Yield Of Progenitor Cells Research Articles

Stem Cell Factor in Combination With Filgrastim After Chemotherapy Improves Peripheral Blood Progenitor Cell Yield and Reduces Apheresis Requirements in Multiple Myeloma Patients: A Randomized, Controlled Trial

Stem cell factor (SCF) has been shown to synergize with filgrastim to mobilize CD34+ cells into the peripheral blood. To determine if addition of SCF to chemotherapy and filgrastim reduces the number of leukaphereses required to achieve a target yield of 5 × 106 CD34+ cells/kg, 102 patients with multiple myeloma were randomized to receive mobilization chemotherapy with cyclophosphamide (4 g/m2) and either SCF (20 μg/kg/d) combined with filgrastim (5 μg/kg/d) or filgrastim alone (5 μg/kg/d), administered daily until leukaphereses were completed. After collection, patients were treated with myeloablative therapy supported by autologous peripheral blood progenitor cell (PBPC) infusion and filgrastim (5 μg/kg/d). There was a significant difference between the treatment groups in the number of leukaphereses required to collect 5 × 106 CD34+ cells/kg (median of 1 v 2 for SCF + filgrastim and filgrastim alone, respectively, P = .008). Patients receiving the combination of SCF plus filgrastim had a 3-fold greater chance of reaching 5 × 106 CD34+ cells/kg in a single leukapheresis compared with patients mobilized with filgrastim alone. The median CD34+ cell yield was significantly increased for the SCF group in the first leukapheresis (11.3 v 4.0 × 106/kg, P = .003) and all leukaphereses (12.4v 8.2 × 106/kg, P = .007). Total colony-forming unit–granulocyte-macrophage (CFU-GM) and mononuclear cell counts were also significantly higher in the SCF group in the first leukapheresis and in all leukaphereses. As expected for patients mobilized to an optimal CD34+ cell yield, the time to engraftment was similar between the 2 treatment groups. Cells mobilized with the combination of SCF plus filgrastim were thus considered effective and safe for achieving rapid engraftment. Treatment with SCF plus filgrastim was well tolerated, with mild to moderate injection site reactions being the most frequently reported adverse events. There were no serious allergic-like reactions to SCF. The addition of SCF to filgrastim after cyclophosphamide for PBPC mobilization resulted in a significant increase in CD34+cell yield and a concomitant reduction in the number of leukaphereses required to collect an optimal harvest of 5 × 106CD34+ cells/kg.

Peripheral blood progenitor cell (PBPC) counts during steady-state haemopoiesis enable the estimation of the yield of mobilized PBPC after granulocyte colony-stimulating factor supported cytotoxic chemotherapy: an update on 100 patients.

Peripheral blood progenitor cells (PBPC) can be mobilized using chemotherapy and granulocyte colony-stimulating factor (G-CSF). We and others previously reported a correlation of steady-state PBPC counts and the PBPC yield during mobilization in a small group of patients. Here we present data on 100 patients (patients: 25 non-Hodgkin's lymphoma (NHL), five Hodgkin's disease, 35 multiple myeloma (MM), 35 solid tumour) which enabled a detailed analysis of determinants of steady-state PBPC levels and of mobilization efficiency in patient subgroups. Previous irradiation (P = 0.0034) or previous chemotherapy in patients with haematological malignancies (P = 0.0062) led to a depletion of steady-state PB CD34+ cells. A correlation analysis showed steady-state PB CD34+ cells (all patients: r = 0.52, P < 0.0001; NHL patients, r = 0.69, P = 0.0003; MM patients: r = 0.66, P = 0.0001) and PB colony-forming cells can reliably assess the CD34+ cell yield in mobilized PB. In patients with solid tumour a similar trend was observed in mobilization after the first chemotherapy cycle (r = 0.51, P = 0.05) but not if mobilization occurred after the second or further cycle of a sequential dose-intensified G-CSF-supported chemotherapy regimen, when premobilization CD34+ counts were 18-fold elevated (P = 0.004). When the patients with MM (r = 0.63, P = 0.0008) or with NHL (r = 0.65, P = 0.006) were analysed separately, a highly significant correlation of the steady-state PB CD34+ cell count to the mean leukapheresis CD34+ cell yield was found, whereas no correlation was observed for patients with a solid tumour. For patients with haematological malignancies estimates could be calculated which, at a specific steady-state PB CD34+ cell count, could predict with a 95% probability a defined minimum progenitor cell yield. These results enable recognition of patients who mobilize PBPC poorly and may assist selection of patients for novel mobilization regimens.

