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E Frindel

Publications and source records attributed to E Frindel.

At least 37 records · Page 2Linked to original sources
PubMed1989

Inhibitor of hematopoietic pluripotent stem cell proliferation: purification and determination of its structure.

We report here a five-step purification procedure that led to the isolation from fetal calf bone marrow extract of a tetrapeptide, Ac-Ser-Asp-Lys-Pro (Mr 487), exerting a high inhibitory activity on the proliferation of hematopoietic pluripotent stem cells [defined here as spleen colony-forming units (CFU-S)]. The structure of this molecule was established from amino acid analysis, fast atom bombardment mass spectrometry, and 1H nuclear magnetic resonance spectral data. This structure was confirmed by comparison with the corresponding synthetic molecule, which presents identical physiochemical characteristics and biological properties. Natural and synthetic peptides administered to mice (at a dose of 100 ng per mouse) after one injection of cytosine arabinonucleoside prevent CFU-S recruitment into DNA synthesis.

Animals↗
PubMed1989

Mock retroviral infection alters the developmental potential of murine bone marrow stem cells.

Retroviral vectors were used to introduce an activated ras gene into murine pluripotent hemopoietic stem cells. We attempted to reconstitute the hemopoietic system of lethally irradiated mice with isolated spleen colonies obtained in vivo after injection of infected bone marrow cells. Spleen colonies derived from infected bone marrow were inefficient in promoting long-term survival of irradiated hosts. This loss of reconstitutive capacity of spleen colonies was not due to the retroviral infection per se but to the in vitro culture of spleen colony precursors. Incubation for 24 h in the presence of fetal calf serum and interleukin-3 without virus-producing cells was sufficient to abolish completely the reconstitutive capacity of spleen colonies while maintaining both self-renewal and pluripotential capacities of spleen colony precursors. These results show that the in vitro manipulation of stem cells that is included in current protocols for retroviral infection can modify the developmental potential of these cells. This finding clearly indicates that the use of retroviral vectors can introduce a bias in the analysis of hemopoiesis.

Animals↗
PubMed1989

Further studies on the biological activities of the CFU-S inhibitory tetrapeptide AcSDKP. I. The precise point of the cell cycle sensitive to AcSDKP. Studies on the effect of AcSDKP on GM-CFC and on the possible involvement of T-lymphocytes in AcSDKP response.

In order to further investigate the mechanisms of spleen colony-forming unit (CFU-S) inhibition by the tetrapeptide acetyl-N-Ser-Asp-Lys-Pro (AcSDKP), the following related subjects were studied: 1) the effects of AcSDKP on the kinetics of granulocyte and macrophage precursor cells (granulocyte-macrophage colony-forming cells; GM-CFC); 2) the precise point in the cell cycle of CFU-S that is sensitive to AcSDKP; and 3) the role of lymphocytes in the chain of events leading to the inhibition of CFU-S entry into the cell cycle. The effects of AcSDKP on CFU-S and GM-CFC were tested using the spleen colony assay and methylcellulose culture technique, respectively; the cell cycle kinetic status was determined by the tritiated thymidine suicide technique. Nude mice were studied to assess the role of T-lymphocytes in the inhibitory phenomenon. Our results indicate that: 1) there is no inhibitory effect of AcSDKP on GM-CFC in vitro or in vivo; 2) AcSDKP is active at only the G0 or early G1 phases; and 3) AcSDKP activity is not modulated by T cells.

Amino Acid Sequence↗
PubMed1989

The physiological role of the endogenous colony forming units-spleen (CFU-S) inhibitor acetyl-N-Ser-Asp-Lys-Pro (AcSDKP).

The physiological role of the colony forming units-spleen (CFU-S) inhibitor Acetyl-N-Ser-Asp-Lys-Pro (AcSDKP) has been studied by observing the effects of AcSDKP deprivation. This deprivation was obtained by injecting polyclonal antiserum directed against AcSDKP into normal untreated mice in order to neutralize the endogenous inhibitor. The dramatic increase in the percentage of CFU-S in DNA synthesis as compared to controls receiving anti-KLH antiserum suggests that AcSDKP plays an important role in the maintenance of CFU-S in physiological quiescent state.

Animals↗
PubMed1989

Thymidine suicide and hydroxyurea kill ratios accurately reflect the proliferative status of stem cells (CFU-S).

