Tissue Engineering: Selecting the Optimal Fixative for Immunohistochemistry

Background: In the immunohistochemical analysis of tissue-engineered structures, aggressive treatments for fixation and antigen retrieval can impair the quality of specimen staining and visualization. Hypothesis: We hypothesized that the adequate choice of fixative and antigen-retrieval method might improve the quality of immunohistochemical staining. Methods: Tissue-engineered vascular grafts were fixed using formalin, Carnoy's, or HOPE® fixative. Antigen retrieval was performed where necessary and samples from each group were stained using hematoxylin and eosin to assess overall tissue preservation. For a set of proteins relevant to cardiovascular tissue development, immunohistochemical staining was applied to formalin-, Carnoy's-, and HOPE-fixed specimens to allow a comparative analysis. Results: In tissue-engineered constructs, antigen retrieval methods necessary after formalin fixation led to significant destruction of the overall tissue structure. Carnoy's fixation resulted in good overall tissue pr...