Future prospects

Mobilized peripheral blood cells are emerging to be the main haematopoietic progenitor cell sources in both autologous and allogeneic transplantation. The superior engraftment kinetics make high-dose therapy (HDT) safer and more cost-effective. Advances in mobilization protocols will enable an adequate, efficacious and predictable progenitor cell yield for most patients, and may even permit differential mobilization of normal and tumour cells. Peripheral blood stem cell transplantation is going to make an impact on tumour control by allowing dose escalation through multiple HDT and rescues, promoting various purging manoeuvres and facilitating immunomodulatory approaches to enhance graft-versus-tumour responses. Technological advances in ex vivo expansion and manipulation of haematopoietic progenitor cell grafts will add to our armamentarium of new therapeutic approaches and broaden our dimensions in the use of peripheral blood stem cell transplantation.

Factors influencing platelet recovery after autologous transplantation of G-CSF-mobilized peripheral blood stem/progenitor cells following myeloablative therapy in 50 heavily pretreated lymphoma patients.

Delayed platelet recovery following autologous PBPCs transplantation after myeloablative therapy remains an unresolved problem in lymphoma patients heavily pretreated with several chemotherapy cycles and/or radiotherapy. In the present study of 50 lymphoma patients, the factors influencing platelet recovery after myeloablative therapy followed by autologous PBPCs transplantation were analysed retrospectively. The median age was 42 years (range, 15-58). Fourteen patients had HD and 36 had NHL (13 high-grade and 23 low-grade); most (80%) had stage III or IV. Twenty-two patients had received radiotherapy to various extents before mobilization. The mean number of previous chemotherapy cycles was seven (range 3-24) of different regimens (range 1-4). A median of three leukapheresis procedures (range 1-5) was performed after G-CSF mobilization. Single leukapheresis was sufficient in only one patient. A significant correlation was found between the BFU-E content of autografts and platelet recovery after transplantation. Neither the patient's age and sex nor the stage and grade of lymphoma had any effect on platelet recovery after transplantation. Neither the type of myeloablative therapy used or the dose of G-CSF administered after transplantation had any effect on platelet recovery after transplantation. The type of previous chemotherapy cycles was a major adverse factor affecting the progenitor cell yield in the autografts. Lymphoma patients previously treated with ASHAP and/or Dexa-BEAM cycles had less progenitor cell yield. The chemotherapeutic agents used in previous cycles also had a clear adverse effect on the progenitor cell yield in the autografts. Lymphoma patients previously treated with cycles including cytarabine and/or cisplatin showed significantly less progenitor cell yield and slower platelet recovery after transplantation. All seven patients with delayed platelet recovery had received cytarabine and/or cisplatin in several previous ASHAP and/or Dexa-BEAM cycles. All seven patients had a BFU-E count of less than 1 x 10(5)/kg yield in the autografts.

Optimal timing for processing and cryopreservation of umbilical cord haematopoietic stem cells for clinical transplantation.

Some of the factors that may influence the number and quality of cord blood haematopoietic progenitor cells available for transplantation have been investigated including site of collection, delayed processing after collection and cryopreservation protocol. We used the granulocyte-macrophage progenitor (CFU-GM) and erythroid burst-forming unit (BFU-E) assays to quantify progenitors. The capacity of CFU-GM to produce secondary colonies was used as a measure of progenitor cell quality. We found that: (1) there were no significant differences in total nucleated cells (TNC), mononuclear cells (MNC), CFU-GM or BFU-E numbers in paired specimens from the umbilical vein or veins at the base of the placenta. The potential of the CFU-GM to produce secondary colonies from the two sites was similar; (2) storing cord blood at room temperature or at 4 degrees C resulted in a significant reduction in progenitor cell numbers beyond 9 h; and (3) cryopreservation following either controlled rate freezing or passive cooling reduced MNC numbers, viability and CFU-GM survival insignificantly but the potential of CFU-GM to produce secondary colonies was significantly reduced post cryopreservation (P = 0.04). We conclude that the yield of CB progenitor cells is not affected by the site of collection, but is adversely affected by delays between collection and cryopreservation. Furthermore, cryopreservation reduced the CFU-GM potential to produce secondary colonies. Measures of progenitor cell quality as well as quantity may be relevant to assessing CB blood collections.

