Chondrocyte response to cyclic hydrostatic pressure in alginate versus pellet culture

Abstract

Cells are often cultured at high density (e.g., confluent monolayer and as pellets) to promote chondrogenic differentiation and to maintain the chondrocyte phenotype. They are also frequently suspended in hydrogels such as agarose or alginate for the same purposes. These culture techniques differ markedly with respect to frequency of direct contact between cells and overall intercellular spacing. Because these factors may significantly affect mechanotransduction, the purpose of this study was to determine if the response of articular chondrocytes to cyclic hydrostatic pressure would depend on the culture condition. Primary articular chondrocytes from young and mature pigs were cultured either as pellets or suspended in alginate beads. Both groups were exposed to dynamic hydrostatic pressure (4 MPa, 1 Hz, 5400 cycles per day) for 7 days. Cell proliferation was unaffected by pressure, but pressurized chondrocytes in pellet culture had significantly greater sGAG content and incorporated [ 3 H]proline at a higher rate than nonpressurized controls. Electron microscopy revealed a fibrous extracellular matrix (ECM) surrounding pellets, but not cells in alginate. In addition, expression of Connexin 43 (Cx43) mRNA was slightly lower in alginate than in pellet cultures and was not significantly altered by loading. Thus, metabolic response of chondrocytes to dynamic hydrostatic pressure was affected by culture technique; chondrocytes cultured as pellets exhibited the classical anabolic response to dynamic hydrostatic pressure, but those in alginate did not. Although cell-ECM interaction could be important, the differential response is not likely attributable to differential expression of Cx43 mRNA. ß

VEGF Production by Osteoarthritic Chondrocytes Cultured in Micromass and Stimulated by IL-17 and TNF-α

“…These different methods seem to induce or maintain cell differentiation markers, as we also have previously demonstrated by culturing the chondrocytes in hyaluronan-based polymer derivative and in micromasss [22,25]. Different results can be obtained, according to the chosen 3D method [21,26,27]. We have investigated the phenotype of chondrocytes cultured in micromass and their ability to synthesize ECM proteins [22,25].…”

Comparative chondrogenesis of human cells in a 3D integrated experimental–computational mechanobiology model

“…Despite these positive effects of cyclic pressurisation, chondrocytes embedded in hydrogels exhibit a decreased sensitivity to this stimulus, when compared to chondrocytes in pellets (Elder et al 2006). The presence or absence of a pericellular matrix is believed to play a crucial role in the responsiveness to pressure in this model (Nakamura et al 2006).…”

Self-Organization and the Self-Assembling Process in Tissue Engineering

“…spinner shear, elevated temperatures, toxic polymerizing chemicals), which leads to increased cell viability (10). During construct formation, scaffoldless tissue engineering provides a biomimetic microenvironment allowing for a high degree of cell-cell communication and the maintenance of cell phenotype, both of which can increase ECM production (11–14). Additionally, without an intervening scaffold, tissue synthesis and remodeling may occur more readily and without the need for scaffold degradation.…”