Synergistic stimuli by hydrodynamic pressure and hydrophilic coating on PLGA scaffolds for extracellular matrix synthesis of engineered cartilage

Scaffold surface properties and mechanical stimuli have been known to have a critical influence on cell proliferation and extracellular matrix synthesis in cultured cells for tissue engineering. Hydrophilic surface and hydrodynamic pressure (HP) stimulation have been shown to have a beneficial effect on chondrocyte activity. The aim of this study was, thus, to assess the synergic influences of HP and hydrophilic coating on cell activity using primary porcine chondrocytes inoculated in hydrophilic-coated poly(lactide-co-glycolide) (PLGA) sponge scaffolds. The natural materials hyaluronic acid (HA), chitosan and HA/chitosan were cross-linked on porous PLGA as a hydrophilic surface modification. HP was applied to scaffolds at an amplitude of 2.24 MPa and a frequency of 0.1 Hz for 30 min per day, twice a week, over a period of 28 days. Cell activities were determined by the MTS assay and the dimethylmethylene blue assay for glycosaminoglycan (GAG) quantification. Our results displayed that PLGA coated with both HA and chitosan had the best hy-drophilicity (contact angle 49.46°) and initial compressive modulus (1.10 ± 0.13 MPa) among the tested scaffold groups. Additionally, HP stimulation enhanced cell proliferation as well as GAG production (up to 3-fold in culture medium and 15-fold in scaffolds at 28 days compared to static culture of PLGA alone in the scaffold group) in the hydrophilic-coated scaffold groups. The synergistic benefit from hydrophilic coating and HP stimulation may be imperative in regenerating engineered cartilage in the long-term.