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 75mM solution of CaCl2. 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. (C) 2003 Published by Elsevier Ltd.