Preparation And Properties Of Porous Semi-degradable PVA/PLGA Hydrogel For Articular Cartilage Repair

Tissue engineering for articular cartilage repair has shown success in ensuring the integration of neocartilage with surrounding tissue, but the rapidrestoration of biomechanical and biotribological functions remains a significant challenge. Poly (vinyl alcohol)(PVA) hydrogel is regarded as a potential articular cartilage replacement for its good mechanical strength and low surface friction, while its lack of bioactivity limits its utility. In order to obtain a scaffold with both good bioactivity and initial biotribological function, we herein report a novel salt-leaching technique to fabricate a porous PVA hydrogel simultaneously imbedded with ploy (lactic-co-glycolic acid)(PLGA) microspheres. Several approaches were used to investigate the properties of porous PVA/PLGA semi-degradable hydrogel for articular cartilage replacement. The main contents and results are given as follows:1. Structure characterization was carried on by SEM. The novel PVA/PLGA semi-degradable hydrogel prepared by this technique had a proper porous structure, which is beneficial for cell culture and immigration. The porosities uniformly located and the PLGA microspheres embedded in the matrix. The porosity of semi-degradable hydrogel increased with more porogen content.2. The swelling characteristics and the variation of porosity with swelling were observed. In PBS solution, the swelling ratio decreased in the first week and then kept stable, obviously, increasing in the6、7week. In PEG solution, the swelling ratio decreased dramatically in the first week and then remained stable without any change. The porosity of semi-degradable hydrogel increased in the PBS solution but obvious decrease in PEG solution.3. The compressive mechanical properties of PVA/PLGA hydrogel existed significant nonlinear behavior. The compressive modulus was influenced little by porogen content while increased by the PLGA microspheres content. The cell-cultured hydrogel had higher compressive modulus than initial ones. At30%strain, compressive modulus decreased with the compressive velocity, but that increased and then decreased at60%strain. The creep resistance of cell-cultured hygrogel was much higher than initial ones. 4. Friction coefficient, continuous friction tested by a ball-plate tribometer and worn surface morphology was observed by Environmental Scanning Electron Microscopy (ESEM). The results showed that friction coefficient increased with a rise in porogen content, while it firstly increased and then decreased with more PLGA content. Similar results were obtained from cell-cultured hydrogel. In continuous friction test and worn morphology characterization, samples were more prone to bedamaged with an increase in porogen and PLGA content. However, wear resistance obviously improved for all hydrogel after4week cell culture, though friction coefficient went up to a certain extent. Friction coefficient and continuous friction test revealed a little difference between physiological saline and bovine serum.5. The adhesion ratio of chondrocytes on semi-degradable hydrogel was above70%, which mainly depended on the porosity of hydrogel. In3or7days culture, chondrocytes distributed uniformly and porosity and PLGA microsphere were beneficial to cells culture. DAPI staining demonstrated that the distribution and quantity of chondrocytes were influenced by the PLGA content rather than the porogen content.