGA-collagen hybrid sponge and collagen sponge than in the PLGA sponge. Hybridization of the PLGA sponge and collagen sponge facilitated cell seeding and promoted the in vivo formation of cartilaginous tissue. (C) 2001 Elsevier Science B. V. All rights reserved.