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S A Burstein

Publications and source records attributed to S A Burstein.

65 records · Page 4Linked to original sources
PubMed1985

Separation of murine megakaryocytes and their progenitors on continuous gradients of Percoll.

Murine bone marrow was separated on continuous Percoll density gradients to analyze the distribution of cells of the megakaryocyte lineage. Eighty-seven percent of the recovered megakaryocytes were found in fractions of density less than 1.058 g/cm3, with 63% of these cells found between 1.020 and 1.036 g/cm3. When megakaryocytes were classified according to size, 92% of the large (greater than or equal to 18 micron) acetylcholinesterase (AchE) positive cells were found in the least dense fractions (1.016-1.039 g/cm3), whereas 86% of the small (less than or equal to 10.6 micron) AchE positive cells were found in fractions of higher density (1.039-1.078 g/cm3). The distribution of enzymatic AchE activity of the separated fractions corresponded to the location of the histochemically positive cells. When ploidy measurements were made of various fractions, most of the high ploidy (32N and 64N) cells were found at low density (1.028-1.036 g/cm3), whereas no cells greater than 4N were found at density greater than 1.071 g/cm3. Thus, large AchE positive cells and the cells of highest ploidy were found at lower densities of Percoll, while small AchE positive cells and cells of low ploidy were found at higher densities. An exception to this inverse relationship was found in fractions of lowest density (less than 1.030 g/cm3) where an anomalous distribution of size and ploidy was found. The majority of megakaryocytic colony-forming cells (CFU-MK) were found at high density, as were the granulocyte-macrophage colony-forming cells (CFU-GM; approximately 1.074 g/cm3). The density distribution of the incorporation of tritiated thymidine into liquid marrow cultures was concordant with the high density distribution of colony-forming cells. The data show that megakaryocytic maturity and Percoll density varies inversely and that fractionation of marrow on continuous Percoll gradients may be a useful method for the separation and/or enrichment of megakaryocytes at different stages of differentiation.

Acetylcholinesterase↗
PubMed1984

Human megakaryocytic progenitors (CFU-M) assayed in methylcellulose: physical characteristics and requirements for growth.

The basic culture requirements and several physical characteristics were defined for megakaryocytic colony-forming cells (CFU-M) from normal human marrow growing in methylcellulose. Ficoll-hypaque separated mononuclear cells from human marrow gave rise to megakaryocytic colonies in the presence of normal human plasma and phytohemagglutinin-stimulated leukocyte-conditioned medium (PHA-LCM). Their identity as megakaryocytic colonies was confirmed by immunofluorescence staining with a monoclonal antibody to human factor VIII antigen and by electron microscopy of individually harvested colonies. Demonstration of the single-cell origin of the colonies was provided by analysis of the glucose-6-phosphate dehydrogenase (G-6-PD) enzyme type of individually harvested colonies grown from a G-6-PD heterozygote. The colonies grew best in heparinized or citrated plasma as opposed to serum. Detailed studies suggested that platelet-release products were responsible for this difference. Tritiated thymidine suicide studies showed that the percentage of CFU-M in DNA synthesis was 23 +/- 8% (n = 10). The modal velocity sedimentation rate of CFU-M was 4.9 +/- 0.6 mm/hr (n = 4) while that of concurrently studied granulocyte/macrophage colony-forming cells (CFU-GM) was 5.7 +/- 0.5 mm/hr. Examination of the PHA-LCM dose-response characteristics suggested the presence in the conditioned medium of an inhibitor to megakaryocyte colony growth which was partially removed by chromatography of the medium on Sephadex G-100. The resulting conditioned medium increased the cloning efficiency for CFU-M compared with that with crude PHA-LCM (15.3 +/- 7.0 and 8.2 +/- 5.3/10(5) marrow cells, respectively).

Blood↗
PubMed1984

Platelet factor-4 excretion in myeloproliferative disease: implications for the aetiology of myelofibrosis.

Experimental evidence suggests that the fibroblastic proliferation often associated with the myeloproliferative disorders is not part of the neoplastic process, but is secondary to an unknown stimulus. This stimulus may be a factor derived from platelets which promotes the proliferation of fibroblasts in vitro (PDGF). Platelet-derived growth factor is localized to platelet alpha-granules together with PF4 and beta-TG. As an indicator of alpha-granule release, we have measured PF4 levels in plasma, platelets and urine in 46 normal subjects and 49 patients with myeloproliferative disorders, secondary thrombocytosis and miscellaneous malignancies. All 11 patients with elevated urinary PF4 excretion exhibited myelofibrosis, whereas 11 of 22 patients with documented myelofibrosis had urinary PF4 excretion in the normal range. No correlation was seen between marrow fibrosis and plasma levels or the platelet content of PF4. The data are consistent with the possibility that release of mitogen(s) from platelet or megakaryocyte alpha-granules in some patients with myeloproliferative disorders is pathogenetically related to the development of marrow fibrosis.

Blood Platelets↗
PubMed1984

Fluorescence cytophotometric analysis of megakaryocytic ploidy in culture: studies of normal and thrombocytopenic mice.

