Highly Open Porous Biodegradable Microcarriers: In Vitro Cultivation of Chondrocytes for Injectable Delivery

Injectable cell therapy would provide a patient-friendly procedure for treatment of degenerated or wounded tissue. Biodegradable injectable porous microspheres were fabricated to use as dual-purpose microcarriers for cell culture and injectable scaffold for tissue regeneration. Gas foaming in a water-in-oil-in-water double emulsion was performed for fabricating the well-interconnected porous microcarriers using poly(lactic-co-glycolic acid) (PLGA). The gas foaming conditions were finely tuned to control the structural and morphological characteristics. Porous microcarriers with a mean size of approximately 175 μm and an average pore diameter of approximately 29 μm were produced for cell cultivation and injectable delivery. To promote cell seeding, amine-functionalized porous microcarriers were prepared by blending amine-functionalized PLGA with unreacted PLGA. To assess the porous microcarriers for chondrocyte cultivation, bovine articular chondrocytes were seeded and cultured in vitro in spinner flasks for 4 weeks. Visualization and biochemical analyses of the microcarrier–cell constructs were performed to demonstrate cell proliferation and phenotypic expression. Quantification of deoxyribonucleic acid, glycosaminoglycan, and collagen content showed that much greater cell proliferation and expression of cartilage-specific phenotype were observed for cultures in the following order: amine-functionalized porous microcarriers, porous microcarriers, nonporous microcarriers, and monolayer culture.