Skin cryopreservation: I. Incorporation of radioactive sulfate as a criterion of pigskin graft viability after freezing to −196 °C in the presence of cryoprotectants

Abstract

The incorporation of radioactive sulfate into glycosaminoglycans was used as a criterion of pigskin graft viability after surface treatment of the pig hide and after cooling and freezing of the graft. Complete surface treatment of the hide (soap, ethanolic iodine, antibiotics, and saline) diminished the incorporation of sulfate by about 40% compared with the control graft. During cooling and freezing the pigskin graft was submitted to 30-min exposures at 20, 4, −18, −50, −150, and −196 °C sequentially in a medium containing 0.65% NaCl, 3% sorbitol, and either 15% glycerol or 15% Me 2SO. Cooling to −18 °C reduced the incorporation of sulfate only in the grafts protected by glycerol. A considerable decrease of incorporation was observed after freezing the graft to −150 and −196 °C in both cryoprotective solutions. The inclusion of a hold at −50 °C was important, especially in the case of the Me 2SO medium when about 30% of 35S radioactivity was recovered in the cryopreserved graft compared with the control sample.