scholarly journals Heterogeneity of γH2AX Foci Increases in Ex Vivo Biopsies Relative to In Vivo Tumors

2018 ◽  
Vol 19 (9) ◽  
pp. 2616 ◽  
Author(s):  
Treewut Rassamegevanon ◽  
Steffen Löck ◽  
Michael Baumann ◽  
Mechthild Krause ◽  
Cläre von Neubeck
Keyword(s):  
Cell Cycle ◽  
Ex Vivo ◽  
Human Head ◽  
Cellular Adaptation ◽  
Γh2ax Foci ◽  
Damage Repair ◽  
Intrinsic Radiosensitivity ◽  
Cell Cycle Alteration ◽  
Degree Of Heterogeneity

The biomarker for DNA double stand breaks, gammaH2AX (γH2AX), holds a high potential as an intrinsic radiosensitivity predictor of tumors in clinical practice. Here, two published γH2AX foci datasets from in and ex vivo exposed human head and neck squamous cell carcinoma (hHNSCC) xenografts were statistically re-evaluated for the effect of the assay setting (in or ex vivo) on cellular geometry and the degree of heterogeneity in γH2AX foci. Significant differences between the nucleus areas of in- and ex vivo exposed samples were found. However, the number of foci increased linearly with nucleus area in irradiated samples of both settings. Moreover, irradiated tumor cells showed changes of nucleus area distributions towards larger areas compared to unexposed samples, implying cell cycle alteration after radiation exposure. The number of residual γH2AX foci showed a higher degree of intra-tumoral heterogeneity in the ex vivo exposed samples relative to the in vivo exposed samples. In the in vivo setting, the highest intra-tumoral heterogeneity was observed in initial γH2AX foci numbers (foci detected 30 min following irradiation). These results suggest that the tumor microenvironment and the culture condition considerably influence cellular adaptation and DNA damage repair.

EXTH-48. NOVEL COMBINATION THERAPY IN PRECLINICAL GLIOMA MODELS USING THE CELL CYCLE STABILIZING COMPOUND ARGYRIN F AND CHECKPOINT INHIBITION

2021 ◽  
Vol 23 (Supplement_6) ◽  
pp. vi174-vi174
Author(s):  
Bianca Walter ◽  
Denis Canjuga ◽  
Simge G Yuez ◽  
Michael Ghosh ◽  
Przemyslaw Bozko ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Ex Vivo ◽  
Tumor Infiltrating Lymphocytes ◽  
Clonogenic Survival ◽  
Autologous Tumor ◽  
Cycle Arrest ◽  
Resected Tissue ◽  
Infiltrating Lymphocytes

Abstract Glioblastoma are incurable aggressive tumors and remain a therapeutic challenge. Glioblastoma frequently harbor alterations in the retinoblastoma pathway with subsequent cell cycle abnormalities. Here, we aimed to investigate the anti-glioma activity of the cell cycle-stabilizing compound Argyrin F and its potential treatment-induced vulnerabilities to exploit possibilities for novel combination therapies. We investigated cell viability, clonogenic survival, cell cycle status and immunoblots of human and murine glioma cells treated with Argyrin F. Moreover, we established an ex vivo glioma model using residual freshly resected tissue from patients, i.e. patient-derived microtumors (PDMs). Additionally, we extracted autologous tumor infiltrating lymphocytes (TILs) to perform co-culturing experiments. We performed mass spectrometry-based immunopeptidomics and used the orthotopic syngeneic SMA560/VM/Dk glioma mouse model. Argyrin F displayed anti-glioma efficacy in glioma cell lines in vitro and in PDM models ex vivo. Moreover, Argyrin F treatment induced cell cycle arrest, reduced clonogenic survival in vitro and prolonged survival in vivo. Argyrin F-treated SMA560 glioma displayed 4.6-fold more glioma-infiltrating CD8+ T cells. We discovered a distinctive treatment-induced immunopeptidome. Combination of Argyrin F plus PD-1 antibody increased cellular toxicity in PDM/TILs co-cultures ex vivo and prolonged overall survival compared with monotherapies in vivo. We conclude that our experimental data suggest a novel combination of Argyrin F plus PD-1 blockade and its clinical translation.

