Optimal conditions for long term storage of native collagens

Cryopreservation was used to maintain the biological activity of collagen, i.e., its fibril formation property, after isolation from tissues. Freezer temperatures commonly available in laboratories, -15 degrees C and -90 degrees C, and liquid nitrogen temperature, -196 degrees C, were compared for efficacy in preserving both type I collagen structure (amino acid and subunit composition, triple helix) and activity (fibril formation in vitro). Whether the collagen was stored dry or in acetic acid solution at -196 degrees C, the kinetics of fibril formation were completely stable for at least two and a half years, but decreased after several months storage at -15 degrees C or -90 degrees C. Types II and III collagens, also with intact nonhelical ends, are also completely stable in liquid nitrogen for at least two and a half years.