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Blood, Vol. 90 No. 12 (December 15), 1997:
pp. 4779-4788
By
From the Divisions of Hematology, Pediatric Hematology/Oncology, the University of Washington, Seattle, WA; and the Fred Hutchinson Cancer Research Center, Seattle, WA.
Although the use of cytokine-mobilized peripheral blood stem cells has gained a significant momentum in clinical transplantation, the mobilization schemes practiced are guided by a great deal of empiricism. The mechanism(s) by which cytokines or chemokines, alone or in combination, bring about redistribution of stem/progenitor cells from bone marrow to peripheral blood are poorly understood. Likewise the fate of mobilized stem/progenitor cells and their biological properties are incompletely defined. One of the leading hypotheses to explain the mechanism of cytokine-induced mobilization encompasses the view that cytokines disrupt, directly or indirectly, cytoadhesive interactions of stem/progenitor cells with their bone marrow stroma. Compatible with this view are changes in the expression and/or function of several cytoadhesion molecules, especially integrins, postmobilization, and extensive in vitro experimentation supporting the concept of cytokine/integrin interactions. To provide a further insight on the cytokine/integrin interplay in vivo, we have combined cytokine treatments with anti-integrin treatments for mobilization in primates and mice. We found that anti-VLA4 treatment combined with either granulocyte colony-stimulating factor (G-CSF ) treatment or kit ligand treatment leads to significant enhancement of mobilization efficiency (fivefold to eightfold) well above the levels produced by either cytokine alone or anti-VLA4 treatment alone. Similar enhancement was seen when combinations of cytokines, ie, G-CSF plus kit ligand or G-CSF plus Flt3-ligand were used with anti-VLA4 in primates and mice. Furthermore, when anti-VLA4 was given in 5-Fluorouracil-treated primates, significant numbers of progenitor cells were circulating for several days during the recovery period only in the anti-VLA4 treated animals. These data suggest that (1) the effect of anti-VLA4 on mobilization, when used alone, is unlikely to be mediated by secondary cytokine elaboration in vivo; (2) three different cytokines and their combinations do not appear to influence the in vivo responsiveness to anti-VLA4 in coadministration schemes; (3) even if cytokine treatments on their own exert downmodulation of VLA4 function, the target progenitor cells influenced by anti-VLA4 or by cytokines may not necessarily overlap; and (4) augmentation of mobilization in cytokine/anti-VLA4 treatments is most likely caused by an amplification of the pool of target cells on which anti-VLA4 exerts its effects. Because cytokines or anti-VLA4 are each capable of mobilizing long-term repopulating cells and because we show with the present studies that anti-VLA4 in an autologous bone marrow cell transplantation setting does not cause any delay in engraftment, the combination of cytokine/anti-integrin treatment enhancing mobilization may have a clinical use.
IN STEADY STATE hematopoiesis only small numbers of hematopoietic progenitors circulate in peripheral blood.1,2 Administration of cytokines, such as granulocyte colony-stimulating factor (G-CSF ), kit ligand (KL), interleukin-1 (IL-1), IL-7, IL-8, IL-11, or Flt3 ligand (FL) and cytotoxic drugs, such as cyclophosphamide, is associated with striking increases in the number of circulating hematopoietic progenitors in mice, primates, and humans.3-7 In addition to mobilizing committed progenitors, these agents increase the concentration of long-term repopulating cells in the peripheral blood. As a consequence, peripheral blood has become an increasingly important source of hematopoietic progenitors for use in both autologous and allogeneic stem cell transplantation.8
The mechanism(s) by which cytokines/chemokines or cytotoxic drugs cause progenitor mobilization remain poorly understood. Although an increase in the overall size of the progenitor pool and in the survival of circulating progenitors may contribute to this process, it is also clear that dramatic increases in the number of circulating progenitors can be achieved in the absence of any increase in the size of the progenitor pool. For example, IL-1 or IL-8 cause progenitor mobilization within minutes of administration before any increase in overall progenitor number has occurred.9,10 Thus, a major underlying event in progenitor cell increases in peripheral blood applicable to all treatments is a change in the distribution of hematopoietic progenitors between the bone marrow and peripheral blood.