Relevance of Peripheral Blood Progenitor Cell Counts during Steady-State Hematopoiesis to Estimate the Number of Progenitor Cells Mobilized following Granulocyte Colony-Stimulating Factor-Supported Chemotherapy

Background: Peripheral blood progenitor cells can be mobilized using cytotoxic chemotherapy and cytokines. We were looking for predictive parameters indicating a patient’s response to a given mobilization regimen. Patients and Methods: Flow cytometry analysis and clonogenic assays were used to examine hematopoietic progenitor cells in bone marrow and peripheral blood prior to G-CSF-supported chemotherapy and were compared to CD34+ cell counts in peripheral blood and leukapheresis products in the recovery phase. Stroma-dependent long-term cultures were performed from steady-state bone marrow and leukapheresis product samples. 90 patients (24 non-Hodgkin’s lymphoma, 5 Hodgkin’s disease, 33 multiple myeloma, 28 solid tumor) were included in this study. Results: A correlation analysis revealed steady-state peripheral blood CD34+ cells (all patients: r = 0.59, p < 0.0001; non-Hodgkin’s lymphoma, r = 0.7, p = 0.0003; multiple myeloma: r = 0.71, p < 0.0001) and peripheral blood colony-forming cells but not their bone marrow counterparts to be a measure of a patient’s mobilizable CD34+ cell number which may reflect different degrees of blood dilution in the bone marrow aspirates. The proliferative potential of primitive stem cell clones in the CD34+ population was comparable between steady-state bone marrow and mobilized peripheral blood cells. An increasing number of chemotherapy cycles prior to mobilization lead to a depletion of CD34+ cells from steady-state peripheral blood (p = 0.001), mobilized peripheral blood (p = 0.0001), or the mean leukapheresis product CD34+ cell yield (p = 0.0021). Steady-state peripheral blood CD34+ cell counts could be related to the individual progenitor cell yields. In order to obtain in one leukapheresis product 2.5 × 10⁶ CD34+ cells/kg body weight, a steady-state peripheral blood CD34+ cell count of 0.6 × 10⁶/l and 0.16 × 10⁶/l were required if regular (10 l) and large-volume (median 20 l) leukaphereses were performed, respectively. Conclusion: These results contribute to the further optimization of stem cell therapy since – depending on the tumor entity – they allow to estimate the expected stem cell yield before the mobilization therapy is administered.

Stem cell mobilization with G-CSF alone in breast cancer patients: higher progenitor cell yield by delivering divided doses (2 x 5 microg/kg) compared to a single dose (1 x 10 microg/kg).

We investigated the schedule dependency of G-CSF (10 microg/kg) alone in mobilizing peripheral blood progenitor cells (PBPC) in breast cancer patients. After a median of three cycles (range, 2-6) of anthracycline-based chemotherapy, 49 patients with breast cancer (stage II/III, > or = 10+ Ln n = 36; locally advanced/inflammatory n = 8, stage IV (NED) n = 5) underwent PBPC collection after steady-state mobilization either with 1 x 10 microg/kg (n = 27) or with 2 x 5 microg/kg (n = 22) G-CSF daily for 4 consecutive days until completion of apheresis. Apheresis was started on day 5. Priming with 2 x 5 microg/kg resulted in a higher median number of CD34+ cells (5.8 vs 1.9 x 10(6)/kg, P = 0.003), MNC (6.6 vs 2.6 x 10(8)/kg, P < 0.001) and CFU-GM (6.5 vs 1.3 x 10(4)/kg, P = 0.001) in the first apheresis than with 1 x 10 microg/kg. Also the overall number of collected BFU-E was higher in the 2 x 5 microg group (9.2 vs 3.1 x 10(4)/kg; P = 0.01). After high-dose chemotherapy with cyclophosphamide/thiotepa/mitoxantrone (n = 46) hematopoietic engraftment with leukocyte count > 1.0/nl was reached in both groups after a median of 10 days (range, 8-15) and with platelets count > 50/nl after 12 (range, 9-40) and 13 days (range, 12-41), respectively. A threshold of > 2.5 x 10(6)/kg reinfused CD34+ cells ensured rapid platelet engraftment (12 vs 17 days; P = 0.12). Therefore, the target of collecting > 2.5 x 10(6) CD34+ cells was achieved in 21/27 (80%) patients of the 1 x 10 microg group and in 21/22 (95%) patients of the 2 x 5 microg/kg group with a median of two aphereses (range, 1-4). None in the 10 microg/kg group, but 6/22 (28%) patients in the 2 x 5 microg/kg group required only one apheresis procedure, resulting in fewer apheresis procedures in the 2 x 5 microg/kg group (mean, 1.8 vs 2.3, P = 0.01). These results demonstrate that priming with 10 microg/kg G-CSF alone is well tolerated and effective in mobilizing sufficient numbers of CD34+ cells in breast cancer patients and provide prompt engraftment after CTM high-dose chemotherapy. G-CSF given 5 microg/kg twice daily (2 x 5 microg) leads to a higher harvest of CD34+ cells and required fewer apheresis procedures than when given 10 microg/kg once daily (1 x 10 microg).