Activity of MK1775, a selective Wee1 inhibitor, alone or in combination with gemcitabine, in sarcomas.

2012 ◽  
Vol 30 (15_suppl) ◽  
pp. 10084-10084
Author(s):  
Jenny Kreahling ◽  
Damon R. Reed ◽  
Parastou Foroutan ◽  
Gary Martinez ◽  
Robert Gillies ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Death ◽  
Soft Tissue ◽  
Soft Tissue Sarcoma ◽  
Therapeutic Efficacy ◽  
Ex Vivo ◽  
Apoptotic Cell ◽  
Apoptotic Cell Death ◽  
Primary Therapy

10084 Background: Sarcomas consist of more than 50 subtypes of mesenchymal tumors. Doxorubicin alone or in combination has been the primary therapy for treatment of sarcomas; however, the response rates are suboptimal in many of the more common adult subtypes of soft tissue sarcoma. Accordingly, new agents are needed for the treatment of this heterogeneous group of diseases. Wee1 is a critical component of the G2/M cell cycle checkpoint control and mediates cell cycle arrest by regulating the phosphorylation of CDC2. Methods: MK1775 treatment of multiple sarcoma preclinical models at clinically relevant concentrations leads to unscheduled entry into mitosis and initiation of apoptotic cell death. In our current study we have investigated the therapeutic efficacy of MK1775 in sarcoma cell lines, patient-derived tumor explants ex vivo and in vivo in a xenograft model of osteosarcoma both alone and in combination with gemcitabine. Results: In patient-derived bone and soft tissue sarcoma samples ex vivo treatments show MK1775 in combination with gemcitabine causes significant apoptotic cell death suggesting that this treatment may represent a novel approach in the treatment of sarcomas. The cytotoxic effect of Wee1 inhibition on sarcoma cells appears to be independent of p53 mutational status. Furthermore, in a patient-derived osteosarcoma xenograft mouse model we show the therapeutic efficacy of MK1775 in vivo by utilizing magnetic resonance imaging (MRI) and diffusion MRI methods. Our data shows MK1775 in combination with gemcitabine dramatically slows tumor growth, increases apoptotic cell death and increases CDC2 activity. Cell viability, a clinically established prognostic indicator of survival, was lowest with the combination and very low in animals treated with MK1775 alone. This was mainly due to increased mineralization of the tumors. Caspase-3 was increased in MK1775 treated animals by immunohistochemistry as well. Conclusions: These results together with the promising safety profile of MK1775 strongly suggest that this drug can be used as a potential therapeutic agent alone or in combination with gemcitabine in the treatment of both adult as well as pediatric sarcoma patients.

scholarly journals Functional Heterogeneity of Human CD34+ Cells Isolated in Subcompartments of the G0 /G1 Phase of the Cell Cycle

Blood ◽  
1997 ◽  
Vol 90 (11) ◽  
pp. 4384-4393 ◽  
Author(s):  
André Gothot ◽  
Robert Pyatt ◽  
Jon McMahel ◽  
Susan Rice ◽  
Edward F. Srour
Keyword(s):  
Cell Cycle ◽  
Ex Vivo ◽  
G1 Phase ◽  
Dna And Rna ◽  
Human Cd34 ◽  
Rna Content ◽  
Cd34 Cells ◽  
Ex Vivo Culture

