To maintain the viability of cells in cord blood, samples should be kept at room temperature and processed within 24 hours. Samples should not be left unprocessed at room temperature longer than 24 hours as the granulocytes will begin to die, which will affect the viability of other cells. If samples are to be frozen for longer-term storage, red blood cells and granulocytes must be removed by density gradient centrifugation prior to freezing.