The colony stimulating factors. Discovery, development, and clinical applications

Molecular and functional characterization of two granulocyte colony stimulating factors in goldfish (Carassius auratus L.)

Granulocyte colony-stimulating factor (GCSF) is a member of the hematopoietic growth factor family that acts primarily on neutrophils and neutrophilic precursors to promote cell proliferation and differentiation. Although multiple GCSF genes have been found in teleosts, knowledge of their functions during fish hematopoietic development is still limited. Here, we report for the first time the molecular and functional characterization of two goldfish GCSFs (gfGCSF-a and gfGCSF-b). The open reading frame (ORF) of the gfGCSF-a and gfGCSF-b cDNA transcript consisted respectively of 624 bp and 678 bp with its ORF encoding 207 and 225 amino acids (aa), with a 17 aa signal peptide for each gene and a conserved domain of the IL-6 superfamily. Treatment of goldfish head kidney leukocytes (HKLs) with LPS increased gfGCSF-a and gfGCSF-b mRNA expression levels, also exposure of HKLs to either heat-killed or live A. hydrophila, induced transcriptional upregulation of gfGCSF-a and gfGCSF-b levels. Recombinant gfGCSF-a and gfGCSF-b protein (rgGCSF-a and rgGCSF-b) induced a dose-dependent production of TNFα and IL-1β from goldfish neutrophils. In vitro experiments showed rgGCSF-a and rgGCSF-b differentially promoted the proliferation and differentiation of leukocytes in goldfish. Furthermore, treatment of HKLs with rgGCSF-a showed significant upregulation of mRNA levels of the hematopoietic transcription factor GATA2, Runx1, MafB, and cMyb, while gfGCSF-b induces not only all four transcriptional factors mentioned above but also CEBPα. Our results indicate that goldfish GCSF-a and GCSF-b are important regulators of neutrophil proliferation and differentiation, which could stimulate different stages and lineages of hematopoiesis.

Mobilization-based engraftment of haematopoietic stem cells: a new perspective for chemotherapy-free gene therapy and transplantation

INTRODUCTION

In haematopoietic stem cell transplantation (HSCT), haematopoietic stem cells (HSCs) from a healthy donor replace the patient's ones. Ex vivo HSC gene therapy (HSC-GT) is a form of HSCT in which HSCs, usually from an autologous source, are genetically modified before infusion, to generate a progeny of gene-modified cells. In HSCT and HSC-GT, chemotherapy is administered before infusion to free space in the bone marrow (BM) niche, which is required for the engraftment of infused cells. Here, we review alternative chemotherapy-free approaches to niche voidance that could replace conventional regimens and alleviate the morbidity of the procedure.

SOURCES OF DATA

Literature was reviewed from PubMed-listed peer-reviewed articles. No new data are presented in this article.

AREAS OF AGREEMENT

Chemotherapy exerts short and long-term toxicity to haematopoietic and non-haematopoietic organs. Whenever chemotherapy is solely used to allow engraftment of donor HSCs, rather than eliminating malignant cells, as in the case of HSC-GT for inborn genetic diseases, non-genotoxic approaches sparing off-target tissues are highly desirable.

AREAS OF CONTROVERSY

In principle, HSCs can be temporarily moved from the BM niches using mobilizing drugs or selectively cleared with targeted antibodies or immunotoxins to make space for the infused cells. However, translation of these principles into clinically relevant settings is only at the beginning, and whether therapeutically meaningful levels of chimerism can be safely established with these approaches remains to be determined.

GROWING POINTS

In pre-clinical models, mobilization of HSCs from the niche can be tailored to accommodate the exchange and engraftment of infused cells. Infused cells can be further endowed with a transient engraftment advantage.

AREAS TIMELY FOR DEVELOPING RESEARCH

Inter-individual efficiency and kinetics of HSC mobilization need to be carefully assessed. Investigations in large animal models of emerging non-genotoxic approaches will further strengthen the rationale and encourage application to the treatment of selected diseases.

Human amniotic mesenchymal stromal cells support the ex vivo expansion of cord blood hematopoietic stem cells

Currently, more than 30 000 allogeneic hematopoietic stem cell (HSC) transplantations have been performed for the treatment of hematological and nonhematological diseases using HSC from umbilical cord blood (CB). However, the wide utilization of CB as a source of HSC is limited by the low number of cells recovered. One strategy to expand ex vivo CB‐HSC is represented by the use of bone marrow mesenchymal stromal cells (BM‐MSCs) as a feeder to enhance HSC proliferation while maintaining HSC stemness. Indeed, BM‐MSCs have been recognized as one of the most relevant players in the HSC niche. Thus, it has been hypothesized that they can support the ex vivo expansion of HSC by mimicking the physiological microenvironment present in the hematopoietic niche. Due to the role of placenta in supporting fetal hematopoiesis, MSC derived from the amniotic membrane (hAMSC) of human term placenta could represent an interesting alternative to BM‐MSC as a feeder layer to enhance the proliferation and maintain HSC stemness. Therefore, in this study we investigated if hAMSC could support the ex vivo expansion of HSC and progenitor cells. The capacity of hAMSCs to support the ex vivo expansion of CB‐HSC was evaluated in comparison to the control condition represented by the CB‐CD34⁺ cells without a feeder layer. The coculture was performed at two different CD34⁺:MSC ratios (1:2 and 1:8) in both cell‐to‐cell contact and transwell setting. After 7 days, the cells were collected and analyzed for phenotype and functionality. Our results suggest that hAMSCs represent a valuable alternative to BM‐MSC to support: (a) the ex vivo expansion of CB‐HSC in both contact and transwell systems, (b) the colony forming unit ability, and (c) long‐term culture initiating cells ability. Overall, these findings may contribute to address the unmet need of high HSC content in CB units available for transplantation.

Characterizing Chemotherapy-Induced Neutropenia and Monocytopenia Through Mathematical Modelling

In spite of the recent focus on the development of novel targeted drugs to treat cancer, cytotoxic chemotherapy remains the standard treatment for the vast majority of patients. Unfortunately, chemotherapy is associated with high hematopoietic toxicity that may limit its efficacy. We have previously established potential strategies to mitigate chemotherapy-induced neutropenia (a lack of circulating neutrophils) using a mechanistic model of granulopoiesis to predict the interactions defining the neutrophil response to chemotherapy and to define optimal strategies for concurrent chemotherapy/prophylactic granulocyte colony-stimulating factor (G-CSF). Here, we extend our analyses to include monocyte production by constructing and parameterizing a model of monocytopoiesis. Using data for neutrophil and monocyte concentrations during chemotherapy in a large cohort of childhood acute lymphoblastic leukemia patients, we leveraged our model to determine the relationship between the monocyte and neutrophil nadirs during cyclic chemotherapy. We show that monocytopenia precedes neutropenia by 3 days, and rationalize the use of G-CSF during chemotherapy by establishing that the onset of monocytopenia can be used as a clinical marker for G-CSF dosing post-chemotherapy. This work therefore has important clinical applications as a comprehensive approach to understanding the relationship between monocyte and neutrophils after cyclic chemotherapy with or without G-CSF support.

