Abstract
Three different closed procedures for concentrating bone marrow progenitor cells prior to cryopreservation have been compared. These were by a manual double centrifugation method, a Hemonetics 30 cell separator and an Aminco Celltrifuge. The best results were achieved using the paediatric pheresis set on the Hemonetics model 30. Marrow was frozen in 120 ml aliquots in a programmed freezer with rapid cooling of the freezing chamber during the phase change from the liquid to the solid state. After freeze-thawing the average nucleated cell recovery was approximately 50% and the progenitor cell recovery 80%.