Factors associated with successful mobilization of peripheral blood progenitor cells in 200 patients with lymphoid malignancies.

Peripheral blood progenitor cells (PBPC) were mobilized and harvested in 200 patients treated for non-Hodgkin's lymphoma (n = 148), Hodgkin's disease (n = 22) and multiple myeloma (n = 30). The variables predicting the collection of a minimal (>2.5 x 10(6)/kg) or a high (>10 x 10(6)/kg) CD34+ cell count were analysed. Patients were mobilized with haemopoietic growth factors following either standard chemotherapy (n = 49) or high-dose cyclophosphamide, given alone (n = 55) or combined with high-dose VP16 (n = 86). 10 patients received haemopoietic growth factors only. The first mobilization resulted in a PBPC harvest with enough CD34+ cells in 179/200 patients (90%). High-dose cyclophosphamide, with or without VP16, did not mobilize a higher progenitor cell yield than standard chemotherapy. When performing multiple regression analysis in the 190 patients who received chemotherapy-containing mobilization, only the number of previous chemotherapy regimens and the exposure to fludarabine predicted for a failure to collect a minimal PBPC count (P=0.06 and 0.0008 respectively). The target to collect a high CD34+ cell count was negatively associated with the number of previous chemotherapy regimens (P=0.002). When only non-Hodgkin's lymphoma patients were considered for multivariate analysis, low-grade histology with fludarabine appeared to be associated with poor PBPC cell yield (P=0.08 and 0.005 respectively). This data confirms that PBPC harvest should be planned early in the disease course in transplant candidates, and can be obtained after a standard course of chemotherapy.

Progenitor cell yields are frequently poor in patients with histologically indolent lymphomas especially when mobilized within 6 months of previous chemotherapy.

High-dose therapy with peripheral blood stem cell (PBSC) support is a frequently used treatment option in younger patients with poor prognosis histologically indolent (low-grade) non-Hodgkin's lymphoma (NHL), usually at the time of second or subsequent response to conventional-dose therapy. We have undertaken PBSC collection in 57 patients with histologically indolent NHL mobilized with either cyclophosphamide 1.5 g/m2 or the ESHAP regimen, followed by daily G-CSF. Progenitor cell yields were determined by quantification of CD34+ cells and GM-CFC. Twelve patients (21%) failed to achieve the minimum progenitor cell requirements of 1 x 10(6)/kg CD34+ cells or 1 x 10(5)/kg GM-CFC in their pooled harvests and 40 patients (70%) failed to achieve the optimal harvest thresholds of 3.5 x 10(6)/kg CD34+ cells or 3.5 x 10(5)/kg GM-CFC. This high failure rate is significantly higher than that in patients with histologically aggressive NHL or Hodgkin's disease. A multivariate analysis was performed to identify factors contributing to the low stem cell yields in this group. This identified the time interval from the last chemotherapy to the priming chemotherapy as the most important predictive factor. With respect to CD34 and GM-CFC numbers, on the single harvest on the day the white cell count first exceeded 5 x 10(9)/l the P values were 0.0078 and 0.0065, respectively, and for the progenitor cell values on the pooled harvests the P values were 0.004 for CD34+ cells and 0.015 for GM-CFC. Progenitor cell yields may therefore be improved in patients with low grade lymphoma by harvesting at diagnosis if no marrow disease is present, or by delaying mobilization for 6 months post-chemotherapy in patients in first or subsequent remission.

