DIMETHYL-SULFOXIDE CONCENTRATION IN FRESH AND CRYOPRESERVED PORCINE VALVED CONDUIT TISSUES

The time-dependent penetration of the cryoprotectant dimethylsulfoxide (DMSO) into porcine aortic conduit and the effectiveness of dilutiona l removal of cryoprotectant from these tissues were evaluated using hi gh performance liquid chromatography. Incubation of intact conduit tis sues in 1.4 mol/liter (10%) DMSO at 4 degrees C revealed that the cryo protectant penetrated the tissues in a nonlinear time-dependent manner requiring 80 to 120 min to achieve a tissue concentration of approxim ately 0.7 mol/liter tissue water volume. This concentration approximat ed 54% of the theoretical media concentration (1.3 mol/liter) occurrin g through dilution effects of addition of the tissue to the medium. Th e osmolality of the medium decreased linearly in a time-dependent mann er from 2975 to 2860 mOsmol/kg water over 80 min for a negative slope of 1.28 mOsmol/kg water/min. Analysis of the concentrations of DMSO in tissues undergoing dilutional removal at 4 degrees C revealed that di lutional removal at low temperatures may not be an effective means of removing DMSO from cryopreserved cardiovascular tissues. It requires a pproximately 40 to 50 min at 4 degrees C for tissue concentrations of DMSO to be reduced to 0.24 mol/liter tissue water volume, which is far in excess of the concentration expected to be present in the tissue a nd suspending solution (< 0.03 mol/liter media) at equilibrium. It is suggested that protocols for removal of DMSO from thawed allograft hea rt valves which do not allow the temperature to increase above 4 degre es C during the removal process may not provide sufficient incubation time to permit the cryoprotectant (DMSO) to diffuse from the tissues d uring a clinical post-thawing preparation for clinical transplantation . (C) 1994 Academic Press, Inc.