REVIEW OF BULK CRYOPRESERVATION ENABLED BY NANOWARMING

Scaling up the warming of larger vitrified biomaterials has been a barrier to cryopreservation of organs and other bulk systems. The two main challenges are ice recrystallization and physical cracking/fractures, which occur due to slow rates and thermal nonuniformity, respectively, which are inherent to traditional boundary rewarming. This chapter reviews this issue and various attempts to address it through volumetric rewarming, including radiofrequency (RF) rewarming with magnetic nanoparticles (nanowarming), dielectric/microwave rewarming, and high-intensity focused ultrasound. Of these approaches, only nanowarming has demonstrated scalability of rates up to ∼ 1500^◦ C/min and volumes as large as 2 l. To enhance translation and practical use of nanowarming, a comparison table for RF coils and magnetic nanomaterial (nanoparticles) based on the literature is provided, highlighting different commercial and laboratory-built options. Furthermore, regarding the ease of implementation of nanowarming, this chapter summarizes biological outcomes for vitrified samples (organs and tissues) rewarmed using nanowarming to date. Lastly, we lay out the current state-of-the-art technology for nanowarming and the potential role this volumetric technique can play in the success of organ banking and beyond.