Influence of DMSO distribution upon renal function following freezing and thawing

Thermographic studies of phantom and canine kidneys thawed by microwave radiation

Whole organs, such as kidneys, must be thawed quickly and uniformly to prevent damage during thawing due to excessive heating. Electromagnetic heating with microwaves thaws the kidneys quickly but frequently produces "hot spots" with heat damage. To study heat damage, phantom gelatin kidneys with different dielectric constants and canine kidneys perfused with 12.5% glycerol, ethylene glycol, or dimethyl sulfoxide before freezing were microwave thawed, and the interior temperature was measured by thermography. Phantom kidneys were thawed free standing and canine kidneys were either free standing or packed in a gel mixture. Both phantom and canine kidneys were split symmetrically and separated with a sheet of Styrofoam to facilitate immediate separation and evaluation of the halves after thawing (approximately 3 sec). All the phantoms, regardless of dielectric properties, had areas less than 0 degrees C or greater than 37 degrees C after thawing. The free-standing canine kidneys and the gel-packed ethylene glycol-perfused kidneys had frozen areas (less than 0 degrees C) and hot spots (greater than 37 degrees C). However, glycerol- and dimethyl sulfoxide-perfused kidneys packed in gel before thawing had no areas less than 0 degrees C or greater than 37 degrees C. Altering the geometry from a "kidney shape" to a cylindrical shape with increased volume improved the uniformity of thawing and was more effective than altering the dielectric constant over the range evaluated.

The effect of freeze rate, duration of phase transition, and warming rate on survival of frozen canine kidneys

The effect of cooling rate, warming rate, and duration of phase transition upon survival of frozen canine kidneys was investigated. In the present study, 11 kidneys out of 14 rapidly cooled (2--4degreesC/min) to --22degreesC and thawed (70--110degreesC/min) were viable following contralateral nephrectomy. The serum creatinine and BUN levels rose to a maximum of 8.4 and 30 mg%, respectively, on the eighth day post-contralateral nephrectomy. Average survival time was 10 days; however, two of the dogs in this group were allowed to survive, one for 3 months and one for over 2 years. Eight kidneys out of 16 slowly cooled (0.25-1.0degreesC/min) and either rapidly or slowly warmed (20-30degreesC/min) had function to produce small amounts of urine; however, they did not survive more than 5 days after contralateral nephrectomy. Cooling rates of 0.1 and 10degreesC/min were too harmful to the kidney to have renal function after reimplantation. The minimum renal cell damage as assessed by LDH and GOT in the post-freeze perfusate was found in the 2-4degreesC/min cooling rate following rapid warming (70degrees-110degreesC/min). Correlation of the duration of phase transition time to renal cell damage was linear for LDH and GOT (r=0.93). This result suggests that the duration of phase transition time also is an important factor during the freezing process, affecting post-thaw survival of canine kidneys.