Investigation of Rapid Rewarming Chips for Cryopreservation by Joule Heating

Rapid and uniform rewarming is critical to cryopreservation.Currentrapid rewarming methods require complex physical field applicationdevices (such as lasers or radio frequencies) and the addition ofnanoparticles as heating media. These complex devices and nanoparticleslimit the promotion of the rapid rewarming method and pose potentialbiosafety concerns. In this work, a joule heating-based rapid electricheating chip (EHC) was designed for cryopreservation. Uniform andrapid rewarming of biological samples in different volumes can beachieved through simple operations. EHC loaded with 0.28 mL of CPAsolution can achieve a rewarming rate of 3.2 x 10(5) & DEG;C/min (2.8 mL with 2.3 x 10(3) & DEG;C/min),approximately 2 orders of magnitude greater than the rewarming ratesobserved with an equal capacity straw when combined with laser nanowarmingor magnetic induction heating. In addition, the degree of supercoolingcan be significantly reduced without manual nucleation during thecooling of the EHC. Subsequently, the results of cryopreservationvalidation of cells and spheroids showed that the cell viability andspheroid structural integrity were significantly improved after cryopreservation.The viability of human lung adenocarcinoma (A549) cells postcryopreservationwas 97.2%, which was significantly higher than 93% in the cryogenicvials (CV) group. Similar results were seen in human mesenchymal stemcells (MSCs), with 93.18% cell survival in the EHC group, significantlyhigher than 86.83% in the CV group, and cells in the EHC group werealso significantly better than those in the CV group for further apoptosisand necrosis assays. This work provides an efficient rewarming protocolfor the cryopreservation of biological samples, significantly improvingthe quantity and quality of cells and spheroids postcryopreservation.