Abstract
Noninvasive quality evaluation methods that make it possible to monitor culture processes are ideal for tissue-engineered cartilage made of autologous chondrocytes and collagen gel. However, usual methods are quite invasive because the products are examined chemically and observed histologically with dye. Here we employed second-harmonic-generation (SHG) microscopy, which can be used to observe collagen without any preparation such as staining or fixing. We demonstrated SHG imaging of tissue-engineered cartilage composed of rabbit chondrocytes and type I collagen gel. Our results showed that aggregations of round cells that produced type II collagen were observed as spherical dark spaces in the SHG images. The volumes of these spaces were related to the numbers of cells in the aggregations. These results indicate that we can estimate the number of the matrix-producing cells by SHG imaging. Because SHG microscopy is a noninvasive method, it is suitable for evaluating the quality of tissue-engineered cartilage and also for quality control during the manufacturing process.