Hematopoietic progenitors and stem cells in bone marrow are in close proximity with hematopoietic stromal cells and their extracellular matrix. Interactions between these cells and stromal cells are important not only in retaining them within the marrow but for their subsequent proliferative expansion and differentiation.11-13 Several cytoadhesion molecules of the integrin or selectin family or CD44 and certain chemokines are considered to be instrumental in the interactions between hematopoietic cells and stromal cells.14-16 As this association is lost during the stem/progenitor exportation from the bone marrow, one of the leading hypotheses advanced to explain progenitor mobilization is that there are alterations in the cytoadhesive interactions of progenitor/stem cells with the bone marrow microenvironment.3 Direct in vivo evidence implicating the involvement of cytoadhesion molecules in mobilization was provided by our in vivo treatments with antibodies to VLA4 in primates17 or mice,18 which resulted in peripheralization of progenitors. In vitro experiments have also shown that cytokines are able to modulate the functional activity of integrins in certain cell populations.19-24 Because of these data and direct studies with mobilized progenitor cells, alterations in the expression and/or functional status of integrins after administration of cytokines have been embraced as the main mechanism underlying progenitor mobilization induced by cytokines.25-28 However, it is likely that additional mechanisms exerted on progenitor cells and/or stromal cells cooperate for these effects, but these remain undefined.
To provide further insights into the mechanism(s) of cytokine-induced mobilization as well as that of anti-VLA4, we have used in the present studies combinations of cytokines and anti-VLA4 treatment and studied the consequences in progenitor mobilization. We have found that concurrent blockade of VLA4-mediated progenitor adhesion achieved by administration of anti-VLA4 could augment the mobilization of hematopoietic progenitors yielded by G-CSF, KL, or FL and their combinations. We speculate that this augmentation is achieved by the action of anti-VLA4 on an expanded pool of target cells induced by cytokines. Further experiments are in progress to secure these speculations. Whatever the mechanism, the significant augmentation achieved could be exploited for clinical purposes to boost mobilization in certain cases of transplantation. This statement is supported by the fact that anti-VLA4 alone is capable of mobilizing long-term repopulating cells and that ex vivo anti-VLA4-treated cells do not compromise their engraftment in vivo, as shown in the present studies.
Studies in Mice
Studies in Nonhuman Primates
Cell Cycle Studies To provide estimates on the number of cycling cells present in bone marrow or peripheral blood before or after anti-VLA4 or G-CSF treatments, we used the Ara-C suicide method as described by Cannistra et al.36
Anti-VLA4 Antibody Mobilizes CFU-S and Long-Term Repopulating Cells In previous studies we have shown that antibodies to VLA4 increased the numbers of clonogenic progenitors in peripheral blood17 presumably by displacing them from bone marrow. To study whether more primitive hematopoietic progenitors or stem cells are also mobilized, we assessed the effect of anti-VLA4 antibody treatment on the number of circulating CFU-S, radioprotective cells, and long-term repopulating cells. Treatment with anti-VLA4 for 3 consecutive days increased the number of circulating CFU-S from ~0.2/mL of blood (1 CFU-S in six control spleens) to 53.3 ± 8.25 CFU-S/mL in the group of six mice treated with anti-VLA4. Recipient mice were injected with 150 µL of blood from VLA4 treated but 1 mL from PBS/BSA-treated animals. We next studied whether the anti-VLA4 treatment mobilized cells with radioprotective capacity. Survival of lethally irradiated mice transplanted with mononuclear cells isolated from peripheral blood of mice treated with either anti-VLA4 or PBS/BSA was compared. All mice (14 of 14) transplanted with mononuclear cells (5 × 105 per mouse) from the