scholarly journals The effect of chemotherapy on the kinetics and proliferative capacity of normal and tumorous tissues in vivo

Blood ◽  
1975 ◽  
Vol 45 (1) ◽  
pp. 107-118 ◽  
Author(s):  
SH Rosenoff ◽  
JM Bull ◽  
RC Young
Keyword(s):  
Bone Marrow ◽  
Dna Synthesis ◽  
Colony Formation ◽  
Antitumor Agents ◽  
Tritiated Thymidine ◽  
Chemotherapeutic Agents ◽  
Proliferative Capacity

Abstract The proliferative state of a given tissue is a major determinant of its sensitivity to both phase-specific and cycle-specific chemotherapeutic agents. To study the extent of injury induced by antitumor agents to normal and tumorous tissues, a technique for following DNA synthesis as reflected in the incorporation of tritiated thymidine (3H-TdR) into DNA was compared to the conventional radioautographic technique of the labeling index (LI) and to the functional kinetic technique of granulocyte colony formation in vitro. Alterations in DNA synthesis induced by a single dose of cyclophosphamide in normal and tumorous tissues in vivo paralleled in many respects the changes seen when the more time-consuming techniques of the LI or granulocyte colony formation were employed. However, the recovery of granulocyte colony formation after cyclophosphamide therapy laged behind the recovery of DNA synthesis in the bone marrow, obscuring a kinetic event of potential therapeutic significance. The determination of DNA synthesis simultaneously in normal and tumorous tissues in vivo was easy to perform and supplied therapeutically pertinent results comparatively quickly.

scholarly journals The effect of chemotherapy on the kinetics and proliferative capacity of normal and tumorous tissues in vivo

Blood ◽  
1975 ◽  
Vol 45 (1) ◽  
pp. 107-118
Author(s):  
SH Rosenoff ◽  
JM Bull ◽  
RC Young
Keyword(s):  
Bone Marrow ◽  
Dna Synthesis ◽  
Colony Formation ◽  
Antitumor Agents ◽  
Tritiated Thymidine ◽  
Chemotherapeutic Agents ◽  
Proliferative Capacity

The proliferative state of a given tissue is a major determinant of its sensitivity to both phase-specific and cycle-specific chemotherapeutic agents. To study the extent of injury induced by antitumor agents to normal and tumorous tissues, a technique for following DNA synthesis as reflected in the incorporation of tritiated thymidine (3H-TdR) into DNA was compared to the conventional radioautographic technique of the labeling index (LI) and to the functional kinetic technique of granulocyte colony formation in vitro. Alterations in DNA synthesis induced by a single dose of cyclophosphamide in normal and tumorous tissues in vivo paralleled in many respects the changes seen when the more time-consuming techniques of the LI or granulocyte colony formation were employed. However, the recovery of granulocyte colony formation after cyclophosphamide therapy laged behind the recovery of DNA synthesis in the bone marrow, obscuring a kinetic event of potential therapeutic significance. The determination of DNA synthesis simultaneously in normal and tumorous tissues in vivo was easy to perform and supplied therapeutically pertinent results comparatively quickly.

scholarly journals In Vivo Localization of Heterologous Anti-Erythrocyte Antibodies in the Rat Bone Marrow and Their Effect on the Proliferative Capacity of Immature Erythroid Cells

Blood ◽  
1965 ◽  
Vol 25 (2) ◽  
pp. 161-168 ◽  
Author(s):  
TAKEO KUROYANAGI ◽  
MASANOBU SAITO ◽  
AKIRA KURISU
Keyword(s):  
Bone Marrow ◽  
Intravenous Injection ◽  
Tritiated Thymidine ◽  
Inhibitory Effect ◽  
Red Cell ◽  
Proliferative Capacity ◽  
Rat Bone ◽  
Incomplete Antibody

Abstract The in vivo localization of heterologous anti-erythrocyte antibodies in the rat bone marrow was determined by the I131-labeled antibody technic. I131-labeled anti-erythrocyte antibodies localized specifically in the bone marrow indicating the presence of localizing antibody. Both the localizing antibody and the incomplete antibody were thermostable, whereas hemolysins and hemagglutinins were thermolabile. Following an intravenous injection of antierythrocyte antibodies in rats, hemolysins and hemagglutinins were cleared rapidly from the plasma. The incomplete antibodies became attached to circulating red cells within 6 hours and red cell sensitization persisted for 1 week. The localizing antibody localized in the bone marrow within 30 minutes, leaving no activity in plasma. The anti-erythrocyte antibodies markedly reduced the uptake of tritiated thymidine by erythroblasts in vitro, demonstrating their inhibitory effect on the proliferative capacity of erythroblasts.

