Stability of a biological tissue fixed with a naturally occurring crosslinking agent (genipin)

The study was undertaken to investigate the stability of a biological tissu e fixed with a naturally occurring crosslinking agent (genipin) at distinct elapsed storage durations. The glutaraldehyde-fixed counterpart was used a s a control. Porcine pericardia procured from a slaughterhouse were used as raw materials. After fixation, the fixed tissues were sterilized in a grad ed series of ethanol solutions and thoroughly rinsed in phosphate buffered saline for 1 day, and then stored in a jar containing sterilized water. Tl; e samples were taken out and tested for their stability during the duration s of 1 day through 6 months after storage. The stability of each study grou p was tested by measuring its tensile strength, free-amino-group content, a nd denaturation temperature. Additionally, the cytotoxicity of each test sa mple and its corresponding storage solution were investigated in vitro usin g 3T3 fibroblasts. The results were examined using a microscope and 3-(4,5- dimethylthiazol-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. It was fou nd that the stability of the genipin-fixed tissue during storage was superi or to its glutaraldehyde-fixed counterpart. The differences in stability be tween the genipin- and glutaraldehyde-fixed tissues during storage may be c aused by their differences in crosslinking structure. There was no apparent cytotoxicity for both the genipin-fixed tissue and its corresponding stora ge solution throughout the entire course of the study, whereas significant cytotoxicity was observed for both the glutaraldehyde-fixed tissue and its storage solution. However, the cytotoxicity of the glutaraldehyde-fixed tis sue decreased with increasing elapsed storage duration, whereas that of its corresponding storage solution increased. This suggested that the toxic re sidues remaining in the glutaraldehyde-fixed tissue leached out slowly into its corresponding storage solution during the course of storage. (C) 2001 John Wiley & Sons, Inc. J Biomed Mater Res 55: 538-546, 2001.