Using simultaneous Hoechst 33342 (Hst) and Pyronin Y (PY) staining for determination of DNA and RNA content, respectively, human CD34+ cells were isolated in subcompartments of the G0 /G1 phase of the cell cycle by flow cytometric cell sorting. In both bone marrow (BM) and mobilized peripheral blood (MPB) CD34+ cells, primitive long-term hematopoietic culture-initiating cell (LTHC-IC) activity was higher in CD34+ cells isolated in G0 (G0CD34+ cells) than in those residing in G1 (G1CD34+ cells). However, as MPB CD34+ cells displayed a more homogeneous cell-cycle status within the G0 /G1 phase and a relative absence of cells in late G1 , DNA/RNA fractionation was less effective in segregating LTHC-IC in MPB than in BM. BM CD34+ cells belonging to four subcompartments of increasing RNA content within the G0 /G1 phase were evaluated in functional assays. The persistence of CD34 expression in suspension culture was inversely correlated with the initial RNA content of test cells. Multipotential progenitors were present in G0 or early G1 subcompartments, while lineage-restricted granulomonocytic progenitors were more abundant in late G1 . In vitro hematopoiesis was maintained for up to 6 weeks with G0CD34+ cells, whereas production of clonogenic progenitors was more limited in cultures initiated with G1CD34+ cells. To test the hypothesis that primitive LTHC-ICs would reenter a state of relative quiescence after in vitro division, BM CD34+ cells proliferating in ex vivo cultures were identified from their quiescent counterparts by a relative loss of membrane intercalating dye PKH2, and were further fractionated with Hst and PY. The same functional hierarchy was documented within the PKH2dim population whereby LTHC-IC frequency was higher for CD34+ cells reselected in G0 after in vitro division than for CD34+ cells reisolated in G1 or in S/G2 + M. However, the highest LTHC-IC frequency was found in quiescent PKH2bright CD34+ cells. Together, these results support the concept that cells with distinct hematopoietic capabilities follow different pathways during the G0 /G1 phase of the cell cycle both in vivo and during ex vivo culture.

scholarly journals Interferon-beta enhances sensitivity to gemcitabine in pancreatic cancer

2020 ◽  
Author(s):  
Amber Blaauboer ◽  
Stephanie Booy ◽  
Peter M. van Koetsveld ◽  
Bas Karels ◽  
Fadime Dogan ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Pancreatic Cancer ◽  
Colony Formation ◽  
Interferon Beta ◽  
Ex Vivo ◽  
Treatment Resistance ◽  
Proliferating Cells ◽  
Increased Sensitivity

Abstract Background: Adjuvant gemcitabine for pancreatic cancer has limited efficacy in the clinical setting. Impaired drug metabolism is associated with treatment resistance. We aimed to evaluate the chemosensitising effect of interferon-beta (IFN-β).Methods: BxPC-3, CFPAC-1, and Panc-1 cells were pre-treated with IFN-β followed by gemcitabine monotherapy. The effect on cell growth, colony formation, and cell cycle was determined. RT-qPCR was used to measure gene expression. BxPC-3 cells were used in a heterotopic subcutaneous mouse model. Results: IFN-β increased sensitivity to gemcitabine (4-, 7.7-, and 1.7-fold EC50 decrease in BxPC-3, CFPAC-1, and Panc-1, respectively; all P<0.001). Findings were confirmed when assessing colony formation. The percentage of cells in the S-phase was significantly increased after IFN-β treatment only in BxPC-3 and CFPAC-1 by 12% and 7%, respectively (p<0.001 and p<0.05, respectively). Thereby, IFN-β upregulated expression of the drug transporters SLC28A1 in BxPC-3 (252%) and SLC28A3 in BxPC-3 (127%) and CFPAC-1 (223%) (all p<0.001). In vivo, combination therapy reduced tumor volume with 45% (P=0.01). Both ex vivo and in vivo data demonstrate a significant reduction in the number of proliferating cells, whereas apoptosis was increased. Conclusions: For the first time, we validated the chemosensitising effects of IFN-β when combined with gemcitabine in vitro, ex vivo, and in vivo. This was driven by cell cycle modulation and associated with an upregulation of genes involving intracellular uptake of gemcitabine. The use of IFN-β in combination with gemcitabine seems promising in patients with pancreatic cancer and needs to be further explored.

scholarly journals Interferon-beta enhances sensitivity to gemcitabine in pancreatic cancer

BMC Cancer ◽  
2020 ◽  
Vol 20 (1) ◽  
Author(s):  
Amber Blaauboer ◽  
Stephanie Booy ◽  
Peter M. van Koetsveld ◽  
Bas Karels ◽  
Fadime Dogan ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Pancreatic Cancer ◽  
Colony Formation ◽  
Interferon Beta ◽  
Ex Vivo ◽  
Treatment Resistance ◽  
Proliferating Cells ◽  
Increased Sensitivity

