Thawing for Cryopreserved Tissues

Girish Srinivas
TDA Research Inc, Colorado, United States

Keywords: cryopreservation, vitrification, transplantation, nanoparticles, electromagnetic warming

Cryopreservation of large, complex tissues is a difficult problem. There are mutually competing needs with regard to minimzing toxicity due to cryoprotective agents (CPAs), cooling and warming quickly in order to prevent crystallization, and the need for uniform cooling/warming to minimize mechanical stress. Recent work has shown that low frequency alternating electromagnetic fields (which pass uniformly through tissue) can be used with super paramagnetic iron oxide nanoparticles (SPIONs) to uniformly thaw cryopreserved tissue. The main drawback of this approach is that its specific absorption rate (SAR), i.e. the amount of heat produced per mass of nanoparticles, is low, either requiring a high nanoparticle concentrations or a fairly slow warming rate. TDA Research Inc has developed an alternative strategy to nanoparticle electromagnetic warming. Our preliminary results are extremely encouraging, with SAR values that are at least an order of magnitude higher than what has been reported for SPIONs. This means that TDA can use lower nanoparticle loading or heat faster (allowing for lower CPA concentration without rewarming phase crystallization). TDA is working with collaborators to build on those results to test our system with a larger volume and to test with tissues.