Vitrification or freezing to a ?glassy? rather than crystalline phase, is a form of biopreservation and an important enabling approach for cellular and regenerative medicine. In principle, this approach offers the powerful ability to store and transport cells, tissues and organs which can be used in biomedical labs, biological banking organizations and companies worldwide. Unfortunately, practical application of vitrification has been limited to smaller systems such as cells and thin tissues due to diffusive (heat and mass transfer) and phase change limitations. Specifically, devitrification (crystallization) and cracking during thawing preclude the use of vitrification in bulk systems such as organs and larger tissues. To circumvent this fundamental problem we propose here to use radiofrequency (RF) excited magnetic nanoparticles (mNPs) to create uniform heat generation within biomaterials thereby avoiding size or boundary condition dependence which can lead to failure during thawing. As a part of this work, we will characterize the heating and phase change behavior of mNP-laden cryoprotective solutions. This will include selection of cryoprotective agent (CPA) and mNPs (magnetic nanoparticles), physicochemical characterization of these solutions (i.e. thermal and magnetic properties, aggregation, and devitrification), and RF thawing measurement and modeling to demonstrate improvements over traditional approaches. After characterizing the mNP CPA solutions we will investigate the impact of more uniform and rapid thaw on biological outcomes. Here the solutions will be loaded into cells and tissues by diffusion or perfusion, then these loaded systems will be assessed by imaging, staining and other analytical approaches to demonstrate where the CPA and mNPs have loaded. Further, the critical cooling and warming rates necessary to vitrify during cooling and avoid devitrification or cracking upon thaw will be determined. Finally, improvements to the viability and structure of these systems by avoiding devitrification and cracking after RF excited mNP thawing will be demonstrated.
This project has the potential to dramatically improve biomaterial vitrification and therefore biopreservation which impacts cell banking and therapies, tissue transplantation and other important regenerative medicine and biomedical applications worldwide. Our approach will yield faster and more uniform thawing rates that are expected to improve both viability and structural integrity upon thawing of biopreserved systems. The most dramatic opportunity of this new technology will be use for larger biomaterials where devitrification and cracking routinely result in preservation failures, and where faster thaw rates may also help reduce the amount of potentially toxic CPAs needed. More broadly, the proposed research will lead to greater understanding of the interactions of NPs within frozen and vitrified biological systems, with potential applications that go beyond biopreservation. The research undertaken will provide educational opportunities for several graduate and undergraduate students and collaboration with both academic and industrial colleagues.
