Structural changes in pericardium tissue modified with tannic acid

Structural modification of proteins, mainly collagen in connective tissues, is important in the manufacture of tissue-derived biomaterials. Natural compounds like genipin or tannic acid (TA) have been proposed instead of glutaraldehyde which shows cytotoxic effects on the processed tissue. Furthermore, calcification of glutaraldehyde-treated tissue limits the functional lifetime of bioprostheses. TA is known to form numerous hydrogen bonds with proteins. The purpose of our study was to investigate structural changes in porcine pericardium upon chemical modification with tannic acid.

Porcine pericardium tissue (PP) was soaked in 2% TA for 4, 24 or 48 hours. Changes in tissue structure were studied using electrophoresis (SDS-PAGE) and histological examination. Structural stability of PP tissue was evaluated by SDS/NaCl extraction method and enzymatic digestion with pancreatin.

TA-modification of PP caused a time-dependent decrease in the number of peptides extracted from tissue. Microscopic studies revealed no significant morphological differences between native and TA-modified tissues, except for the native pancreatin-digested tissue where lack of both cells and low molecular peptides was observed.

Modification of PP with TA causes the structural changes leading to an increase in the tissue resistance to SDS/NaCl extraction and enzymatic digestion, providing experimental evidence for the higher structural stability of TA-treated tissue.