Thrombopoietin-Induced Stimulation of Megakaryocyte- Enriched Bone Marrow Cultures

1979 ◽  
Author(s):  
K. L. Kellar ◽  
B. L. Evatt ◽  
C. R. McGrath ◽  
R. B. Ramsey
Keyword(s):  
Bone Marrow ◽  
Dna Synthesis ◽  
Bone Marrow Cells ◽  
Rabbit Plasma ◽  
Bone Marrow Cultures ◽  
Plasma Fractions ◽  
Marrow Cultures ◽  
Stimulation Of

Liquid cultures of bone marrow cells enriched for megakaryocytes were assayed for incorporation of 3H-thymidine (3H-TdR) into acid-precipitable cell digests to determine the effect of thrombopoietin on DNA synthesis. As previously described, thrombopoietin was prepared by ammonium sulfate fractionation of pooled plasma obtained from thrombocytopenic rabbits. A control fraction was prepared from normal rabbit plasma. The thrombopoietic activity of these fractions was determined in vivo with normal rabbits as assay animals and the rate of incorporation of 75Se-selenomethionine into newly formed platelets as an index of thrombopoietic activity of the infused material. Guinea pig megakaryocytes were purified using bovine serum albumin gradients. Bone marrow cultures containing 1.5-3.0x104 cells and 31%-71% megakaryocytes were incubated 18 h in modified Dulbecco’s MEM containing 10% of the concentrated plasma fractions from either thrombocytopenic or normal rabbits. In other control cultures, 0.9% NaCl was substituted for the plasma fractions. 3H-TdR incorporation was measured after cells were incubated for 3 h with 1 μCi/ml. The protein fraction containing thrombopoietin-stimulating activity caused a 25%-31% increase in 3H-TdR incorporation over that in cultures which were incubated with the similar fraction from normal plasma and a 29% increase over the activity in control cultures to which 0.9% NaCl had been added. These data suggest that thrombopoietin stimulates DNA synthesis in megakaryocytes and that this tecnique may be useful in assaying thrombopoietin in vitro.

270. Androgens augment the mitogenic effects of oocyte-secreted factors and growth differentiation factor 9 on porcine granulosa cells

2005 ◽  
Vol 17 (9) ◽  
pp. 111
Author(s):  
T. E. Hickey ◽  
D. L. Marrocco ◽  
F. Amato ◽  
L. J. Ritter ◽  
R. J. Norman ◽  
...  
Keyword(s):  
Dna Synthesis ◽  
Tritiated Thymidine ◽  
Paracrine Signalling ◽  
Secreted Factors ◽  
Differentiation Factor ◽  
Porcine Granulosa Cells ◽  
Growth Differentiation Factor 9 ◽  
Growth Promoting

Androgens, acting directly through the androgen receptor (AR), are thought to promote granulosa cell (GC) growth in vivo, but generally inhibit growth and promote GC differentiation in vitro. We hypothesised that the growth-promoting action of androgens on GC requires paracrine signalling from the oocyte. To test this hypothesis, we cultured mural GC from small antral (1–3mm) pre-pubertal pig follicles in the presence or absence of denuded oocytes (DO) from the same follicles to examine whether mitogenic responses, determined by uptake of tritiated thymidine, to combinations of FSH, insulin like growth factor 1 (IGF1) and dihydrotestosterone (DHT; 500 nM), were influenced by oocyte-secreted factors (OSFs). To further explore the identity of such factors, we performed the same experiments, substituting recombinant mouse growth differentiation factor 9 (GDF9), a known OSF, for the DO. Alone, DHT induced a small (<2-fold), but consistent increase in IGF1-stimulated DNA synthesis. OSFs stimulated DNA synthesis in all experimental combinations, most significantly in the presence of IGF1 (P < 0.0001), and DHT enhanced (P<0.05) the stimulatory effect of OSFs in all instances. Like OSFs, GDF9 substantially increased IGF1-stimulated DNA synthesis (P < 0.0001), and again, DHT enhanced (P > 0.01) this effect. In further experiments, two AR agonists, testosterone (10-1000nM) and DHT (5–500 nM), dose-dependently augmented the mitogenic effect of OSFs or GDF9 in the presence of IGF1. Only the highest doses of androgen had an independent stimulatory effect; lower doses required the presence of an OSF(s). Antiandrogen (hydroxyflutamide) treatment, used to block AR activity, antagonized the androgen X GDF9 interaction. In conclusion, androgens, via activation of the AR, stimulate porcine GC proliferation in vitro by potentiating the growth-promoting effects of oocytes or GDF9. These signalling pathway interactions are likely to be important regulators of folliculogenesis in vivo and may cause the excess follicle growth that is observed in androgen-treated female animals.