A system for the accurate and rapid measurement of the ploidy of cultured megakaryocytes derived from megakaryocytic colony-forming cells (CFU-M) has been developed. Thirty thousand murine marrow cells per milliliter were cultured for varying time periods in agar in the presence of horse serum and pokeweed mitogen-stimulated spleen cell-conditioned medium (PWM-SCM). To ensure the inclusion of all the megakaryocytic cells in the analysis, entire agar discs were transferred onto glass slides and dried. Cells of the megakaryocytic lineage were identified by staining for acetylcholinesterase (AchE) for two hours. Subsequently, the nuclei of the cells were stained using 1.7 X 10(-5) mol/L chromomycin A3, a specific DNA-binding fluorochrome. Megakaryocytic colonies (greater than or equal to 2 AchE+ cells) were located under transmission light. The fluorescence emission of each cell of the colony was then measured by a photometer interfaced with a computer. The mean fluorescence emission of about 20 random granulocytes per slide was used as a 2N standard. There was no significant cell loss, quenching of fluorescence by AchE staining, or overlapping of colonies or cells. Approximately 100 megakaryocytes per hour could be analyzed. Modal ploidy of cultured megakaryocytes increased from 2N to 32N between days 3 and 6 in culture. Varying concentrations of PWM-SCM from 5% to 20% did not affect the ploidy distribution when examined at day 5. The heterogeneity of the ploidy of cells within colonies increased continuously with increasing cell numbers per colony. Clonal analyses of mean ploidy and ploidy heterogeneity did not show distinct types or classes of colonies; rather, the data show that megakaryocytic colonies are structured as a continuum. An inverse correlation was found between the number of cells constituting the colonies and their mean DNA content. To determine if short-term in vivo exposure of CFU-M to a thrombocytopenic environment could affect the ploidy of their progeny, mice were given rabbit antimouse-platelet serum while control animals were given normal rabbit serum. Twenty-four hours after injection, marrow derived from these animals was cultured. At day 5, the ploidy distributions and ploidy heterogeneity were identical in both treated and control groups. Thus, factor(s) that promote CFU-M proliferation do not affect megakaryocytic endoreduplication, while stimuli that acutely influence megakaryocytic ploidy in vivo do not determine the ultimate ploidy potential of megakaryocytes derived from a CFU-M.

Acetylcholinesterase↗
PubMed1983

Lithium enhancement of megakaryocytopoiesis in culture: mediation via accessory marrow cells.

To examine the effect of lithium (Li) on early megakaryocytopoiesis, murine marrow megakaryocytic (CFU-M) and granulocyte-macrophage (CFU-C) progenitors were assayed in vitro with and without addition of lithium chloride (LiCl) to culture. At 2 mM LiCl, the numbers of CFU-M- and CFU-C-derived colonies were increased to 146% +/- 8% and 128% +/- 6% of controls, respectively (p less than 0.005). Enumeration of megakaryocytes per colony showed a 78% increase of colonies (p less than 0.05) containing from 6 to 22 cells, suggesting an increased proliferative capacity of CFU-M in the presence of LiCl. Conditioned media from spleen cells cultured in the presence of both pokeweed mitogen (PWM-SCM) and 2 mM Li increased the numbers of CFU-M and CFU-C to 157% +/- 8% and 183% +/- 8%, respectively (p less than 0.025), compared to control cultures stimulated by PWM-SCM alone. Since the production of active colony-stimulating activities (CSA) from mitogen-stimulated conditioned media requires T lymphocytes, we hypothesized that the enhancement of the growth of early hematopoietic progenitors in marrow cultures was due to a Li-induced CSA production by accessory marrow cells, rather than a direct effect of Li on stem cells. To test this, cyclosporin-A (CyA), a T-lymphocyte function inhibitor known to suppress CSA production in PWM-SCM, was added to marrow cultures in the presence of 2 mM Li. CyA (3 micrograms/ml) abrogated the Li-induced enhancement of CFU-M and CFU-C growth, but had no effect on colony formation when added alone. The data suggest that the Li-induced enhancement of early megakaryocytopoiesis and granulocytopoiesis is due to local production of CSA(s) by an accessory cell population and requires the integrity of T-lymphocyte function.

Animals↗
PubMed1982

Immunologic stimulation of early murine hematopoiesis and its abrogation by cyclosporin A.

Mice injected chronically with antiplatelet serum develop an increase in the number of megakaryocytic progenitor cells compared to animals given normal rabbit serum. To examine the specificity of this response, progenitor cells giving rise to megakaryocyte, granulocyte-macrophage, erythroid, and mixed-cell colonies were assayed after injection of various heterosera or saline. All four colony types increased in the serum-treated groups. Since the in vitro proliferation of hematopoietic progenitor cells is promoted by supernatants of mitogen-stimulated spleen cells, we hypothesized that the immune response following antiserum administration resulted in the in vivo activation of T lymphocytes which produced or led to the production of colony stimulating activities. To test this hypothesis, cyclosporin A, a preferential inhibitor of T lymphocyte function, was given to mice concurrently with antiserum and also added to spleen cell cultures in the presence of pokeweed mitogen. Cyclosporin A abrogated the antiserum-related increases in progenitor cell numbers in vivo and the production of colony stimulating activity in vitro. The results suggest that the immune response related to antiserum administration results in the in vivo production of hematopoietic colony stimulating activities that may be identical to those produced in vitro by mitogen-stimulation of spleen cells.

