Role of Cells in Freezing-Induced Cell-Fluid-Matrix Interactions Within Engineered Tissues

Abstract

During cryopreservation, ice forms in the extracellular space resulting in freezing-induced deformation of the tissue, which can be detrimental to the extracellular matrix (ECM) microstructure. Meanwhile, cells dehydrate through an osmotically driven process as the intracellular water is transported to the extracellular space, increasing the volume of fluid for freezing. Therefore, this study examines the effects of cellular presence on tissue deformation and investigates the significance of intracellular water transport and cell-ECM interactions in freezing-induced cell-fluid-matrix interactions. Freezing-induced deformation characteristics were examined through cell image deformetry (CID) measurements of collagenous engineered tissues embedded with different concentrations of MCF7 breast cancer cells versus microspheres as their osmotically inactive counterparts. Additionally, the development of a biophysical model relates the freezing-induced expansion of the tissue due to the cellular water transport and the extracellular freezing thermodynamics for further verification. The magnitude of the freezing-induced dilatation was found to be not affected by the cellular water transport for the cell concentrations considered; however, the deformation patterns for different cell concentrations were different suggesting that cell-matrix interactions may have an effect. It was therefore determined that intracellular water transport during freezing was insignificant at the current experimental cell concentrations; however, it may be significant at concentrations similar to native tissue. Finally, the cell-matrix interactions provided mechanical support on the ECM to minimize the expansion regions in the tissues during freezing.

Preservation of tissue microstructure and functionality during freezing by modulation of cytoskeletal structure

“…We reached this conclusion based on measurement of multiple aspects of tissue functionality such as viscosity and elastic modulus, allowing us to propose a mechanistic understanding of tissue-specific response to freezing. With regard to native tissues, our findings should be applied with caution given differences in cell density, which influences cellular and extracellular water transport as discussed in Seawright et al (Seawright et al, 2013). …”

“…However, as the cell concentration is increased, the freezing-induced deformation becomes smaller. This can occur because at higher concentrations, the cells occupy more space in the tissue, which decreases the porosity and the relative amount of interstitial fluid (Seawright et al, 2012). The reduction in the water content that is available for extracellular freezing results in a decrease in the freezing-induced deformation.…”

“…Since all these aspects are attributed to the tissue functionality, tissues may be successfully cryopreserved if the freezing-induced deformation can be minimized. During the freezing-induced interactions, cells embedded in the ECM are actively interacting with the ECM by providing additional mechanical support via cell-matrix adhesion complex (Ghosh et al, 2014; Seawright et al, 2013). Thus, if the cytoskeletal structure and cell-matrix adhesion can be modulated to provide additional mechanical support to the ECM, it may be hypothesized that the amount of CPA necessary to preserve tissue is reduced.…”

DNA Walker‐Regulated Cancer Cell Growth Inhibition

“…The blue spots in Figure 3c represent the cells stained by Hoechst, while the dead cells are washed away. [14] …”

Measurement of Spatiotemporal Intracellular Deformation of Cells Adhered to Collagen Matrix During Freezing of Biomaterials

“…This protective role of the cells is thought to be associated with increased structural strength by cell-matrix adhesion and the strength of the cytoskeleton [24]. This finding is potentially very useful to design cryomedicine applications by (i) providing a new way to preserve functional tissues with a reduced amount of toxic cryoprotective agents and (ii) controlling and modulating the hierarchical porous structures (i.e., ECM and cytoskeleton) mechanistically during freezing, which may enable decellularization with minimal structural change of the ECM during freezing.…”