Tissue engineering of cartilage using a hybrid scaffold of synthetic polymer and collagen

A biodegradable hybrid scaffold of synthetic polymer, poly (DL-lactic-co-glycolic acid) (PLGA), and naturally derived polymer, collagen, was prepared by forming collagen microsponges in the pores of PLGA sponge. This was then used as the three-dimensional scaffold for tissue engineering of bovine articular cartilage, both in vitro and in vivo. In vitro studies show that hybridization with collagen facilitated cell seeding in the sponge and raised seeding efficiency. Chondrocytes adhered to the collagen microsponges, where they proliferated and secreted extracellular matrices with time, filling the space within the sponge. Hematoxylin and eosin staining revealed that most of the chondrocytes after 4 weeks of culture, and almost all cell types after 6 weeks of culture, maintained their phenotypically rounded morphology. While new tissue formed, the scaffold degraded and lost almost 36.9% of its original weight after 10 weeks. Subcutaneous implantation studies in nude mice demonstrated more homogeneous tissue formation in hybrid sponge than in PLGA sponge. The new tissue formed maintained the original shape of the hybrid sponge. The synthetic PLGA sponge, serving as a skeleton, facilitated easy formation into desired shapes and provided appropriate mechanical strength to define the ultimate shape of engineered tissue. Incorporation of collagen microsponges facilitated cell seeding and homogeneous cell distribution and created a favorable environment for cellular differentiation. The hybrid sponge could therefore represent a promising candidate as a three-dimensional scaffold for articular cartilage tissue engineering.