Harvesting of peripheral blood progenitor cells with different programmes of discontinuous flow systems

From a technical point of view two problems arise during the collection of peripheral blood progenitor cells (PBPC): first, the volume of the apheresis product is often large, requiring volume reduction prior to cryopreservation. Second, the platelet (PLT) loss due to the harvesting of the buffy coat is an unwanted side effect. With respect to these problems, the present study was designed to compare programs for PBPC collection with discontinous-flow cell separators.

Three different protocols for PBPC harvesting were investigated in 32 patients with malignancies. In the first protocol, the blood cell separator Haemonetics MCS 3p was used. In the second protocol using the same machine, the opening and closure of the stem cell valve was modified in combination with a centri surge to reduce the PLT loss. The MCS+ device with another configuration of the valves was used in the third protocol. PBPC were mobilised by chemotherapy plus cytokine administration or application of growth factor alone. Blood counts and CD34 antigen-expressing cells were determined before apheresis and in the PBPC product. Colony-forming unit granulocyte/macrophage (CFU-GM) were determined in the apheresis product.

55 PBPC collections were carried out with a median end product volume of 105 ml. The median counts for CD34+ antigen-expressing cells and CFU-GM were 1.5x10(6 )and 2.5x10(4)/kg body weight, respectively. PLT loss was significantly lower in protocol III.

The study reported here revealed that PBPC could be easily collected in a reduced product volume by the intermittent-flow cell separators. No additional centrifugation prior to cryopreservation was necessary to remove the plasma from the apheresis product. Patient's PLT loss was reduced by the centri surge technique but this still has to be improved.