Mobilization and homing of peripheral blood progenitors is related to reversible downregulation of alpha4 beta1 integrin expression and function

Despite the wide use of mobilized peripheral blood (PB) progenitor cells (PBPC) for clinical transplantation the mechanism(s) underlying their mobilization and subsequent engraftment are still unknown. We compared the adhesive phenotype of CD34(+) colony-forming cells (CFC) in bone marrow (BM) and PB of normal donors before and after administration of granulocyte colony-stimulating factor (G-CSF) for 5 d. G-CSF-mobilized PB CFC cells adhered significantly less to BM stroma, fibronectin, and to the alpha4 beta1 binding fibronectin peptide, CS1, because of decreased expression of the alpha4 integrin. Since incubation of BM CD34(+) cells for 4 d with G-CSF at concentrations found in serum of G-CSF- treated individuals did not affect alpha4-dependent adhesion, G-CSF may not be directly responsible for the decreased alpha4-mediated adhesion of PB CFC. Culture of G-CSF-mobilized PB CD34(+) cells with cytokines at concentrations found in BM stromal cultures upregulated alpha4 expression and restored adhesion of mobilized PB CFC to stroma, fibronectin, and CS1. Adhesion of cultured, mobilized PB CFC to stroma and CS1 could not be further upregulated by the beta1 activating antibody, 8A2. This indicates acquisition of a maximally activated alpha4 beta1 integrin once PB CFC have been removed from the in vivo mobilizing milieu. Thus, decreased alpha4 expression on CD34(+) CFC in PB may be responsible for the aberrant circulation of mobilized PB CD34(+) cells. Reexpression of a maximally activated alpha4 beta1 integrin on mobilized PB CFC removed from the mobilizing in vivo milieu may contribute to the early engraftment of mobilized PBPC.     

Combination chemotherapy with mitoguazon, ifosfamide, MTX, etoposide (MIME) and G-CSF can efficiently mobilize PBPC in patients with Hodgkin's and non-Hodgkin's lymphoma

Many centers use CY and G-CSF to mobilize PBPC. In this study we explored whether a standard chemotherapy regimen consisting of mitoguazon, ifosfamide, MTX and etoposide (MIME) combined with G-CSF was capable of mobilizing PBPC in lymphoma patients. Twelve patients with Hodgkin's disease (HD) and 38 patients with non-Hodgkin's lymphoma (NHL) were mobilized with MIME/G-CSF. Most patients were heavily treated with different chemotherapy regimens receiving a median of 11 cycles (range 3 to 20) of chemotherapy prior to mobilization. It was found that the optimal time of PBPC harvest was at days 12 and 13 after initiating the mobilization regimen. The median number of collected CD34+ cells per kg body weight was 7.1 x 10(6) (range 0.5-26.2). More than 2.0 x 10(6) CD34+ cells/kg were achieved in 69% of the patients after one apheresis. When additional cycles of apheresis were done, only 6% failed to harvest this number of CD34+ cells. There was a statistically significant inverse correlation between the number of prior chemotherapy cycles and CD34+ cell yield (P = 0.003). No such association was found between CD34+ cell yield and prior radiotherapy. When MIME/G-CSF was compared with Dexa-BEAM/G-CSF, it was found that MIME/G-CSF tended to be more efficient in mobilizing PBPC in spite of being less myelotoxic. All patients transplanted with MIME/G-CSF mobilized PBPC had fast and sustained engraftment. These results demonstrate that an ordinary salvage chemotherapy regimen, such as MIME combined with G-CSF can be successfully used to mobilize PBPC.     

Marrow repopulating cells in mobilized PBPC can be serially transplanted for up to five generations or be remobilized in PBPC reconstituted mice

We have evaluated the durability of engraftment and the potential of remobilization in mice reconstituted with mobilized peripheral blood progenitor cells (PBPC). Female mice which had been reconstituted with cytokine-mobilized PBPC from male donors were serially transplanted into second, third, fourth and fifth lethally irradiated female recipients at intervals of 6-10 months. Male-derived hematopoiesis was determined in recipient mice at each serial transplantation. Male-positive CFCs were detected after 5 passages for 45 months, but declined from >95% at passage 1 to 74% at passage 2, 33% at passage 4, and 28% at passage 5. Long-term survival also declined from 97% at passage 2 to 53% at passage 4, and 27% at passage 5. The results demonstrated that mobilized PBPC were able to provide engraftment for more than 45 months, but the engraftment provided by mobilized PBPC decreased at each serial passage. In addition, mice reconstituted with mobilized PBPC (at 1 year post transplantation) were treated with the same cytokines as in the primary mobilization (remobilization). The remobilized PBPC were harvested and transplanted into lethally irradiated secondary recipients. Male-derived CFCs were evaluated at 20 months post transplantation. Mice transplanted with PBPC remobilized with rhG-CSF or rhG-CSF plus rrSCF-PEG showed 70% and 89% male-positive CFCs respectively, demonstrating that mice reconstituted with mobilized PBPC could be remobilized and that the remobilized PBPC were also capable of providing long-term hematopoietic reconstitution. Our studies demonstrated that mobilized PBPC have extensive proliferative or self-renewal capacity to provide durable engraftment and that marrow repopulating cells in PBPC reconstituted mice can be remobilized, suggesting that patients who relapse after PBPC transplantation may be remobilized for a second transplantation to support additional chemotherapy.     

