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H Mayani

Publications and source records attributed to H Mayani.

46 records · Page 3Linked to original sources
PubMed1991

Inhibition of hematopoiesis in normal human long-term marrow cultures treated with recombinant human macrophage colony-stimulating factor.

The effects of recombinant human macrophage colony-stimulating factor (rhCSF-1) in long-term marrow cultures (LTMC) established from normal bone marrow cells were examined. When added during the first 3 weeks of culture (every second day, at 15 ng/mL), rhCSF-1 strongly inhibited the growth of all hematopoietic progenitors analyzed (colony-forming unit-MIX [CFU-MIX], CFU-granulocyte macrophage [CFU-GM], CFU-M, CFU-G, burst-forming unit-erythroid). Paralleling the inhibition of progenitors was the complete loss of adipocytes from the stromal layer of rhCSF-1-treated cultures. The inhibitory effect of rhCSF-1 correlated in all instances with the accumulation in the supernatants of these cultures of an activity (different from CSF-1) that inhibited colony formation in semisolid cultures. When addition of rhCSF-1 was delayed 3 weeks, its inhibitory effects were significantly reduced, which correlated with reduced inhibitory activity detected in the supernatants. Analysis of CSF-1 concentration by radioreceptor assay confirmed that added rhCSF-1 increased culture CSF-1 levels and showed that the decreased inhibition observed when rhCSF-1 is added later in culture was not due to decreased CSF-1 levels at that point. In contrast, the ability of rhCSF-1 to inhibit hematopoiesis and accumulate inhibitory activity in LTMC correlated with its rate of utilization, much higher in the first 2 weeks of culture, when the stromal layer was being established, than later. These observations document the inhibitory effect of rhCSF-1 on all aspects of hematopoiesis conducted in cultures that simulate the hematopoietic microenvironment, demonstrate the importance of accessory/stromal cells in mediating the effects of rhCSF-1 in LTMC, and point to an inhibitory activity as the mediating agent.

Bone Marrow↗
PubMed1991

Similarities in long-term cultures of blood and bone marrow from patients with acute myelogenous leukemia.

Dexter-type long-term cultures (LTC) were initiated with peripheral blood (PB) and/or bone marrow cells from 11 patients with acute myelogenous leukemia (AML), and 2 with myelodysplastic syndrome in blastic transformation. Marrow and PB cells from normal subjects served as controls. Assessment of nucleated cells and clonogenic progenitors in the adherent and nonadherent fractions of LTC revealed active hemopoiesis for greater than 5 wks in 4 of 8 cultures of AML blood, and 4 of 7 of AML marrow. The morphology and kinetics of nucleated cells and progenitors with putative normal (granulocyte-macrophage colony-forming units or CFU-gm), and abnormal (blast) phenotype in LTC from AML blood were similar to those from AML marrow, and adherent cells positive for collagen I and III and vimentin were found in both types of LTC. Growth of CFU-gm colonies ceased by wk 5-8 in AML cultures, significantly earlier than in LTC of normal marrow cells (survival of greater than 10 wks), which may indicate derivation of the CFU-gm from a transformed clone or deficiency of stromal function in the leukemic state. In most AML blood and AML marrow LTCs, growth of abnormal (blast) colonies continued until wk 4-6. This study demonstrates certain similarities of morphology and function between LTC of AML blood and AML marrow cells. LTC may provide a useful model for further analysis of circulating primitive hemopoietic progenitor cells in leukemic states.

Blood Cells↗
PubMed1991

Effect of rhCSF-1 on human hemopoiesis in long-term cultures from patients with acute myelogenous leukemia.

Bone marrow and/or peripheral blood cells from seven patients with acute myelogenous leukemia (AML) were maintained for 7 weeks in Dexter-type long-term culture (LTC) in order to study the effect of exogenous recombinant human colony-stimulating factor-1 (rhCSF-1) and to quantitate endogenous levels of CSF-1. rhCSF-1 was added every 2 days during the first 3 weeks of culture at 15 ng/ml. In all but one culture, adding rhCSF-1 inhibited putative leukemic hemopoiesis [i.e. decreased numbers of abnormal (blast) colony-forming cells and blasts] and stimulated putative normal hemopoiesis (increased numbers of CFU-GM and macrophages). Our data, however, do not distinguish direct effects of rhCSF-1 on normal or leukemic cells from indirect effects mediated by accessory cells. In cultures with a poorly formed adherent layer (all derived from patients classified as M5), the endogenous levels of CSF-1 were lower than those in cultures with a good (confluent) adherent layer, indicating that the levels of CSF-1 in LTC from AML patients positively correlate with the formation of the adherent layer. Our data indicate that CSF-1 is an important modulator of human hemopoiesis in LTC established from AML bone marrow or peripheral blood, and that rhCSF-1 might be valuable for purging leukemic cells in LTC established from AML patients' bone marrow or peripheral blood for autologous transplantation.

