Histological processing of hydrogel scaffolds for tissue-engineering applications

Tissue-engineered scaffolds (e.g., select absorbable scaffolds or hydrogels) are very fragile in nature and are filled with severe histological artifacts when processed using routine histological techniques (e.g., paraffin processing). The presence of artifacts compromises adequate microscopic evaluation and the characterization of the material and device performance. This article discusses approaches used to histologically evaluate hydrogel scaffolds. In addition to routine techniques, the use of plastic resins such as Caroplastic(R) and Technovit 7100(R) are discussed and illustrated. A modified Technovit 7100(R) embedding procedure was the most effective in preserving and retaining the hydrogel scaffold throughout the histological process. The dehydration and embedding protocol can be easily modified to accommodate scaffolds of different sizes as well as different physical and chemical properties. It is also possible to complete polymerization of the Technovit 7100(R) plastic resin at 4degreesC, which has the added benefit of preserving lipid and enzyme activity.