Abstract Background Adjuvant gemcitabine for pancreatic cancer has limited efficacy in the clinical setting. Impaired drug metabolism is associated with treatment resistance. We aimed to evaluate the chemosensitising effect of interferon-beta (IFN-β). Methods BxPC-3, CFPAC-1, and Panc-1 cells were pre-treated with IFN-β followed by gemcitabine monotherapy. The effect on cell growth, colony formation, and cell cycle was determined. RT-qPCR was used to measure gene expression. BxPC-3 cells were used in a heterotopic subcutaneous mouse model. Results IFN-β increased sensitivity to gemcitabine (4-, 7.7-, and 1.7-fold EC50 decrease in BxPC-3, CFPAC-1, and Panc-1, respectively; all P < 0.001). Findings were confirmed when assessing colony formation. The percentage of cells in the S-phase was significantly increased after IFN-β treatment only in BxPC-3 and CFPAC-1 by 12 and 7%, respectively (p < 0.001 and p < 0.05, respectively). Thereby, IFN-β upregulated expression of the drug transporters SLC28A1 in BxPC-3 (252%) and SLC28A3 in BxPC-3 (127%) and CFPAC-1 (223%) (all p < 0.001). In vivo, combination therapy reduced tumor volume with 45% (P = 0.01). Both ex vivo and in vivo data demonstrate a significant reduction in the number of proliferating cells, whereas apoptosis was increased. Conclusions For the first time, we validated the chemosensitising effects of IFN-β when combined with gemcitabine in vitro, ex vivo, and in vivo. This was driven by cell cycle modulation and associated with an upregulation of genes involving intracellular uptake of gemcitabine. The use of IFN-β in combination with gemcitabine seems promising in patients with pancreatic cancer and needs to be further explored.

Uptake of Protamine Sulphate Complexed Fluorescent Nano-Particles Is Defined by Cell Cycle Status in Primary Human CD34+ Cells: Use of a Multi-Color p27 kip1 Based Flow Cytometric Assay.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 1363-1363
Author(s):  
Ryan Lahey ◽  
Jesper Bonde ◽  
Jan A. Nolta
Keyword(s):  
Cell Cycle ◽  
In Vivo Imaging ◽  
Ex Vivo ◽  
Nano Particles ◽  
Flow Cytometry Assay ◽  
Hematopoietic Stem ◽  
Protamine Sulphate ◽  
Flow Cytometric ◽  
Cd34 Cells

Abstract The use of iron based nano-particles for multi-modal imaging is gaining interest, since it allows high resolution non-invasive in vivo imaging of human hematopoietic homing and engraftment events in xenograft models. The uptake of ferridex nano-particles complexed to cationic protamine sulphate is believed to be non-specific through mechanisms like endocytosis, but this has not been well defined for hematopoietic stem cells (HSC). In defining ex vivo cultivation strategies for manipulation of human HSC, a key factor is the responsiveness of the most primitive cells to the in vitro conditions, with the aim of maintaining viability without inducing terminal differentiation. Here, we present a novel flow cytometry assay which assesses the earliest molecular responses to a defined clinically applicable ex vivo protocol, aimed at facilitating labeling of human stem/progenitor cells using protamine sulphate complexed nano-particles for subsequent in vivo imaging. We used intracellular staining for the cell cycle inhibitor p27kip1, which is present in the highest levels in non-cycling cells, as the primary flow cytometric marker in combination with CD34, CD133 and Alexa 488, 647 and 750 conjugated ferridex nano-particles and the membrane dye PKH26. An assay was developed to simultaneously assess the molecular events occurring in individual human cord blood Lin− or CD34+ cells while they were cultured for up to 72 hours in X-Vivo 15 serum free medium supplemented with Flt3, SCF and TPO on Retronectin (RN) coated plates with or without nano-particles. Co-expression of p27kip1, CD34 or CD133 in the cultured cells slowly decreases from 86.1% CD34+p27kip1 (T=0) to 76.7%+/−12.2% (T=72) and from 89.6% CD133+p27kip1+ (T=0) to 54.1%+/−10.4% (T=72). We suggest that this slow decrease represents cells dividing and potentially differentiating over the time course of the ex vivo cultivation period. Assessing uptake of fluorescent conjugated nano-particles over a 72 hr period showed that the uptake of particles in CD34+ and CD133+ cells declined significantly after the first 24 hrs., from 32.5+/−3.7% nano-positive CD34+ cells to 19.2+/−2.9% at 48 hours ex vivo with a more significant decline to only 8.3+/−3.7% nano positive CD34+ cells in the culture after 72 hours ex vivo. The same decline in uptake over time was observed in cultured human CB cells that were positive for CD133. PKH26 co-staining demonstrated that the majority of cells that undergo cell division within the first 24 hours of ex vivo culture are the most likely to uptake the nano-particles. In summary, using a multi color p27kip1 based flow-cytometry assay, we found that human Lin−, CD133+, and CD34+ cells uptake Fe-Pro in a fashion which is not entirely cell cycle independent as previously suggested. These data indicate that cell cycle or metabolic status may influence the ability of human hematopoietic stem and progenitor subsets to uptake the protamine sulphate-complexed nano-particles. These findings emphasize the need to carefully develop ex vivo conditions for nano-particle labeling of primary human stem cells in order to perform accurate in vivo imaging of the most primitive human hematopoietic stem and progenitor cells.