Allogeneic bone marrow transplantation vs filgrastim-mobilised peripheral blood progenitor cell transplantation in patients with early leukaemia: first results of a randomised multicentre trial of the European Group for Blood and Marrow Transplantation

In a multicentre trial involving 20 transplant centres from 10 countries haematopoietic stem cells were obtained either from the bone marrow of 33 sibling donors or from the peripheral blood of 33 such donors after administration of filgrastim (10 microg/kg/day). The haematopoietic stem cells were infused into their HLA-identical recipients suffering from acute leukaemias in remission or chronic myeloid leukaemia in chronic phase. PBPC donors tolerated filgrastim administration and leukapheresis well with the most frequent side-effects being musculoskeletal pain, headache, and mild increases of LDH, AP, Gamma-GT or SGPT. Pain and haematoma at the harvest site and mild anaemia were the most frequent complaints of BM donors. Severe or life-threatening complications were not seen with any type of harvest procedure. Time to platelet recovery greater than 20 x 10(9)/l was 15 days (95% confidence interval (CI) 13-16 days) in the PBPCT group and 19 days (CI 16-25) in the BMT group. Time to neutrophil recovery greater than 0.5 x 10(9)/l was 14 days (CI 12-15 days) in the PBPCT group as compared to 15 days (CI 15-16 days) in the BMT group. The numbers of platelet transfusions administered to PBPCT and BMT patients were 12 (range: 1-28) and 10 (range: 3-39), respectively. Sixteen patients (48%) transplanted with bone marrow and 18 patients (54%) transplanted with PBPC developed acute GVHD of grades II-IV; acute GVHD of grades III or IV developed in six (18%) and seven (21%) patients, respectively. Kaplan-Meier plots for transplant-related mortality until day 100 and leukaemia-free survival at a median of 400 days after BMT or PBPCT showed no significant differences. Administration of filgrastim and leukapheresis in normal donors were feasible and well tolerated. The number of days with restricted activity and of nights spent in hospital was lower in donors of PBPC. Transplantation of PBPC to HLA-identical siblings with early leukaemia resulted in earlier platelet engraftment. The incidence of moderate to severe acute GVHD, transplant-related mortality, and leukaemia-free survival did not show striking differences. Further investigation of allogeneic PBPCT as a substitute for allogeneic BMT is warranted.     

Prevention of graft-versus-host disease and the induction of transplant tolerance by low-dose UV-B irradiation of BM cells combined with cyclosporine immunosuppression

GVHD is prevented and stable chimerism is induced in the rat BMT model by 700 J/m2 but not 100-500 J/m2 UV-B irradiation of allogeneic BM cells. Paradoxically, CsA which prevents GVHD in clinical BMT causes an aggressive autoimmune disease termed syngeneic GVHD in irradiated syngeneic BMT recipients after its withdrawal. Recently, we have shown that while 500-700 J/m2 UV-B irradiation of syngeneic BM cells combined with a 30-day course of CsA recipient immunosuppression impairs hemopoiesis due to lack of hemopoietic factors, a low dose of 100-300 J/m2 UV-B is effective in preventing CsA-induced autoimmune disease without endangering BM engraftment. This study extends these findings to the P-to-F1 hybrid and fully allogeneic rat BMT models and examines the effectiveness of low-dose UV-B irradiation of BM cells combined with a short course of CsA treatment in the prevention of GVHD and induction of transplant tolerance. Lethally gamma-irradiated (10.5 Gy) LBNF1 recipients of naive or UV-B irradiated (100-700 J/m2) BMT were treated with CsA (12.5 mg/kg/day) for 30 consecutive days after BMT. All lethally irradiated LBNF1 that did not receive BMT died in < 16 days, while animals transplanted with UV-B (700 J/m2) BMT survived > 1 year without GVHD. In contrast, all recipients of naive BMT died of lethal GVHD in < 50 days. Similarly, all recipients of naive BMT that received a 30-day course of CsA therapy developed severe GVHD with 60% mortality after cessation of CsA therapy. CsA-treated recipients of BMT irradiated with 700 J/m2 died between 12 and 25 days from failure of hemopoiesis. In contrast, CsA-treated recipients of 100-200 J/m2 UV-B irradiated BMT showed full BM engraftment without GVHD after cessation of CsA and survived > 1 year. These results were reproducible in the fully allogeneic UV-B BMT model. To test for donor-specific tolerance, the animals challenged 100 days after BMT with cardiac allografts accepted permanently (> 100 days) Lewis but not BN (non-BMT parental donor) cardiac allografts. Our results confirm that 700 J/m2 UV-B irradiation of BM cells combined with CsA recipient immunosuppression impairs the recovery capacity of stem cells while the use of lower UV-B (100-200 J/m2) is effective in preventing CsA-induced autoimmune disease without endangering BM engraftment and leads to induction of transplant tolerance.     

