LPS induced cellular and matrix degradation and apoptosis in cartilage tissue. Primary human chondrocytes were either left untreated (a) or were treated with 100 ng/ml lipopolysaccharides (LPS) (b-d), pretreated with BMS-345541 (5 mM) (e-g), wortmannin (20 nM) (h-j) followed by LPS treatment, or pretreated in combination with BMS-345541 and wortmannin (5 mM and 20 nM) (k-m) for 12 h and then stimulated with LPS for another 24 h. The cells were transferred to high-density culture for 14 days. Ultrastructural morphology was evaluated by electron microscopy. Control cultures of chondrocytes showed well-developed chondrocytes (Ch) embedded in a well-developed extracellular matrix (ECM) (a). Treatment with LPS resulted in matrix breakdown and cell lysis and apoptosis (arrows) (b-d). Pretreatment with BMS-345541 alone (e-g), with wortmannin alone (h-j) or in combination with BMS and wortmannin (k-m) resulted in a marked improvement of chondrocyte phenotype and the formation of cartilage nodules. The formation of a dense extracellular matrix (ECM) surrounding well-developed chondrocytes (Ch) was observed. Magnification x5000; bar, 1 µm.