anti-VLA4-treated animals survived 30 days after transplantation, whereas only 14% of mice (2 of 14) who received mononuclear cells from PBS/BSA-treated animals were alive 30 days after transplantation. All mice that received radiation alone without donor blood died. Eight months after the transplantation of mononuclear cells from blood harvested from mice treated with three doses of anti-VLA4, 12 mice were alive and 9 of them were sacrificed to assess the level of donor cells in the peripheral blood using a Y chromosome-specific probe.32 All mice studied showed evidence of engraftment with donor long-term reconstituted stem cells and the percentage of Y chromosome-positive interphase nuclei were from 70% to 90%. Chimerism was not assayed on mice transplanted with mononuclear cells from PBS/BSA-treated mice, because no mice survived long term.Effect of Anti-VLA4 Treatment on Progenitor Proliferative Status To test whether anti-VLA4 treatment per se exerted any influence on proliferation of progenitors as evaluated by our in vitro assays or in vivo (1) we performed clonogenic in vitro assays in the presence or absence of the anti-VLA4 antibody or control antibody (anti-CD18); (2) we assessed bone marrow cellularity before and after 3-day antibody treatment in primates, or the cellularity per femur in a group of mice treated with anti-VLA4 (3-day treatment) compared with a vehicle-treated control group; and (3) we assessed cell cycling changes, post-anti-VLA4 treatment, and compared them with pretreatment values. In three independent experiments using mononuclear cells from bone marrow or peripheral blood or CD34+ cells we found no evidence that the addition of anti-VLA4 or anti-CD18 antibody influenced the number of the clonogenic progenitors or the size of colonies in vitro (data not shown). Regarding bone marrow cellularity, a group of 5 mice treated with anti-VLA4 or 10 vehicle-treated controls had 21.3 ± 1.4 × 106 nucleated cells or 19.4 ± 0.5 × 106 per femur, respectively, and a total progenitor content of 56,818 ± 5,261 or 58,200 ± 3,000 per femur, respectively. In the two primates treated for 3 days with anti-VLA4 (1 mg/kg/d) we aspirated bone marrow before treatment and after the 3-day treatment. Before treatment, bone marrow total progenitor content was 17,208 (BFUe = 2,677) and 8,650 (BFUe = 3,554) per mL of aspirated marrow. After treatment it was 239,496 (BFUe = 81,305) and 17,484 (BFUe = 4,141) for the two animals, respectively. Thus, a significant increase both in nucleated cell number and progenitor content was noted after treatment. Although a sampling error could be a factor, we do not think that this increment is simply explained by peripheral blood contamination of a posttreatment bone marrow sample. An independent assessment of CFUe content showed 6,604 ± 357 CFUe/mL of bone marrow before treatment, at a time when none was seen in peripheral blood and 561,181 ± 147,411 CFUe/mL bone marrow after treatment, when only very rare CFUe were present in blood. However, given the absence of any effect of VLA4 on the proliferative status of progenitors and of cellularity changes in mice in which assessment of cellularity is more readily quantifiable, we believe that the increase in cellularity post-anti-VLA4 treatment reflects easiness of bone marrow aspiration rather than a proliferative change, similar to a situation concerning bone marrow changes post-anti-vascular cell adhesion molecule-1 (VCAM-1) treatment.37 Finally, assessment of cell cycling status of progenitors present in bone marrow or blood at baseline and after anti-VLA4 treatment showed no significant changes in bone marrow before versus after treatment. Cycling progenitors were in low proportion in blood before treatment compared with bone marrow (bone marrow suicide rate, 39% [298 of 490] and 31% [93 of 136]; peripheral blood, 15.6% [1.4 of 1.7] and 17.1% [5.6 of 6.8]). After treatment lower rates were observed but the differences were not statistically significant from pretreatment values (bone marrow, 19.4% [158 of 196] and 17.8% [111 of 135]; peripheral blood, 0% [26 of 21 and 13 of 8 for