We have previously found that on average 30% of hematopoietic stem cells (CFU-S) are in the S phase, which is at least three times the value published by others. Therefore, it seemed desirable to investigate the reliability of the methods used to measure the percentage of CFU-S in S phase. Various modifications of the [3H]thymidine suicide were tested and it could be demonstrated that results were not affected by them. Furthermore, results obtained with the [3H]thymidine suicide were compared to those obtained with methods utilizing hydroxyurea to kill CFU-S in S phase. The [3H]thymidine- and hydroxyurea-based methods gave parallel results. The parallel behavior validated all of these methods as reliable indicators of the turnover of CFU-S and presumably other stem cell populations.

Animals↗
PubMed1988

Thymic dependency of the humoral regulation of CFU-s proliferation in mice bearing a CSF-producing tumor.

A better understanding of the mechanisms involved in the proliferation of splenic colony-forming units (CFU-s) during tumor growth is important for the prevention of bone marrow aplasia during chemotherapy. The in vivo growth of EMT6 cells, a colony-stimulating factor-secreting mammary tumor, in BALB/c and nude mice resulted in splenomegaly and an increase in the number of splenic granulocyte/macrophage colony-forming cells (GM-CFC). Proliferation of CFU-s, observed in BALB/c mice but not in nude mice, most likely resulted from combined direct and indirect actions of factors secreted by tumor and host cells (in particular helper T cells). These factors were detectable in the serum immediately following tumor cell injection. Thus, the GM-CFC response to factors secreted by the EMT6 tumors is thymus-independent while the CFU-s response is dependent upon the presence of T cells. Finally, we show that EMT6 tumor growth had no effect on the determination of CFU-s differentiation toward the various myeloid cell lineages.

Animals↗
PubMed1988

Radioprotection of hemopoiesis conferred by Acanthopanax senticosus Harms (Shigoka) administered before or after irradiation.

Acanthopanax senticosus Harms (Shigoka) extract has been observed to have radioprotective effects on hemopoiesis of irradiated mice (CBA/olac) when administered before or after irradiation by 60Co. The mechanisms of action were explored by studying the following parameters: 1) survival after lethal doses of irradiation; 2) recovery of spleen colony-forming units (CFU-S); 3) protective effect on endogenous CFU-S; and 4) effect on self-renewal of CFU-S. 1) The 30-day mortality due to bone marrow failure after irradiation was significantly reduced in Shigoka-treated mice. The maximum effect of the extract (80% survival) at a dose of 5 mg was observed when given intraperitoneally 24 h before a lethal dose of irradiation (9.5 Gy) and it was still effective when administered as late as 12 h after irradiation (30% survival). The radioprotective effect of Shigoka extract given before irradiation was not due to an increase in the total number of CFU-S but probably due to quiescent CFU-S that entered DNA synthesis (S-phase) 24 h after the injection of Shigoka extract. 2) Recovery of CFU-S in mice given the extract within 15 min after 4.75 Gy of whole body irradiation was also enhanced, especially in the spleen. The number of CFU-S in the bone marrow 24 h after irradiation showed a marked decrease. It returned to normal values in the bone marrow at day 11 in Shigoka-treated mice and at day 15 in nontreated irradiated mice. CFU-S in the spleen recovered more rapidly with an overshoot from days 7 to 21 in the Shigoka-treated mice, whereas in control irradiated mice it did not reach the normal value until day 21. 3) Nine days after sublethal doses of irradiation (7.0 Gy) the number of endogenous spleen colonies (endogenous CFU-S) was highest in mice given the extract 24 h before irradiation. The extract administered as late as 24 h after irradiation also resulted in an increase of the endogenous CFU-S. 4) The number of CFU-S in each 9-day endogenous CFU-S was 73.9 +/- 7.2 per nodule in treated mice and 0.2 +/- 0.1 per nodule in irradiated control mice, which suggests increased self-renewal of CFU-S in Shigoka-treated groups. These results suggest that the radioprotection conferred by Shigoka extract results from enhanced stimulation of CFU-S not only toward proliferation but also toward CFU-S self-renewal. These two phenomena could explain the protective effects of Shigoka extract administered even after irradiation.

Animals↗
PubMed1987

Further studies on the mechanism of CFU-S determination--I. Pluripoietin(s) responsible for CFU-S determination toward granulopoiesis after fractionated doses of Ara-C.

Fractionated doses of Ara-C orient CFU-S differentiation towards granulopoiesis and megakaryocytopoiesis in vivo in contrast to the preferential channelling towards erythropoiesis after a similar dose of Ara-C given as a single injection. In this paper, we show that pluripoietin found in the serum of mice treated with fractionated doses of Ara-C is responsible for the choice of CFU-S differentiation towards granulopoiesis. Therefore, we confirm our previous results involving single doses of Ara-C, that humoral factors can commit CFU-S preferentially towards one of the cell lineages. It is not as yet known whether there is a specific pluripoietin for each cell lineage or whether the same pluripoietin has a different effect according to its concentration in the organism. The difference in response of CFU-S commitment to single and fractionated doses of Ara-C is not due to the difference in the kinetic status of CFU-S:CFU-S are cycling after both treatments.

