Biological effects of retroviral transfection of the murine interleukin-3 gene into FDCP-Mix cells.
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Animals↗
Biomedical subjects
T M Dexter
Publications and source records attributed to T M Dexter.
The role of growth factors in haemopoietic development: clinical and biological implications.
Mature blood cells of all lineages are derived from a single class of cell, the haemopoietic stem cell. Stem cells are pluripotent and capable of almost limitless self-renewal. In the bone marrow they form part of a hierarchy that includes progenitor cells, which are more restricted in the lineages their progeny can adopt, and precursor cells, which are committed to differentiation. The mechanisms that regulate progression through this hierarchy are not fully understood, but evidence suggests that both bone marrow stromal cells and soluble growth factors have a role in controlling haemopoiesis. Four growth factors act on progenitor cells to promote their survival, proliferation, differentiation, and maturation: interleukin-3 (IL-3), granulocyte/macrophage-colony stimulating factor (GM-CSF), granulocyte-CSF (G-CSF), and macrophage-CSF (M-CSF). They can also activate the function of mature cells. Considerable overlap is found in the target cells for these four growth factors. We have found that growth factors acting in synergy can recruit more primitive cells than had previously been appreciated. These factors can also determine the lineage that the progeny of multipotential progenitors will adopt. Thus, colony-stimulating factors (CSFs) have the potential to regulate the development of primitive haemopoietic cells in vivo. The properties of CSFs have made them useful in treating malignant disease: G-CSF, in particular, has been used to reduce the period of neutropaenia that follows cytotoxic therapy for various malignancies. The success of these early trials gives ground for cautious optimism about the clinical use of these compounds.
Animals↗
Clinical use of haematopoietic growth factors.
Over the past decade experimental haematologists have identified and eventually characterised a number of polypeptide growth factors capable of stimulating the proliferation and differentiation of haemopoietic progenitor cells in vitro. The molecular cloning of these growth factors has now allowed their use in vivo, and some of them have shown promise in recent clinical trials. Most of the work has been done on erythropoietin and myeloid growth factors, which are discussed in this review. Erythropoietin has been used successfully as replacement therapy in the anaemia of end-stage renal failure, but may also prove clinically useful in other chronic anaemias and, in combination with other growth factors, as a stimulant of bone marrow regeneration following bone marrow transplant. Myeloid growth factors, and, in particular, granulocyte colony-stimulating factor, have been shown to accelerate neutrophil recover in cancer patients following chemotherapy, with a reduction in the number of severe infections and mucositis.
Colony-Stimulating Factors↗
The use of granulocyte colony-stimulating factor to increase the intensity of treatment with doxorubicin in patients with advanced breast and ovarian cancer.
Granulocyte colony stimulating factor (G-CSF) was given to 17 patients with advanced breast and ovarian cancer in order to increase the intensity and effectiveness of chemotherapy. Treatment with doxorubicin, at doses of 75 mg m-2 (n = 4 patients), 100 mg m-2 (n = 5), 125 mg m-2 (n = 6) and 150 mg m-2 (n = 2), was followed by infusion of G-CSF for 11 days. G-CSF administration resulted in a return of the absolute neutrophil count to normal or above normal levels within 12-14 days at all dose levels of doxorubicin used and allowed the administration of up to three cycles of high dose chemotherapy at 14 day intervals. An absolute neutrophil count greater than 2.5 x 10(9)l-1 was not reached until day 19-21 after 75 mg m-2 of doxorubicin given without G-CSF. At doses of doxorubicin of 125 mg m-2 and 150 mg m-2 all tumours regressed rapidly, although there was marked epithelial toxicity. The overall response rate in patients with advanced breast cancer was 80% with a median time to progression of 6 months. Two months after doxorubicin-G-CSF therapy there was a pronounced improvement of symptoms compared with before treatment. Thus the effectiveness of chemotherapy may be enhanced and treatment duration shortened by the use of G-CSF infusions. Further studies of this promising approach are warranted.