the two animals]).Cytokine-Induced Mobilization Is Enhanced by Concomitant Anti-VLA4 Treatment To study whether treatment with anti-VLA4 antibody alters the efficacy of G-CSF-induced mobilization, mice were treated simultaneously with G-CSF at 200 µg/kg (100 µg/kg twice daily) and either anti-VLA4 or PBS/BSA for 3 consecutive days (single daily injections). On the fourth day peripheral blood was collected by cardiac puncture and the numbers of CFU-C measured. Simultaneous treatment with G-CSF and anti-VLA4 increased significantly the number of circulating CFU-C above the level observed with G-CSF alone (Fig 1). G-CSF plus PBS/BSA treatments (5 mice) yielded 1,240 ± 842 CFU-C/mL. G-CSF plus anti-VLA4 yielded 5,012 ± 1,031/mL of blood (P < .0002). Likewise, anti-VLA4 augmented G-CSF-induced mobilization of CFU-S12 into blood as 5 mice treated with G-CSF plus PBS/BSA had 160 CFU-S12 ± 3.1/mL of blood, whereas mice treated with G-CSF plus anti-VLA4 had 664 CFU-S12 ± 39/mL (Fig 1; P < .0002). Additional limited data from primate G-CSF and anti-VLA4 treatments are in accord with the murine data. Eight baboons treated previously with G-CSF (100 µg/kg/d for 5 days) had an average peak of 8,405 ± 3,024/mL mobilized CFU-C between days 5 and 7.33 One animal treated with 30 µg/kg/d G-CSF showed 2,579 ± 134/mL at peak time, whereas another animal treated also with 30 µg/kg G-CSF followed by anti-VLA4 for the next 2 days had a peak level of 13,255 ± 515/mL after discontinuation of G-CSF treatment (Fig 2). Although only one animal each was treated with this scheme, which may not be an optimal one, it is important to note that at a time when a decline in circulating progenitors is expected post-G-CSF treatment, significantly high numbers of CFU-C were seen (at days 7 to 9 CFU-C/mL were 13,255 to 7,800/mL) higher than or similar to the average peak values of CFU-C noted in eight animals treated with higher doses of G-CSF alone.33 To test whether cooperativity in G-CSF+ anti-VLA4-induced mobilization concerned only this particular cytokine, we combined in subsequent experiments KL-induced mobilization with concurrent anti-VLA4 treatment. Control mice (five mice) were treated with KL (100 µg/kg) for 7 days and received in addition PBS/BSA for 7 days. Another group of five mice received KL in the same dose and anti-VLA4 (2 mg/kg/d) on the last 3 days of KL treatment. Because the peak of KL-induced mobilization is slightly longer than the G-CSF,31 the mice were treated for 7 days to ensure that peak values were not missed. On the eighth day the mice were sacrificed, peripheral blood was obtained by cardiac puncture, and the numbers of CFU-C and CFU-S12 were assessed. In the mice receiving combined KL and anti-VLA4 treatment, ninefold as many circulating CFU-C were present compared with mice treated with only KL and PBS/BSA (664 ± 133 in controls; 6,132 ± 812 in KL plus anti-VLA4; P < .003). A difference of similar magnitude was observed when CFU-S12 were evaluated from the two groups of animals (eight mice with KL, 45 ± 10.5 CFU-S/mL; eight mice with KL plus anti-VLA4, 359 ± 32 CFU-S/mL; P < .000015).
Mobilization Induced by Combinations of Cytokines Is Also Augmented by Anti-VLA4 Treatment Because combinations of cytokines synergistically induce mobilization of progenitors at higher levels, we tested whether the most successful combination treatments, ie, G-CSF plus KL31,34-35 or G-CSF plus FL,33 when combined with concurrent treatment with anti-VLA4 were able to further enhance optimum mobilization. The G-CSF plus KL combination was given to four baboons at a dosage of 100 µg/kg/d G-CSF plus 25 µg/kg/d KL for 5 days, and one animal was treated with 100 µg/kg/d G-CSF and 100 µg/kg/d KL both for 5 days. G-CSF plus FL combinations were tested in mice. Control groups of mice with G-CSF alone and G-CSF plus FL were also studied. As seen in Fig 3, anti-VLA4 treatment significantly enhanced mobilization induced by G plus KL in baboons or by G plus FL treatments in mice (Fig 4). Concurrent anti-VLA4 treatments with cytokines rather than sequential seemed to be more effective (Fig 3C and D).