Animals↗
PubMed1987

Further studies on the mechanism of CFU-S determination--II. Feedback regulation.

In previous papers, we have demonstrated that the determination of CFU-S differentiation is under the control of humoral factors, which we have called pluripoietins. The activity of these regulators varies according to the experimental protocol. The aim of this work was to determine the mechanisms involved in the regulation of pluripoietin secretion after each treatment. The results suggest that the production of pluripoietin(s) is under the control of a feedback mechanism, originating, at least in part, in the progenitor compartments. After one dose of 20 mg of Ara-C, CFU-S determination is channelled towards erythropoiesis when the BFU-E compartment is more depleted than the GM-CFC compartment. During fractionated doses of Ara-C, at the time of the third injection, GM-CFC survival is lower than BFU-E survival and CFU-S orient their differentiation towards granulopoiesis. After bleeding, there is no difference of survival between the two compartments and CFU-S determination is not changed. These results seem to indicate that CFU-S determination is modified in order to restore normal homeostasis of the hemopoietic tissues by preferentially replenishing the more depleted compartment. This is most likely achieved by the secretion of pluripoietin(s) that vary in either their nature or their concentration according to the events occurring in the more mature compartments.

Animals↗
PubMed1987

Further studies on the mechanism of CFU-S determination--III. CFU-S cell lineage determination is not influenced by GM-CSF, Epo, multi-CSF nor WEHI 3B conditioned medium.

CFU-S proliferation is under the control of factors such as stimulators and inhibitors whereas commitment of CFU-S is controlled by pluripoietins. We have studied the effects in vitro of Epo, GM-CSF, multi-CSF and WEHI 3B conditioned medium in order to elucidate their eventual role on CFU-S proliferation and cell lineage determination. Neither Epo nor GM-CSF are able to induce the entry of CFU-S into cycle. Multi-CSF and WEHI 3B conditioned medium (similar to interleukin 3) stimulate CFU-S into DNA synthesis. However, we were able to show that the stimulator we have studied is different from IL 3. Epo, GM-CSF, multi-CSF and WEHI 3B CM have no effect on CFU-S commitment. Therefore, these four hemopoietic regulators are different from the pluripoietins we have previously described and have no influence on CFU-S determination.

Animals↗
PubMed1987

Preferential differentiation of murine CFU-S toward granulopoiesis and megakaryocytopoiesis after in vitro incubation of bone marrow with ASTA-Z 7557.

We investigated the in vitro effect of ASTA-Z 7557 on the qualitative aspects of murine CFU-S differentiation, as assessed by the histological nature of day-9 colonies generated in the spleen of irradiated mice by bone marrow exposed to the drug at concentrations ranging from 0 to 150 micrograms/ml. The proportion of erythrocytic colonies declined linearly with the logarithm of the dose (a 22% decrease per log), whereas the granulocytic and megakaryocytic colony proportions increased linearly (a 10% increase per log for both cell lineages). This suggests a preferential channeling of CFU-S differentiation toward granulopoietic and megakaryocytic cell lineages as a consequence of the in vitro chemotherapy, and supports the hypothesis that some alteration of the qualitative potential of CFU-S to differentiate after in vitro purging of bone marrow with ASTA-Z 7557 takes place prior to autologous bone marrow transplantation.

Animals↗
PubMed1987

Stimulatory effects of plasma from patients with acute nonlymphoblastic leukemia on early erythroid progenitors and pluripotent stem cells.

To examine mechanisms of cytopenia in acute nonlymphoblastic leukemia (ANLL), we determined whether leukemic plasma (LP) contains growth-promoting factors that support mammalian erythroid progenitor and pluripotential stem cell proliferation in vitro. When added to serum-free cultures of human bone marrow and peripheral blood cells, LP from anemic patients with ANLL stimulated erythroid burst formation to greater levels than did normal human plasma (p less than 0.05 for each). While LP also enhanced erythroid burst development in murine bone marrow cells, preincubation of marrow cells with LP did not alter the formation of splenic colonies (CFU-S-derived colonies) in irradiated mice (p greater than 0.10). To determine whether erythropoietin or other growth factors (functionally similar to burst-promoting activity, BPA) are important in mediating the erythropoietic effects observed in vitro, LP was preabsorbed with monospecific IgG raised against human erythropoietin or human BPA. Although elevated erythropoietin levels were found in each LP, preabsorption with antierythropoietin IgG did not alter its capacity to enhance human burst formation. In contrast, preabsorption with antimembrane IgG capable of recognizing human BPA abrogated the stimulatory effects of LP (p less than 0.05). In addition, LP was found to increase the percentage of murine CFU-S that are synthesizing DNA by the (3H) Tdr suicide technique, an effect which was not abrogated by preabsorption of LP with monospecific IgG raised against human BPA. We conclude that both erythropoietin and BPA are appropriately increased in ANLL. In addition, a factor is present in LP which induces DNA replication in murine pluripotential stem cells.