2-Hydroxyisonicotinate dehydrogenase isolated from Mycobacterium sp. INA1

The objective of this study was to identify factors associated with poor mobilization of peripheral blood progenitor cells (PBPCs) or delayed platelet engraftment after high-dose therapy and autologous stem cell transplantation in patients with lymphoma. Fifty-eight patients with Hodgkin's disease or non-Hodgkin's lymphoma underwent PBPC transplantation as the "best available therapy" at Memorial Sloan-Kettering Cancer Center (New York, NY) between 1993 and 1995. PBPCs were mobilized with either granulocyte colony-stimulating factor (G-CSF) alone (n = 19) or G-CSF following combination chemotherapy (n = 39). Forty-eight of these patients underwent a PBPC transplant, receiving a conditioning regimen containing cyclophosphamide, etoposide, and either total body irradiation, total lymphoid irradiation, or carmustine. A median number of 4.6 x 10(6) CD34+ cells/kg were obtained with a median of three leukapheresis procedures. Mobilization of PBPCs using chemotherapy plus G-CSF was superior to G-CSF alone (6.7 x 10(6) versus 1.5 x 10(6) CD34+ cells/kg; P = 0.0002). Poorer mobilization of progenitor cells was observed in patients who had previously received stem cell-toxic chemotherapy, including (a) nitrogen mustard, procarbazine, melphalan, carmustine or > 7.5 g of cytarabine chemotherapy premobilization (2.0 x 10(6) versus 6.0 x 10(6) CD34+ cells/kg; P = 0.005), or (b) > or = 11 cycles of any previous chemotherapy (2.6 x 10(6) versus 6.7 x 10(6) CD34+ cells/kg; P = 0.02). Platelet recovery to > 20,000/microliter was delayed in patients who received < 2.0 x 10(6) CD34+ cells (median, 13 versus 22 days; P = 0.06). Patients who received > or = 11 cycles of chemotherapy prior to PBPC mobilization tended to have delayed platelet recovery to > 20,000/microliter and to require more platelet transfusions than less extensively pretreated patients (median, 13.5 versus 23.5 days; P = 0.15; median number of platelet transfusion episodes, 13 versus 9; P = 0.17). These data suggest that current strategies to mobilize PBPCs may be suboptimal in patients who have received either stem cell-toxic chemotherapy or > or = 11 cycles of chemotherapy prior to PBPC mobilization. Alternative approaches, such as ex vivo expansion or the use of other growth factors in addition to G-CSF, may improve mobilization of progenitor cells for PBPC transplantation.     

Transplantation of allogeneic peripheral hematopoietic progenitor cells instead of bone marrow

In a pilot study we tested the feasibility and safety of peripheral blood precursor cells instead of bone marrow cells for allogeneic transplantation. 13 patients, 7 male and 6 female between 24 and 52 years of age with hematological malignancies (10 with acute leukemias, 3 with myeloproliferative syndromes-were conditioned for bone marrow transplantation with VP-16, cyclophosphamide and total body irradiation followed by graft-versus-host disease prophylaxis with cyclosporin and methotrexate. Precursor cells were mobilized in the donors by granulocyte colony stimulating factor (G-CSF, Neupogen) 10 micrograms/kg s.c. from day-5 on. A total of 14.05 x 10(8) nucleated cells/kg recipient body weight (range 9.52-20.23 x 10(8)/kg), corresponding 6.82 x 10(6)/kg CD 34+ cells (range 1.43-15.84 x 10(8)/kg) or 113.9 x 10(4) CFU/kg (range 45.15-431.64 x 10(4)/kg) were collected by 3 phereses (1 patient 5 phereses) of 27-45 liters and infused without further manipulation. All patients engrafted with a recovery of total white blood cell count > 1 x 10(9)/l on day 15 (day 10-26) and of platelets > 20 x 10(9)/l on day +18 (day 12-39). 11 of the 12 patients developed aGvHD, 8 with grade II, 3 with grade > or = II. 9 of 13 patients are alive and well +4 to +16 months posttransplant, 3 patients died of aGvHD, one of veno-occlusive disease. These preliminary results confirm the capacity of peripheral blood precursor cells for rapid and complete engraftment in the allogeneic setting. Whether they induce more or equal aGvHD is an open question. Their value in allogeneic transplantation is currently under investigation in prospective randomized trials.     