Post-5FU Mobilization in Primates and Anti-VLA4 Treatment Early observations have suggested that mobilization of progenitors postcytotoxic chemotherapy is observed during the recovery phase4,38-41 and mobilization efficiency varies with different chemotherapy agents. Whether the cytotoxic treatment damages progenitor/stromal cell relationships directly or whether indirect effects (ie, an increase in cytokines) are responsible for this mobilization is unclear. To test whether anti-VLA4 could enhance not only cytokine-induced mobilization but also the postchemotherapy-induced mobilization, we treated two baboons with 5FU (single injection of 100 mg/kg 5FU) and followed their blood counts and circulating progenitors for approximately 3 weeks post-5FU. One animal showed a significant number of circulating progenitors at day 14 and 19 (10-fold to 20-fold above pretreatment values) after several days of 0 to 20 CFU-C/mL of blood; the other animal showed increased numbers at day 12 (Fig 5). Two other primates were treated with the same dose of 5FU but at days 5 to 8 were given three injections of anti-VLA4 (1 mg/kg/d). As seen in Fig 5, in these two animals there are several days with significant output of CFU-C during and after anti-VLA4 treatment in contrast to control 5FU animals. Peak levels of 5,667 CFU-C/mL of blood and 8,020 CFU-C/mL were observed compared with 635/mL and 2,331/mL in the two 5FU controls. In addition to CFU-C, macroscopically visible colonies of >0.5 mm in diameter of compact growth (HPP) were seen in all 5FU-treated animals. Peak HPP levels in two control animals were 118 ± 11 and 116 ± 6 at days 12 and 14, respectively. Peak levels in the two anti-VLA4-treated animals were 433 ± 96 and 932 ± 179 at days 13 and 11, respectively. Bone marrow was aspirated from one control 5FU and one 5FU plus anti-VLA4-treated animal once before treatment and on three occasions posttreatment. In the latter animal there was a sharp increase in CFU-C and HPP/mL of bone marrow aspirate between days 8 and 11 (from 2,921 ± 152 to 24,990 ± 1,225 CFU-C/mL and from 267 ± 18 to 2,254 HPP/mL). Concomitantly, CFU-C (see Fig 5) and HPP values in peripheral blood were increased between days 8 to 12. Similar observations were made in the control animal (data not shown). These data suggest that there is no significant delay between bone marrow progenitor recovery and their exportation to peripheral blood.
Transplantation of Ex Vivo Anti-VLA4-Treated Autologous Primate Bone Marrow Cells As shown previously, anti-VLA4 treatment induces mobilization not only of committed clonogenic progenitors but of long-term repopulating cells and enhances mobilization induced by a single cytokine or by a combination of cytokines. In view of our previous data suggesting an impairment of anti-VLA4 on lodgement of intravenously infused cells in bone marrow, we needed to ascertain whether anti-VLA4 treatment compromised engraftment of properly conditioned recipients by interfering with homing.18 Therefore, we transplanted two baboons shortly after lethal irradiation with autologous bone marrow cells treated in vitro with anti-VLA4 and infused without washing off the excess antibody. The kinetics of total white blood cell count recovery as well as of platelet recovery are shown in Fig 6. White blood cells were over 1,000 by day 15 and platelets were over 100,000 by day 18. This recovery rate appears to be comparable with previously observed rates with autologous bone marrow transplantation.35 In addition to white blood cell counts, circulating clonogenic progenitors 24 to 48 hours after transplantation and for the next 10 days were also assessed to see whether a large circulating pool of progenitors was present because of the administration of anti-VLA4. The data show that for the first 3 days, significant numbers of CFU-C were present in the peripheral blood of the irradiated recipients. Similar early data are not available for other transplanted animals for comparison. However, recent data from human transplants (with mobilized blood) showing virtual clearance of injected CD34+ progenitors by 8 hours postinfusion (John Di Persio, personal communication) would suggest that the levels observed are likely higher than expected. In the murine model <0.5% of injected CFU-C are expected to remain in the peripheral blood by 48 hours (Papayannopoulou et al18 and unpublished data). In the present experiments we estimated (based on the total number of infused CFU-C) that 5% and 7% of injected CFU-C were in circulation. However, it is not clear whether the murine data are applicable to primate data because a significant seeding is occurring in the spleen of mice, which is not expected to occur in the spleen of primates. If indeed there is a delayed homing for the first few days because of excess anti-VLA4 antibody in circulation, this will imply that our prior data on anti-VLA4 effects on murine bone marrow homing are applicable to primates and possibly humans. However, despite an initial delay it is important to emphasize that engraftment was not ultimately compromised in this setting.