Absorption↗
PubMed1986

Differentiation pathways of pluripotent hemopoietic stem cells in long-term mouse bone marrow culture.

Differentiation pathways of CFU-S were examined in mouse bone marrow long-term culture system. E/G ratios of non-adherent CFU-S in this system increased from 2 to 7-9 by 2-3 weeks of culture and then fluctuated during the culture period. On the other hand, E/G ratios of adherent CFU-S were lower than that of non-adherent CFU-S, and always remained under 2. Some of the supernatants collected from culture flasks at weekly intervals increased E/G ratios of normal bone marrow CFU-S after 18-20 h of incubation. These results suggest that the differentiation of CFU-S is controlled by humoral factors, secreted from yet unknown cells in bone marrow, in this system.

Animals↗
PubMed1986

Modulation of protein expression in murine bone marrow cells following in-vivo cytosine arabinoside treatment.

The technique of SDS-PAGE followed by autoradiography was applied to study the changes in protein synthesis occurring in murine bone marrow cells in response to AraC administration. It was found that following AraC injection the medullary population undergoes pronounced changes in protein synthesis. Marked increases were noted in the 20, 28 and 70 kD protein labelling, concomitantly with CFU-S stimulating activity of the AraC treated mice bone marrow conditioned medium.

Animals↗
PubMed1986

Pluripotent haemopoietic stem cell entry into DNA synthesis in vitro after stimulation by Ara-C treatment in vivo.

Non-cycling pluripotent bone marrow stem cells (CFU-S), taken 3 hrs after injection of 20 mg of Ara-C, have been shown to enter DNA synthesis at 1 to 3 hr after being cultured in alpha-medium. This phenomenon was observed when bone marrow was incubated as a plug, but not when incubated as a cell suspension in the present experimental conditions. These results suggest that a medullary structure is necessary in order to observe this effect and/or that accessory cells are destroyed during the process of single cell preparation.

Animals↗
PubMed1985

Modifications of CFU-S differentiation pathways by pluripoietins: influence of treatment protocols.

Similar total doses of Ara-C given as a single injection or given in a fractionated protocol have reverse effects on CFU-S differentiation pathways. Whereas a single dose of 20 mg channels CFU-S towards erythropoiesis, 5 X 5 mg given at 8 or 24 hour intervals channels CFU-S to granulopoiesis and megakaryocytopoiesis. It therefore seems possible to manipulate CFU-S differentiation not only by varying the inducing agents but also by varying the protocols using the same agent. Hypotheses to explain the mechanisms of CFU-S regulation are presented.

Animals↗
PubMed1984

Pluripoietin effects on CFU-S lineage determination: possible mechanisms.

Regulation of pluripotent stem cell (CFU-S) proliferation kinetics by humoral factors is now well documented. However, the mechanism of choice of CFU-S differentiation pathways is still a controversial issue. We suggest that long-range humoral factors (pluripoietins) are capable of preferentially channelling CFU-S towards one of the cell lineages after various perturbations such as irradiation and drug treatment. The differentiation pathway depends on the treatment protocol. We present data concerning one of the protocols: injection of 20 mg of cytosine arabinoside (Ara-C). When conditioned medium from bone marrow of treated mice is incubated with normal marrow, CFU-S of the latter generate spleen colonies with an E/G ratio above normal values. Clonal analyses of spleen colonies demonstrate that they are generated by pluripotent stem cells. Therefore, any modification in the E/G ratio is due to modifications of CFU-S channelling and not to the variations of committed cells. It was of interest to determine the mechanism of pluripoietin activity. This was studied at three levels: membrane receptors, gene activation and protein synthesis. These studies suggest that CFU-S have receptors for pluripoietins which activate genes responsible for specific mRNA synthesis. De novo synthesis of proteins is a necessary prerequisite for pluripoietin activity to be expressed. Hypotheses for these mechanisms are presented.

Animals↗