PTX-sensitive signals in bone marrow homing of fetal and adult hematopoietic progenitor cells

Blood ◽  
2004 ◽  
Vol 104 (8) ◽  
pp. 2299-2306 ◽  
Author(s):  
Halvard Bonig ◽  
Gregory V. Priestley ◽  
Lina M. Nilsson ◽  
Yi Jiang ◽  
Thalia Papayannopoulou
Keyword(s):  
Bone Marrow ◽  
Progenitor Cells ◽  
Progenitor Cell ◽  
Fetal Liver ◽  
Hematopoietic Progenitor Cell ◽  
Hematopoietic Progenitor ◽  
Short Term ◽  
Migratory Capacity ◽  
Gi Protein

Abstract Several examples suggest a relationship between in vitro migratory capacity and bone marrow (BM) homing. Pertussis toxin (PTX) is a potent inhibitor of serpentine receptor–associated inhibitory trimeric guanidine nucleotide binding (Gi) protein signals. As such, it blocks hematopoietic progenitor cell migration in vitro, but contrary to expectation, no effects on BM homing were observed in previous studies. We therefore re-examined the effect of PTX on homing of murine BM and fetal liver (FL). We found that BM homing of PTX-incubated progenitor cells (colony-forming cells in culture [CFU-Cs]) from BM or FL in irradiated and nonirradiated recipients was reduced by more than 75%, with a concomitant increase in circulating CFU-Cs in peripheral blood. Additional studies confirmed the functional significance of this reduction in homing: PTX-treated cells did not provide radioprotection, and their short-term engraftment in BM and spleen was drastically reduced. Furthermore, several approaches show that cell-intrinsic rather than host-derived mechanisms are responsible for the PTX-induced homing defect. In summary, we show that Gi protein signals are required for BM homing and, as such, provide a new example of the association between BM homing and in vitro migration. Moreover, our data suggest that the behavior of hematopoietic progenitors in obeying Gi signaling does not diverge from that of mature leukocytes.

scholarly journals Effects of recombinant alpha and gamma interferons on the in vitro growth of circulating hematopoietic progenitor cells (CFU-GEMM, CFU-Mk, BFU-E, and CFU-GM) from patients with myelofibrosis with myeloid metaplasia

Blood ◽  
1987 ◽  
Vol 70 (4) ◽  
pp. 1014-1019 ◽  
Author(s):  
C Carlo-Stella ◽  
M Cazzola ◽  
A Gasner ◽  
G Barosi ◽  
L Dezza ◽  
...  
Keyword(s):  
Progenitor Cells ◽  
Progenitor Cell ◽  
Hematopoietic Progenitor Cells ◽  
Definitive Treatment ◽  
Hematopoietic Progenitor Cell ◽  
In Vitro Growth ◽  
Hematopoietic Progenitor ◽  
Myeloid Metaplasia ◽  
Myelofibrosis With Myeloid Metaplasia

Myelofibrosis with myeloid metaplasia (MMM) is a chronic myeloproliferative disorder due to clonal expansion of a pluripotent hematopoietic progenitor cell with secondary marrow fibrosis. No definitive treatment has as yet been devised for this condition, which shows a marked variability in clinical course. To evaluate whether excessive hematopoietic progenitor cell proliferation could be controlled by recombinant human interferon alpha (rIFN-alpha) and gamma (rIFN-gamma), we studied the effects of these agents on the in vitro growth of pluripotent and lineage-restricted circulating hematopoietic progenitor cells in 18 patients with MMM. A significant increase in the growth (mean +/- 1 SEM) per milliliter of peripheral blood of CFU-GEMM (594 +/- 253), CFU-Mk (1,033 +/- 410), BFU-E (4,799 +/- 2,020) and CFU- GM (5,438 +/- 2,505) was found in patients as compared with normal controls. Both rIFN-alpha and rIFN-gamma (10 to 10(4) U/mL) produced a significant dose-dependent suppression of CFU-GEMM, CFU-Mk, BFU-E, and CFU-GM growth. Concentrations of rIFN-alpha and rIFN-gamma causing 50% inhibition of colony formation were 37 and 163 U/mL for CFU-GEMM, 16 and 69 U/mL for CFU-Mk, 53 and 146 U/mL for BFU-E, and 36 and 187 U/mL for CFU-GM, respectively. A marked synergistic effect was found between rIFN-alpha and rIFN-gamma: combination of the two agents produced inhibitory effects greater than or equivalent to those of 10- to 100- fold higher concentrations of single agents. These studies (a) confirm that circulating hematopoietic progenitors are markedly increased in MMM, (b) indicate that these presumably abnormal progenitors are normally responsive to rIFNs in vitro, and (c) show that IFNs act in a synergistic manner when used in combination. Because rIFN-gamma can downregulate collagen synthesis in vivo, this lymphokine could be particularly useful in the treatment of patients with MMM.

