Large-scale cryopreservation of isolated dog hepatocytes

This study aimed to develop methods for the large-scale preparation of hepatocytes from large animal livers and for the mass cryopreservation of isolated hepatocytes. Isolated hepatocytes were obtained from Beagle dogs weighing around 10 kg by collagenase digestion plus preperfusion with the Ca2+ chelator ethylene glycol bis N,N'-tetraacetic acid. The cell yield was 2.1 +/- 0.45 x 10(10)/liver with 90% viability by the trypan blue dye exclusion test, and the estimated cell yield was 72 +/- 13%. The optimal conditions were large-scale cryopreservation of dog hepatocytes were (i) a freezing rate of 1-10 degrees C/min, (ii) a dimethyl sulfoxide (Me2SO) concentration of 20% (final concentration: 10%), (iii) a cell density that did not exceed 10(8)/ml, and (iv) rapid thawing in a 37 degrees C water bath. The viability of preserved hepatocytes was 75 +/- 3.0% and the estimated recovery rate was approximately 50%. Preserved hepatocytes showed 20-50% of the metabolic activity of fresh cells, as assessed by ammonia and fructose loading tests, ATP content, and [14C]leucine uptake. Following culture after thawing, the morphological normalization of preserved cells was confirmed by light and electron microscopy.