Autologous chondrocyte implantation (ACI) has been used to treat cartilage defects in thousands of patients worldwide with good clinical effectiveness 10–20 years after implantation. Information concerning the quality of the repair cartilage is still limited because biopsies are small and rare. Glycosaminoglycan structure influences physiological function and is likely to be important in the long term stability of the repair tissue. The aim of this study was to assess glycosaminoglycans in ACI tissue over a two year period.
Biopsies were taken from one patient (25 years old) at 12 months and 20 months post-ACI-treatment and from three normal cadavers (21, 22 and 25 years old). Fluorophore-assisted carbohydrate electrophoresis (FACE) was used to quantitatively assess the individual glycosaminoglycans.
At 12 months the ACI biopsy had 40% less hyaluronan than the age-matched cadaveric biopsies but by 20 months the ACI biopsy had the same amount of hyaluronan as the controls. Both the 12 and 20 month ACI biopsies had less chondroitin sulphate disaccharides and shorter chondroitin sulphate chains than the age-matched cadaveric biopsies. However, chondroitin sulphate chain length doubled as the ACI repair tissue matured at 12 months (3913 Da ± 464) and 20 months (6923 Da ± 711) and there was less keratan sulphate as compared to the controls.
Although the glycosaminoglycan composition of the repair tissue is not identical to mature articular cartilage its quality continues to improve with time.