Cryopreservation of sheep red blood cells. 2. Purified polyvinylpyrrolidone and hydrolyzed starch as protective agents.

The protection of sheep erythrocytes against damage at low temperature (−196°C) was investigated using purified polyvinylpyrrolidone (PVP) and hydrolyzed starch as cryoprotective agents. Identical results were obtained with untreated PVP, neutralized PVP and PVP purified by chromatography. With hydrolyzed starch the cryoprotection was dependent on the type and concentration of the starch used and on the extent of hydrolysis of the starch prior to use. Cell recovery with some starch types was the same (80–85 %) as that obtained with PVP.