Adult↗
The kinetics of human granulopoiesis following treatment with granulocyte colony-stimulating factor in vivo.
Cell proliferation in the bone marrow and blood of two patients with metastatic breast cancer who were treated with granulocyte colony-stimulating factor was studied by using [3H]thymidine labeling and autoradiography. Additionally, the fate of neutrophils labeled with 99mTc-hexamethylpropyleneamineoxime was observed following granulocyte colony-stimulating factor infusion. Proliferation increased in all stages of granulopoiesis, but a significant amount of the increased production stemmed from a greater input to the myeloblast compartment. Changes in the myelogram combined with the increased labeling indicated a faster throughput of cells, which resulted in labeled cells appearing in the circulation within 1 day compared to the normal 4 or 5 days. The 99mTc studies demonstrated no sequestration of circulating neutrophils by spleen, lungs, or liver. The half-life of the circulating neutrophils was not significantly changed, and calculations from the flow of labeled cells to the peripheral blood indicated an increase of 3.2 extra amplification divisions during neutrophil development. The dramatic neutrophil response to granulocyte colony-stimulating factor can therefore be accommodated by a relatively modest increase in granulopoietic activity.
Adult↗
Haemopoietic growth factors.
The growth and development of mature blood cells in vitro is supported by a series of glycoproteins with a range of biological activities. Many of these growth factors have been molecularly cloned, purified to homogeneity, and their biological effects determined on various target cells. Some of these growth factors promote the proliferation and differentiation of multipotent stem cells; others are more restricted in their action and, when used alone, can support only the development of lneage-restricted progenitor cells. When used in combinations however, the spectrum of target cells supported by these growth factors can be considerably enlarged. Furthermore, other molecules (which are not themselves growth promoters for multipotent stem cells) can synergise with these growth factors and permit primitive cells to undergo proliferation and development. These findings are likely to have major therapeutic implications.
Animals↗
Haemopoietic growth factors: their role in acute myeloblastic leukaemia.
The chromosome alterations specifically associated with leukaemia are found largely in the regions where the genes for the haemopoietic growth factors (as well as other regulatory molecules or their receptors) are located, indicating a crucial role of the growth factors in leukaemogenesis. However, growth factor genes per se do not generally induce leukaemia when inserted into normal haemopoietic cells, although they will do so if they are inserted into immortalized haemopoietic stem cell lines. The response of AML cells to these growth factors is extremely heterogeneous, and the tilting of the balance between self-reproduction (leading to perpetuation of the leukaemic process) and differentiation ('death' of the malignant cells) depends on several parameters, on the type and combination of factors to which the cells are exposed, with IL-3 and GM-CSF tending to favour self-renewal, and G-CSF and M-CSF tending to favour differentiation. These findings open the possibility to consider the use of growth factors to control the leukaemic process, although such treatment should be approached with considerable caution, and on an individual patient basis.
Animals↗
Clinical use of growth factors.
Cellular proliferation and differentiation in the living organism are regulated, at least in part, by a complex network of interacting peptides, or growth factors. The purification and molecular cloning of these growth factors has now led to the exciting task of ascertaining their physiological role in vivo and to verify their value as therapeutic substances worthy of clinical use. Rigorous methods of drug evaluation are required to prove the efficacy and safety of these new biological agents, particularly now that so many of them are being produced by the new genetic engineering techniques. Haemopoietic growth factors and growth factors involved in the regulation of the immune response have been more extensively studied clinically and are discussed in this section.
Anemia↗
Long-term hematopoietic damage: concepts, approaches, and results relevant to the study of environmental toxins.