The role of granulocyte colony‑stimulating factor in breast cancer development: A review

Granulocyte-colony-stimulating factor (G-CSF) is a member of the hematopoietic growth factor family that primarily affects the neutrophil lineage. G-CSF serves as a powerful mobilizer of peripheral blood stem cells and recombinant human G-CSF (rhG-CSF) has been used to treat granulocytopenia and neutropenia after chemotherapy for cancer patients. However, recent studies have found that G-CSF plays an important role in cancer progression. G-CSF expression is increased in different types of cancer cells, such as lung cancer, gastric cancer, colorectal cancer, invasive bladder carcinoma, glioma and breast cancer. However, it is unclear whether treatment with G-CSF has an adverse effect. The current review provides an overview of G-CSF in malignant breast cancer development and the data presented in this review are expected to provide new ideas for cancer therapy.

Analysis of Neuroprotection by Taurine and Taurine Combinations in Primary Neuronal Cultures and in Neuronal Cell Lines Exposed to Glutamate Excitotoxicity and to Hypoxia/Re-oxygenation

Ischemic stroke is one of the greatest contributors to death and long term disability in developed countries. Ischemia induced brain injury arises due to excessive release of glutamate and involves cell death due to apoptosis and endoplasmic reticulum (ER) stress responses. Despite major research efforts there are currently no effective treatments for stroke. Taurine, a free amino acid found in high concentrations in many invertebrate and vertebrate systems can provide protection against a range of neurological disorders. Here we demonstrate that taurine can combat ER stress responses induced by glutamate or by hypoxia/re-oxygenation in neuronal cell lines and primary neuronal cultures. Taurine decreased expression of ER stress markers GRP78, CHOP, Bim and caspase 12 in primary neuronal cultures exposed to hypoxia/re-oxygenation. In analyzing individual ER stress pathways we demonstrated that taurine treatment can result in reduced levels of cleaved ATF6 and decreased p-IRE1 levels. We hypothesized that because of the complex nature of stroke a combination therapy approach may be optimal. For this reason we proceeded to test combination therapies using taurine plus low dose administration of an additional drug: either granulocyte colony stimulating factor (G-CSF) or sulindac a non-steroidal anti-inflammatory drug with potent protective functions through signaling via ischemic preconditioning pathways. When primary neurons were pretreated with 25 mM taurine and 25 ng/mL G-CSF for I hour and then exposed to high levels of glutamate, the taurine/G-CSF combination increased the protective effect against glutamate toxicity to 88% cell survival compared to 75% cell survival from an individual treatment with taurine or G-CSF alone. Pre-exposure of PC12 cells to 5 mM taurine or 25 μM sulindac did not protect the cells from hypoxia/re-oxygenation stress whereas at these concentrations the combination of taurine plus sulindac provided significant protection. In summary we have demonstrated the protective effect of taurine in primary neuronal cultures against hypoxia with re-oxygenation through inhibition of ATF6 or p-IRE-1 pathway but not the PERK pathway of ER stress. Furthermore the combinations of taurine plus an additional drug (either G-CSF or sulindac) can show enhanced potency for protecting PC 12 cells from glutamate toxicity or hypoxia/re-oxygenation through inhibition of ER stress responses.

Sources of Hematopoietic Stem and Progenitor Cells and Methods to Optimize Yields for Clinical Cell Therapy

Bone marrow (BM) aspirates, mobilized peripheral blood, and umbilical cord blood (UCB) have developed as graft sources for hematopoietic stem and progenitor cells (HSPCs) for stem cell transplantation and other cellular therapeutics. Individualized techniques are necessary to enhance graft HSPC yields and cell quality from each graft source. BM aspirates yield adequate CD34⁺ cells but can result in relative delays in engraftment. Granulocyte colony-stimulating factor (G-CSF)-primed BM HSPCs may facilitate faster engraftment while minimizing graft-versus-host disease in certain patient subsets. The levels of circulating HSPCs are enhanced using mobilizing agents, such as G-CSF and/or plerixafor, which act via the stromal cell-derived factor 1/C-X-C chemokine receptor type 4 axis. Alternate niche pathway mediators, including very late antigen-4/vascular cell adhesion molecule-1, heparan sulfate proteoglycans, parathyroid hormone, and coagulation cascade intermediates, may offer promising alternatives for graft enhancement. UCB grafts have been expanded ex vivo with cytokines, notch-ligand, or mesenchymal stromal cells, and most studies demonstrated greater quantities of CD34⁺ cells ex vivo and improved short-term engraftment. No significant changes were observed in long-term repopulating potential or in patient survival. Early phase clinical trials using nicotinamide and StemReginin1 may offer improved short- and long-term repopulating ability. Breakthroughs in genome editing and stem cell reprogramming technologies may hasten the generation of pooled, third-party HSPC grafts. This review elucidates past, present, and potential future approaches to HSPC graft optimization.

Pulp regeneration by transplantation of dental pulp stem cells in pulpitis: a pilot clinical study

Background

Experiments have previously demonstrated the therapeutic potential of mobilized dental pulp stem cells (MDPSCs) for complete pulp regeneration. The aim of the present pilot clinical study is to assess the safety, potential efficacy, and feasibility of autologous transplantation of MDPSCs in pulpectomized teeth.

Methods

Five patients with irreversible pulpitis were enrolled and monitored for up to 24 weeks following MDPSC transplantation. The MDPSCs were isolated from discarded teeth and expanded based on good manufacturing practice (GMP). The quality of the MDPSCs at passages 9 or 10 was ascertained by karyotype analyses. The MDPSCs were transplanted with granulocyte colony-stimulating factor (G-CSF) in atelocollagen into pulpectomized teeth.

Results

The clinical and laboratory evaluations demonstrated no adverse events or toxicity. The electric pulp test (EPT) of the pulp at 4 weeks demonstrated a robust positive response. The signal intensity of magnetic resonance imaging (MRI) of the regenerated tissue in the root canal after 24 weeks was similar to that of normal dental pulp in the untreated control. Finally, cone beam computed tomography demonstrated functional dentin formation in three of the five patients.