Factors Influencing Yields of Progenitor Cells for Allogeneic Transplantation: Optimization of G-CSF Dose, Day of Collection, and Duration of Leukapheresis

Mobilization of hematopoietic progenitor cells by G-CSF was attempted on 89 occasions in 85 healthy donors. Three dose ranges of G-CSF were chosen for analysis: low (4-7.4 micrograms/kg), intermediate (7.5-10 micrograms/kg) and high (> 10 micrograms/kg). A target blood level for apheresis of 20 x 10(6)/L CD34+ cells was reached by day 3 in 75 patients (84%) and by day 4 in all but 1 (99%). Target yields above 2.5 x 10(6)/kg for 75 unmanipulated transplants were exceeded in a single collection in 73 donors (97%). Correlation of CD34+ cell yields to blood CD34+ cell level before leukapheresis was moderate only (r2 = 0.32). There was close linear correlation between processed volume and cumulative CD34+ cell yield, with a median r2 value of 0.98 (range 0.74-1.00). Yields of CD34+ cells achieved on day 3 were significantly lower after the high dose than after the intermediate G-CSF dose (21 +/- 3 versus 29 +/- 6 x 10(6)/L blood processed, p = 0.03). After the low dose of G-CSF, yields on day 4 were higher than on day 3 (48 +/- 10 versus 22 +/- 4 x 10(6)/L blood processed, p = 0.01). There was no difference between day 3 and day 4 yields with the intermediate G-CSF dose. In 73 of 93 (78%) leukaphereses, the CD34+ cell yield was more than 100% of the estimated intravascular CD34+ cells at the beginning of collection and ranged up to 342%. These data indicate that a daily dose of 7.5-10 micrograms/kg G-CSF, given as a multiple of 300 and 480 micrograms ampoules, is a convenient regimen giving adequate yields from a single collection on day 3 or 4 in most donors. Measuring blood CD34+ cell levels is of limited value in predicting yields, but monitoring CD34+ cell yields during leukapheresis may help to minimize unnecessary or inefficient collection.

Analysis of the effect of prior therapy on progenitor cell yield: use of a chemotherapy scoring system.

A quantitative analysis of peripheral blood stem cell (PBSC) yield, measuring absolute numbers of CD34+ cells x 10(6)/kg and CFU-C x 10(4)/kg was performed in 74 consecutive patients. The interval or 'gap' from the end of previous chemotherapy to the date of priming was recorded in weeks. Geometric mean CD34 and CFU-C values were significantly higher in patients with a score of < or = 60 compared to those with score > 60 (P = 0.003 and 0.02, respectively) and a significant difference in CD34 values was also found when scores of < or = 38 were compared with scores > 38 (P = 0.003), with the difference in CFU-C values approaching significance (P = 0.08). Patients exposed to toxicity factor 4 drugs had significant lowering of both CD34 and CFU-C values (P < 0.001 and P = 0.038) and this emerged as the only independent factor when analysed using linear regression. No significant difference in the geometric mean CD34 or CFU-C values of patients was found in any of the gap categories analysed. Prior exposure to toxicity factor 4 drugs had a significant adverse effect on stem cell yield and should be avoided or minimized prior to stem cell harvesting.

The COBE Spectra cell separator is more effective than the Haemonetics MCS‐3P cell separator for peripheral blood progenitor cell harvest after mobilization with cyclophosphamide and filgrastim

Peripheral blood is rapidly replacing bone marrow as a source of hematopoietic progenitor cells for autologous transplantation. The advantages of peripheral blood progenitor cell transplantation are enhanced by the ability to collect sufficient progenitor cells to ensure rapid neutrophil and platelet recovery in a single procedure on some cell separators. A prospective randomized study was undertaken to compare peripheral blood progenitor cell yields from two cell separators (MCS-3P, Haemonetics and Spectra, COBE). Fifteen consecutive patients were mobilized with cyclophosphamide 2 g per m2 (Day 0) and filgrastim 10 micrograms per kg (Days 1-11). Consecutive collections (Day 10, Day 11) were performed with each machine once: patients were randomly assigned to either machine for the initial collection. Collection time was longer on the MCS-3P (p = 0.001), and the volume processed was greater with the Spectra (p < 0.0001). Despite similar nucleated cell yield (p = 0.62), the yield of CD34+ cells (p = 0.001) and colony-forming units-granulocytic-monocytic (p = 0.0001) was significantly higher with the Spectra. The yield of nucleated cells per unit of blood volume processed was higher for the MCS-3P (p = 0.0007), while the CD34+ cell yield (p = 1) and colony-forming units-granulocytic-monocytic yield (p = 1) per unit of blood volume processed were similar for the two machines. The collection of CD34+ cells at levels > 2 x 10(6) per kg (p = 0.063), 5 x 10(6) per kg (p = 0.031), and colony-forming units-granulocytic-monocytic > 1 x 10(5) per kg (p = 0.25) after a single collection was superior for the Spectra. The yield of progenitor cells after collection on the Spectra was superior to that achieved with the MCS-3P, because of the larger volume of blood processed per procedure. This would permit more patients to undergo only one collection.

