Freezing of biological tissue occurs in many modern biomedical applications. These include cryosurgery for cancer, cryoablation for cardiac arrhythmia, cryoplasty for restenosis, and cryopreservation of native and engineered biomaterials. While the short-term success of these applications depends on the cellular viability — low viability for the therapeutic applications, and high viability for the preservation applications, the long-term success is determined by whether the functional properties of tissue are controlled as well as the viability. This becomes more important as the freezing-based technologies begin to be applied to larger and more complex biomaterials. However, the effects of freezing on these functional properties are rarely understood. Although several studies have been done on the freezing-induced change of the mechanical properties, the results are highly tissue-type dependent and the underlying biophysical mechanisms are poorly understood. Since the functional properties are associated with or often determined by the microstructural characteristics of the extracellular matrix (ECM), it is hypothesized that freezing-induced changes on the ECM microstructure affect the post-thaw functional properties. Thus, in this study, microstructural changes of collagen matrix were investigated using scanning electron microscopy and image analysis.

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