Conclusions

Human MDPSCs are safe and efficacious for complete pulp regeneration in humans in this pilot clinical study.

Recombinant Hemopoietic Growth Factors: Comparative Hemopoietic Response in Younger and Older Subjects

OBJECTIVE

To study the effectiveness of hemopoietic growth factors in older patients.

DESIGN

Literature review. All articles published in English language between 1987 and 1990 were reviewed. Those reporting studies without age limits as entry criteria and describing the effects of growth factors in individual patients were suitable for analysis. Bone marrow transplantation related articles were excluded.

MAIN OUTCOME MEASURES

The meanfold increase of granulocytes for Granulocyte-Colony Stimulating Factor, Granulocyte Macrophage-Colony Stimulating Factor, and Interleukin 3 and of hemoglobin for erythropoietin were compared in subjects younger and older than 65, by Mann-Whitney U test.

RESULTS

Of 68 studies, 23 were suitable for analysis. These included patients with myelodysplastic syndromes, aplastic anemia, chemotherapy-induced myelosuppression, chronic granulocytopenia, anemia, and myelosuppression of malignancies and of chronic disease. Of 204 patients, 67 were 65 years of age or older and 42 were over 70. No difference was seen in meanfold increase of granulocyte and hemoglobin in time of response to growth factors or in response in presence of an absolute neutrophil count lower than 1000/microliters between younger and older patients.

CONCLUSION

Early response to hemopoietic growth factors appears well maintained with advanced age. Prospective studies of the prolonged effects of these factors in older and younger patients are needed.

Intrathecal Administration of Autologous CD34 Positive Cells in Patients with Past Cerebral Infarction: A Safety Study

Regenerative strategies in treatment of stroke have great potential. The goal of the current study was to investigate safety of intrathecal administration of autologous CD34 positive cells in treatment of patients with poststroke. A total of eight male patients with a history of stroke were enrolled. The patients were treated subcutaneously with 5 μg/kg body weight rhG-CSF for 5 consecutive days, and then leukapheresis was performed to concentrate cells for CD34 positive immunoselection. All patients underwent intrathecal administration of CD34 positive cells via lumbar puncture. The primary outcome was safety evaluation for 12-month followup. In addition, behavioral function was evaluated with NIH stroke scale and Barthel index 1, 6, and 12 months after the last treatment, respectively. There were no major adverse events, and abnormal changes of blood tests during the whole treatment process included intrathecal administration and 12-month followup. The main message from the current study was that administration of G-CSF-mobilized autologous CD34 positive cells in patients with poststroke was safe. Future studies with larger population and control group are needed to confirm the safety and investigate the efficacy.

A novel combinatorial therapy with pulp stem cells and granulocyte colony-stimulating factor for total pulp regeneration

Treatment of deep caries with pulpitis is a major challenge in dentistry. Stem cell therapy represents a potential strategy to regenerate the dentin-pulp complex, enabling conservation and restoration of teeth. The objective of this study was to assess the efficacy and safety of pulp stem cell transplantation as a prelude for the impending clinical trials. Clinical-grade pulp stem cells were isolated and expanded according to good manufacturing practice conditions. The absence of contamination, abnormalities/aberrations in karyotype, and tumor formation after transplantation in an immunodeficient mouse ensured excellent quality control. After autologous transplantation of pulp stem cells with granulocyte-colony stimulating factor (G-CSF) in a dog pulpectomized tooth, regenerated pulp tissue including vasculature and innervation completely filled in the root canal, and regenerated dentin was formed in the coronal part and prevented microleakage up to day 180. Transplantation of pulp stem cells with G-CSF yielded a significantly larger amount of regenerated dentin-pulp complex compared with transplantation of G-CSF or stem cells alone. Also noteworthy was the reduction in the number of inflammatory cells and apoptotic cells and the significant increase in neurite outgrowth compared with results without G-CSF. The transplanted stem cells expressed angiogenic/neurotrophic factors. It is significant that G-CSF together with conditioned medium of pulp stem cells stimulated cell migration and neurite outgrowth, prevented cell death, and promoted immunosuppression in vitro. Furthermore, there was no evidence of toxicity or adverse events. In conclusion, the combinatorial trophic effects of pulp stem cells and G-CSF are of immediate utility for pulp/dentin regeneration, demonstrating the prerequisites of safety and efficacy critical for clinical applications.

Quantifying hematopoietic stem and progenitor cell mobilization

Allogeneic donor blood cells and autologous peripheral blood leukocytes (PBL), obtained following -clinical mobilization procedures, are routinely used as a major source of hematopoietic stem and progenitor cells (HSPC) for transplantation protocols. It is, therefore, essential to evaluate and to quantify the extent by which the HSPC are mobilized and enriched in the circulation in correlation with their long-term hematopoietic reconstitution capacity. In this chapter, we describe quantitative methods that measure the number of mobilized HSPC according to specific criteria, as well as their functional properties in vitro and in vivo. The described assays are useful for assessment of progenitor cell mobilization as applied to both human and murine HSPC.

Mobilisation of hematopoietic CD34+ precursor cells in patients with acute stroke is safe--results of an open-labeled non randomized phase I/II trial

Background

Regenerative strategies in the treatment of acute stroke may have great potential. Hematopoietic growth factors mobilize hematopoietic stem cells and may convey neuroprotective effects. We examined the safety, potential functional and structural changes, and CD34⁺ cell–mobilization characteristics of G-CSF treatment in patients with acute ischemic stroke.

Methods and Results

Three cohorts of patients (8, 6, and 6 patients per cohort) were treated subcutaneously with 2.5, 5, or 10 µg/kg body weight rhG-CSF for 5 consecutive days within 12 hrs of onset of acute stroke. Standard treatment included IV thrombolysis. Safety monitoring consisted of obtaining standardized clinical assessment scores, monitoring of CD34⁺ stem cells, blood chemistry, serial neuroradiology, and neuropsychology. Voxel-guided morphometry (VGM) enabled an assessment of changes in the patients' structural parenchyma. 20 patients (mean age 55 yrs) were enrolled in this study, 5 of whom received routine thrombolytic therapy with r-tPA. G-CSF treatment was discontinued in 4 patients because of unrelated adverse events. Mobilization of CD34⁺ cells was observed with no concomitant changes in blood chemistry, except for an increase in the leukocyte count up to 75,500/µl. Neuroradiological and neuropsychological follow-up studies did not disclose any specific G-CSF toxicity. VGM findings indicated substantial atrophy of related hemispheres, a substantial increase in the CSF space, and a localized increase in parenchyma within the ischemic area in 2 patients.