Effectiveness of a Novel Humanized VB22B Minibody against Human TPO Receptor Compared with Recombinant TPO and Eltrombopag Using Primary Human CD34+ Cells and Platelets.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 4559-4559
Author(s):  
Eri Matsuki ◽  
Akiko Yamane ◽  
Shinichiro Okamoto ◽  
Yoshitaka Miyakawa
Keyword(s):  
Bone Marrow ◽  
Platelet Aggregation ◽  
Colony Formation ◽  
Human Platelets ◽  
Receptor Agonists ◽  
Human Cd34 ◽  
Cd34 Cells ◽  
Proplatelet Formation

Abstract Abstract 4559 Thrombopoietin (TPO) is a cytokine produced primarily by the liver and kidney that regulates platelet production by stimulating proliferation and differentiation of hematopoietic stem cells, megakaryocytic progenitor cells and megakaryocytes via activation of its receptor, c-Mpl. Recently, TPO receptor agonists such as eltrombopag and romiplostim have been approved for chronic ITP. huVB22B was created as a novel humanized form of murine sc(Fv) 2VB22B minibody (BLOOD, 2005) which activates human c-Mpl by CDR grafting. The advent of these various TPO receptor agonists prompted us to consider the differences in their mechanisms of action, efficacy or potency. However, to date, there has been no in vivo or in vitro study directly comparing the effects of different TPO receptor agonists. In this study, we compared the efficacy of huVB22B on CFU-GM, CFU-E, CFU-Megakaryocyte (CFU-MK), megakaryocyte maturation (DNA ploidy and proplatelet formation) with those of recombinant human TPO (rhTPO) and eltrombopag. Primary human CD34+ bone marrow cells were cultured with various concentrations of rhTPO, huVB22B and eltrombopag using methylcellulose based media. In serum-free condition, 0.286 nM rhTPO, 0.182 nM huVB22B and 17.7 mcM eltrombopag demonstrated almost equivalent efficacy of megakaryocyte colony formation. At these concentrations, all agents demonstrated similar in vitro efficacy for colony formation of CFU-GM and CFU-E, proplatelet formation and nuclear maturation of megakaryocytes. In preliminary results, huVB22B induced maturation of CFU-MK earlier than rhTPO and eltrombopag, suggesting that huVB22B might have some potential to increase human platelets faster than other agents in vivo. This is compatible with the observation that huVB22B induced tyrosine phosphorylation of STAT3, STAT5 and JAK2 faster and stronger than rhTPO and eltrombopag in human primary platelets. Both rhTPO and huVB22B enhanced low-dose ADP and collagen-induced human platelet aggregation in vitro. In contrast, eltrombopag did not enhance ADP or collagen-induced platelet aggregation, although it induced activation of JAK-STAT pathway in human platelets. Contrary to the fact that huVB22B induces phosphorylation of intracellular signaling molecules faster and stronger than rhTPO in human platelets, the priming effect by huVB22B on platelet aggregation was much weaker than rhTPO. In conclusion, we confirmed that newly created huVB22B minibody induced colony formation of CFU-MK, CFU-E, CFU-GM and maturation of megakaryocytes from human bone marrow-derived CD34+ cells in vitro. The differences among TPO receptor agonists observed in our study would lead to further understanding of the basic biology of megakaryopoiesis and the action of TPO receptor agonists. Disclosures: Okamoto: Alexion: Research Funding. Miyakawa:GlaxoSmithKline: Consultancy.

Hoxa9/Meis1 Mediate Leukemic Programming through Microrna-155

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 884-884
Author(s):  
Edith Schneider ◽  
Anna Staffas ◽  
Milijana Mirkovic-Hoesle ◽  
Bernhard Gentner ◽  
Jens Ruschmann ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Colony Formation ◽  
Healthy Donor ◽  
Molecular Mechanisms ◽  
Acute Leukemias ◽  
Self Renewal ◽  
Hematopoietic Stem ◽  
Donor Bone Marrow

