Biphasic calcium phosphate: a scaffold for growth plate chondrocyte maturation

While skeletal development can occur by either intramembranous or endochondral bone formation, all current tissue engineering approaches for bone repair and regeneration try to mimic intramembranous ossification. In this study, we propose to create an in vitro cartilage template as the transient model for in vivo endochondral bone formation. The goals of this study are to (1) establish a method of growing chondrocytes in a well-characterized macroporous biphasic calcium phosphate (MBCP) scaffold and (2) induce maturation of chondrocytes grown in the MBCP scaffold. Chondrocytes isolated from chick embryonic tibia were grown on MBCP particles and treated with retinoic acid to induce chondrocyte maturation and extracellular matrix deposition. Chondrocytes were observed to attach and proliferate on the MBCP scaffold. The thickness of the chondrocyte and extracellular matrix layer increased in the presence of the retinoid. Alkaline phosphatase activity and expression, proteoglycans synthesis, cbfa1 and type I collagen mRNA levels also increased in the presence of retinoic acid. These results demonstrated for the first time the proliferation, maturation of chondrocytes, and matrix deposition on MBCP, suggesting the potential for such scaffold in tissue engineering via the endochondral bone formation mechanism.