Large volume leukapheresis maximizes the progenitor cell yield for allogeneic peripheral blood progenitor donation.

We have investigated the efficiency and safety of large volume leukapheresis (LVL) for the collection of granulocyte colony-stimulating factor (G-CSF)-mobilized peripheral blood progenitor cells (PBPCs) from healthy donors. In six apheresis sessions in four healthy individuals on a COBE-BCT Spectra cell separator (median processed volume 3.5 X total blood volume, TBV, range 3.3-4.4 X TBV), harvested cells were collected sequentially into three single bags. The collection bags were changed after processing 33%, 66%, and 100% of the prospective apheresis volume, allowing analysis of PBPCs collected at different periods during one harvest. Mononuclear cells (MNCs), CD34+ cells, CD34+ subsets, and lymphocyte subsets were determined in each bag. Substantially more PBPCs were harvested than were in the circulation before G-CSF administration preceding LVL (median 171%, range 69-267%), reflecting progenitor release during the procedure. In donors 1 and 3, the CD34+ cell yields decreased in the third bag to 53% and 42% of that collected in the first bag, whereas the progenitor cell yields in donors 2 and 4 were stable or rose during the procedure, achieving in the third bag 157% and 105% of the number of CD34+ cells collected in the first bag. Minor changes were found in the subsets of CD34+ cells, lymphocytes, and monocytes collected at different periods during a single harvest. LVL was well tolerated. Reversible thombocytopenia developed in all cases. No late effects attributable to LVL or G-CSF were found in the 4 donors and 16 other healthy individuals who have undergone LVL in our institution. We conclude that LVL is safe and maximizes PBPC yields for allogeneic transplantation.

Efficacy and kinetics of bone marrow processing and enrichment of haematopoietic progenitor cells (HPC) by a large-volume apheresis procedure.

We investigated the efficacy of bone marrow (BM) processing by an automated large-volume apheresis procedure (6 x original BM volume) in 10 paediatric and adult patients undergoing BM harvesting before myeloablative therapy. Volume-dependent kinetics during apheresis were analyzed by sequential collection of processed cells into a six-fold collection bag system with consecutive analysis of the single bags. BM processing resulted in an 83.3% (+/- 21) recovery of mononuclear cells (MNC), a 97.9% (+/- 1.1) reduction of erythrocytes (RBC) and a 87.7% (+/- 2.9) volume reduction. To determine volume-dependent kinetics of haematopoietic progenitor cell (HPC) enrichment during apheresis, leukocytes (WBC), mononuclear cells (MNC), CD34 cells and colony-forming cells (CFU-GM) were serially quantitated in subsequent collection bags. Large-volume BM processing significantly enhanced absolute yields of CD34+ cells (mean: 4.01 (+/- 2.81) x 10(6)/kg bw) and CFU-GM (mean: 1.92 (+/- 1.47) x 10(4)/kg bw) compared with the standard procedure (3 x BM volume) by 26.9% (+/- 10.9) and 27.2% (+/- 11.6), respectively. We concluded that large-volume apheresis for BM processing is an efficient technique significantly improving the yields of haematopoietic progenitor cells (HPC) without any relevant changes in the purity of the final product. Moreover, sequential collection and analysis of HPC represents a good model to investigate the volume-dependent kinetics and efficacy of BM processing.

Preapheresis peripheral blood CD34+ mononuclear cell counts as predictors of progenitor cell yield.

