Chondrocyte Response to High Regimens of Cyclic Hydrostatic Pressure in 3-Dimensional Engineered Constructs

Abstract

Purpose Despite widespread use of 3-dimensional (3D) micro-porous scaffolds to promote their potential application in cartilage tissue engineering, only a few studies have examined the response to hydrostatic pressure of engineered constructs. A high cyclic pressurization, currently believed to be the predominant mechanical signal perceived by cells in articular cartilage, was used here to stimulate bovine articular chondrocytes cultured in a synthetic 3D porous scaffold (DegraPol). Methods Construct cultivation lasted 3 days with applied pressurization cycles of amplitude 10 MPa, frequency 0.33 Hz, and stimulation sessions of 4 hours/day. Results At 3 days of culture, with respect to pre-culture conditions, the viability of the pressurized constructs did not vary, whereas it underwent a 16% drop in the unpressurized controls. Synthesis of α-actin was 34% lower in all cultured constructs. Synthesis of collagen II/collagen I did not vary in pressurized constructs, was 76% lower in unpressurized controls, and was around 230% higher in pressurized constructs with respect to unpressurized controls. Chondrocytes showed a phenotypic spherical morphology at time zero and at 3 days of pressurized culture. Conclusions Although the passage from 2D expansion to 3D geometry was effective to guide cell differentiation, only mechanical conditioning enabled the maintenance and further cell differentiation toward a mature chondrocytic phenotype.