Animals Birds Cartilage, Articular Cell Proliferation Chondrocytes Dietary Supplements Dinoprostone Drugs, Chinese Herbal Extracellular Matrix Gene Expression Glycoproteins Humans Inflammation Mediators Knee Knee Joint Osteoarthritis, Knee Saliva aggrecan article cartilage cell catabolism cell proliferation cell structure chondroprotective agent collagen type 2 controlled study edible bird nest extract enzyme linked immunosorbent assay gene expression glycosaminoglycan