Design,development, and performance of an electromagnetic illumination system for thawing cryopreserved kidneys of rabbits and dogs

Kidneys from rabbits and dogs were perfused with one of several DMSO concentrations (0.0, 0.7, 1.4, 2.1 m) in a K⁺-Mg²⁺-rich perfusate, frozen, and then thawed with equipment providing electromagnetic (EM) illumination. Electrical properties (dielectric constant and loss tangent) of kidneys were measured both before and after EM thawing. The kidneys thawed were evaluated by simple anatomical (macroscopic and microscopic) and physiological observations rather than by transplantation.Rabbit kidneys which are no thicker than 2 cm could be optimally (uniformly and rapidly) thawed by use of illumination at 2450 MHz, a frequency which has a penetration depth of 2.1 cm at 0 °C, Optimal thawing of canine kidneys, which are twice as thick as rabbit kidneys, required the insertion of steel spheres (electroseeds) into the renal pelvis prior to freezing and illumination at 7 MHz in addition to that at 2450 MHz. Increasing the DMSO concentration (0.0 to 2.1 m) in renal tissue illuminated with 2450 MHz increased the conductivity and the permittivity regardless of whether the renal tissue was frozen or thawed. The use of DMSO decreased the time for thawing with EM illumination and yielded kidneys with improved post-thaw morphology.