Conclusions

We demonstrate a good safety profile for daily administration of G-CSF when begun within 12 hours after onset of ischemic stroke and, in part in combination with routine IV thrombolysis. Additional analyses using VGM and a battery of neuropsychological tests indicated a positive functional and potentially structural effect of G-CSF treatment in some of our patients.

Trial Registration

German Clinical Trial Register DRKS 00000723

Defining the hematopoietic stem cell niche: the chicken and the egg conundrum

Understanding the in vivo regulation of hematopoietic stem cells (HSCs) will be critical to identifying key factors involved in the regulation of HSC self-renewal and differentiation. The niche (microenvironment) in which HSCs reside has recently regained attention accompanied by a dramatic increase in the understanding of the cellular constituents of the bone marrow HSC niche. The use of sophisticated genetic models allowing modulation of specific lineages has demonstrated roles for mesenchymal-derived elements such as osteoblasts and adipocytes, vasculature, nerves, and a range of hematopoietic progeny of the HSC as being participants in the regulation of the bone marrow microenvironment. Whilst providing significant insight into the cellular composition of the niche, is it possible to manipulate any given cell lineage in vivo without impacting, knowingly or unknowingly, on those that remain?

Protection of taurine and granulocyte colony-stimulating factor against excitotoxicity induced by glutamate in primary cortical neurons

Abstracts

Effects of G-CSF treatment on neutrophil mobilization and neurological outcome after transient focal ischemia

Several recent studies demonstrated beneficial effects of G-CSF treatment (granulocyte colony-stimulating factor) in various CNS disease. Possible mechanisms underlying this activity are neuroprotection, anti-apoptosis, angiogenesis and anti-inflammation. Hence, we investigated the efficacy of G-CSF administration in experimental stroke by determining infarct volume and neurological score in wildtype, G-CSF-deficient and G-CSF-treated G-CSF-deficient mice. Besides, cerebral ischemia is followed by an upregulation of endothelial adhesion molecules which promote leukocyte recruitment to the injured area. In combination with G-CSF-induced leukocytosis, increased peripheral neutrophils could aggregate within microvasculature and additionally impair blood perfusion of the ischemic tissue. Therefore, we analyzed the neutrophil counts in both vessel and tissue compartment 2 and 5 days post-stroke by immunohistochemistry. Here we show that G-CSF deficiency leads to increased infarct volumes, whereas G-CSF substitution revokes detrimental effects by reducing lesion size and enhancing neurological outcome compared to untreated animals. Administration of G-CSF is accompanied by significant increase of circulating neutrophils 2 days post-ischemia but leukocytosis is restricted to the vessel compartment and has no deleterious effect on lesion formation and functional recovery. These observations are likely to be important for therapeutic targeting of G-CSF-mediated neuroprotection in stroke.

LIM domain only 4 protein promotes granulocyte colony-stimulating factor-induced signaling in neurons

Granulocyte colony-stimulating factor (GCSF) is currently in clinical trials to treat neurodegenerative diseases and stroke. Here, we tested whether LIM domain only 4 protein (LMO4), a hypoxia-inducible gene that protects neurons from ischemic injury, could modulate the neuroprotective effect of GCSF. We showed that GCSF treatment acetylates and phosphorylates Stat3, activates expression of a Stat3-dependent anti-apoptotic gene, p27, and increases neuron survival from ischemic injury. LMO4 participates in Stat3 signaling in hepatocytes and associates with histone deacetylase 2 (HDAC2) in cancer cells. In the absence of LMO4, GCSF fails to rescue neurons from ischemic insults. In wild-type neurons, inhibition of HDAC promoted Stat3 acetylation and the antiapoptotic effect of GCSF. In LMO4 null cortical neurons, expression of wild-type but not HDAC-interaction-deficient LMO4 restored GCSF-induced Stat3 acetylation and p27 expression. Thus, our results indicate that LMO4 enhances GCSF-induced Stat3 signaling in neurons, in part by sequestering HDAC.

Molecular cloning and expression of cDNAs for two distinct granulocyte colony stimulating factor genes from black rockfish Sebastes schlegelii

Granulocyte-colony stimulating factor (G-CSF) is a cytokine that stimulates the proliferation and differentiation of hematopoietic progenitor cells committed to the neutrophil/granulocyte lineage. Here, we report the two distinct granulocyte colony stimulating factor homologues from black rockfish Sebastes schlegelii. The G-CSF homologue cDNAs were isolated from the black rockfish LPS or Con A/PMA stimulated leukocyte cDNA libraries. The cDNA for the Black rockfish G-CSF-1 homologue predicts a peptide of 202 amino acids that is the closest to the Bastard halibut (Paralichthys olivaceus) G-CSF, whereas the cDNA of the Black rockfish G-CSF-2 homologue predicts a peptide of 212 amino acids that is the closest to the Fugu (Takifugu rubripes). In a healthy fish, the mRNAs of both G-CSF homologues were predominantly expressed in leukocytes, spleen, and gill. Expression of the black rockfish G-CSF-1 homologue was induced in peripheral blood leukocytes (PBLs) after stimulation with LPS, Con A/PMA, or Poly I:C, and G-CSF-2 homologue was strongly induced in PBLs after stimulation with Con A/PMA for 24 h only.

The use of experimental murine models to assess novel agents of hematopoietic stem and progenitor cell mobilization

The recent explosion in the understanding of the cellular and molecular mechanisms underlying hematopoietic stem and progenitor cell (HSPC) mobilization has facilitated development of novel therapeutic agents, targeted at improving mobilization kinetics as well as HSPC yield. With the development of new agents comes the challenge of choosing efficient and relevant preclinical studies for the testing of the HSPC mobilization efficacy of these agents. This article reviews the use of the mouse as a convenient small animal model of HSPC mobilization and transplantation, and outlines the range of murine assays that can be applied to assess novel HSPC mobilizing agents. Techniques to demonstrate murine HSPC mobilization are discussed, as well as the role of murine assays to confirm human HSPC mobilization, and techniques to investigate the biologic phenotype of HSPC mobilized by these novel agents. Technical aspects regarding mobilization regimens and control arms, and choice of experimental animals are also discussed.

Effects of granulocyte-colony stimulating factor on peritoneal defense mechanisms and bacterial translocation after administration of systemic chemotherapy in rats

AIM: To investigate the effects of granulocyte-colony stimulating factor (G-CSF) on peritoneal defense mechanisms and bacterial translocation after systemic 5-Fluorouracil (5-FU) administration.