Research issues in cancer survivorship: report of a workshop sponsored by the Office of Cancer Survivorship, National Cancer Institute

We present the results of a prospective, randomised study comparing PBPC and BM focusing on engraftment, acute and chronic GVHD and survival. Forty patients with haematological malignancies received HLA-identical sibling BM (group A) or PBPC (group B). Evaluable patients were 19 (A) and 18 (B). Median age was 35 (17-56) in A and 29.5 (9-51) in B. Conditioning was mainly Bu-Cy2; GVHD prophylaxis was CSA-MTX. PBPC were harvested after 5 days of G-CSF 10 microg/kg/day. Median days for an ANC >0.5 x 10(9)/l was 18 (13-30) in A and 16 (11-25) in B (P = 0.10). Platelets >20 x 10(9)/l occurred at +17 (10-40) in A and +12 (9-36) in B (P = 0.01). The probability of > or =2 grade a-GVHD was 19% (A) and 27% (B) (P = 0.53). The probability of all grade c-GVHD was 70% with BM. In spite of the small number of patients in group B (PBPC), our data suggest the great majority of them will have c-GVHD (P = 0.08); extensive disease was present in 50 and 100%, respectively (P = 0.05). The estimates of overall survival for A and B at 1000 days are 51 and 47%, respectively (P = 0.67); DFS at 1000 days are 52 and 58%, respectively (P = 0.50). PBPC resulted in faster platelet engraftment. The incidence of acute and chronic GVHD was similar in both groups, but the severity of c-GVHD was higher with PBPC. No differences in survival and DFS have been observed to date.     

Antimicrobial substances produced by Staphylococcus aureus strains isolated from cattle in Brazil

Many studies have documented faster engraftment after transplantation with peripheral blood stem cells (PBSC) compared to bone marrow (BM) stem cells. Most comparisons, however, have been between unprimed BM and primed PBSC. We have collected engraftment data on 39 patients from 4 Danish centres and compared G-CSF primed BM with G-CSF primed PBSC in malignant lymphoma and solid tumours. In the lymphoma group 6 BM transplants were compared with 8 PBSC transplants, whereas in the testicular cancer group 16 BM transplants were compared with 9 PBSC transplants. In the lymphoma group, the time to platelet engraftment (platelets >20x10(9)/l unsupported) was median 15 d in PBSC transplants and median 34 d in BM transplants (p=0.003). In the solid tumour patients the difference in time to platelet engraftment was 11 and 18 d in PBSC and BM transplants, respectively (p<0.0001). In an attempt to explain this difference we performed CD34+ subset analysis of BM and PBSC. This analysis revealed a higher content of lineage restricted cells (CD34+CD61+ and CD34+GlyA+) in PBSC compared to BM. In conclusion, G-CSF mobilized PBSC seems to result in faster engraftment than G-CSF primed BM, which could be explained by an increased number of lineage specific progenitors in PBSC compared to BM.     

Rapid engraftment without significant graft-versus-host disease after allogeneic transplantation of CD34+ selected cells from peripheral blood

We have prospectively evaluated the feasibility and results of the biotin-avidin immunoadsorption method (Ceprate SC system) for a phase I/II study of T-cell depletion of granulocyte colony-stimulating factor (G-CSF) mobilized peripheral blood progenitor cells (PBPC) for allogeneic transplantation. Twenty consecutive patients, median age, 40 years (21 to 54) and diagnoses of chronic myeloid leukemia in chronic phase (n = 5), acute myeloblastic leukemia (n = 7), acute lymphoblastic leukemia (n = 2), chronic myelomonocytic leukemia (n = 1), refractory anemia with excess of blasts in transformation (n = 3), histiocytosis X (n = 1), and chronic lymphocytic leukemia (n = 1), were conditioned with cyclophosphamide (120 mg/kg) and total body irradiation (13 Gy; 4 fractions). HLA identical sibling donors received G-CSF at 10 microg/kg/d subcutaneously (SC); on days 5 and 6 (19 cases) and days 5 to 8 (1 case) donors underwent 10 L leukapheresis. PBPC were purified by positive selection of CD34+ cells using immunoadsorption biotin-avidin method (Ceprate SC) and were infused in the patients as the sole source of progenitor cells. No growth factors were administered posttransplant. The median recovery of CD34+ cells after the procedure was of 65%. The median number of CD34+ cells infused in the patients was 2.9 (range, 1.5 to 8.6) x 10(6)/kg. The median number of CD3+ cells administered was 0.42 x 10(6)/kg (range, 0.1 to 2). All patients engrafted. Neutrophil counts >500 and >1,000/microL were achieved at a median of 14 days (range, 10 to 18) and 15 days (range, 11 to 27), respectively. Likewise, platelet counts >20,000 and >50,000/microL were observed at a median of 10 days (range, 6 to 23) and 17 days (range, 12 to 130), respectively. Graft-versus-host disease (GVHD) prophylaxis consisted of cyclosporine plus methylprednisolone. No patient developed either grade II to IV acute or extensive chronic GVHD. After a median follow-up of 7.5 months (range, 2 to 22) three patients have relapsed, and one of them is again in hematologic and cytogenetic remission after infusion of the donor lymphocytes. Two patients died in remission: one on day +109 of pulmonary aspergillosis and the other on day +251 of metastasic relapse of a previous breast cancer. Sixteen of the 20 patients are alive in remission after a median follow-up of 7.5 months (range, 2 to 22). In conclusion, despite the small number of patients and limited follow-up, it appears that this method allows a high CD34+ cell recovery from G-CSF mobilized PBPC and is associated with rapid engraftment without significant GVHD, and with low transplant related mortality.     

