In Vivo Implantation of Chondrocytes Seeded into a Three-dimensional PLGA Sponge: Is in Vitro Culture before Implantation Necessary?

ABSTRACT

For tissue-engineered neocartilage formation in vivo, most studies have cultured chondrocytes within a biodegradable polymer in vitro before implantation of cell-polymer complex into an animal. The present study was performed to investigate the necessity of in vitro culture (preconditioning). Cell-polymer complex was made of chondrocytes obtained from a rabbit ear and a 8515 poly(DL-lactic-co- glycolic acid) (PLGA) sponge. The complex was implanted into a nude mouse either after or without in vitro preconditioning. For control groups, PLGA sponge without chondrocytes was used. One, 2, and 4 weeks after the implantation, each group was examined by measurement of weight and volume of sponges as well as histologic study with Safranin-O staining. The control groups showed loss of weight as time passed. The non-preconditioned group, on the other hand, showed weight loss for the first week, but increased in weight afterwards. The preconditioned group also had weight loss in the first week after the implantation with no noticeable weight changes thereafter. Neither weight nor volume of PLGA sponges in preconditioned group was significantly different from those in non-preconditioned group until the 2nd week. In the 4th week, volume of sponges in non-preconditioned group was significantly larger than that in preconditioned group. On histological observation, chondrocytes seeded into a PLGA sponges proliferated and differentiated into cartilage tissues both in preconditioned and non-preconditioned groups, but non-preconditioned group formed cartilage tissue more extensively than the preconditioned group. Based on the above results, it is suggested that new cartilage tissues can be formed successfully following the implantation of cell- polymer complex into a living body without any prior conditioning in a separate culture system.