Collagen type II: From biosynthesis to advanced biomaterials for cartilage engineering

Abstract

Collagen type II is the major constituent of cartilage tissue. Yet, cartilage engineering approaches are primarily based on collagen type I devices that are associated with suboptimal functional therapeutic outcomes. Herein, we briefly describe cartilage's development and cellular and extracellular composition and organisation. We also provide an overview of collagen type II biosynthesis and purification protocols from tissues of terrestrial and marine species and recombinant systems. We then advocate the use of collagen type II as a building block in cartilage engineering approaches, based on safety, efficiency and efficacy data that have been derived over the years from numerous in vitro and in vivo studies.

Keywords: Articular cartilage; Chondrocytes; Chondrogenic induction; Collagen type II.

Fig. 1

Sequential stem cell differentiation to chondrocytes and associated ECM changes (A). Chondrocyte secreted ECM and interactions (B). Chondrocyte cellular (left) and extracellular (right) organisation (C).

Fig. 2

Collagen type II extraction flow chart from cartilage tissues (the detailed protocol can be found here [131, 143]) and electrophoretic mobility of collagen type I and collagen type II (the detailed protocol can be found here [223]). Notes: As the same protocol is used to extract collagen type I , , , attention should be paid during dissection to remove all not cartilaginous tissues. Tissue to acetic acid / pepsin solution ratio: 1:1 g/l. Tissue to pepsin ratio: 10:1 w/w. High activity pepsin (e.g. 3200-4500 units per mg protein) is recommended. Sieve: approximately 1,000 μm in diameter. Filter mesh: 100 μm in diameter. Centrifugation details: 20 min, 8000 rpm, < 8 °C. After the second NaCl precipitation, dissolution is conducted in minimum amount of acetic acid in order to produce a high in concentration collagen type II solution. All experiments are conducted at 4-8 ºC to avoid collagen denaturation.