Characterization of different thawing mechanisms of fibroblast cell-containing tissue models by Mueller polarimetry and statistical analysis

Long-term storage and cryopreservation of biological tissues is a global challenge in the fields of regenerative medicine, tissue engineering and implants, because of the formation of large ice crystals that may damage cellular membranes and extracellular matrix (ECM) of collagen. In our studies different thawing mechanisms were tested to achieve more uniform warming of 3D in vitro tissue models, prepared from magnetic nanoparticles (NPs)-modified 3D electrospun nanofiber fleeces and fibroblasts. 3D tissue models frozen in liquid nitrogen were defrosted either with water bath or with radio-frequency (RF) inductive heating of the magnetic NPs and their morphology was compared to that of a non-frozen tissue model using a transmission Mueller microscope and thin sections of all three types of tissue models. Our results demonstrate a sensitivity of the polarimetric parameters obtained with the differential decomposition of Mueller matrices to small changes in sample morphology caused by the different thawing methods. A detailed statistical analysis proved the statistical significance of the experimental data from the three groups of all tissue models.