Animals↗
PubMed1981

Megakaryocytopoiesis in the mouse: response to varying platelet demand.

The response of murine megakaryocytopoiesis was studied under conditions of varying platelet demand. Twenty-four hours after mice were given a single injection of rabbit anti-platelet serum, megakaryocyte number and volume were increased, becoming maximal at 65 and 40 hr, respectively. Total body megakaryocytic colony-forming unit (CFU-M) numbers did not change until 90 hr, when a 35% increase in the experimental group was noted. The percentage of CFU-M in DNA synthesis in the experimental group was 38 +/-2% at 24 hr, 49 +/- 1% at 40 hr, and returned to normal (11 +/- 3%) at 90 hr. When mice were made thrombocytotic by platelet transfusions, both megakaryocyte number and volume were decreased compared to controls, while no difference was noted in the number and percentage of CFU-M in DNA synthesis. Finally, experiments were performed to examine the effect of platelet transfusions on regenerating marrow. Experimental mice were given platelet transfusions while control animals received platelet buffer solution. At sacrifice the number and volume of megakaryocytes in the experimental group (platelet count 2.568 X 10(6)/microliters) were less than controls (platelet count 0.363 X 10(6)/microliters), while the number and percentage of CFU-M in DNA synthesis were similar in both groups. These results demonstrate that CFU-M are not immediately responsive to acute changes in platelet demand. The data suggest that megakaryocytopoiesis is structured on at least two levels which are independently regulated.

Animals↗
PubMed1980

Studies of marmoset megakaryocytopoiesis in vitro.

Liquid culture of the mononuclear fraction of the blood of marmosets without any added stimulator resulted in the appearance of megakaryocytes. These cells could not be identified by light microscopy or by indirect immunofluorescence using antiplatelet antiserum. Ultrastructural identification was made using platelet peroxidase. Some megakaryocytes demonstrated sparse but detectable demarcation membranes, early granule formation, and platelet formation. The results indicate that marmoset megakaryocytic progenitor cells circulate and can begin to differentiate in vitro, although unstimulated liquid culture conditions do not promote the development of the usual light-microscopic features of differentiation.

Animals↗
PubMed1980

Megakaryocytopoiesis in culture: modulation by cholinergic mechanisms.

Treatment of murine bone marrow cultures with the cholinergic agonist carbamylcholine enhanced megakaryocytic colony growth by as much as 65%. In contrast, adrenergic agonists had no such effect. Addition to cultures of dibutyryl cyclic GMP (db-cGMP) also enhanced megakaryocytic colonies up to 50%, whereas dibutyryl cyclic AMP (db-cAMP) had no effect. Sodium nitroprusside and sodium nitrite, putative guanyl cyclase activators, also enhanced colony numbers, as did imidazole, a postulated cGMP phosphodiesterase inhibitor. Preincubation of marrow for two hours with carbamylcholine resulted both an increase in colony numbers (58%) and percent of progenitors in DNA synthesis (48%, compared to 14% for controls) as determined by tritiated thymidine suicide studies. Treatment of mice with the acetylcholinesterase inhibitor neostigmine resulted in an increase in CFU-M/humerus (62%) and percent in DNA synthesis (45%). These data indicate that 1) cholinergic, but not adrenergic, agonists modulate megakaryocytopoiesis in culture; 2) this effect may be mediated by cyclic GMP; and 3) only a brief period of exposure of marrow cells to agonist results in enhancement of megakaryocytic colonies.

Adrenergic alpha-Agonists↗
PubMed1979

Characteristics of murine megakaryocytic colonies in vitro.

Characteristics of murine megakaryocytic colonies and their progenitor cells (CFU-m) were studied in vitro in agar gel. Colony growth required the presence of poke-weed-mitogen-stimulated spleen-conditioned medium. The number of colonies formed was linearly related to both the number of marrow cells plated and the amount of conditioned medium added. In addition, CFU-m were found in both the spleen and peripheral blood. Conditioned medium was also made without plasma, and this resulted in a cloning efficiency greater than that of conditioned medium prepared with plasma. The percentage of CFU-m in DNA synthesis was low (10%), as determined both in vivo and in vitro. Velocity sedimentation revealed that the majority of CFU-m sedimented at 4.3 mm/hr and had a tritiated thymidine (3H-TdR) suicide rate of 1.5 +/- 1.5%. A shoulder on the profile of CFU-m sedimented at approximately 6 mm/hr, with a suicide rate of 79 +/- 2%. Analysis of these data indicated that the majority of CFU-m were not in cycle or were in a long G1 period. The results suggest that CFU-m is a primitive progenitor, possibly closely related to murine splenic colony-forming units (CFU-s), analogous to erythroid bursts and granulocytic colony-forming units.

Animals↗