The effect of fibroblast growth factor and transforming growth factor-beta on porcine chondrocytes and tissue-engineered autologous elastic cartilage

Abstract

Elastic cartilage responds mitogenically in vitro to transforming growth factor-beta (TGF-beta) and basic fibroblast growth factor (basic FGF). We studied the effects of these growth factors separately or in a combination on porcine auricular chondrocytes in vitro and on the autologous elastic cartilage produced. Cells were harvested from the elastic auricular cartilage of 16- to 18-kg Yorkshire swine. Viability and quantification of the cells was determined. Cells were plated at equal concentration and studied in vitro in one of four identical media environments except for the growth factors: Group I contained Ham's F-12 with supplements but no growth factors, Group II also contained basic-FGF, Group III also contained TGF-beta, and Group IV also contained a combination of both growth factors. After 3 weeks in vitro, the cells were chemically dissociated with 0.25% trypsin. Cell suspensions composed of 3 x 10(7) cells/cc in 30% Pluronic F-127/Ham's F-12 were injected subcutaneously. Implants were harvested at 6, 8, 10, and 12 weeks of in vivo culture and then were examined with histologic stains. After 3 weeks of in vitro culture the total number of cells was as follows: Group I, 1.8 x 10(8); Group II, 3.5 x 10(8); Group III, 1.3 x 10(8); Group IV, 2.5 x 10(8). After 8 weeks of in vivo autologous implantation, the average weight (g) and volume (cm3) of each group was as follows: Group I, 0.7 g/0.15 cm3; Group II, 1.5 g/0.8 cm3; Group III, 0.6 g/0.1 cm3; Group IV, 1.2 g/0.3 cm3. Histologically, Groups I, II, and IV generated cartilage similar to native elastic cartilage, but Group III specimens demonstrated fibrous tissue ingrowth. Basic FGF produced the most positive enhancement on the quantity and quality of autologous tissue engineered elastic cartilage produced in this porcine model both in vitro and in vivo.