METHODS: Thirty Wistar albino rats were divided into three groups; the control, 5-FU and 5-FU + G-CSF groups. We measured bactericidal activity of the peritoneal fluid, phagocytic activity of polymorphonuclear leucocytes in the peritoneal fluid, total peritoneal cell counts and cell types of peritoneal washing fluid. Bacterial translocation was quantified by mesenteric lymph node, liver and spleen tissue cultures.

RESULTS: Systemic 5-FU reduced total peritoneal cell counts, neutrophils and macrophage numbers. It also altered bactericidal activity of the peritoneal fluid and phagocytic activity of polymorphonuclear leucocytes in the peritoneal fluid. 5-FU also caused significant increase in frequencies of bacterial translocation at the liver and mesenteric lymph nodes. G-CSF decreased bacterial translocation, it significantly enhanced bactericidal activity of the peritoneal fluid and phagocytic activity of polymorphonuclear leucocytes in the peritoneal fluid. It also increased total peritoneal cell counts, neutrophils and macrophage numbers.

CONCLUSION: Systemic 5-FU administration caused bacterial translocation, decreased the bactericidal activity of peritoneal fluid and phagocytic activity of polymorphonuclear leucocytes in the peritoneal fluid. G-CSF increased both bactericidal activity of the peritoneal fluid and phagocytic activity of polymorphonuclear leucocytes in the peritoneal fluid, and prevented the bacterial translocation. We conclude that intraperitoneal GCSF administration protects the effects of systemic 5-FU on peritoneal defense mechanisms.

Acute myeloid leukemia or myelodysplastic syndrome following use of granulocyte colony-stimulating factors during breast cancer adjuvant chemotherapy

BACKGROUND

Recently, increasing numbers of women receiving adjuvant chemotherapy for breast cancer have also received granulocyte colony-stimulating factors (G-CSFs) or granulocyte-macrophage colony-stimulating factors (GM-CSFs). Although these growth factors support chemotherapy, their long-term safety has not been evaluated. We studied the association between G-CSF use and incidence of leukemia in a population-based sample of breast cancer patients.

METHODS

Among women aged 65 years or older in the Surveillance, Epidemiology, and End Results-Medicare database who were diagnosed with stages I-III breast cancer from January 1, 1991, to December 31, 1999, we identified those who received G-CSF or GM-CSF concurrently with chemotherapy. We used Cox proportional hazards models to estimate hazard ratios for the association of treatment with G-CSF or GM-CSF and subsequent (through December 31, 2003) diagnosis of acute myeloid leukemia (AML) or myelodysplastic syndrome (MDS). All statistical tests were two-sided.

RESULTS

Of 5510 women treated with chemotherapy, 906 (16%) received G-CSF or GM-CSF therapy, and 64 (1.16%) were subsequently diagnosed with either MDS or AML before a cancer recurrence. Use of G-CSF and GM-CSF was associated with more recent diagnosis, younger age, urban residence, fewer comorbidities, receipt of radiation therapy, positive lymph nodes, and cyclophosphamide treatment. Of the 906 patients who were treated with G-CSF, 16 (1.77%) developed AML or MDS; of the 4604 patients not treated with G-CSF, 48 (1.04%) developed AML or MDS. The hazard rate ratio for AML or MDS among those treated with G-CSF or GM-CSF compared with those who were not was 2.14 (95% confidence interval [CI] = 1.12 to 4.08). AML or MDS developed within 48 months of breast cancer diagnosis in 1.8% of patients who received G-CSF or GM-CSF but only in 0.7% of patients who did not (hazard ratio = 2.59, 95% CI = 1.30 to 5.15).

CONCLUSIONS

The use of G-CSF was associated with a doubling in the risk of subsequent AML or MDS among the population that we studied, although the absolute risk remained low. Even if this association is confirmed, the benefits of G-CSF may still outweigh the risks. Meanwhile, however, G-CSF use should not be assumed to be risk free.

Granulocyte and granulocyte macrophage colony-stimulating factors as therapy in human and veterinary medicine

Granulocyte colony-stimulating factors (G-CSFs) and granulocyte macrophage colony-stimulating factors (GM-CSFs) are endogenous cytokines that regulate granulocyte colonies and play a major role in the stimulation of granulopoiesis (neutrophils, basophils and eosinophils) and in the regulation of microbicidal functions. There are numerous pathological conditions in which neutrophils are decreased, the most common being neutropenia associated with cancer chemotherapy, which increases the risk of serious microbial infections developing with the potential for high morbidity and mortality. New methods in molecular biology have led to the identification and cloning of CSF genes and biopharmaceutical production. Since then, CSFs have been widely used for the prevention and treatment of neutropenia associated with cancer chemotherapy, for mobilising haematopoietic cell precursors, and for other neutropenia-related pathologies. This review focuses on the use of CSFs within both human and veterinary medicine. Clinical applications, pharmacology, tolerability and the potential role of these factors in veterinary medicine are considered.

MicroRNAs as regulators of mammalian hematopoiesis

MicroRNAs (miRNAs) are an abundant class of approximately 22 nucleotide non-coding RNAs and play important regulatory roles in animal and plant development at the post-transcriptional level. Many miRNAs cloned from mouse bone marrow cells are differentially regulated in various hematopoietic lineages, suggesting that they might influence hematopoietic lineage differentiation. miR-181, a miRNA specifically expressed in B cells within mouse bone marrow, promotes B-cell differentiation when expressed in hematopoietic stem/progenitor cells. Some human miRNAs are linked to leukemias: the miR-15a/miR-16 locus is frequently deleted or down-regulated in patients with B-cell chronic lymphocytic leukemia and miR-142 is at a translocation site found in a case of aggressive B-cell leukemia. Collectively, these results indicate that miRNAs may be important regulators of mammalian hematopoiesis. Here, we provide background on the biogenesis and function of miRNAs and discuss how miRNA-mediated post-transcriptional regulation may influence the development and function of blood cells.