In previous studies we have shown that treatment of primates17 or mice18 with function blocking antibodies to VLA4 can induce peripheralization of hematopoietic progenitor cells. A nonfunction blocking anti-VLA4 antibody (B5G10) was without effect,42 and the half-life of the antibodies used correlated with the duration of the mobilizing effect. Thus, primates treated with a humanized antibody having a longer half-life in circulation showed a longer lasting effect (Fig 2 and Dr R.R. Lobb, personal communication). Furthermore, in the present study we show that not only committed progenitors are mobilized by these treatments but also long-term repopulating cells. This is in accord with previous observations showing that CFU-S (and very likely, long-term repopulating cells) express VLA4 integrins.43 It is important to emphasize that late progenitor cells, like CFUe, or precursor cells at different levels of maturation, despite the fact that they all express VLA4 integrins on their surface,44 are not mobilized by these treatments. Only rare CFUe and a small number (up to 1,000/mL) of nucleated red blood cells were present in blood (Fig 7), implying that the integrins in these later cells are either constitutively nonfunctional or differently regulated than the ones in progenitor cells. We found no evidence that anti-VLA4-induced mobilization is secondary to effects on progenitor proliferation. Instead, we think that the antibody's adhesion-blocking property is directly involved in the mobilization process, especially when administration of a nonfunction blocking antibody (B5G10) did not have a mobilizing effect.42 Whether adhesion blockade per se and/or de-adhesion are sufficient for mobilization, or whether a sequence of events, which includes stimulation of migration secondary to inside-out signaling, is also triggered by antibody treatment and is responsible for mobilization is unclear. Furthermore, because anti-VCAM-1 antibody also induces mobilization, whereas a fibronectin connecting segment-1 competitor peptide does not,45 VCAM-1 rather than fibronectin is the likely partner in vivo for VLA4 on progenitors. In addition, our data with anti-VCAM-1 provide a direct demonstration that effects on stromal cells can cause progenitor mobilization.
Submitted June 16, 1997;
accepted August 14, 1997.
The publication costs of this article were defrayed in part by page charge payment. This article must therefore be hearly marked ``advertisment'' in accordance with 18 U.S.C. section 1734 solely to indicate this fact.
We are grateful to Debra Glanister and Ray Colby for their help with the primate studies. We are also indebted to Dr Roy R. Lobb for the generous gift of antibodies, Dr M. Hemler for the B5G10 antibody, and to Sherri Brenner for her skillful secretarial assistance.
1.
Goodman JW,
Hodgson GS:
Evidence for stem cells in the peripheral blood of mice.
Blood
19:702,
1962
2.
Cavins JA,
Scheer SC,
Thomas ED,
Ferrebee JW:
The recovery of lethally irradiated dogs given infusions of autologous leukocytes preserved at -80°C.
Blood
23:38,
1964
3.
To LB,
Haylock DN,
Simmons PJ,
Juttner CA:
The biology and clinical uses of blood stem cells.
Blood
89:2233,
1997
4.
Craddock CF,
Apperley JF,
Wright EG,
Healy LE,
Bennett CA,
Evans M,
Grimsley PG,
Gordon MY:
Circulating stem cells in mice treated with cyclophosphamide.
Blood
80:264,
1992
5.
Grzegorzewski K,
Komschlies KL,
Mori M,
Kaneda K,
Usui N,
Faltyneck CR,
Keller JR,
Ruscetti FW,
Wiltrout RH:
Administration of recombinant human interleukin-7 to mice induces the exportation of myeloid progenitor cells from the bone marrow to peripheral sites.
Blood
83:377,
1994
6.
Mauch P,
Lamont C,
Neben TY,
Quinto C,
Goldman SJ,
Witsell A:
Hematopoietic stem cells in the blood after stem cell factor and interleukin-11 administration: Evidence for different mechanisms of mobilization.
Blood
86:4674,
1995
7.
Molineux G,
McCrea C,
Yan XQ,
Kerzic P,
McNiece I:
Flt-3 ligand synergizes with granulocyte colony-stimulating factor to increase neutrophil numbers and to mobilize peripheral blood stem cells with long-term repopulating potential.
Blood
89:3998,
1997
8.
Goldman J:
Peripheral blood stem cells for allografting.
Blood
85:1413,
1995 9. Fibbe WE, Hamilton MS, Laterveer LL, Kibbelaar RE, Falkenburg JHF, Visser JWM, Willemze R: Sustained engraftment of mice transplanted with IL-1 primed blood-derived stem cells. J Immunol 148:417, 1992[Abstract]
10.
Laterveer L,
Lindley IJ,
Hamilton MS,
Willemze R,
Fibbe WE:
Interleukin-8 induces rapid mobilization of hematopoietic stem cells with radioprotective capacity and long-term myelolymphoid repopulating ability.