Mobilization of peripheral blood progenitor cells by disease-specific chemotherapy in patients with soft tissue sarcoma

We investigated peripheral blood progenitor cell (PBPC) mobilization by disease-specific chemotherapy in patients with metastatic soft tissue sarcoma (STS). Nine patients, five females and four males, aged 12-51 years, pretreated by one to nine courses of cytotoxic chemotherapy, underwent STS-specific mobilization followed by G-CSF at 5 microg/kg/day. PBPC were collected by 19 conventional-volume aphereses (8-12 l) with one to four procedures in individual patients. Leukaphereses started on median day 15 (range 13-18) from the first day of mobilization chemotherapy at medians of 25.8 x 10(3) WBC/microl (6.8-46.9), 3.5 x 10(3) MNC/microl (1.1-8.8), 122 x 10(3) platelets/microl (72-293) and 30.7 CD34+ cells/microl (6.7-207.8). Cumulative harvests resulted in medians of 4.6 x 10(8) MNC/kg (3.0-6.4), 2.9 x 10(6) CD34+ cells/kg (1.1-11.1) and 12.0 x 10(4) CFU-GM/kg (2.0-37.8). Eight patients underwent high-dose chemotherapy (HDCT) followed by PBPC rescue. Seven patients recovered hematopoiesis at medians of 12 days (8-15) for ANC >0.5 x 10(3)/microl and 14 days (8-27) for platelets >20 x 10(3)/microl. One patient, who received 1.6 x 10(6) CD34+ cells/kg, exhibited delayed ANC recovery on day +37 and failed to recover platelets until hospital discharge on day +55. We conclude that in patients with metastatic STS, who are pretreated by standard chemotherapy, PBPC can be mobilized by a further course of STS-specific chemotherapy plus G-CSF. One to four conventional-volume aphereses result in PBPC autografts that can serve as hematopoietic rescue for patients scheduled for HDCT.     

粒细胞集落刺激因子对供体造血干细胞移植物中树突状细胞的影响

目的 探讨粒细胞集落刺激因子(G-CSF)对正常异基因造血干细胞移植供者外周血与骨髓移植物中Ⅰ型树突状细胞(DC1)、Ⅱ型树突状细胞(DC2)的数量及DC2/DC1比例的影响.方法 以G-CSF每天10μg/kg动员5 d后,以流式细胞术(FCM)检测11例G-CSF动员的异基因外周血造血干细胞移植物及20例G-CSF动员的异基因骨髓移植物中的DC1、DC2数量及DC2/DC1比例,并与8例正常供者动员前外周血及10例健康者动员前骨髓进行比较.结果 动员前后骨髓DC2由14.37×106/L增至29.68×106/L(t=2.433,P=0.022),而骨髓DC1分别为13.77×10a/L和18.88×106/L(t=0.625,P=0.541);DC2/DC1比例在动员后为1.83±0.81,较动员前的1.12±0.32明显升高(t=2.685,P=0.013).正常供者以G-CSF动员前、后移植物中外周血DC2数量分别为14.92×106/L和26.76×106/L(t=2.390,P=0.029),DC2/DC1比例分别为1.00±0.37和2.02±1.43(t=2.158,P=0.044),但外周血DC1分别为14.21×106/L和18.02×106/L(t=0.625,P=0.541).结论 移植前以G-CSF动员正常异基因干细胞移植供者,可选择性提高外周血及骨髓移植物中DC2的数量,而DC1数量无明显增加.     

