Osteogenic differentiation and osteochondral tissue engineering using human adipose-derived stem cells.

Osteogenesis and the production of composite osteochondral tissues were investigated using human adult adipose-derived stem cells and polyglycolic acid (PGA) mesh scaffolds under dynamic culture conditions. For osteogenesis, cells were expanded with or without osteoinduction factors and cultured in control or osteogenic medium for 2 weeks. Osteogenic medium enhanced osteopontin and osteocalcin gene expression when applied after but not during cell expansion. Osteogenesis was induced and mineralized deposits were present in tissues produced using PGA culture in osteogenic medium. For development of osteochondral constructs, scaffolds seeded with stem cells were precultured in either chondrogenic or osteogenic medium, sutured together, and cultured in dual-chamber stirred bioreactors containing chondrogenic and osteogenic media in separate compartments. After 2 weeks, total collagen synthesis was 2.1-fold greater in the chondroinduced sections of the composite tissues compared with the osteoinduced sections; differentiation markers for cartilage and bone were produced in both sections of the constructs. The results from the dual-chamber bioreactor highlight the challenges associated with achieving simultaneous chondrogenic and osteogenic differentiation in tissue engineering applications using a single stem-cell source.