scholarly journals Mutation of the Cell Cycle Regulator p27kip1 Drives Pseudohypoxic Pheochromocytoma Development

Cancers ◽  
2021 ◽  
Vol 13 (1) ◽  
pp. 126
Author(s):  
Hermine Mohr ◽  
Simone Ballke ◽  
Nicole Bechmann ◽  
Sebastian Gulde ◽  
Jaber Malekzadeh-Najafabadi ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Ex Vivo ◽  
Light Sheet ◽  
Epigenetic Mark ◽  
Angiogenic Potential ◽  
Optoacoustic Tomography ◽  
Oncogenic Pathways ◽  
Aggressive Tumors ◽  
Light Sheet Fluorescence Microscopy

Background: Pseudohypoxic tumors activate pro-oncogenic pathways typically associated with severe hypoxia even when sufficient oxygen is present, leading to highly aggressive tumors. Prime examples are pseudohypoxic pheochromocytomas and paragangliomas (p-PPGLs), neuroendendocrine tumors currently lacking effective therapy. Previous attempts to generate mouse models for p-PPGLs all failed. Here, we describe that the rat MENX line, carrying a Cdkn1b (p27) frameshift-mutation, spontaneously develops pseudohypoxic pheochromocytoma (p-PCC). Methods: We compared rat p-PCCs with their cognate human tumors at different levels: histology, immunohistochemistry, catecholamine profiling, electron microscopy, transcriptome and metabolome. The vessel architecture and angiogenic potential of pheochromocytomas (PCCs) was analyzed by light-sheet fluorescence microscopy ex vivo and multi-spectral optoacoustic tomography (MSOT) in vivo. Results: The analysis of tissues at various stages, from hyperplasia to advanced grades, allowed us to correlate tumor characteristics with progression. Pathological changes affecting the mitochrondrial ultrastructure where present already in hyperplasias. Rat PCCs secreted high levels of norepinephrine and dopamine. Transcriptomic and metabolomic analysis revealed changes in oxidative phosphorylation that aggravated over time, leading to an accumulation of the oncometabolite 2-hydroxyglutarate, and to hypermethylation, evident by the loss of the epigenetic mark 5-hmC. While rat PCC xenografts showed high oxygenation, induced by massive neoangiogenesis, rat primary PCC transcriptomes possessed a pseudohypoxic signature of high Hif2a, Vegfa, and low Pnmt expression, thereby clustering with human p-PPGL. Conclusion: Endogenous rat PCCs recapitulate key phenotypic features of human p-PPGLs. Thus, MENX rats emerge as the best available animal model of these aggressive tumors. Our study provides evidence of a link between cell cycle dysregulation and pseudohypoxia.

