New cartilage formation in vivo using chondrocytes seeded on poly(L‐lactide)

A chondrocyte‐poly(L‐lactide) (PLLA) composite was employed in an attempt to regenerate cartilage. Rat chondrocytes showed good proliferation on adherent polymer substrates like PLLA and type II collagen production under the in vitro condition. The collagen production became maximal on the 10th day after cultivation. From the in vivo study, seeded chondrocytes spread throughout the scaffold dispersively and a lot of small blood vessels were observed around the matrix when bFGF was coated on the PLLA scaffold. When the chondrocyte‐PLLA composite was transplanted into nude mouse, injection of an immunosuppressive agent was not necessary even in an xenograft implantation. A thin layer fibrous capsule was observed surrounding all of the implanted composites, and the inflammatory response of the host to the implants was mild. From the clear histological staining with thionin, it was obvious that the implanted cells exhibited their phenotypes and formed new matured cartilage.