Abstract Synergistic deregulation of HOXA9 and the HOX-gene cofactor MEIS1 is a commonly observed phenomenon in acute myeloid leukemia (AML). The leukemogenic potential of aberrant Hoxa9 and Meis1 expression has been shown in several AML models. However, the molecular mechanisms behind Hoxa9- and Meis1-induced leukemogenesis are still not well understood. In order to identify functionally relevant Meis1-induced microRNAs (miRNA), we profiled the global miRNA expression using a Hoxa9-Meis1 murine AML progression model. This two-step model allowed us to quantify miRNAs at a pre-leukemic stage through the overexpression of the proto-oncogene Hoxa9 (Hoxa9/ctrl), as well as after full leukemic transformation through co-overexpression of Hoxa9 and Meis1 (Hoxa9/Meis1). The pre-leukemic stage is characterized by in vitro immortalization without in vivo engraftment, whereas the transplanted leukemic cells induce full-blown AML in vivo. MiR-155 turned out to be one of the most significant differentially expressed miRNA species and its upregulation was independently validated in Hoxa9/Meis1 cells by qRT-PCR. Subsequent analysis of various AML subtypes (CN-AML, t(11q23), t(8;21), t(15;17), n=38) showed significantly elevated levels of miR-155 in CN-AML with NPM1mut (n=10, p<0.01) and AML with t(11q23) (n=8, p<0.05) compared to healthy donor bone marrow (MNC). These results are in line with overexpression of HOXA9 (CN-AML NPM1mut: p<0.05, t(11q23): p<0.05) and MEIS1 (CN-AML NPM1mut: p<0.01, t(11q23): p<0.05) in these AML samples compared to healthy donor bone marrow cells (MNC). Expression analysis of miR-155 in healthy murine bone marrow (mbm) cells revealed miR-155 enrichment in hematopoietic stem- and progenitor cells compared to mature myeloid cells (p<0.05), mirroring a similar expression pattern as observed for Meis1. Therefore, to dissect the leukemic potential of miR-155 to program mbm, 5-FU-stimulated mbm cells were retrovirally transduced with miR-155, leading to significantly increased proliferation in vitro (p<0.05). This finding suggests enhancement of self-renewal on the stem-/progenitor cell level by miR-155. Furthermore, mbm cells overexpressing Hoxa9 together with miR-155 (Hoxa9/miR-155) significantly increased colony formation (p<0.05) in a methylcellulose assay. In turn, absence of miR-155 (miR-155-/- mbm) significantly reduced colony formation in conjunction with Hoxa9 (p<0.05) and MLL-AF9 (p=0.05), a known positive regulator of Hoxa9 and Meis1. These findings suggest a role for miR-155 in both proliferation and self-renewal indicating that the oncogenic program of Hoxa9/Meis1 relies on the presence of miR-155. The leukemic potency of Hoxa9/miR-155 was further investigated in a murine transplantation model in vivo. Transplantation of mbm co-overexpressing Hoxa9/miR-155 led to significantly increased engraftment levels already after four weeks (wks) (57.8%±31.3, n=16) compared to Hoxa9/ctrl (11.7%±19.3%, p<0.0001, n=17), but less than with Hoxa9/Meis1 (74.5%±20.3%, p<0.01, n=14). In contrast to Hoxa9/ctrl (22±7 wks), mice that received Hoxa9/miR-155 mbm cells had a significantly accelerated onset of a myeloproliferative disease (MPD)-like leukemia within 11 wks (11±6 wks, p<0.0001), but still a less aggressive course of disease compared to mice transplanted with Hoxa9/Meis1 (5±1 wks, p<0.0001). This result is striking considering the aggressive nature of the Hoxa9/Meis1 AML model and given how little is known about its central mechanisms. It also highlights the relevant contribution of miR-155 to the leukemic programming induced by Hoxa9/Meis1 and provides a further rational to target miR-155 in AML. Considering the central role of the Hoxa9/Meis1 in both myeloid and lymphoid acute leukemias, we demonstrate for the first time the leukemogenic relevance of a miRNA within this transcriptional axis. Disclosures No relevant conflicts of interest to declare.

scholarly journals Characterization of the potentiation effect of activin on human erythroid colony formation in vitro

Blood ◽  
1989 ◽  
Vol 73 (4) ◽  
pp. 952-960 ◽  
Author(s):  
J Yu ◽  
L Shao ◽  
J Vaughan ◽  
W Vale ◽  
AL Yu
Keyword(s):  
Bone Marrow ◽  
T Lymphocytes ◽  
Dna Synthesis ◽  
Peripheral Blood ◽  
Colony Formation ◽  
Mononuclear Cells ◽  
Erythroid Progenitors ◽  
Potentiation Effect ◽  
Proliferation And Differentiation

