Banking of human placental/umbilical cord blood (PCB) requires volume reduction for prevention of hemolysis-related side effects and cost-effective storage. We collected, separated, and cryopreserved PCB following the New York Blood Center's protocol, and obtained PCB with an mean volume of 70.0±28.1ml (n=100). Red cells were sedimented by addition of 1% hydroxyethyl starch with gentle centrifugation. Recovery of nucleated cells (NC) and colonyforming units (CFU) was 82.9±13.7% and 90.4±18.9%, respectively (n=25). Volume of the NC suspension was reduced to 20ml by centrifugation and 5ml of 50% dimethylsulfoxide and 5% Dextran 40 solution were added slowly. The frozen cells were washed with a solution containing 10% Dextran 40 and 5% human serum albumin. NC and CFU recovery was 88.8±7.13% and 81.2±20.3%, respectively (n=18). No aggregation of cells occurred after the washing procedure.
We studied the effect of storage after collection, cell separation, and cryopreservation under various conditions. Results suggested that collected PCB should be prestored at 25°C for less than 24 hours, and that HES of moleculer weight 400, 000 should be used at the concentration of 1-4% for efficient cell separation. Further, the cryoprotective solution could maintain the number of NCs, CFUs, and CD34+ cells under slow cooling.