Blood
85:2269,
1995 11. Yoder MC, Williams DA: Matrix molecule interactions with hematopoietic stem cells. Exp Hematol 23:961, 1995[Medline] [Order article via Infotrieve] 12. Klein G: The extracellular matrix of the hematopoietic microenvironment. Experientia 51:914, 1995[Medline] [Order article via Infotrieve] 13. Müller-Sieburg CE, Deryugina E: The stromal cells' guide to the stem cell universe. Stem Cells 13:477, 1995[Abstract] 14. Long MW: Blood cell cytoadhesion molecules. Exp Hematol 20:288, 1992[Medline] [Order article via Infotrieve] 15. Kinashi T, Springer TA: Adhesion molecules in hematopoietic cells. Blood Cells 20:25, 1994[Medline] [Order article via Infotrieve]
16.
Aiuti A,
Webb IJ,
Bleul C,
Springer T,
Guiterrez-Ramos JC:
The chemokine SDF-1 is a chemoattractant for human CD34+ hematopoietic progenitor cells and provides a new mechanism to explain the mobilization of CD34+ progenitors to peripheral blood.
J Exp Med
185:111,
1997
17.
Papayannopoulou T,
Nakamoto B:
Peripheralization of hemopoietic progenitors in primates treated with anti-VLA4 integrin.
Proc Natl Acad Sci USA
90:9374,
1993
18.
Papayannopoulou T,
Craddock C,
Nakamoto B,
Priestely GV,
Wolf NS:
The VLA4 /VCAM-1 adhesion pathway defines contrasting mechanisms of lodgement of transplanted murine hemopoietic progenitors between bone marrow and spleen.
Proc Natl Acad Sci USA
92:9647,
1995
19.
Kovach NL,
Lin N,
Yednock T,
Harlan JM,
Broudy VC:
Stem cell factor modulates avidity of alpha 4 beta 1 and alpha 5 beta 1 integrins expressed on hematopoietic cell lines.
Blood
85:159,
1995 20. Kodama H, Nose M, Niida S, Nishikawa S, Nishikawa S-I: Involvement of the c-kit receptor in the adhesion of hematopoietic stem cells to stromal cells. Exp Hematol 22:979, 1994[Medline] [Order article via Infotrieve]
21.
Kinashi T,
Springer TA:
Steel factor and c-kit regulate cell-matrix adhesion.
Blood
83:1033,
1994 22. Fernández M, Minguell JJ: Adhesive interactions in the hematopoietic system: Regulation by cytokines. Proc Soc Exp Biol Med 212:313, 1996[Medline] [Order article via Infotrieve]
23.
Levesque JP,
Leavesley DI,
Niutta S,
Vadas M,
Simmons PJ:
Cytokines increase human hemopoietic cell adhesiveness by activation of very late antigen (VLA)-4 and VLA-5 integrins.
J Exp Med
181:1805,
1995 24. Leavesley DI, Oliver JM, Swart BW, Berndt MC, Haylock DN, Simmons PJ: Signals from platelet/endothelial cell adhesion molecule enhance the adhesive activity of the very late antigen-4 integrin of human CD34+ hemopoietic progenitor cells. J Immunol 153:4673, 1994[Abstract] 25. Mohle R, Haas R, Hunstein W: Expression of adhesion molecules and c-kit on CD34+ hematopoietic progenitor cells: Comparison of cytokine mobilized blood stem cells with normal bone marrow and peripheral blood. J Hematother 2:483, 1993[Medline] [Order article via Infotrieve] 26. Simmons PJ, Leavesley DI, Levesque JP, Swart BW, Haylock DN, To LB, Ashman LK, Juttner CA: The mobilization of primitive hemopoietic progenitors into the peripheral blood. Stem Cells 12:187, 1994[Abstract] 27. Mohle R, Murea S, Kirsch M, Haas R: Differential expression of L-selectin, VLA-4, and LFA-1 on CD34+ progenitor cells from bone marrow and peripheral blood during G-CSF-enhanced recovery. Exp Hematol 23:1535, 1995[Medline] [Order article via Infotrieve]
28.
