Summary:The optimal dose and schedule of G-CSF for mobilization of peripheral blood stem cells (PBSC) is not well defined. G-CSF mobilization was performed in a group of healthy donors and paediatric patients for autologous back-up before receiving allogeneic stem cell transplant. Seventeen consecutive subjects who received G-CSF at 5 g/kg/dose twice daily (group A) were compared with a historical control group of 25 subjects who received a single daily dose of 10 g/kg/day G-CSF (group B). Double blood volume apheresis for PBSC collection was started on day 5. G-CSF was continued and apheresis repeated until the targeted CD34 ϩ cell dose was achieved. Both groups were comparable for sex, age, body weight and reason for PBSC collection. Over two-thirds of the subjects in both groups were less than 16 years of age. The G-CSF priming and apheresis were well tolerated. When the first day apheresis products were analyzed, group A resulted in significantly higher yield of total nucleated cells (5.91 vs 3.92 ؋ 10 8 /kg, P ‫؍‬ 0.013), mononuclear cells (5.73 vs 3.92 ؋ 10 8 /kg, P ‫؍‬ 0.017), CD34 ؉ cells (2.80 vs 1.69 ؋ 10 6 /kg, P ‫؍‬ 0.049) and colony-forming units (107 vs 54 ؋ 10 4 /kg, P ‫؍‬ 0.010) as compared with group B. We conclude that the two dose schedule is more efficient in mobilizing PBSC in normal donors and children with non-malignant diseases. This approach may reduce the number of aphereses required and thus reduce the transplant cost. Bone Marrow Transplantation (2000) 25, 931-935.

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Summary:The number of nucleated cells infused into the recipient of a cord blood (CB) transplant has emerged as the most important factor affecting the probability and speed of engraftment. At present, there is no international consensus on the procedure of CB collection in the maternity ward. In order to maximise the yield of viable cells in a CB unit, we aimed to investigate the efficiency of CB collection, with respect to the time of delivery of the placenta. We analysed stem and progenitor cells in terms of CD34+ cell content and colony-forming activities, lymphocyte subpopulations and the presence of macroscopic clots in 93 paired CB samples, collected before and after the delivery of the placenta. Our results demonstrated that the median concentrations of nucleated cells and total colony-forming unit (CFU) were significantly lower in CB collected after placenta delivery by 9.5% (P Ͻ 0.001) and 11.6% (P = 0.015), respectively, when compared to their counterparts collected before placental delivery. A reduction of granulocytes (P Ͻ 0.001), monocytes (P Ͻ 0.001) and CD19 + B lymphocytes (P = 0.031) was observed, with no significant change in the proportion of T cell subsets (CD4 + , CD8+ cells) or activated T cells (CD25 + , CD45RO + cells) in samples collected after placenta delivery. The incidence of macroscopic clots was also higher in these samples (31% vs 1%, P Ͻ 0.001). The reduction of stem and progenitor cells correlated significantly with that of major cell populations, indicating a general cell loss, possibly due to clotting activities developed with time. Our study has documented strong evidence for recommending the collection of CB before the delivery of the placenta. haematopoietic reconstitution has been sustained for over 10 years.1 Since then, CB transplants have been performed in over 700 patients with malignancies, haematological disorders and inborn errors of metabolism.2 Many CB banks have been set up worldwide. However, there are limitations in the application of CB for transplant. The yield of stem and progenitor cells in a collection has been a prime concern especially to patients with large body weights. Recently, the statistics of accumulated clinical data confirmed that the number of nucleated cells/kg and therefore the number of stem and progenitor cells infused into the recipient was the most important factor influencing the probability and speed of engraftment. [3][4][5] It is thus critical that all efforts be made to ensure a large cell dose in the CB unit sufficient for a rapid and sustained engraftment.In order to maximise the cell quantity in a single unit of CB, various studies have been carried out for their collection, processing and cryopreservation. Broxmeyer et al 6 described a two-phase method by which CB was firstly collected from the severed cord during placental delivery and then additional CB was obtained from multiple needle aspirations from the umbilical vein. A modified method for overcoming the collapse of the umbilical vein was later described.7 Bertolini et al...