Effects of cyclic hydrostatic pressure on the metabolism of human osteoarthritic chondrocytes cultivated in a collagen gel.

Among other parameters, the application of mechanical force may provide an important stimulus in modulating the structure and function of tissue-engineered articular cartilage. We developed a cultivation chamber in which six collagen type-I gel samples, seeded with human osteoarthritic chondrocytes, can be cultivated simultaneously. A cyclic hydrostatic pressure of up to 40 kPa with a frequency of 0.0125 Hz was applied, and cultivation was performed for 1, 4, 7, or 14 days. Histological examinations revealed a spheroidal cell morphology in the treatment group. In contrast, control samples of the same patients represented a more fibroblastic appearance. Collagen type-II (col-II) protein was found in the very pericellular region of all investigated samples; the col-II content did not obviously vary between the control and treatment groups. In the treatment group, col-II and aggrecan gene expression were elevated. A spectrophotometric quantification of proteoglycan concentrations in media supernatants revealed a statistically significant enhancement in the treatment group.