Peripheral blood progenitor cells, harvested by apheresis after mobilization, provide rapid hematologic recovery after high-dose chemotherapy. However, because harvesting these cells is expensive and time-consuming, there has been much interest in optimizing collection protocols. An investigation was made to determine whether, in this clinical setting, peripheral blood progenitor cell yields may be predicted from preapheresis progenitor cell counts, allowing the length of each procedure to be "fine tuned" to achieve specific target goals. Preapheresis peripheral blood CD34+ cell and total colony-forming cell counts were assessed before 78 peripheral blood progenitor cell collections from 13 consecutive patients were performed. Preapheresis counts were correlated with actual progenitor cell yields. Factors affecting this correlation were analyzed. With the use of linear regression analysis preapheresis progenitor cell counts were found to correlate significantly but weakly with actual yields per kg of body weight per liter of blood processed (CD34+ cells: r = 0.43; colony-forming cells: r = 0.56). Further analysis revealed two possible causes: 1) circulating progenitor cell concentrations fluctuate widely during harvest, which implies that preapheresis counts are not representative of actual concentrations during apheresis, and 2) the efficiency with which apheresis machines extract mononuclear cells varies greatly between procedures. Preapheresis CD34+ and colony-forming cell counts correlated poorly with subsequent yields in this clinical setting, which suggests that it is not practical to use such counts to predict with certainty the length of apheresis needed to achieve a target yield.

Progenitor cell yield in sequential blood stem cell mobilization in the same patients: insights into chemotherapy dose escalation and combination of haemopoietic growth factor and chemotherapy

Between April 1988 and March 1994 a total of 23 patients with haematological or non-haematological malignancies received serial peripheral blood stem cell (PBSC) mobilization to attain sufficient harvest for PBSC transplant at our institution. There was no improvement in yield with the second mobilization for group A patients (n = 12) who had the same dose of cyclophosphamide twice as mobilizing agent. For group B patients (n = 6). who had a higher dose of cyclophosphamide with the second mobilization, there was significant increase in CFU-GM yield. CD34+ cell yield was not measured. For group C patients, who received interleukin-3 plus granulocyte-macrophage colony-stimulating factor (GM-CSF) with the first mobilization and chemotherapy plus GM-CSF with the second, there was significant increase in CFU-GM as well as CD34+ cell yield. Our results demonstrate that, at the doses studied, chemotherapy dose escalation and combining haemopoietic growth factor with chemotherapy improve progenitor cell yield in PBSC mobilization.

Estimation of the Progenitor Cell Yield in a Leukapheresis Product by Previous Measurement of CD34+ Cells in the Peripheral Blood

To assess whether measurement of CD34+ cells in the peripheral blood allows one to estimate the progenitor cell yields of subsequent leukapheresis procedures, 733 corresponding blood and leukapheresis samples were analyzed. Peripheral blood progenitor cells of cancer patients were mobilized with hematopoietic growth factors alone or postchemotherapy, and harvested processing 10 liters of blood for each leukapheresis product. The CD34+ cell count (CD34+ cells/microliter blood) correlated most closely with the progenitor cell yield in the corresponding leukapheresis product (CD34+ cells/kg bodyweight, r = 0.80), while the proportion of circulating CD34+ cells to the white blood and mononuclear cells predicted the yield less reliably (r = 0.74 and r = 0.60). The CD34+ cell yield was independent of the white blood count (r = 0.04), whereas a weak correlation was found between the mononuclear cell count and the number of CD34+ cells/kg collected (r = 0.42). It was unlikely to obtain the threshold quantity of 2.5 x 10(6) CD34+ cells/kg required for rapid engraftment when counts below 10 CD34+ cells/microliter blood were detected. At levels between 10 and 30 CD34+ cells/microliter sufficient autografts could be harvested, whereas 30-100 CD34+ cells/microliter were required to achieve this by a single leukapheresis. A surplus of CD34+ cells was likely above 100 CD34+ cells/microliter which could be useful for progenitor cell enrichment techniques. The correlation between the CD34+ cell count and progenitor cell yield was independent of the mobilizing regimen and whether leukaphereses had been performed previously. In conclusion, the number of CD34+ cells/microliter blood allows a reliable prediction of the CD34+ progenitor cell yield in subsequent leukapheresis procedures. However, rare cases of unexpectedly sufficient progenitor cell yields may be observed even at CD34+ cell levels below detection limit.