The hematopoietic tissue is one of the prime examples of hierarchical tissues, where mature cells with a limited life span are continually replaced as a result of proliferation and differentiation from stem and progenitor cells. In the bone marrow, these processes are controlled by growth factors and by cell to cell interactions, the latter being specially important for the regulation of the stem-cell population. In the study of long-term hematopoietic damage, we have to distinguish between deleterious effects of the environmental toxins on the stem and progenitor cells, and on the stromal bone marrow cells which are part of the regulatory hematopoietic microenvironment. In some experimental situations, the function of the tissue may be subnormal, not because of stem cell damage (which may also be present), but because of damage to regulatory environmental populations. Because of the high degree of organization of the hematopoietic tissue (not immediately obvious from histological sections), the heterogeneity of the stromal cell populations, and their different capacities to regenerate after cytotoxic insult, the stromal damage is likely to be heterogeneous and would tend to be expressed functionally at later times than acute hematopoietic injury. While microenvironmental damage may be of importance in the induction of hematopoietic failure, the primary target in leukemogenesis is likely to be the stem cell. However, experimental data support the concept that regulatory microenvironmental influences may hinder or favor the development of leukemia.
Animals↗
The effects of TGF beta on haemopoietic cells.
Transforming growth factor beta (TGF beta) suppresses the growth of differentiation inducible, murine IL-3-dependent multipotential cell lines but has no growth inhibitory effect upon an IL-3-independent (leukaemic) cell line arising from one of them, nor on IL-3-dependent cell lines that are unable to undergo differentiation. TGF beta inhibits in vitro colony formation by normal multipotential haemopoietic progenitor cells. Bipotential progenitors recruited by GM-CSF are, however, more resistant to the inhibitory effects of TGF beta, whereas progenitors recruited by the lineage restricted factor, M-CSF, are sensitive to the inhibitory effects. These data indicate that responsiveness to TGF beta is differentiation linked and studies with the cell lines suggest that response (or lack of response is not determined solely by levels of expression of TGF beta receptors. Furthermore, the effects of TGF beta 2 on haemopoietic progenitors are very similar to those induced by TGF beta.
Animals↗
Marrow grown in long-term culture can be used for autologous transplantation in the treatment of acute myeloid leukaemia.
Leukaemic cells can be selectively depleted in the conditions of long-term bone marrow culture (LTBMC). Use can be made of LTBMC to purge bone marrow of leukaemic cells in autologous bone marrow transplantation (ABMT).
Adolescent↗
Evaluation of a mouse Y chromosome probe for assessing marrow transplantation.
The multicopy mouse Y chromosome DNA probe 80Y/B (1) has been used to probe genomic DNA isolated from male and female bone marrow cells, mixed together in known ratios. It was found that in a mixture with a ratio of 1 male:200 female marrow cells the male cells could readily be detected by this method. The potential use of this technique for assessing repopulation kinetics of marrow transplantation is discussed.
Animals↗
The use of bone marrow cells grown in long-term culture for autologous bone marrow transplantation in acute myeloid leukaemia: an update.
Eleven patients with acute myeloid leukaemia have been transplanted with autologous marrow grown in long-term bone marrow culture. In the high risk group (six patients who had all previously relapsed) the procedure induced a remission in two patients who were in florid relapse at the time of the transplant. Five patients were transplanted in first remission and they remain well and disease-free between 150 and 12 weeks after their autologous transplant.
Adolescent↗
Regulation of hemopoietic cell growth and development: experimental and clinical studies.
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Animals↗
Effects of long-term in vivo treatment of mice with purified murine recombinant GM-CSF.
Normal adult BDF1 mice were injected s.c. with 1 or 10 micrograms/kg/day of recombinant murine granulocyte-macrophage colony-stimulating factor (rmGM-CSF; specific activity 3.9 x 10(7) U/mg) for periods up to 11 weeks. After 1, 3, 7, 9, or 11 weeks, groups of three mice were killed and various hematological parameters were evaluated. Such treatment induced a sustained increase in the number and phagocytic activity of peritoneal macrophages, increased weight and cellularity of the spleen, and increased numbers of lineage-restricted precursor cells and multipotent stem cells in the spleen. No significant differences in blood cell numbers or differential counts were observed during the experiment. Femoral granulocyte-macrophage colony-forming cells (GM-CFCs), mixed-lineage colony-forming cells (Mix-CFCs), and 7- and 12-day spleen colony-forming units (CFU-S) were increased in the first week of treatment, but returned to normal (or subnormal levels) later. Examination of histological preparations of liver, lung, skin, ileum, thymus, Peyer's patches, kidney, skin, and brain revealed no differences from control preparations. Mast cell numbers were not increased in any of these tissues. Despite continuing treatment, most hematological parameters normalized upon prolonged rmGM-CSF treatment. The reasons for this are unclear but are not apparently due to the presence of inhibitory factors in the blood of treated mice. The results indicate little evidence of side effects during prolonged therapy with doses of rGM-CSF commonly used in clinical situations.
