Collagen in tissue-engineered cartilage: Types, structure, and crosslinks

TLDR

The function of articular cartilage as a weight‑bearing tissue depends on the specific arrangement of collagen types II and IX into a three‑dimensional organized collagen network that balances the swelling pressure of the proteoglycan/water gel. To determine whether cartilage engineered in vitro contains a functional collagen network, chondrocyte‑polymer constructs were cultured for up to six weeks and analyzed for collagen composition and ultrastructure using biochemical, immunochemical methods and scanning electron microscopy. Engineered cartilage had 57 % less total collagen and 70 % fewer pyridinium crosslinks than bovine calf articular cartilage, yet its collagen type composition, network organization, density, and fibril diameter were comparable to natural cartilage, demonstrating that differentiated chondrocytes can form a complex collagen matrix in vitro. © 1998 Wiley‑Liss, Inc.; Biochem. Cell.

Abstract

The function of articular cartilage as a weight-bearing tissue depends on the specific arrangement of collagen types II and IX into a three-dimensional organized collagen network that can balance the swelling pressure of the proteoglycan/ water gel. To determine whether cartilage engineered in vitro contains a functional collagen network, chondrocyte-polymer constructs were cultured for up to 6 weeks and analyzed with respect to the composition and ultrastructure of collagen by using biochemical and immunochemical methods and scanning electron microscopy. Total collagen content and the concentration of pyridinium crosslinks were significantly (57% and 70%, respectively) lower in tissue-engineered cartilage that in bovine calf articular cartilage. However, the fractions of collagen types II, IX, and X and the collagen network organization, density, and fibril diameter in engineered cartilage were not significantly different from those in natural articular cartilage. The implications of these findings for the field of tissue engineering are that differentiated chondrocytes are capable of forming a complex structure of collagen matrix in vitro, producing a tissue similar to natural articular cartilage on an ultrastructural scale. J. Cell. Biochem. 71:313–327, 1998. © 1998 Wiley-Liss, Inc.