Tissue engineering models of human digits: effect of periosteum on growth plate cartilage development
Tissue-engineered middle phalanx constructs of human digits were investigated to determine whether periosteum wrapped partly about model midshafts mediated cartilage growth plate formation. Models were fabricated by suturing ends of polymer midshafts in a human middle phalanx shape with polymer sheets seeded with heterogeneous chondrocyte populations from bovine articular cartilage. Half of each midshaft length was wrapped with bovine periosteum. Constructs were cultured, implanted in nude mice for up to 20 weeks, harvested and treated histologically to assess morphology and cartilage proteoglycans. After 20 weeks of implantation, chondrocyte-seeded sheets adjacent to periosteum-wrapped midshaft halves established cartilage growth plates resembling normal tissue in vivo. Sheets adjacent to midshafts without periosteum had disorganized cells and no plate formation. Proteoglycans were present at both midshaft ends. Periosteum appears to guide chondrocytes toward growth plate cartilage organization and tissue engineering provides means for carefully examining construct development of this tissue.