scholarly journals Heparanase regulates retention and proliferation of primitive Sca-1+/c-Kit+/Lin− cells via modulation of the bone marrow microenvironment

Blood ◽  
2008 ◽  
Vol 111 (10) ◽  
pp. 4934-4943 ◽  
Author(s):  
Asaf Spiegel ◽  
Eyal Zcharia ◽  
Yaron Vagima ◽  
Tomer Itkin ◽  
Alexander Kalinkovich ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Stem Cell ◽  
Progenitor Cells ◽  
Progenitor Cell ◽  
Cathepsin K ◽  
Hematopoietic Progenitors ◽  
Hematopoietic Progenitor ◽  
Cell Mobilization ◽  
Tumor Growth And Metastasis

Abstract Heparanase is involved in tumor growth and metastasis. Because of its unique cleavage of heparan sulfate, which binds cytokines, chemokines and proteases, we hypothesized that heparanase is also involved in regulation of early stages of hematopoiesis. We report reduced numbers of maturing leukocytes but elevated levels of undifferentiated Sca-1+/c-Kit+/Lin− cells in the bone marrow (BM) of mice overexpressing heparanase (hpa-Tg). This resulted from increased proliferation and retention of the primitive cells in the BM microenvironment, manifested in increased SDF-1 turnover. Furthermore, heparanase overexpression in mice was accompanied by reduced protease activity of MMP-9, elastase, and cathepsin K, which regulate stem and progenitor cell mobilization. Moreover, increased retention of the progenitor cells also resulted from up-regulated levels of stem cell factor (SCF) in the BM, in particular in the stem cell–rich endosteum and endothelial regions. Increased SCF-induced adhesion of primitive Sca-1+/c-Kit+/Lin− cells to osteoblasts was also the result of elevation of the receptor c-Kit. Regulation of these phenomena is mediated by hyperphosphorylation of c-Myc in hematopoietic progenitors of hpa-Tg mice or after exogenous heparanase addition to wildtype BM cells in vitro. Altogether, our data suggest that heparanase modification of the BM microenvironment regulates the retention and proliferation of hematopoietic progenitor cells.

Flt3 Ligand Negatively Regulates In Vitro Migration, Intracellular Signaling Activated by SDF-1α/CXCR4 and In Vivo Homing of Hematopoietic Progenitor Cells.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 2674-2674
Author(s):  
Seiji Fukuda ◽  
Hal E. Broxmeyer ◽  
Louis M. Pelus
Keyword(s):  
Bone Marrow ◽  
Progenitor Cells ◽  
Hematopoietic Progenitor Cells ◽  
Leukemia Cells ◽  
Flt3 Ligand ◽  
Hematopoietic Progenitor ◽  
Short Term ◽  
Hematopoietic Stem