Activin, also named FSH-releasing protein, was previously shown to induce hemoglobin accumulation in K562 cells and potentiate the proliferation and differentiation of CFU-E in human bone marrow cultures. Present studies indicate that the potentiation effect of activin is lineage specific. In addition to CFU-E, activin caused an increase in the colony formation of BFU-E from either bone marrow or peripheral blood. It had little effect on the colony formation of CFU- GM and the mixed colonies from CFU-GEMM. In serum-depleted culture, the effect of activin was shown to be dose-dependent with doses effective at picomolar concentrations. The potentiation effect of activin was exerted indirectly through mediation of both monocytes and T lymphocytes. Activin was also found to increase specifically the proportion of DNA-synthesizing erythroid progenitors from both bone marrow and peripheral blood. It had little effect on DNA synthesis in CFU-GM and in mitogen-stimulated lymphocytes. Addition of the monocytes or T lymphocytes to their respective depleted subpopulations of mononuclear cells reconstituted the enhancing effect of activin on the colony formation and DNA synthesis of erythroid progenitors. These results strongly suggest a specific role of activin in potentiating the proliferation and differentiation of erythroid progenitors in vitro.

Leukemia Stem/Progenitor Cells From AML Patients Treated With The Multi-Kinase Inhibitor TG02 Demonstrate Increased Proliferation and Are Sensitized To Chemotherapeutic Agents

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 3892-3892 ◽  
Author(s):  
Monica L. Guzman ◽  
Wen Xie ◽  
Jeanne P. De Leon ◽  
Francis Burrows ◽  
Eric J. Feldman ◽  
...  
Keyword(s):  
Progenitor Cells ◽  
Peripheral Blood ◽  
Colony Formation ◽  
Kinase Inhibitor ◽  
Chemotherapeutic Agents ◽  
Positive Staining ◽  
Annual Meeting Abstract ◽  
The Impact

Abstract TG02 is a multi-kinase inhibitor that targets cyclin-dependent kinases (CDKs), ERK5, JAK2, and Flt3. In vitro studies of TG02 have shown robust induction of apoptosis in both acute myeloid leukemia (AML) cell lines and primary cells (Goh et al, 2011). Leukemia stem cells (LSCs) comprise a largely quiescent, highly chemotherapy-resistant cell population and are believed to initiate and maintain AML, as well as contribute to its poor prognosis. Thus, we sought to investigate the impact of TG02 on LSCs collected from patients with relapsed/refractory AML enrolled in a phase I dose escalation trial. Patients ≥ 18 years with advanced hematological malignancies or newly diagnosed AML pts ≥ 65 years unfit for intensive therapy were enrolled onto daily (A) and intermittent (B, 5 days on 2 days off X 2 weeks) schedules in 28-day cycles. Pts had acceptable organ function and ECOG PS 0-2. Dose levels were 10 - 70 mg on arm A and 30 - 150 mg on arm B. We evaluated immunophenotypically defined leukemia stem and progenitor cells (LSPCs) by flow cytometry, cell cycle status and colony forming assays. A total of 16 patients were evaluated with treatment doses ranging from 10-150 mg of TG02. Clinically, treatment with TG02 did not have an effect in AML tumor burden, and most patients at our center only received one cycle of treatment (Roboz et al ASCO 2012 Annual Meeting Abstract #6557, J Clin. Oncol. 30, 2012). However, we found that 8 patient samples showed increased LSPCs in both the bone marrow and peripheral blood. Interestingly, we observed an increase in LSPC cell proliferation, as determined by Ki-67 positive staining. AML colony forming assays also showed increased colony formation (n=5) after one cycle of treatment, which suggests an increase in the frequency of LSPCs. The increase in colony formation in peripheral blood samples suggests mobilization of LSPCs from the marrow into the circulation. Thus, we hypothesized that exposure to TG02 in vivo may result in sensitization to other chemotherapeutic agents, such as Ara-C. We evaluated the effects of Ara-C and other chemotherapeutics, such as vincristine, in primary AML cells obtained from patients before and after treatment with TG02. We found that in vivo exposure to TG02 resulted in significantly increased sensitivity to Ara-C in vitro in 3 out of 4 samples tested Together, our data suggest that TG02 induces an effect in LSCs resulting in increased proliferation and, thus, sensitization to other chemotherapeutic drugs, such as Ara-C. Importantly, although no patients at our center receiving single agent TG02 met the criteria for an objective response, by performing correlative studies in association with the clinical trial, we found the TG02 has a marked effect in AML LSCs that could potentially be exploited by combining it with other agents. Disclosures: Burrows: Tragara Pharmaceuticals: Employment, Equity Ownership. Feldman:Tragara Pharmaceuticals: Consultancy.

