Transmission Electron Microscopy of Tissue-Polymer Constructs

Numerous publications have described the histology of tissue-engineered constructs and tissue-biomaterial interfaces observed with the light microscope (1 –5 ). Indeed, this approach has become a routine method for the evaluation of the biological quality of engineered tissues. Additional microscopical techniques, including immunohistochemistry and confocal microscopy, have also been described. These methods have enabled the localization of important biological molecules in the tissue-engineered construct. However, all of these techniques are limited to describing relatively gross structural features, and they give little insight into the ultrastructural relationships between cells and biomaterials within a construct. Scanning electron microscopy (SEM) has been applied more recently to the study of constructs, but it too provides only limited information and not the “fine detail” of cell-biomaterial interaction (6 ,7 ). Despite the limitations noted here, relatively little research has been reported in which the transmission electron microscope (TEM) has been used to study the ultrastructure of cell-polymer constructs. This may be partly because of the difficulties associated with specimen preparation when living tissues and materials are both present. However, these difficulties are not insurmountable. Studies of the cell-biomaterial interface using electron microscopy have been reported in the general field of biomaterials and medical devices (8 –11 ). Here, they have enabled researchers to gain a greater understanding of the response of cells and tissues to biomaterial surfaces.