A rapid-curing alginate gel system: utility in periosteum-derived cartilage tissue engineering

In this study, we have developed a rapid-curing alginate gel system and demonstrated its utility as a scaffold for periosteum-derived chondrogenesis for articular cartilage tissue engineering applications. A homogeneous mechanically stable gel was formulated by inducing gelation of a 2% (w/v) solution of a high G content alginate (65-75% G) with a 75 mM solution of CaCl(2). The gel exhibited near-elastic behavior at low levels of deformation (15%, R(2)=0.996), Young's modulus of 0.17+/-0.01 MPa, and rapid gelation kinetics (<1 min to completion). The in vitro cell culture of chondrocytes in the gel yielded alginate/cell constructs that lacked the continuous, interconnected collagen/proteoglycan network of hyaline cartilage. In addition, we have demonstrated that this gel system is capable of supporting periosteum-derived chondrogenesis. We observed that when whole-tissue explants of periosteum were cultured in vitro within the gel, after 6 weeks, significant quantities (>50%) of the total area of the periosteal explants was composed of cartilage that was hyaline-like in appearance and contained cartilage-specific proteoglycans and type-II collagen. It is envisioned that such explants could be transplanted or regenerated in vivo within the biodegradable alginate matrix for the treatment of partial or full-thickness defects in articular cartilage. Importantly, the injectable delivery of the gel could be used in filling complex defects in the articular surface via minimally invasive procedures.