Abstract The Flt3 receptor tyrosine kinase (Flt3) is expressed on primitive normal and transformed hematopoietic cells and Flt3 ligand (FL) facilitates hematopoietic stem cell mobilization in vivo. The CXC chemokine SDF-1α(CXCL12) attracts primitive hematopoietic cells to the bone marrow microenvironment while disruption of interaction between SDF-1α and its receptor CXCR4 within bone marrow may facilitate their mobilization to the peripheral circulation. We have previously shown that Flt3 ligand has chemokinetic activity and synergistically increases migration of CD34+ cells and Ba/F3-Flt3 cells to SDF-1α in short-term migration assays; this was associated with synergistic phosphorylation of MAPKp42/p44, CREB and Akt. Consistent with these findings, over-expression of constitutively active ITD (internal tandem duplication) Flt3 found in patients with AML dramatically increased migration to SDF-1α in Ba/F3 cells. Since FL can induce mobilization of hematopoietic stem cells, we examined if FL could antagonize SDF-1α/CXCR4 function and evaluated the effect of FL on in vivo homing of normal hematopoietic progenitor cells. FL synergistically increased migration of human RS4;11 acute leukemia cells, which co-express wild-type Flt3 and CXCR4, to SDF-1α in short term migration assay. Exogenous FL had no effect on SDF-1α induced migration of MV4-11 cells that express ITD-Flt3 and CXCR4 however migration to SDF-1α was partially blocked by treatment with the tyrosine kinase inhibitor AG1296, which inhibits Flt3 kinase activity. These results suggest that FL/Flt3 signaling positively regulates SDF-1α mediated chemotaxis of human acute leukemia cells in short-term assays in vitro, similar to that seen with normal CD34+ cells. In contrast to the enhancing effect of FL on SDF-1α, prolonged incubation of RS4;11 and THP-1 acute myeloid leukemia cells, which also express Flt3 and CXCR4, with FL for 48hr, significantly inhibited migration to SDF-1α, coincident with reduction of cell surface CXCR4. Similarly, prolonged exposure of CD34+ or Ba/F3-Flt3 cells to FL down-regulates CXCR4 expression, inhibits SDF-1α-mediated phosphorylation of MAPKp42/p44, CREB and Akt and impairs migration to SDF-1α. Despite reduction of surface CXCR4, CXCR4 mRNA and intracellular CXCR4 in Ba/F3-Flt3 cells were equivalent in cells incubated with or without FL, determined by RT-PCR and flow cytometry after cell permeabilization, suggesting that the reduction of cell surface CXCR4 expression is due to accelerated internalization of CXCR4. Furthermore, incubation of Ba/F3-Flt3 cells with FL for 48hr or over-expression of ITD-Flt3 in Ba/F3 cells significantly reduced adhesion to VCAM1. Consistent with the negative effect of FL on in vitro migration and adhesion to VCAM1, pretreatment of mouse bone marrow cells with 100ng/ml of FL decreased in vivo homing of CFU-GM to recipient marrow by 36±7% (P<0.01), indicating that FL can negatively regulate in vivo homing of hematopoietic progenitor cells. These findings indicate that short term effect of FL can provide stimulatory signals whereas prolonged exposure has negative effects on SDF-1α/CXCR4-mediated signaling and migration and suggest that the FL/Flt3 axis regulates hematopoietic cell trafficking in vivo. Manipulation of SDF-1α/CXCR4 and FL/Flt3 interaction could be clinically useful for hematopoietic cell transplantation and for treatment of hematopoietic malignancies in which both Flt3 and CXCR4 are expressed.

Integrin alpha 6 Is Essential for Fetal Hematopoietic Progenitor, but Not Fetal Stem Cell Homing to Bone Marrow.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 1387-1387
Author(s):  
Hong Qian ◽  
Sten Eirik W. Jacobsen ◽  
Marja Ekblom
Keyword(s):  
Bone Marrow ◽  
Stem Cell ◽  
Progenitor Cells ◽  
Progenitor Cell ◽  
Fetal Liver ◽  
Hematopoietic Stem ◽  
Stem And Progenitor Cells ◽  
Integrin Alpha 6

Abstract Homing of transplanted hematopoietic stem cells (HSC) in the bone marrow (BM) is a prerequisite for establishment of hematopoiesis following transplantation. However, although multiple adhesive interactions of HSCs with BM microenviroment are thought to critically influence their homing and subsequently their engraftment, the molecular pathways that control the homing of transplanted HSCs, in particular, of fetal HSCs are still not well understood. In experimental mouse stem cell transplantation models, several integrins have been shown to be involved in the homing and engraftment of both adult and fetal stem and progenitor cells in BM. We have previously found that integrin a6 mediates human hematopoietic stem and progenitor cell adhesion to and migration on its specific ligands, laminin-8 and laminin-10/11 in vitro (Gu et al, Blood, 2003; 101:877). Furthermore, integrin a6 is required for adult mouse HSC homing to BM in vivo (Qian et al., Abstract American Society of Hematology, Blood 2004 ). We have now found that the integrin a6 chain like in adult HSC is ubiquitously (>99%) expressed also in fetal liver hematopoietic stem and progenitor cells (lin−Sca-1+c-Kit+, LSK ). In vitro, fetal liver LSK cells adhere to laminin-10/11 and laminin-8 in an integrin a6b1 receptor-dependent manner, as shown by function blocking monoclonal antibodies. We have now used a function blocking monoclonal antibody (GoH3) against integrin a6 to analyse the role of the integrin a6 receptor for the in vivo homing of fetal liver hematopoietic stem and progenitor cells to BM. The integrin a6 antibody inhibited homing of fetal liver progenitors (CFU-C) into BM of lethally irradiated recipients. The number of homed CFU-C in BM was reduced by about 40% as compared to the cells incubated with an isotype matched control antibody. To study homing of long-term repopulating stem cells, BM cells were first incubated with anti-integrin alpha 6 or anti-integrin alpha 4 or control antibody, and then injected intravenously into lethally irradiated primary recipients. After three hours, BM cells of the primary recipients were analysed by competitive repopulation assay in secondary recipients. Blood analysis up to 16 weeks after transplantation showed that no reduction of stem cell reconstitution from integrin a6 antibody treated cells as compared to cells treated with control antibody. In accordance with this, fetal liver HSC from integrin a6 gene deleted embryos did not show any impairment of homing and engraftment in BM as compared to normal littermates. These results suggest that integrin a6 plays an important developmentally regulated role for homing of distinct hematopoietic stem and progenitor cell populations in vivo.