Animals↗
Long-term bone marrow cultures: their use in autologous marrow transplantation.
When cultured together, hemopoietic cells and marrow stromal cells can support hemopoiesis in vitro in the absence of added growth factors. The continued production of stem cells, progenitor cells, and mature cells within these "long-term bone marrow cultures" (LTBMC) requires their physical association with the stromal cells. For reasons that are not well understood, leukemic cells often fail to survive in such cultures. We and others have undertaken studies to examine whether LTBMC can be exploited as a way of purging the bone marrow of leukemia patients prior to autologous marrow transplantation.
Bone Marrow Cells↗
A comparative morphometric study on the ultrastructure of adherent cells in long-term bone marrow culture from normal and congenitally anemic mice.
The relationship between structure and function of bone marrow stromal tissue in adherent layers of long-term bone marrow cultures (LTBMCs) from normal and congenital anemic mice (C57BL, Sl/Sld, Sl+/Sl+, W/Wv, and W+/W+) was investigated. Many previously reported features were confirmed. However, in LTBMC from all strains of mice examined, isolated cilia with the axonemal structure of a 9 + O pattern with obvious dynein arms were observed in the blanket cells. The frequency of cilia was approximately 2%-5% of total number of profiles of blanket cells examined. Crystalloid inclusions (CI) were observed in cultured macrophages similar to those reported in vivo in all strains of murine LTBMC. The CI could be classified into four types according to their structure in the same way as in vivo (type A to type D), with a predominance of type A in the cultures. Viral particles were also apparent in adherent cells of all strains (except W/Wv and W+/W+), which were compatible with a type C retrovirus. Gap junctions occurred regularly between the adherent cells of LTBMC, particularly between blanket cells and preadipocytes. The most frequent appearance of gap junctions was found in Sl/Sld cultures. The phenomena of normal and abnormal hematopoiesis appear to be accurately reproduced in culture, thus retaining the same relationship between function and structure as occurs in vivo. The surface of isolated cilia of blanket cells, CI of macrophages, viral particles among adherent cells, and gap junctions between blanket cells and preadipocytes is discussed.
Anemia↗
Interleukin-3-stimulated haemopoietic stem cell proliferation. Evidence for activation of protein kinase C and Na+/H+ exchange without inositol lipid hydrolysis.
Interleukin 3 (IL-3) is an important regulator of haemopoietic stem cell proliferation both in vivo and in vitro. Little is known about the possible mechanisms whereby this growth factor acts on stem cells to stimulate cell survival and proliferation. Here we have investigated the role of intracellular pH and the Na+/H+ antiport in stem cell proliferation using the multipotential IL-3-dependent stem cell line, FDCP-Mix 1. Evidence is presented that IL-3 can stimulate the activation of an amiloride-sensitive Na+/H+ exchange via protein kinase C activation. IL-3-mediated activation of the Na+/H+ exchange is not observed in FDCP-Mix 1 cells where protein kinase C levels have been down-modulated by treatment with phorbol esters. Also the protein kinase C inhibitor H7 can inhibit IL-3-mediated increases in intracellular pH. This activation of Na+/H+ exchange via protein kinase C has been shown to occur with no measurable effects of IL-3 on inositol lipid hydrolysis or on cytosolic Ca2+ levels. Evidence is also presented that this IL-3-stimulated alkalinization acts as a signal for cellular proliferation in stem cells.
1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