Thermophysical stability and biodegradability of regenerative tissue scaffolds

Biological scaffolds are increasingly used for tissue repair and regeneration. In order to provide critical data for rational design of tissue matrix products, the present study evaluated thermophysical stability and biodegradability of seven commercially available bio-scaffold products that have been approved for clinical implantation by Chinese and US Regulatory Authorities. Calorimetrical analysis shows that the onset denaturation temperature (T d ) of these scaffolds in the dry state (equilibrated to the same water activity ( a w ) of 0.75) varies from 89.7 to 106.9 °C, but T d decreases to 36.2 ~ 59.5 °C upon rehydration, suggesting that some of these products might be unstable at body temperature. The incubation study at 37 °C indicates that T d of tissue matrix needs to be > 43 °C for implantation. T d of tissue matrices tested in the dry state is correlated poorly to T d measured after rehydration in physiological saline, demonstrating that the design of biological scaffolds should consider the role of water in stability of supramolecular assemblies. T d of hydrated tissue matrices is highly correlated with degradation rate by collagenase, while no such correlation exists between T d measured in the dry state and collagenase degradation. This study has discovered that calorimetrical analysis is a valuable analytical tool, not only for thermophysical stability of regenerative tissue matrices, but also for the rapidly-indirect evaluation of their biodegradability.