Vascular endothelial growth factor in articular cartilage of healthy and osteoarthritic human knee joints

Objective-To determine the levels of vascular endothelial growth factor (VE GF) mRNA and protein expression in normal and osteoarthritic (OA) human art icular cartilage, and whether VEGF expression alters during the progression of OA. Methods-Sections from normal and OA human knee cartilage were immunotained with a polyclonal antibody recognising VEGF. In addition, total RNA was iso lated from normal and osteoarthritic human knee cartilage and analysed by r everse transcriptase-polymerase chain reaction (RT-PCR) for VEGF mRNA expre ssion. Results-VEGF was found to be present in normal and OA human knee cartilage in all cartilage layers. A significant increase of VEGF immunopositive chon drocytes to up to similar to 82% was detected in severe OA cartilage compar ed with normal articular cartilage (similar to 56% of immunopositive chondr ocytes). RT-PCR analysis showed the expression of VEGF also on the mRNA lev el. Conclusions-VEGF is expressed by articular chondrocytes in normal and OA hu man knee cartilage. The percentage of VEGF immunopositive chondrocytes sign ificantly increases in late stages of the disease. The VEGF transcript leve ls encoding all four isoforms shows a big variability in samples from diffe rent donors, suggesting a distinct regulation of the expression of the four VEGF isoforms in normal and OA cartilage.