G-CSF reduces infarct volume and improves functional outcome after transient focal cerebral ischemia in mice

Growth factors possess neuroprotective and neurotrophic properties in vitro, but few have been extensively studied in vivo after stroke. In the present study, we investigated the potential functional benefits of granulocyte colony-stimulating factor (G-CSF) administration after focal cerebral ischemia. Male mice underwent 60-minute middle cerebral artery occlusion (MCAO) and received G-CSF (50 microg/kg, subcutaneously) or vehicle (saline) at the onset of reperfusion. Granulocyte colony-stimulating factor-treated mice killed at 48 hours after MCAO revealed a >45% reduction (P<0.05) in lesion volume. In terms of body weight recovery, and in tests of motor (grid test and rotarod) and cognitive ability (water maze), MCAO significantly worsened the outcome in vehicle-treated mice as compared with shams (P<0.05). However, G-CSF treatment was beneficial as, compared with vehicle, this significantly improved weight recovery and motor ability. This effect was most apparent on the water maze where G-CSF-treated mice were indistinguishable from shams in terms of acquiring the task. These results indicate long-term beneficial effects of a single dose of G-CSF administered on reperfusion, and illustrate the need to further investigate the mechanisms of G-CSF action.

Effects of Granulocyte-Colony Stimulating Factor on Wound Healing in a Mouse Model of Burn Trauma

The effects of burn trauma and granulocyte-colony stimulating factor (G-CSF) treatment on wound healing in a surgical incision model were studied. Sixty adult male mice were used in this study. Under general anesthesia hot water at 97 degrees C was applied for 3 sec to the dorsum of the mice in order to achieve 20% burn wound. After burn trauma, full thickness midline skin incision 2 cm in length was performed on the abdominal wall and then were sutured primarily with 4/0 polypropylene. In Group I only skin incision was performed, group II had skin incision and burn, in group III G-CSF (0.03 BU/30 g) was applied intraperitoneally after burn and skin incision. Breaking strength and 5-hydroxyproline (5-HP) levels of the wounds were calculated 5 and 10 days after the procedure. 5-HP levels and breaking strength values showed statistical difference between groups II-III and I-II (p<0.05). 5-HP levels were lowest in incision and burn group (41.80 microg/mg). Breaking strength levels were also lowest in the same group (0.12 kg) (p<0.05). These results suggest that third degree burn causes a significant impairment on incisional wound healing and G-CSF ameliorates this impairment.

Diagnostic and prognostic value of colony formation of hematopoietic progenitor cells in myeloid malignancies

Hematopoietic progenitor cells are capable of forming colonies of mature blood cells in semisolid media in response to specific growth factors. Colony assays have been extensively used for many years to study normal and malignant hematopoiesis in vitro. In fact, these assays have provided an excellent research tool for investigating growth and differentiation of progenitor cells in response to positive and negative regulators of hematopoiesis. However, apart from their role in basic research, colony assays are also widely used in routine clinical practice in the diagnosis of various hematologic disorders, such as aplastic anemia, myelodysplastic syndromes and myeloproliferative disorders. This review summarizes our current knowledge on the diagnostic value and prognostic significance of the growth of progenitor cells in peripheral blood and bone marrow in patients with myeloid malignancies.

Antibiotic prophylaxis with meropenem after allogeneic stem cell transplantation

In the present study, we analyze the efficacy of prophylaxis with meropenem in patients receiving a matched related donor allogeneic transplant. In total, 38 patients were sequentially treated with meropenem starting on the day of the first febrile episode (n=17, group A) vs prophylactic meropenem starting on the first day with <500/mm(3) granulocytes (n=21, group B), and maintained until resolution of fever or after granulocyte count >500/mm(3). Of these, 16 (94%) patients in group A developed fever as compared to 16 (76%) in group B (P=0.02). While only one patient in group A did not require first-line antibiotherapy, there were seven (33%) in group B who did not require it (P=0.01) since fever lasted less than 72 h. In addition, 52% patients in group B did not require second-line antibiotics as compared to 11% among patients in group A (P=0.04). In multivariate analysis prophylaxis with meropenem (HR=2.83, 95% CI (1-8.02); P=0.04) and disease status at transplant (HR for early stage=0.15, 95% CI (0.04-0.62); P=0.04) significantly influenced the development of fever. In conclusion, the current pilot study suggests that the use of prophylaxis with meropenem during the period of neutropenia in patients undergoing allogeneic transplantation favorably affects the morbidity of the procedure by reducing febrile episodes.

Granulocyte colony-stimulating factor and the risk of secondary myeloid malignancy after etoposide treatment

Event-free survival for children with acute lymphoblastic leukemia (ALL) now exceeds 80% in the most effective trials. Failures are due to relapse, toxicity, and second cancers such as therapy-related myeloid leukemia or myelodysplasia (t-ML). Topoisomerase II inhibitors and alkylators can induce t-ML; additional risk factors for t-ML remain poorly defined. The occurrence of t-ML among children who had received granulocyte colony-stimulating factor (G-CSF) following ALL remission induction therapy prompted us to examine this and other putative risk factors for t-ML in 412 children treated on 2 consecutive ALL protocols from 1991 to 1998. All children received etoposide and anthracyclines, 99 of whom received G-CSF; 284 also received cyclophosphamide, 58 of whom also received cranial irradiation. There were 20 children who developed t-ML at a median of 2.3 years (range, 1.0-6.0 years), including 16 cases of acute myeloid leukemia, 3 myelodysplasia, and 1 chronic myeloid leukemia. Stratifying by protocol, the cumulative incidence functions differed (P =.017) according to the use of G-CSF and irradiation: 6-year cumulative incidence (standard error) of t-ML of 12.3% (5.3%) among the 44 children who received irradiation without G-CSF, 11.0% (3.5%) among the 85 children who received G-CSF but no irradiation, 7.1% (7.2%) among the 14 children who received irradiation plus G-CSF, and 2.7% (1.3%) among the 269 children who received neither irradiation nor G-CSF. Even when children receiving irradiation were excluded, the incidence was still higher in those receiving G-CSF (P =.019). In the setting of intensive antileukemic therapy, short-term use of G-CSF may increase the risk of t-ML.

PEGylation of G-CSF using cleavable oligo-lactic acid linkage

A new class of methoxy-poly(ethylene glycol) (mPEG) derivatives having a cleavable group of oligo-lactic acid (OLA) was synthesized by ring opening polymerization of L-lactide using a terminal hydroxyl end of mPEG as an initiator. The synthesized mPEG derivatives had 0.8 and 3.6 lactic acid units based on the MALDI-TOF data. A terminal end group of mPEG-OLA was further activated with p-nitrophenyl chloroformate to produce mPEG-OLA-p-nitrophenyl carbonate (PC). mPEG-OLA-PC derivatives were conjugated to primary amine groups of recombinant human granulocyte-colony stimulating factor. PEGylated G-CSF conjugated with mPEG-OLA-PC derivatives consisted of native, mono-, di-, and tri-PEGylated species, and they did not show any apparent conformational changes even after PEGylation. When incubating in pH 7.4 buffer at 37 degrees C for 2 days, mPEG-OLA-G-CSF conjugates liberated mPEG by cleaving the OLA spacer, resulting in the gradual regeneration of G-CSF.