scholarly journals Mobilization of hematopoietic progenitor cells for autologous transportation: consensus recommendations

2016 ◽  
Vol 62 (suppl 1) ◽  
pp. 10-15 ◽  
Author(s):  
Fernando Barroso Duarte ◽  
Benedito de Pina Almeida Prado ◽  
Garles Miller Matias Vieira ◽  
Luciano J. Costa
Keyword(s):  
Bone Marrow ◽  
Progenitor Cells ◽  
Blood Circulation ◽  
Progenitor Cell ◽  
National Health System ◽  
Hematopoietic Progenitor Cell ◽  
Cell Transplant ◽  
Hematopoietic Progenitor ◽  
Term Survival

SUMMARY Selected patients with certain hematological malignancies and solid tumors have the potential to achieve long-term survival with autologous hematopoietic progenitor cell transplant. The collection of these cells in peripheral blood avoids multiple bone marrow aspirations, results in faster engraftment and allows treatment of patients with infection, fibrosis, or bone marrow hypocellularity. However, for the procedure to be successful, it is essential to mobilize a sufficient number of progenitor cells from the bone marrow into the blood circulation. Therefore, a group of Brazilian experts met in order to develop recommendations for mobilization strategies adapted to the reality of the Brazilian national health system, which could help minimize the risk of failure, reduce toxicity and improve the allocation of financial resources.

scholarly journals Cell-nonautonomous function of Id1 in the hematopoietic progenitor cell niche

Blood ◽  
2009 ◽  
Vol 114 (6) ◽  
pp. 1186-1195 ◽  
Author(s):  
Hyung Chan Suh ◽  
Ming Ji ◽  
John Gooya ◽  
Michael Lee ◽  
Kimberly D. Klarmann ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Progenitor Cell ◽  
Hematopoietic Progenitor Cell ◽  
Hematopoietic Progenitor ◽  
Hematopoietic Stem ◽  
Cytokine Levels ◽  
Cell Niche ◽  
Marrow Cellularity

Abstract Development of hematopoietic stem cells (HSCs) and their immediate progeny is maintained by the interaction with cells in the microenvironment. We found that hematopoiesis was dysregulated in Id1−/− mice. Although the frequency of HSCs in Id1−/− bone marrow was increased, their total numbers remained unchanged as the result of decreased bone marrow cellularity. In addition, the ability of Id1−/− HSCs to self-renew was normal, suggesting Id1 does not affect HSC function. Id1−/− progenitors showed increased cycling in vivo but not in vitro, suggesting cell nonautonomous mechanisms for the increased cycling. Id1−/− HSCs developed normally when transplanted into Id1+/+ mice, whereas the development of Id1+/+ HSCs was impaired in Id1−/− recipients undergoing transplantation and reproduced the hematologic features of Id1−/− mice, indicating that the Id1−/− microenvironment cannot support normal hematopoietic development. Id1−/− stromal cells showed altered production of cytokines in vitro, and cytokine levels were deregulated in vivo, which could account for the Id1−/− hematopoietic phenotypes. Thus, Id1 is required for regulating the hematopoietic progenitor cell niche but is dispensable for maintaining HSCs.

scholarly journals Effects of recombinant alpha and gamma interferons on the in vitro growth of circulating hematopoietic progenitor cells (CFU-GEMM, CFU-Mk, BFU-E, and CFU-GM) from patients with myelofibrosis with myeloid metaplasia