Hematopoiesis↗
PubMed1990

Modulation of erythropoiesis and myelopoiesis by exogenous erythropoietin in human long-term marrow cultures.

In spite of their ability to support myelopoiesis for several months, human long-term marrow cultures (LTMC) are unable to sustain the production of mature erythroid cells for greater than 4 weeks. Because this preference correlates with the presence of myeloid growth factors and possible absence of erythroid factors in LTMC, we studied the effects of the erythroid growth and differentiation factor erythropoietin (Epo) on both erythropoiesis and myelopoiesis in human LTMC. Either natural or recombinant Epo was added weekly to LTMC for 10 weeks, and total cell number, numbers of hemopoietic progenitors (mixed lineage colony-forming units, CFU-MIX; erythroid burst-forming units, BFU-E; erythroid CFU, CFU-E; granulocyte-macrophage CFU (CFU-GM); granulocyte CFU, CFU-G; and macrophage CFU, CFU-M), erythroblasts (early and late), granulocytes, and macrophages were quantitated separately in the adherent and nonadherent layers of the cultures. In the absence of Epo, mature erythroid cells disappeared within the first 3-4 weeks, whereas in cultures supplemented with Epo, erythropoiesis was supported for up to 8 weeks. Results indicate that erythroid maturation is blocked at the BFU-E stage and that exogenous Epo may act on a mature subpopulation of BFU-E located in the nonadherent fraction of the cultures, promoting its maturation into CFU-E, which in turn develop into erythroblasts. However, despite Epo supplementation, erythropoiesis was not restored to in vivo proportions, suggesting that additional factors or conditions necessary for erythropoiesis are lacking in LTMC. Interestingly, we found that exogenous Epo reduced the numbers of presumably more mature (nonadherent) myeloid CFU (CFU-C), granulocytes, and macrophages compared to controls and did not alter the levels of any of the most primitive hemopoietic progenitors measured (CFU-MIX, adherent BFU-E, and adherent CFU-C). Thus the data show that exogenous Epo modulates hemopoiesis in human LTMC, enhancing erythropoiesis and suppressing myelopoiesis, but that its effects appear limited to modulating levels of the nonadherent (more mature) progenitors, leaving the numbers of the adherent (immature) progenitor cells unchanged.

Bone Marrow Cells↗
PubMed1989

Effects of recombinant human granulocyte-macrophage colony-stimulating factor (rhGM-CSF) on single CD34-positive hemopoietic progenitors from human bone marrow.

To determine the extent accessory cells mediate the effects of recombinant human granulocyte-macrophage colony-stimulating factor (rhGM-CSF) on human hemopoietic progenitors in vitro, we added this hemopoietin to liquid cultures of single CD34-positive marrow cells. These were selected on a fluorescence-activated cell sorter using the HPCA-1 (My10) antibody. Myeloid, erythroid and a few mixed clones developed in 13% of wells in the apparent absence of accessory cells at the beginning of culture. Although accessory cells were generated quickly from the myeloid progenitors and could have mediated the action of rhGM-CSF, this was not the case in the majority of the erythroid clones in which no other cell types were recorded. We conclude that rhGM-CSF can act directly on a subset of erythroid progenitors and probably induces a substantial number of myeloid clones directly.

Bone Marrow↗
PubMed1989

In vitro growth of myeloid and erythroid progenitor cells from myelodysplastic patients in response to recombinant human granulocyte-macrophage colony-stimulating factor.