Dercksen MW,
Gerritsen WR,
Rodenhuis S,
Dirkson MK,
Slaper-Cortenbach IC,
Schaasberg WP,
Pinedo HM,
von dem Borne AE,
van der Schoot CE:
Expression of adhesion molecules on CD34+ cells: CD34+ L-selectin+ cells predict a rapid platelet recovery after peripheral blood stem cell transplantation.
Blood
85:3313,
1995
29.
Molineux G,
Pojda Z,
Hampson IN,
Lord BI,
Dexter TM:
Transplantation potential of peripheral blood stem cells induced by granulocyte colony-stimulating factor.
Blood
76:2153,
1990
30.
Neben S,
Marcus K,
Mauch P:
Mobilization of hematopoietic stem and progenitor cell subpopulations from the marrow to the blood of mice following cyclophosphamide and/or granulocyte colony-stimulating factor.
Blood
81:1960,
1993
31.
Briddell RA,
Hartley CA,
Smith KA,
McNiece IK:
Recombinant rat stem cell factor synergizes with recombinant human granulocyte colony-stimulating factor in vivo in mice to mobilize peripheral blood progenitor cells that have enhanced repopulating potential.
Blood
82:1720,
1993 32. van der Sluijs JP, van den Bos C, Baert MRM, van Beurden CAJ, Ploemacher RE: Loss of long-term repopulating ability in long-term bone marrow culture. Leukemia 7:725, 1993[Medline] [Order article via Infotrieve]
33.
Papayannopoulou T,
Nakamoto B,
Andrews RG,
Lyman SD,
Lee MY:
In vivo effects of Flt3/Flk2 ligand on mobilization of hemopoietic progenitors in primates and potent synergistic enhancement with granulocyte colony-stimulating factor.
Blood
90:620,
1997
34.
Andrews RG,
Briddell RA,
Knitter GH,
Opie T,
Bronsden M,
Myerson D,
Applebaum FR,
McNiece IK:
In vivo synergy between recombinant human stem cell factor and recombinant human granulocyte colony-stimulating factor in baboons: Enhanced circulation of progenitor cells.
Blood
84:800,
1994
35.
Andrews RG,
Briddell RA,
Knitter GH,
Rowley SD,
Applebaum FR,
McNiece IK:
Rapid engraftment by peripheral blood progenitor cells mobilized by recombinant human stem cell factor and recombinant human granulocyte colony-stimulating factor in nonhuman primates.
Blood
85:15,
1995 36. Cannistra SA, Groshek P, Griffin JD: Granulocyte-macrophage colony-stimulating factor enhances the cytotoxic effects of cytosine arabinoside in acute myelobastic leukemia and in the myeloid blast crisis phase of chronic myeloid leukemia. Leukemia 3:328, 1989[Medline] [Order article via Infotrieve]
37.
Funk PE,
Kincade PW,
Witte PL:
Native associations of early hematopoietic stem cells and stromal cells isolated in bone marrow cell aggregates.
Blood
83:361,
1994
38.
Richman CM,
Weiner RS,
Yankee RA:
Increase in circulating stem cells following chemotherapy in man.
Blood
47:1031,
1976 39. Lohrmann HP, Schreml W, Fliedner TM, Heimpel H: Reaction of human granulopoiesis to high dose cyclophosphamide therapy. Blut 38:9, 1979[Medline] [Order article via Infotrieve]
40.
Stiff PJ,
Murgo AJ,
Wittes RE,
DeRisi MF,
Clarkson BD:
Quantification of the peripheral blood colony forming unit-culture rise following chemotherapy 41. To LB, Haylock DN, Kimber RJ, Juttner CA: High levels of circulating hemopoietic stem cells in very early rem |
Abstract
Introduction
Abstract
4 antibody, generously supplied by Dr R.R. Lobb, Biogen, Cambridge, MA) at 2 mg/kg/d for 3 days and sacrificed the next day. Combinations of cytokine plus anti-VLA4 treatments were also done, which included G-CSF plus anti-VLA4, KL plus anti-VLA4, or G-CSF plus FL plus anti-VLA4 at the doses indicated previously. All animal groups were again sacrificed the day after the last treatment and blood was collected.
) and nonerythroid (
) colonies.
1 and 
Could leukocytaphereses replace bone marrow for autologous transplantation?
Transfusion
23:500,
1983