Blood ◽  
1987 ◽  
Vol 70 (4) ◽  
pp. 1014-1019 ◽  
Author(s):  
C Carlo-Stella ◽  
M Cazzola ◽  
A Gasner ◽  
G Barosi ◽  
L Dezza ◽  
...  
Keyword(s):  
Progenitor Cells ◽  
Progenitor Cell ◽  
Hematopoietic Progenitor Cells ◽  
Definitive Treatment ◽  
Hematopoietic Progenitor Cell ◽  
In Vitro Growth ◽  
Hematopoietic Progenitor ◽  
Myeloid Metaplasia ◽  
Myelofibrosis With Myeloid Metaplasia

Abstract Myelofibrosis with myeloid metaplasia (MMM) is a chronic myeloproliferative disorder due to clonal expansion of a pluripotent hematopoietic progenitor cell with secondary marrow fibrosis. No definitive treatment has as yet been devised for this condition, which shows a marked variability in clinical course. To evaluate whether excessive hematopoietic progenitor cell proliferation could be controlled by recombinant human interferon alpha (rIFN-alpha) and gamma (rIFN-gamma), we studied the effects of these agents on the in vitro growth of pluripotent and lineage-restricted circulating hematopoietic progenitor cells in 18 patients with MMM. A significant increase in the growth (mean +/- 1 SEM) per milliliter of peripheral blood of CFU-GEMM (594 +/- 253), CFU-Mk (1,033 +/- 410), BFU-E (4,799 +/- 2,020) and CFU- GM (5,438 +/- 2,505) was found in patients as compared with normal controls. Both rIFN-alpha and rIFN-gamma (10 to 10(4) U/mL) produced a significant dose-dependent suppression of CFU-GEMM, CFU-Mk, BFU-E, and CFU-GM growth. Concentrations of rIFN-alpha and rIFN-gamma causing 50% inhibition of colony formation were 37 and 163 U/mL for CFU-GEMM, 16 and 69 U/mL for CFU-Mk, 53 and 146 U/mL for BFU-E, and 36 and 187 U/mL for CFU-GM, respectively. A marked synergistic effect was found between rIFN-alpha and rIFN-gamma: combination of the two agents produced inhibitory effects greater than or equivalent to those of 10- to 100- fold higher concentrations of single agents. These studies (a) confirm that circulating hematopoietic progenitors are markedly increased in MMM, (b) indicate that these presumably abnormal progenitors are normally responsive to rIFNs in vitro, and (c) show that IFNs act in a synergistic manner when used in combination. Because rIFN-gamma can downregulate collagen synthesis in vivo, this lymphokine could be particularly useful in the treatment of patients with MMM.

scholarly journals Suppressive effects in vivo of purified recombinant human H-subunit (acidic) ferritin on murine myelopoiesis

Blood ◽  
1989 ◽  
Vol 73 (1) ◽  
pp. 74-79 ◽  
Author(s):  
HE Broxmeyer ◽  
DE Williams ◽  
K Geissler ◽  
G Hangoc ◽  
S Cooper ◽  
...  
Keyword(s):  
Progenitor Cells ◽  
Progenitor Cell ◽  
Hematopoietic Progenitor Cells ◽  
Hematopoietic Progenitor Cell ◽  
Hematopoietic Progenitor ◽  
Virus Complex ◽  
Progenitor Cell Proliferation ◽  
Dose Dependent

Purified recombinant human heavy-chain (acidic) ferritin (rHF) was assessed in vivo in mice for effects on the proliferation (percentage of cells in S-phase) and absolute numbers of granulocyte-macrophage (CFU-GM), erythroid (BFU-E), and multipotential (CFU-GEMM) progenitor cells in the femur and spleen and on the nucleated cells in the marrow, spleen, and blood. rHF significantly decreased cycling rates and absolute numbers of marrow and splenic hematopoietic progenitors and marrow and blood nucleated cellularity. These effects were apparent in BDF1, C3H/Hej and DBA/2 mice and were dose dependent, time related, and reversible. Suppressive effects were noted within three hours for progenitor cell cycling, within 24 hours for progenitor cell numbers, and within 48 hours for circulating neutrophils. Additionally, hematopoietic progenitor cells in DBA/2 mice infected with the polycythemia-inducing strain of the Friend virus complex (FVC-P) were insensitive to the in vivo administration of rHF. These studies demonstrate activity of rHF in vivo on myelopoiesis of normal but not FVC-P-infected mice. Since rHF suppresses hematopoietic progenitor cell proliferation from normal donors in vitro and from normal mice in vitro and in vivo but does not suppress progenitor cells from patients with leukemia in vitro or from mice with FVC-P-infection in vitro or in vivo, rHF may be useful as a candidate adjunct molecule for the protection of normal hematopoietic progenitor cells during chemotherapy.

