Several studies have shown that enzymatic digestion could increase integration of cartilage [2-4]. However, the effect of varying digestion conditions on the structure and composition of the ECM had not been systematically explored. The ECM components in cartilage tissue play a critical role in supporting chondrogenesis. Our goal in this study was to determine which structural parameter was best able to represent the degree of cartilage digestion. We observed that the change in dry weight and HYP content were highly relevant. This is a logical result, as the HYP is a major component of the protein collagen and most of the dry weight is contributed by collagen. At all the different digestion conditions, the GAG content of the fragments dropped dramatically. Increasing the temperature or enzyme concentration results in additional modest decreases in GAG levels. The results revealed that the HYP content or dry weight could be utilized as an indicator of the extent of matrix disruption. As we know, chondrocytes are embedded in a dense ECM, which limits their mobility and proliferation. In this study, cartilage fragment shrinkage could be observed by CLSM and enzyme penetration into the cartilage was calculated. SEM images further showed that the ECM of the cartilage tissue fragments was partially digested by the enzyme and the chondrocytes were exposed on the surface. This exposure, and the increase in cell density observed at the cartilage surface may facilitate the integration of cartilage fragments as seen in our experiments. The effect of different enzymatic treatment conditions on cartilage integration will be the topic of future research.
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