Adhesive Force of Chondrocytes to Cartilage

Abstract

Chondrocyte transplantation is a clinical procedure for cartilage repair. Transplanted cells may have difficulty attaching to the surface of chondral lesions because of the antiadhesive properties of the proteoglycan rich matrix. This study used micromanipulation methods to determine if pretreatment of cartilage with chondroitinase ABC affects chondrocyte adhesion to cartilage and if chondrocytes adhere preferentially to the superficial, middle, or deep layers of cartilage. Bovine chondrocytes were transplanted in vitro on articular cartilage sections cut perpendicular to the articular surface. At various times between 15 and 75 minutes after seeding, a micropipette micromanipulation system was used to measure the adhesion force of individual chondrocytes to cartilage. The chondrocyte adhesion force increased with chondroitinase ABC treatment and seeding time but generally was similar for the different regions of articular cartilage (superficial, middle, deep layer) to which the cells were attached. For normal cartilage, the adhesion force increased from 1.29 ± 0.24 mdyne after 15 to 30 minutes seeding to 5.29 ± 0.25 mdyne after 60 to 75 minutes. Treatment with chondroitinase ABC at certain concentrations and durations (1.0 U/mL for 5 minutes or 0.5 or 1 U/mL for 15 minutes) led to an increase in adhesion force, whereas relatively low concentration or treatment time (0.25 U/mL for 15 minutes or 0.5 U/mL for 5 minutes) had little or no detectable effect. The increase in adhesion attributable to chondroitinase ABC treatment appeared most marked (+144% to +292%) for short (15 to 30 minutes) seeding durations but was still significant (+46%) for the longest seeding period (60 to 75 minutes) studied after the 1 U/mL for 15 minute treatment condition. These results provide direct biomechanical evidence that enzymatic treatment of a cartilage surface can enhance chondrocyte adhesion.