Osteochondral tissue engineering using a PLGA–collagen hybrid mesh

Canine bone marrow stromal cells were cultured in a PLGA–collagen hybrid mesh in osteogenic medium in vitro and laminated to construct an osteo layer. Canine articular chondrocytes were cultured in the hybrid mesh in DMEM containing 10% FBS and laminated to construct a chondral layer. The osteo and chondral layers were sutured together and implanted subcutaneously in nude mice. The original round disc shape of the osteochondral constructs was preserved during the implantation. The osteo and chondral layers appeared red and glistening white, respectively. Histological examination of the implant specimens indicated that stromal cells and chondrocytes were evenly distributed throughout the scaffold. The laminated meshes were bound together and the two layers had a distinct interface between them. The cells showed a round morphology in the chondral layer and a spindle morphology in the osteo layer. In the chondral layer, spherical chondrocytes were surrounded by an abundant cartilaginous extracellular matrix. The round morphology and positive stain by safranin-O and toluidine blue, together with the expression of genes encoding type II collagen and aggrecan suggested the formation of neocartilage in the chondral layer. Expressions of genes encoding type I collagen and osteocalcin were detected in the osteochondral implant. These results indicate the formation of osteochondral-like tissue, and the hybrid mesh and lamination method may be useful for osteochondral tissue engineering.