Factors affecting the efficacy of bovine chondrocyte transplantation in vitro

Current therapies for osteoarthritis have been primarily directed at sympto m relief rather than disease modification or cure. Improved understanding o f cartilage biology and metabolism has permitted exploration of disease-mod ifying treatments for OA. Chondrocyte transplantation is one approach to di sease modification that has received increasing attention. To date, most ch ondrocyte transplantation has focused on surgical implantation into isolate d chondral defects. Our hypothesis is that cultured chondrocytes will preferentially transplant to hyaline cartilage after intraarticular injection. The purpose of this s tudy was to quantify chondrocyte adherence to cartilage in an in-vitro bovi ne explant model under differing culture conditions. The effect on chondroc yte transplantation of time, of alginate vs. monolayer culture techniques, and of differing origin of tissue explants within the knee joint were asses sed. The effect on transplantation of physically modifying the explant surf ace was also assessed. In addition to quantification of transplantation adh erence, the morphology of transplanted chondrocytes was assessed with confo cal and electron microscopy. Maximal adherence occurred by 24 h post-transplantation. Baseline transplan t densities exceeding 1x10(6) cells/cm(2) were observed on unmodified carti lage surfaces. No significant differences in binding density were noted bet ween cartilage explants obtained from the patella, femoral condyles, tibial plateaus or the trochlear groove. In addition, no differences in chondrocy te adherence were noted in cells cultured in monolayer or alginate beads. T ransplanted chondrocytes were noted to be spherical irrespective of the cul ture methods employed. Notably, chondrocytes demonstrated significantly imp roved adherence to cartilage surfaces after the superficial layer was remov ed as compared to normal intact cartilage surfaces (increase of 26%, P<0.01 ). This suggests that chondrocytes may preferentially adhere to cartilage s urfaces where the superficial layer has been damaged, as is the case in iso lated chondral lesions, or with diffuse cartilage degeneration. (C) 1999 Os teoArthritis Research Society International.