Population dynamics of the monogenean Anoplodiscus cirrusspiralis on the snapper, Pagrus auratus

Mobilized peripheral blood progenitor cells (PBPC) have been shown to differ qualitatively from bone marrow (BM) progenitors. The released progenitor cells are predominantly in G0/G1 and show a relatively high percentage of rhodamine dull cells. Within the BM these last two features are characteristic of the more primitive progenitors. Although the mobilized PB cells can give rise to long-term repopulation and thus contain stem cells, the frequency of stem cells is not much higher if long-term initiating cell (LTC-IC) assays are used. To determine whether quiescent stem cells are selectively released or the low-cycle status of PB progenitors is related to the release from the BM microenvironment, the cell cycle status and rhodamine content in the PB and BM during mobilization were studied and compared with steady-state BM. More differentiated and more primitive progenitors were separated based on differentiation markers and cloned in single cell assay. In mobilized PB 54% of the CD34+ cells (n=5) were rhodamine dull compared to 22% in steady-state BM (P=0.014) [n=6]. The percentage of CD34+ cells in the S/G2M phases of the cell cycle was 2.1% in the mobilized PB (n=11), and 18% in steady-state BM (n=11) [P=0.002]. During mobilization the fraction of cells in the S/G2M phase of the cell cycle was 16% in BM (n=7), similar to steady-state BM (P=0.34). The released progenitors represented a selection of BM progenitors, with significantly more primitive progenitors (CD34+/13+/33dim) and less lymphoid precursors (CD34+/19+). Within the more differentiated CD34+113+/33bright, myelomonocytic precursors, both in PB as well as in BM, the percentage S/G2M was relatively higher than in the CD34+/13+/33dim subfraction: in normal BM: median 18% vs 8% (P=0.006) [n=8]; in mobilized PB 3% vs 2% (P=0.03) [n=10]; and in BM during mobilization 24% vs 7% (P=0.01) [n=6]. The cycle status of mobilized PB progenitors was low both in the primitive and more differentiated subfractions. During the mobilization period the BM progenitors are cycling as in steady-state BM. The low-cycle status of the mobilized PB progenitors may be related to the loss of contact with the micro-environment.     

A randomized trial of granulocyte colony-stimulating factor (Neupogen) starting day 1 vs day 7 post-autologous stem cell transplantation

The purpose of the study was to evaluate the effect of delayed granulocyte colony-stimulating factor (G-CSF) use on hematopoietic recovery post-autologous peripheral blood progenitor cell (PBPC) transplantation. Patients were randomized to begin G-CSF on day +1 or day +7 post transplantation. Thirty-seven patients with lymphoma or myeloma undergoing high-dose therapy and autologous PBPC rescue were randomized to daily subcutaneous G-CSF beginning on day +1 or day +7 post-transplant. Patients < or =70 kg received 300 microg/day and >70 kg 480 microg/day. All patients were reinfused with PBPCs with a CD34+ cell count >2.0 x 10(6)/kg. Baseline characteristics of age, sex and CD34+ cell count were similar between the two arms, the median CD34+ cell count being 5.87 x 10(6)/kg in the day +1 group and 7.70 x 10(6)/kg in the day +7 group (P=0.7). The median time to reach a neutrophil count of >0.5 x 10(9)/l was 9 days in the day +1 arm and 10 days in the day +7 arm, a difference which was not statistically significant (P=0.68). Similarly, there was no difference in median days to platelet recovery >20000 x 10(9)/l, which was 10 days in the day +1 arm and 11 days in the day +7 arm (P=0.83). There was also no significant difference in the median duration of febrile neutropenia (4 vs 6 days; P=0.7), intravenous antibiotic use (7 vs 8 days; P=0.54) or median number of red blood cell transfusions (4 vs 7 units; P=0.82) between the two arms. Median length of hospital stay was 11 days post-PBPC reinfusion in both groups. The median number of G-CSF injections used was 8 in the day +1 group and 3 in the day +7 group (P < 0.0001). There is no significant difference in time to neutrophil or platelet recovery when G-CSF is initiated on day +7 compared to day +1 post-autologous PBPC transplantation. There is also no difference in number of febrile neutropenic or antibiotic days, number of red blood cell transfusions or length of hospital stay. The number of doses of G-CSF used per transplant is significantly reduced with delayed initiation, resulting in a significant reduction in drug costs. For patients with an adequately mobilized PBPC graft, the initiation of G-CSF can be delayed until day +7 post-PBPC reinfusion.     

