Table 1 The growth factors and matrix proteins evaluated in this study. The essential role in cartilage function and possible dysfunction when improperly expressed are explored
Growth factor/matrix proteins | Effects in cartilage | Improper expression leads to |
|---|---|---|
b-FGF (Basic Fibroblast Growth Factor) | Provides the response to tissue injury, by increasing chondrocyte proliferation, collagen II deposition, while preventing tissue hypertrophy [27, 28]. | Lack of response to injury, hypertrophy of cartilage and non-proliferating cells [28, 29] |
PRG4 (Superficial Zone Protein) | Is the source of joint lubrication, which protects against Osteoarthritis (OA) and inflammation. Also slows growth factor expression [30,31,32,33]. | Joints lose lubrication leading to chondrocyte death and irreversible OA [34, 35] |
TGF-β1 (Transforming Growth Factor Beta 1) | Maintains PRG4 levels allowing it to protect against OA and promotes cellular chondrogenesis [36, 37]. | The onset of OA and eventual osteochondral degeneration [38, 39] |
BMP-7 (Bone Morphogenic Protein 7) | Promotes stem cell chondrogenesis and their production of PRG4 and hyaline cartilage [40,41,42]. | Cartilage tissue degradation [43] |
sGAG (sulfated glycosaminoglycans) | Central role in maintaining cartilage homeostasis while providing structure and biomechanical properties [44]. | The onset of OA and cartilage [45] |