The use of debrided human articular cartilage for autologous chondrocyte implantation: maintenance of chondrocyte differentiation and proliferation in type I collagen gels.

UNLABELLED: Autologous chondrocyte implantation (ACI) is the most promising surgical treatment for large full thickness knee joint articular cartilage (AC) defects where cells from healthy non-weight bearing area AC are multiplied in vitro and implanted into such defects. In the routine surgical procedure for symptomatic knee full thickness AC defects, damaged AC surrounding the edge and the base of such defects is usually debrided and discarded. The purpose of this study was to examine if chondrocytes from this 'debrided' AC can proliferate, synthesize a cartilage specific matrix and thus can be used for ACI. METHODS: Biopsies were retrieved from 12 patients (debrided articular cartilage: DAC, aged 35-61) and from two autopsies (normal articular cartilage: NAC, aged 21 and 25). Chondrocytes were isolated, seeded at low density in type I collagen gels and as monolayer cultures for 4 weeks without passage. RESULTS: After 4 weeks cultures in type I collagen gels, cell proliferation from DAC (18.34 +/- 1.95 fold) was similar to cells from NAC (11.24 +/- 1.02 fold). Syntheses of proteoglycan and collagen in DAC were also similar to NAC. Newly synthesized matrices in gel cultures consisted predominantly of type II collagen as shown by immuno-labelling and SDS-PAGE followed by fluorography. Chondrocytes from 'debrided human AC' cultured at low density in type I collagen gels may be used for the ACI procedure as they provide sufficient viable cell numbers for ACI and maintain their chondrocyte phenotype as they synthesize a cartilage-like matrix.

Effects of growth factors on cell proliferation and matrix synthesis of low-density, primary bovine chondrocytes cultured in collagen I gels.

Low cell density cell numbers and dedifferentiation are two major problems of human chondrocyte culture associated with articular cartilage repair. Bovine chondrocytes seeded at low density (3.5 x 10(4) cells/ml of gels) in three-dimensional collagen type I gels do proliferate and maintain their phenotype as shown by cell counts, morphology and matrix synthesis. The combination of three growth factors (3GFs; 10 ng/ml TGF-beta1 + 100 ng/ml IGF-I + 10 ng/ml b-FGF) added to serum-free culture medium in this culture system enhances the mitotic activity of bovine chondrocytes similar to 20% foetal calf serum (FCS). At day 21, cells proliferated by 41 fold in gels-FCS and 37 fold in gels-3GFs. Protein synthesis by gels-3GFs cultures was similar to 20% FCS when cultured for 3 weeks but much less proteoglycan was synthesized. The matrix deposition as observed by light and electron microscopy was quite different. More small diameter branching collagen fibrils and a denser matrix were presented in gels-FCS culture whilst loosely arranged larger diameter collagen fibrils were observed in gels-3GFs.