Granulocyte colony-stimulating factor: release is not impaired after burn wound infection

BACKGROUND

The production of granulocyte colony-stimulating factor (G-CSF), the lineage specific essential regulator of neutrophil progenitor cell proliferation and differentiation, has been thought to be impaired in the setting of burn infection. The ability to directly measure murine G-CSF allows the further delineation of the G-CSF response in a clinically relevant model of thermal injury and infection.

METHODS

We used a commercially available solid phase enzyme-linked immunoabsorbent assay to quantify G-CSF production after burn wound infection in mice. Bone marrow cells, splenic cells, and serum were obtained from BDF1 mice on day 3 after a 15% total body surface area full-thickness scald burn with or without Pseudomonas aeruginosa burn wound infection. G-CSF production of bone marrow cells or splenic cells and the serum level of G-CSF were measured. A clonogenic assay of bone marrow and spleen granulocyte-macrophage progenitor cells as well as blood leukocyte counts were also performed.

RESULTS

After burn sepsis, we noted that G-CSF production of the bone marrow and spleen was significantly increased; the numbers of progenitor cells in bone marrow and spleen were markedly enhanced; serum values of G-CSF were 14 times greater than control values; serum colony-stimulating activity was greater than in control mice; and total blood leukocyte counts were significantly depressed.

CONCLUSION

These findings support the notion that granulocytopoietic failure after burn sepsis is not significantly related to defective endogenous G-CSF synthesis. More likely, hyporesponsiveness of granulocyte progenitor cells to G-CSF, changes in the relative balance of granulocyte versus monocyte progenitors within the granulocyte-macrophage progenitor cell compartment, and enhanced release of monocyte lineage specific growth factors are the critical elements responsible for burn infection-induced hematopoietic failure.

Assessing the evidence for remodelling of the airway in asthma

Asthma is now described as being characterized by reversible airflow obstruction, with bronchial inflammation and tissue remodelling of the airway wall. The description of remodelling has been usefully invoked to account for a component of airflow obstruction that is unresponsive to usual bronchodilator therapy. It is crucial to examine critically the evidence for this view, particularly the quantitation of specific changes in the epithelium, mucus glands, cell infiltrate, collagen, vessels and smooth muscle of the bronchial wall. The useful tools of immunohistochemistry and molecular biology combined with airway biopsy and well-designed clinical trials will be essential to determine the specific roles of cells and cytokines in airway remodelling in asthma.

Granulocyte colony-stimulating factor in the treatment of high-risk febrile neutropenia: a multicenter randomized trial

BACKGROUND

Granulocyte colony-stimulating factors (G-CSFs) have been shown to help prevent febrile neutropenia in certain subgroups of cancer patients undergoing chemotherapy, but their role in treating febrile neutropenia is controversial. The purpose of our study was to evaluate-in a prospective multicenter randomized clinical trial-the efficacy of adding G-CSF to broad-spectrum antibiotic treatment of patients with solid tumors and high-risk febrile neutropenia.

METHODS

A total of 210 patients with solid tumors treated with conventional-dose chemotherapy who presented with fever and grade IV neutropenia were considered to be eligible for the trial. They met at least one of the following high-risk criteria: profound neutropenia (absolute neutrophil count <100/mm(3)), short latency from previous chemotherapy cycle (<10 days), sepsis or clinically documented infection at presentation, severe comorbidity, performance status of 3-4 (Eastern Cooperative Oncology Group scale), or prior inpatient status. Eligible patients were randomly assigned to receive the antibiotics ceftazidime and amikacin, with or without G-CSF (5 microg/kg per day). The primary study end point was the duration of hospitalization. All P values were two-sided.

RESULTS

Patients randomly assigned to receive G-CSF had a significantly shorter duration of grade IV neutropenia (median, 2 days versus 3 days; P = 0.0004), antibiotic therapy (median, 5 days versus 6 days; P = 0.013), and hospital stay (median, 5 days versus 7 days; P = 0.015) than patients in the control arm. The incidence of serious medical complications not present at the initial clinical evaluation was 10% in the G-CSF group and 17% in the control group (P = 0.12), including five deaths in each study arm. The median cost of hospital stay and the median overall cost per patient admission were reduced by 17% (P = 0.01) and by 11% (P = 0.07), respectively, in the G-CSF arm compared with the control arm.

CONCLUSIONS

Adding G-CSF to antibiotic therapy shortens the duration of neutropenia, reduces the duration of antibiotic therapy and hospitalization, and decreases hospital costs in patients with high-risk febrile neutropenia.

Early tooth loss due to cyclic neutropenia: long-term follow-up of one patient

In young patients with abnormal loosening of teeth and periodontal breakdown, dental professionals should consider a wide range of etiological factors/diseases, analyze differential diagnoses, and make appropriate referrals. The long-term oral and dental follow-up of a female patient diagnosed in early infancy with cyclic neutropenia is reviewed, and recommendations for care are discussed.

Novel peptidomimetic hematoregulatory compounds

The activity of a novel series of peptidomimetic hematoregulatory compounds, designed based on a pharmacophore model inferred from the structure activity relationships of a peptide SK&F 107647 (1), is reported. These compounds induce a hematopoietic synergistic factor (HSF) which in turn modulates host defense. The compounds may represent novel therapeutic agents in the area of hematoregulation.

Treatment of antithyroid drug-induced agranulocytosis by granulocyte colony-stimulating factor: a case of primum non nocere

A 48-year-old woman who was treated for thyrotoxicosis with methimazole developed agranulocytosis. The methimazole was stopped and treatment with subcutaneous granulocyte colony-stimulating factor (G-CSF) was initiated. Administration of the drug for 8 days did not effectively shorten the recovery period compared with the average reported in the literature without the drug, and may have triggered additional iatrogenic complications. A search of the literature yielded 15 instances of severe antithyroid-drug-induced granulocytopenia (ATDIA) (granulocyte count of less than 0.1 x 10(9)/L) treated with G-CSF. Of the 16 patients, including the 1 reported here, only 3 displayed significant shortening of the agranulocytic period after treatment. We conclude that routine therapeutic application of G-CSF in afebrile severe ATDIG is not justified, and in some cases may generate a cascade of iatrogenic adverse events.