Effect of FLT3 ligand and granulocyte colony-stimulating factor on expansion and mobilization of facilitating cells and hematopoietic stem cells in mice: kinetics and repopulating potential

We have previously identified a cellular population in murine bone marrow that facilitates engraftment of highly purified hematopoietic stem cells (HSC) across major histocompatibility complex (MHC) barriers without causing graft-versus-host disease. Here we investigated the effect of flt3 ligand (FL) and granulocyte colony-stimulating factor (G-CSF) on the mobilization of facilitating cells (FC) and HSC into peripheral blood (PB). Mice were injected with FL alone (day 1 to 10), G-CSF alone (day 4 to 10), or both in combination. The number of FC (CD8(+)/alpha betaTCR-/gamma deltaTCR-) and HSC (lineage-/Sca-1(+)/c-kit+) was assessed daily by flow cytometry. Lethally irradiated allogeneic mice were reconstituted with PB mononuclear cells (PBMC). FL and G-CSF showed a highly significant synergy on the mobilization of FC and HSC. The peak efficiency for mobilization of FC (21-fold increase) and HSC (200-fold increase) was reached on day 10. Our data further suggest that the proliferation of FC and HSC induced by FL in addition to the mobilizing effect mediated by G-CSF might be responsible for the observed synergy of both growth factors. Finally, the engraftment potential of PBMC mobilized with FL and G-CSF or FL alone was superior to PBMC obtained from animals treated with G-CSF alone. Experiments comparing the engraftment potential of day 7 and day 10 mobilized PBMC indicate that day 10, during which both FC and HSC reached their maximum, might be the ideal time point for the collection of both populations.     

Mobilization of hematopoietic stem and progenitor cell subpopulations from the marrow to the blood of mice following cyclophosphamide and/or granulocyte colony-stimulating factor

Committed progenitor cells and primitive stem cells mediate early and sustained engraftment, respectively, after lethal irradiation and stem cell transplantation. Peripheral blood stem cells (PBSC) from unstimulated mice are deficient in both cell types. To study techniques to mobilize both progenitor cells and primitive stem cells from the marrow to the blood, we collected peripheral blood from C57BL/6 mice 6 to 7 days after a single dose of cyclophosphamide (CY; 200 mg/kg intraperitoneally), after recombinant human granulocyte colony-stimulating factor (rhG-CSF) (250 micrograms/kg/d twice per day subcutaneously for 4 days), or after CY followed by G-CSF. Significant increases in white blood cell counts (1.6- to 2.7-fold) and circulating day 8 colony-forming unit spleen (CFU-S) (11- to 36-fold) were seen with all three mobilization methods compared with unstimulated control mice. Transplantation of mobilized blood stem cells into lethally irradiated hosts decreased the time to erythroid engraftment. Blood stem cells were analyzed for primitive stem cell content by Rs, an assay for CFU-S self-renewal, and competitive repopulation index (CRI), an assay of long-term repopulating ability. The primitive stem cell content of unstimulated blood was clearly deficient, but was significantly increased following mobilization, approaching normal bone marrow levels. These results were confirmed by an in vitro limiting dilution long-term culture assay that measures the frequency of progenitor cells and primitive stem cells. Mobilization following CY + G-CSF was accompanied by a marked loss of both progenitor cells and primitive stem cells in the marrow. In contrast, following G-CSF alone the progenitor cell and primitive stem cell content of the marrow was unchanged. Stem cell mobilization following CY + G-CSF was not affected by previous exposure of donors to cytosine arabinoside or cyclophosphamide, but was significantly reduced by previous exposure to busulfan. These data show that stem cell content in the blood may reach near-normal marrow levels after mobilization, the mobilization from the marrow to the blood is temporary and reversible, the specific technique used may mobilize different subpopulations of stem cells, and the type of prior chemotherapy may influence the ability to mobilize stem cells into the blood.     

Allogeneic peripheral blood stem cell transplantation in 30 patients with hematologic disorders

Thirty patients (median age of 32 years; range, 6-61) with hematologic disorders received unmanipulated peripheral blood stem cell transplants from HLA-matched or one-antigen-mismatched related donors following myeloablative therapy for acute lymphoblastic leukemia (7), acute myelogenous leukemia (6), chronic myelogenous leukemia (8), myelodysplastic syndrome (3), or other disorders (6). Granulocyte colony stimulating factor (G-CSF) mobilized peripheral blood stem cells were collected from donors in 1 to 3 aphereses. The apheresis products contained mean counts of 11.3 x 10(8) (range, 3.8-17.2) nucleated cells/kg and 6.7 x 10(6) (range, 1.3-16.7) CD34+ cells/kg. Graft-versus-host-disease (GVHD) prophylaxis consisted of cyclosporin A plus methotrexate, or FK506 plus methotrexate. All patients received G-CSF following their transplant. Although 1 patient died of pneumonia 6 days after transplantation, the others demonstrated rapid engraftment. Median days to recovery to 500/microliter neutrophils and 20,000/microliter platelets were 13 (range, 8-21) and 14 (range, 1-23) days, respectively. The incidence of acute GVHD grade II-IV was 33%; chronic GVHD developed in 57% of the assessable patients. There were no episodes of graft failure or rejection. Nineteen patients (63%) were alive and in complete remission from 147 to 839 days following their transplant (median follow-up of 560 days). Further follow-up study will be required to assess the incidence of chronic GVHD and graft-versus-leukemia (GVL) effects.     

