Hydrostatic pressure increases apoptosis in cartilage-constructs produced from human osteoarthritic chondrocytes

Tissue-engineering is considered a promising avenue for developing human articular cartilage implants that can be employed for resurfacing damaged cartilage in the early stages of osteoarthritis. In the present study, human cartilage-constructs were produced from human osteoarthritic chondrocytes maintained on a scaffold of HYAFF (R)-11 in perfusion mini-bioreactors or after implantation and recovery from nude or SCID mice after 3 weeks. The human cartilage-construct extracellular matrix reacted positively with anti-Type II collagen monoclonal antibody, but not with anti-Type I or anti-Type X collagen monoclonal antibodies. A significant portion of the cartilage-construct extracellular matrix stained metachromatic with Toluidine blue-O indicative of sulfated-proteoglycan deposition. Cyclic hydrostatic pressure applied for 4 hrs at 5 MPa using a 1 Hertz sinusoidal frequency significantly increased ( p < 0.02) the proportion of apoptotic cells in the cartilage-constructs ( 41% +/- 4.2%; mean +/- SD) compared to control cartilage-constructs ( 28.5 +/- 8.4%).