Glycosylated and non-glycosylated recombinant human granulocyte colony-stimulating factor (rhG-CSF)--what is the difference?

Two forms of recombinant human G-CSF (rhG-CSF) are available for clinical use: filgrastim is expressed in E coli and non-glycosylated, whereas lenograstim is derived from Chinese hamster ovary (CHO) cells and glycosylated. The function of the sugar chain, accounting for approximately 4% of the molecular weight of lenograstim (and native G-CSF), is not known. Glycosylation of the G-CSF molecule does not prolong its circulation half life. Lenograstim is more active than filgrastim (and research-use deglycosylated G-CSF) on a weight-by-weight basis in in vitro colony-forming and cell line assays. An international potency standard assigns a specific activity of 100,000 IU/microgram to filgrastim and 127,760 IU/microgram to lenograstim. Correspondingly, two randomised crossover studies in normal subjects, comparing mass equivalent doses of the two rhG-CSFs, have demonstrated a 25-30% higher concentration of blood stem cells (CD34+, CFU-GM) during lenograstim administration. No difference in side effects was observed. Results from a prospective, randomised, non-crossover trial in breast cancer patients suggest that bioequivalent doses of filgrastim and lenograstim have a similar effect on mobilisation of CD34+ cells and immature CD34+ cell subsets, respectively. Although comparisons outside the setting of stem cell mobilisation are lacking, the clinical relevance of the greater specific activity of lenograstim may thus be limited. The difference in potency between microgram identical doses of the two rhG-CSFs makes dosing in biological units (IU) rather than mass units (microgram) more appropriate.

Design of low molecular weight hematoregulatory agents from the structure-activity relationship of a dimeric pentapeptide

We report herein, a new class of simple hematoregulatory semipeptides, formally derived from the cystine-dimerized peptide pGlu-Glu-Asp-Cys-Lys-OH, where the disulfide bond has been replaced by an isosteric dicarba bridge. The structure-activity relationship (SAR) of a series of analogues incorporating replacements at positions 1 and 2 of peptide 1 led to the design of active conformationally constrained cyclic peptides (12, 13). Ring closure was achieved by cyclization of the N-terminal amino groups at position 2 of peptide 2 using pyrazine-2,3-dicarboxylic acid. Subsequent excision of the putative C-terminal scaffold domain from the active cyclic peptides resulted in the discovery of a new class of low molecular weight hematoregulatory agents exemplified by compound 16. This semipeptide analogue, comprising two D-Ser residues connected via amide bonds to the acid groups of pyrazine-2,3-dicarboxylic acid, had comparable biological activity to the lead peptide 1. The stereochemical requirements for the observed biological activity of these novel compounds were examined. Furthermore, the hematopoietic synergistic activity induced by compound 16 in stromal cell cultures was blocked by an antibody known to neutralize the hematoregulatory effect of 1, indicating a common mechanistic end point. Compounds of the class typified by 16 may form the basis for the development of novel therapeutic agents within the area of immunoregulation.

[Therapy of infections in patients with acute leukemia]

BACKGROUND

Infections are the major cause for treatment failure in acute leukemias. They mostly present as fever of unknown origin (FUO), a smaller but prognostically unfavorable group are pneumonias. The effective management of infectious complications requires a symptom and response adapted interventional strategy.

THERAPEUTICAL APPROACH

In case of FUO standard therapy consists of the two drug combination of aminoglycoside plus acylaminopenicillin or third generation cephalosporine. In case of non-response carbapenems and a glycopeptide should be applied and a systemic antifungal treatment must be initiated. In pneumonia amphotericin B should be added to antibiotics already initially. Potent single agents with a broad spectrum of activity as well as new antifungal drugs provide attractive perspectives for future evaluations.

CONCLUSIONS

By a consequent step-wise oscalating interventional treatment strategy infections in patients with acute leukemias can be successfully treated.

In vivo evaluation for rhGM-CSF wound-healing efficacy in topical vehicles

The wound-healing efficacy of recombinant human granulocyte-macrophage colony stimulating factor (rhGM-CSF) was studied in a mouse model. Full-thickness wounds were treated with liquid crystalline, emulsion, and niosome vehicles alone and with rhGM-CSF. The control group was non-medicated. Observation of the vehicle groups with and without the rhGM-CSF displayed better healing profiles than the control group. The vehicles were also evaluated among themselves and it was noted that emulsion base and niosome base groups gave significantly better healing profiles and histological results than the liquid crystalline base group. Among the rhGM-CSF containing groups, emulsion formulation displayed a stronger wound-healing effectiveness compared to the other formulations. In vitro release characteristics of the recombinant protein from the three vehicle formulations were demonstrated with diffusion cells. Histological and immunohistochemical evaluation was performed on biopsies taken on the last day of the experiment.

Recombinant cytokines and hematopoietic growth factors in allogeneic and autologous bone marrow transplantation

Use of recombinant hematopoietic growth factors in the course of bone marrow transplantation has revolutionized this modality by significantly improving the safety of the procedure. It is anticipated that use of cytokines in combination and the introduction of newer agents will further reduce costs and improve antitumor responses as well.

Intratibial injection of an anti-doxorubicin monoclonal antibody prevents drug-induced myelotoxicity in mice

With few exceptions, the major limit to high-dose chemotherapeutic treatments is the severity and duration of drug-induced myelosuppression. We have recently developed a monoclonal antibody, MAD11, which reacts with the potent anti-tumour antibiotic doxorubicin and other anthracyclines. To protect directly pluripotent stem cells and cells of the haematopoietic microenvironment in the bone marrow against doxorubicin cytotoxicity, the monoclonal antibody MAD11 was injected into the tibial bone of mice before chemotherapeutic treatment. All mice pretreated intratibially with MAD11 and injected with 14 mg kg(-1) body weight of doxorubicin survived, whereas 41% of mice treated with doxorubicin alone died. At a higher dose of doxorubicin (18 mg kg(-1)), early mortality (first 6 days) was similar in the groups, but no deaths were observed thereafter in the intratibially MAD11-treated group, whereas most of the mice treated with doxorubicin alone died. Data obtained in mice injected with P388 leukaemia cells showed that the intratibial injection of MAD11 did not compromise the anti-tumoral activity of doxorubicin. Moreover, the administration of the anti-doxorubicin monoclonal antibody before chemotherapeutic treatment effectively reduced apoptosis induced by doxorubicin in the bone marrow cells. These data suggest the usefulness of monoclonal antibodies against chemotherapeutic drugs in the local protection of bone marrow without influencing the anti-tumour properties of the drug.