scholarly journals Cholesterol and mevalonic acid are independent requirements for the in vitro proliferation of human bone marrow granulocyte progenitor cells: studies using ML-236B

Blood ◽  
1983 ◽  
Vol 61 (4) ◽  
pp. 667-671
Author(s):  
PC Hoffman ◽  
CM Richman ◽  
RA Larson ◽  
S Yachnin
Keyword(s):  
Bone Marrow ◽  
Dna Synthesis ◽  
Colony Formation ◽  
Mononuclear Cells ◽  
Cholesterol Biosynthesis ◽  
Mevalonic Acid ◽  
Human Bone ◽  
Hmg Coa Reductase ◽  
Coa Reductase

ML-236B is a competitive inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A (HMG CoA) reductase, the key regulatory enzyme in the sequence that catalyzes the conversion of acetate to mevalonic acid in cholesterol biosynthesis. This compound caused marked inhibition of human bone marrow granulocyte progenitor cell (CFU-C) proliferation, the 50% inhibitory concentration (IHD50) being 2.0 X 10(6)M. Inhibition of colony formation was reversed by mevalonic acid but not by cholesterol. ML-236B also inhibited DNA synthesis and acetate incorporation into cholesterol in marrow mononuclear cells (IHD50 = 5.6 x 10(6)M and 3.2 x 10(7)M, respectively). No inhibition of mevalonate incorporation into cholesterol was observed. These results differ from those observed with 25-hydroxycholesterol, another inhibitor of HMG CoA reductase. The latter compound also inhibited CFU-C proliferation and cholesterol biosynthesis from acetate; inhibition of colony formation was reversed by cholesterol but not by mevalonic acid. In addition, 25- hydroxycholesterol inhibited cholesterol synthesis from mevalonic acid precursor. We conclude that: (1) ML-236B is a potent inhibitor of CFU-C proliferation, DNA synthesis, and cholesterol biosynthesis from acetate precursor in marrow mononuclear cells; (2) the effects of ML-236B are completely reversed by mevalonic acid but not by cholesterol, suggesting that mevalonic acid per se or one or more of its nonsterol products are critical for cell growth; (3) the inhibitory effects of 25- hydroxycholesterol on CFU-C proliferation and cholesterol biosynthesis are not solely a result of its inhibition of HMG CoA reductase, but are due in part to inhibition of enzymatic steps distal to mevalonic acid in the sterol synthetic pathway; and (4) mevalonic acid and cholesterol are independent requirements for CFU-C proliferation and differentiation in vitro.

scholarly journals Proliferative state of normal in vitro colony-forming cells during development of L5222 rat leukemia and their reaction to chemotherapy

Blood ◽  
1978 ◽  
Vol 51 (2) ◽  
pp. 221-227 ◽  
Author(s):  
EB Harriss ◽  
D Hoelzer
Keyword(s):  
Bone Marrow ◽  
Bone Marrow Cells ◽  
Chemotherapeutic Agents ◽  
S Phase ◽  
Agar Culture ◽  
L5222 Rat Leukemia ◽  
Blast Cells ◽  
Cycle Dependent

Abstract In the experimental rat leukemia, L5222, the decrease of normal in vitro colony-forming cells (CFU-C) after chemotherapy with daunomycin is much less than in nonleukemic controls. The leukemia is therefore used here to test the hypothesis that in leukemia the CFU-C are expelled from the active cell cycle to a resting state and are thereby less sensitive to cycle-dependent chemotherapeutic agents. The L5222 leukemia has the advantage that the leukemic blast cells do not form colonies in agar culture so that normal CFU-C can be assessed under leukemic conditions. To compare the proportions of CFU-C in the S-phase in normal and leukemic rats, two S-phase-specific agents, 3H-thymidine and hydroxyurea, were used to kill proliferating bone marrow cells. Following treatment with 3H-thymidine in vitro, about 41% of the CFU-C were killed in normal and about 25% in leukemic bone marrow. Hydroxyurea administered in vivo resulted in the death of about 33% and 26%, respectively. The results indicate that fewer normal CFU-C are in S-phase in the L5222 leukemia, which might help to explain how enough normal stem cells survive chemotherapy to regenerate the bone marrow.

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