Vitrification, a kinetic process of liquid solidification into glass, poses many potential benefits for tissue cryo-preservation including indefinite storage, banking, and facilitation of tissue matching for transplantation. To date, however, successful rewarming of tissues vitrified in VS55, a cryoprotectant solution, can only be achieved by convective warming of small volumes on the order of 1 ml. Successful rewarming requires both uniform and fast rates to reduce thermal mechanical stress and cracks, and to prevent rewarming phase crystallization. We present a scalable nanowarming technology for 1-to 80-ml samples using radiofrequency-excited mesoporous silica-coated iron oxide nanoparticles in VS55. Advanced imaging including sweep imaging with Fourier transform and microcomputed tomography was used to verify loading and unloading of VS55 and nanoparticles and successful vitrification of porcine arteries. Nanowarming was then used to demonstrate uniform and rapid rewarming at >130°C/min in both physical (1 to 80 ml) and biological systems including human dermal fibroblast cells, porcine arteries and porcine aortic heart valve leaflet tissues (1 to 50 ml). Nanowarming yielded viability that matched control and/or exceeded gold standard convective warming in 1-to 50-ml systems, and improved viability compared to slow-warmed (crystallized) samples. Last, biomechanical testing displayed no significant biomechanical property changes in blood vessel length or elastic modulus after nanowarming compared to untreated fresh control porcine arteries. In aggregate, these results demonstrate new physical and biological evidence that nanowarming can improve the outcome of vitrified cryogenic storage of tissues in larger sample volumes.
Bibliographical noteFunding Information:
This work was supported by an MN Futures grant (University of Minnesota) (to C.L.H., J.C.B., and M.G.), the NSF (CBET 1336659 to J.C.B.), the Kuhrmeyer Chair (to J.C.B.), the NIH (P41EB015894 to M.G.; R43HL123317 to K.G.M.B.), and the U.S. Army Medical Research and Materiel Command (contract no.W81XWH-15-C-0173 to K.G.M.B.). The views, opinions, and findings contained in this report are those of the authors and should not be construed as an official NIH or Department of the Army position, policy, or decision unless so designated by other documentation.