Factors affecting volume reduction and red blood cell depletion of bone marrow on the COBE Spectra cell separator before haematopoietic stem cell transplantation.

The COBE Spectra is used to volume/red blood cell (RBC) deplete BM before transplantation or cryopreservation. We have audited our results to identify the effect of transit time, refrigerated storage, age and cellular composition on mononuclear cells (MNC) and CD34+ cell recoveries, volume/RBC depletion and neutrophil engraftment. In total, 88 consecutive collections from autologous (n = 25) and allogeneic (n = 63) donors were included. The mean collection volume was 1250 +/- 398 ml with RBC content of 341 +/- 113 ml. The MNC and CD34+ cell recoveries were 83.3 +/- 18.5 and 88.1 +/- 18.9%, respectively, volume depletion was 88.2+/-4.4% and RBC depletion 98.3 +/- 1.8%. Neutrophil engraftment was achieved in 20.1 +/- 6.4 days. Factors affecting MNC and CD34+ cell recoveries were transit time (P = 0.0060), overall age (P < 0.0210) and MNC/CD34+ cell concentrations (P < 0.0313). The presence of crenated RBC also reduced CD34+ cell recovery (P = 0.0028). Refrigerated storage did not adversely affect cell recovery (P > 0.8161) or neutrophil engraftment (P = 0.8959). This study demonstrates that time in transit, overall age, MNC and CD34+ cell concentrations and RBC condition were important factors affecting processing. RBCs show artefacts soon after collection at ambient temperatures and these may interfere with the separation and collection of MNC/CD34+ cells. Refrigeration at 4-6 degrees C during transit and storage may reduce formation of RBC artefacts and maximize MNC and CD34+ cell recoveries.