Chondrogenesis of expanded adult human articular chondrocytes is enhanced by specific prostaglandins

Objective. To investigate the effects of the cyclooxygenase-2 (cox-2)-dependent prostaglandins D2 (PGD2), E2 (PGE2) and F2α (PGF2α) on the redifferentiation and cartilage matrix production of dedifferentiated articular chondrocytes. Methods. Human articular chondrocytes from three adult donors were dedifferentiated by monolayer expansion and induced to redifferentiate by culture as 3D pellets in a defined serum-free medium containing TGF-β1 and dexamethasone, without or with further supplementation with PGD2, PGE2 or PGF2α. After 2 weeks, pellets were assessed histologically, immunohistochemically, biochemically and by real-time quantitative reverse transcriptase–polymerase chain reaction. Results. All three PGs, but predominantly PGE2, reduced the staining intensity of pellets for collagen type I, whereas PGD2 and PGF2α increased the staining intensity of pellets for collagen type II and glycosaminoglycans (GAG). The GAG/DNA content of pellets was not affected by PGE2 but was increased 1.5- and 2.1-fold by PGD2 and PGF2α respectively. PGE2 reduced the expression of collagen type I mRNA (9.0-fold), whereas PGD2 and PGF2α increased the mRNA expression of collagen type II (6.2- and 4.1-fold respectively) and aggrecan (29.8- and 10.7-fold respectively). Conclusion. In contrast to PGE2, PGD2 and PGF2α enhanced chondrogenic differentiation and hyaline cartilage matrix deposition by expanded human articular chondrocytes, and could thus be used to improve in vitro or in vivo cartilage regeneration approaches based on these cells.