Comparison between Bone Marrow and G‐CSF‐Mobilized Peripheral Blood Allografts Undergoing Clinical Scale CD34 + Cell Selection

Allogeneic transplantation of selected CD34+ cells, rather than conventional transplantation of bone marrow (BM) harvest or peripheral blood (PB) leukapheresis products, has the advantage of reducing volume, facilitating storage and decreasing the amount of dimethylsulfoxide (DMSO) and cell lysis products, as well as reducing the number of T-lymphocytes responsible for graft-versus-host disease (GVHD). Using biotinavidin immunoaffinity columns (Ceprate SC system, CellPro; Bothell, WA), CD34+ cells were selected from each of 20 allografts (12 G-CSF-mobilized PB and 8 BM) collected from 14 HLA-identical normal healthy donors for transplantation. After the clinical-scale selection, the median concentration of CD34+ cells was 44.6% (range, 13% to 91%) in BM and 50.4% (range, 15% to 77%) in PB. Whereas 75% of the PB allografts had a CD34+ cell yield of more than 65%, only 37.5% of the BM allografts achieved such a yield, p < 0.01. The number of T-lymphocytes in the selected CD34+ cell allografts was reduced by two to three logs from a median of 4.2 x 10(9) to 7.8 x 10(5) CD3+ cells. The enrichment in CD34+ cells was 240-fold (range, 24- to 382-fold) in PB versus only 34-fold (range, 14- to 108-fold) in BM. Also, the enrichment in clonogenic cells was significantly more in PB (median value of 38.6-fold) than in BM (median value of 19.2-fold) and more in allografts from younger (< 50 years old) rather than older (> or = 50 years old) adult donors. A correlation was found between the percentage of CD34 or CD3+ cells before and after selection (r = 0.58 or r = 0.60, respectively, p < 0.05). Selective enrichment of the colony forming units-granulocyte-macrophage (CFU-GM) was found in all 20 allografts. The progenitor cell recovery after freezing and thawing was similar in BM and PB allografts, with a mean of about 60% for the CFU-GM and BFU-E. In the same six donors, the CD34+ cell yield was significantly more in the PB after mobilization (median 78.5%, range 50% to 90%) than in the BM before mobilization (median 41.5%, range 25% to 87%), p < 0.01. Ten patients with hematologic malignancies have been allotransplanted with 14 of the 20 selected CD34+ cells either combined BM + PB (n = 4) or single (n = 6) grafts. Seven patients did not develop acute GVHD, and only two patients developed > or = grade II GVHD, one of whom developed only grade II GVHD that resolved after brief treatment with corticosteriods. Only one patient showed chronic GVHD (skin and liver). The low incidence and severity of GVHD seen in the present study (only 30%) could be due to the two- to three-log reduction of T-lymphocytes in the selected CD34+ cell allotransplants. All 10 patients had stable hematological recovery, and seven had full donor hematopoiesis. In conclusion, G-CSF-mobilized PB leukapheresis products undergoing selection of CD34+ cells have a greater yield and enrichment of progenitor cells than BM harvests collected from HLA-identical normal healthy donors for allogeneic transplantation. The low incidence and severity of both acute and chronic GVHD (30%) seen in the present study are very encouraging.

G-CSF-induced mobilization of peripheral blood stem cells from healthy adults for allogeneic transplantation.

We investigated a dose-escalation effect of G-CSF (5, 10, and 15 micrograms/kg) on mobilization of committed and primitive hemopoietic progenitor cells, including CFU-GM, BFU-E, and long-term culture-initiating cells (LTC-IC) in addition to CD34+ cells and yields of progenitor cells in PBSC harvests obtained by leukapheresis of healthy adult donors. Results indicate that the mobilization of these progenitor cells is both dose and time dependent. Despite the very small number of healthy donors studied, it is estimated from our data that a sufficient number of CD34+ cells for allogeneic PBSC transplant (PBSCT) could be collected using a 5 day administration of 10 micrograms/kg of G-CSF to normal adult donors. Adverse effects include general fatigue and bone pain in most of the donors and fever and headache in some. These symptoms were well tolerated in most instances. Laboratory test abnormalities, including transient thrombocytopenia, increased platelet aggregation, and increased serum levels of some liver enzymes, were induced by G-CSF administration, but all were reversible within a short time. These observations suggest that hemopoietic stem cells for allogeneic PBSCT can be mobilized by short-term administration of a relatively high-dose G-CSF.

Estimation of the Progenitor Cell Yield in a Leukapheresis Product by Previous Measurement of CD34+ Cells in the Peripheral Blood

Estimation of the Progenitor Cell Yield in a Leukapheresis Product by Previous Measurement of CD34+ Cells in the Peripheral Blood