scholarly journals Effects of recombinant human granulocyte colony-stimulating factor on hematopoietic progenitor cells in cancer patients

Blood ◽  
1988 ◽  
Vol 72 (6) ◽  
pp. 2074-2081 ◽  
Author(s):  
U Duhrsen ◽  
JL Villeval ◽  
J Boyd ◽  
G Kannourakis ◽  
G Morstyn ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Progenitor Cells ◽  
Cancer Patients ◽  
Peripheral Blood ◽  
Progenitor Cell ◽  
Hematopoietic Progenitor Cell ◽  
Granulocyte Colony Stimulating Factor ◽  
Colony Stimulating Factor ◽  
Hematopoietic Progenitor ◽  
Stimulating Factor

Hematopoietic progenitor cell levels were monitored in the peripheral blood and bone marrow of 30 cancer patients receiving recombinant human granulocyte-colony stimulating-factor (rG-CSF) in a phase I/II clinical trial. The absolute number of circulating progenitor cells of granulocyte-macrophage, erythroid, and megakaryocyte lineages showed a dose-related increase up to 100-fold after four days of treatment with rG-CSF and often remained elevated two days after the cessation of therapy. The relative frequency of different types of progenitor cells in peripheral blood remained unchanged. The frequency of progenitor cells in the marrow was variable after rG-CSF treatment but in most patients was slightly decreased. The responsiveness of bone marrow progenitor cells to stimulation in vitro by rG-CSF and granulocyte- macrophage colony-stimulating factor did not change significantly during rG-CSF treatment. In patients nine days after treatment with melphalan and then rG-CSF, progenitor cell levels were very low with doses of rG-CSF at or below 10 micrograms/kg/d, but equaled or exceeded pretreatment values when 30 or 60 micrograms/kg/d of rG-CSF was given.

scholarly journals Suppressive effects in vivo of purified recombinant human H-subunit (acidic) ferritin on murine myelopoiesis

Blood ◽  
1989 ◽  
Vol 73 (1) ◽  
pp. 74-79 ◽  
Author(s):  
HE Broxmeyer ◽  
DE Williams ◽  
K Geissler ◽  
G Hangoc ◽  
S Cooper ◽  
...  
Keyword(s):  
Progenitor Cells ◽  
Progenitor Cell ◽  
Hematopoietic Progenitor Cells ◽  
Hematopoietic Progenitor Cell ◽  
Hematopoietic Progenitor ◽  
Virus Complex ◽  
Progenitor Cell Proliferation ◽  
Dose Dependent

Abstract Purified recombinant human heavy-chain (acidic) ferritin (rHF) was assessed in vivo in mice for effects on the proliferation (percentage of cells in S-phase) and absolute numbers of granulocyte-macrophage (CFU-GM), erythroid (BFU-E), and multipotential (CFU-GEMM) progenitor cells in the femur and spleen and on the nucleated cells in the marrow, spleen, and blood. rHF significantly decreased cycling rates and absolute numbers of marrow and splenic hematopoietic progenitors and marrow and blood nucleated cellularity. These effects were apparent in BDF1, C3H/Hej and DBA/2 mice and were dose dependent, time related, and reversible. Suppressive effects were noted within three hours for progenitor cell cycling, within 24 hours for progenitor cell numbers, and within 48 hours for circulating neutrophils. Additionally, hematopoietic progenitor cells in DBA/2 mice infected with the polycythemia-inducing strain of the Friend virus complex (FVC-P) were insensitive to the in vivo administration of rHF. These studies demonstrate activity of rHF in vivo on myelopoiesis of normal but not FVC-P-infected mice. Since rHF suppresses hematopoietic progenitor cell proliferation from normal donors in vitro and from normal mice in vitro and in vivo but does not suppress progenitor cells from patients with leukemia in vitro or from mice with FVC-P-infection in vitro or in vivo, rHF may be useful as a candidate adjunct molecule for the protection of normal hematopoietic progenitor cells during chemotherapy.

Sign in / Sign up

Export Citation Format

Share Document