Marrow progenitor cells from 14 myelodysplastic (MDS) patients and 17 normal donors were assayed in semisolid cultures supplemented with increasing doses of recombinant human granulocyte-macrophage colony-stimulating factor (rhGM-CSF) or medium conditioned by 5637 bladder carcinoma cells (5637CM). At doses of supplements shown to be optimal for colony formation in cultures of normal marrow, myeloid (day 14) colony numbers were subnormal in 10 of 14 MDS marrows cultured in 5637CM and in 8 of 14 cultures containing rhGM-CSF (2.5 ng/ml). However, a high dose of rhGM-CSF (20 ng/ml) raised myeloid colony numbers in cultures of many MDS marrows, so that 9 of 14 now yielded colonies within the normal range; increased levels of 5637CM failed to do this. Erythroid colony growth was poor in 13 of 14 MDS marrow cultures supplemented with erythropoietin in addition to 5637CM or rhGM-CSF. High concentrations of rhGM-CSF did not increase erythroid growth. These data suggest that myeloid progenitors from the MDS clone may have a decreased responsiveness to hemopoietins which can be overcome at high concentrations of growth factors.

Adult↗
PubMed1988

Enrichment of CD34 (My10)-positive myeloid and erythroid progenitors from human marrow and their growth in cultures supplemented with recombinant human granulocyte-macrophage colony-stimulating factor.

Myeloid and erythroid progenitor cells were enriched from human marrow by selecting CD34-positive (CD34 + ve) cells, labeled with the My10 (HPCA-1) antibody, using a fluorescence-activated cell sorter. Seventy-one percent of CD34 + ve cells were blasts and most of these were too primitive to be identified by standard morphological criteria. On average, 9.5% of CD34 + ve cells formed clones after 14 days of culture in semisolid medium supplemented with erythropoietin and medium conditioned by 5637 bladder carcinoma cells. Over 2.5% of CD34 + ve cells were day-14 myeloid colony-forming cells and 2.4% were erythroid colony (burst)-forming progenitors. The remaining progenitors formed myeloid and erythroid clusters. A subpopulation of day-14 myeloid colony-forming cells failed to respond to recombinant human granulocyte-macrophage colony-stimulating factor (rhuGM-CSF) after accessory cells were removed during enrichment, so it appears that this factor can induce myeloid growth indirectly as well as directly. Recombinant human GM-CSF also supported erythroid colony-formation in cultures of CD34 + ve cells, which suggests that this hemopoietin may act directly on erythroid progenitors.

Antigens, CD34↗
PubMedDate not supplied

A study of erythropoiesis and iron metabolism in the rabbit in vivo. I. Characterization and limits of the physiological response.

1. An experimental model system was developed in the rabbit to study the transport of iron and the erythropoietic response to chronic bloodletting. 2. This model presents certain novel features as the capacity to measure total red blood cell production and total hemoglobin production in a daily basis. 3. Daily red blood cell production and output of hemoglobin are directly proportional to the volume of blood extracted. The limits of the erythropoietic response were determined. 4. When only minimal bloodletting was performed (3-6 ml blood/kg body weight) a normocytic response was obtained; with the removal of larger volumes of blood, a switch to macrocytic anemia was observed. Cats and guinea pigs responded in a similar fashion. 5. After induction of macrocytic anemia, the diameter of erythroid precursor cells in the bone marrow of the long bones increased and their numbers increased 11.5-fold.

Anemia↗
PubMedDate not supplied

Rabbit erythropoiesis during recovery from chronic anaemia induced by bleeding.

Rabbit erythropoiesis was studied during recovery from chronic anaemia induced by bleeding. Adult rabbits were made anaemic by daily removal of 10 ml of blood per Kg of body weight, through intracardiac puncture, resulting in a significant stimulation of erythropoiesis. After 14 days, bleeding was stopped and the erythropoietic response was studied during the period of recovery. Peripheral blood and bone marrow were analysed for the two weeks following the last bleeding. While levels of red blood cells and haemoglobin returned to normal values by day 6 of recovery, bone marrow erythroblasts decreased gradually until they reached the normal range by day 11. Once bleeding was stopped, there was a significant decrease in the number of circulating reticulocytes, with a concomitant increase in the number of their marrow counterpart. This suggests that release of reticulocytes from bone marrow into the circulation was temporarily blocked. There was also a rapid shift towards normocytic production and the disappearance of macrocytosis. Non-erythroid cells responded very rapidly during recovery, reaching normal values in both peripheral blood and bone marrow 3 days after the last bleeding. Our results show that under the experimental conditions described here, (i) the rabbit haemopoietic system is able to respond to dramatically different physiological stages, and (ii) since the kinetics of most parameters during the period of recovery, both in peripheral blood and bone marrow, were different from those observed during the induction of anaemia, it is possible that the mechanisms operating under both conditions are different.

Anemia↗