Autologous transplantation of mobilized peripheral blood CD34+ cells selected by immunomagnetic procedures in patients with multiple myeloma

In the use of autologous PBPC transplantation in patients with multiple myeloma, contamination of PBPC with myeloma cells is commonly observed. Enrichment for CD34+ cells has been employed as a method of reducing this contamination. In this study the reduction of myeloma cells in PBPC was accomplished by the positive selection of CD34+ cells using immunomagnetic bead separation (Isolex 300 system). PBPC were mobilized from 18 patients using cyclophosphamide (4.5 g/m2) and G-CSF (10 microg/kg/day). A median of two leukaphereses and one selection was performed per patient. The median number of mononuclear cells processed was 3.50 x 10(10) with a recovery of 1.11 x 10(8) cells after selection. The median recovery of CD34+ cells was 48% (range 17-78) and purity was 90% (29-99). The median log depletion of CD19+ cells was 3.0. IgH rearrangement, assessed by PCR, was undetectable in 13 of 24 evaluable CD34+ enriched products. Patients received 200 mg/m2 of melphalan followed by the infusion of a median of 2.91 x 10(6)/kg CD34+ cells (1.00-16.30). The median time to absolute neutrophil count >0.5 x 10(9)/l was 11 days, and sustained platelet recovery of >20 x 10(9)/l was 14 days. We conclude that immunomagnetic-based enrichment of CD34+ cells results in a marked reduction in myeloma cells without affecting engraftment kinetics.     

A partial conditioning strategy for achieving mixed chimerism in the rat: tacrolimus and anti-lymphocyte serum substantially reduce the minimum radiation dose for engraftment

Development of partial conditioning strategies to achieve reliable engraftment of allogeneic bone marrow with minimum recipient morbidity could extend the therapeutic application of bone marrow transplantation (BMT) to enzyme deficiency states, hemoglobinopathies, autoimmune diseases, and the induction of tolerance for solid organ and cellular allografts. In this study we describe a nonmyeloablative rat BMT model and examine the effect of clinically available immunosuppressants on the minimum amount of total body irradiation (TBI) required for allogeneic engraftment. Donor ACI marrow was depleted of T cells using immunomagnetic beads and transplanted to major histocompatibility complex- and minor antigen-mismatched Wistar Furth (WF) rats (ACI --> WF) conditioned with varying doses of TBI. Recipients conditioned with TBI alone required myeloablation with 1000 cGy for reliable allogeneic marrow engraftment. Administration to WF recipients of a single dose of anti-lymphocyte serum (ALS) 5 days prior to BMT together with a limited course of tacrolimus (1 mg/kg/day) resulted in engraftment of ACI bone marrow at only 500 cGy TBI. ACI --> WF recipients were stable mixed chimeras (mean donor chimerism 49% at 330 days post-BMT). Chimerism was multilineage. All recipient animals were free of graft-versus-host disease. These results suggest that a nonmyeloablative conditioning strategy based on low-dose TBI and a limited course of tacrolimus plus ALS can produce long-term mixed multilineage chimerism.     

Hematopoietic progenitor cell collection and neoplastic cell contamination in breast cancer patients receiving chemotherapy plus granulocyte-colony stimulating factor (G-CSF) or G-CSF alone for mobilization

BACKGROUND: We compared hematopoietic progenitor cell (HPC) collection and neoplastic cell contamination in breast cancer patients given cyclophosphamide (CTX) plus granulocyte-colony stimulating factor (G-CSF) or G-CSF alone for mobilization. PATIENTS AND METHODS: In 57 stage II-III breast cancer patients, CD34+ cells, colony-forming units-granulocyte macrophage (CFU-GM), early HPC and breast cancer cells were counted in HPC collections obtained after CTX plus G-CSF (n = 27) or G-CSF-alone mobilization (n = 30). RESULTS: The CD34+ cell collection was about two-fold greater after CTX plus G-CSF mobilization (11.0 +/- 7.9 vs. 5.8 +/- 3.5 x 10(6)/kg, P < 0.001). Similarly, the total number of CFU-GM, CD34+CD38- cells and of week-5 cobblestone area forming cells (CAFC) collected was significantly higher in patients mobilized with CTX plus G-CSF. Breast cancer cells were found in the apheresis products of 22% of patients mobilized with CTX plus G-CSF and in 10% of patients mobilized with G-CSF alone (P = 0.36). Of seven patients who failed G-CSF-alone mobilization and eventually underwent chemotherapy plus G-CSF mobilization, none had cytokeratin-positive cells after G-CSF mobilization, whereas four out of seven had cytokeratin-positive cells after chemotherapy plus G-CSF (P = 0.07 by chi 2 test). CONCLUSION: The CTX plus G-CSF mobilization protocol was associated with a significantly higher HPC collection. However, this benefit was not accompanied by a reduction in the incidence of tumor-contaminated HPC graft.