ITF2357, a Novel Histone-Deacetylase Inhibitor, Is Effective against Peripheral T-Cell Lymphomas in Vivo

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 4981-4981
Author(s):  
Pier Paolo Piccaluga ◽  
Maura Rossi ◽  
Aurora Esposito ◽  
Pier Luigi Tazzari ◽  
Francesca Ricci ◽  
...  
Keyword(s):  
Cell Cycle ◽  
T Cell ◽  
Cell Viability ◽  
Cell Lines ◽  
Cultured Cells ◽  
Ex Vivo ◽  
Phase Ii Trials ◽  
T Cell Lymphomas ◽  
Peripheral T Cell Lymphomas

Abstract Background. Recently, gene expression profiling (GEP) indicated histone-deacetylases (HDAC) as potential therapeutic targets in peripheral T-cell lymphomas (PTCL) not otherwise specified (NOS), the commonest PTCL type. Consistently, phase II trials demonstrated the efficacy of some HDAC inhibitors (HDACi), including SAHA, which was approved for cutaneous T-cell lymphomas (CTCL) treatment. Aims and methods. We investigated the anti-tumour effects of ITF2357 (Italfarmaco, Italy), a novel hydroxamic acid HDACi, on PTCL primarily-cultured cells and cell lines (HH and FEDP), and in a xenografted mouse-model of CTCL. Cultured cells were incubated with different dosages of ITF2357 and SAHA (ranging from 0.5 to 2.5 mM). Cell viability, assessed by trypan-blue exclusion assay, cell-cycle progression, assessed by bromodeossiuridine assay, and apoptotic rate, determined by flow-cytometry analysis of annexin-V binding populations were determined at 48, 72 and 120 hours. Nude mice, injected with HH cells, received ITF2357 (10–20mg/Kg, per os) for 14 days. Micro-PET scan was adopted for disease measurement and treatment response evaluation. Finally, GEP of cell lines exposed to ITF2357 and SAHA were generated to elucidate their mechanisms of action. Results. Cell viability of HH cells treated with ITF2357 ranged from 50% (0.5 mM, at 48 h), to &lt;10% (0.5–2.5 mM, at 72–120 h), in comparison to untreated cells. Differently, cell viability of HH cells treated with SAHA ranged from 80% (0.5 mM, at 48–120 h) to 25% (2.5 mM at 48 h). Analogue effects were documented in FEDP and primarilycultured PTCL cells. Conversely, viability of normal T-lymphocyte was not significantly affected. Interestingly, exposure to ITF2357 was associated to G0/G1 cell-cycle arrest and apoptosis induction. Finally, ITF2357 determined significant reduction of tumoral masses and survival benefit in a xenografted mice-model inoculated with HH cells. Conclusion. Taken together, these data demonstrate that ITF2357 is effective against PTCLs ex vivo and in vivo, by nominating it for clinical evaluation in this setting.

Cell Cycle-Related Changes in Repopulating Capacity of Human Mobilized Peripheral Blood CD34+ Cells in Non-Obese Diabetic/Severe Combined Immune-Deficient Mice

Blood ◽  
1998 ◽  
Vol 92 (8) ◽  
pp. 2641-2649 ◽  
Author(s):  
André Gothot ◽  
Johannes C.M. van der Loo ◽  
D. Wade Clapp ◽  
Edward F. Srour
Keyword(s):  
Cell Cycle ◽  
Incubation Period ◽  
Peripheral Blood ◽  
Cell Cycle Progression ◽  
Ex Vivo ◽  
Scid Mice ◽  
Cd34 Cells ◽  
Mobilized Peripheral Blood

Abstract Most primitive hematopoietic progenitor cells reside in vivo within the G0/G1 phase of the cell cycle. By simultaneous DNA/RNA staining it is possible to distinguish G0 and G1 states and to isolate cells in defined phases of the cell cycle. We report here the use of cell cycle fractionation to separate human mobilized peripheral blood (MPB) CD34+ cells capable of repopulating the bone marrow (BM) of non-obese diabetic/severe combined immune-deficient (NOD/SCID) mice. In freshly isolated MPB, repopulating cells were predominant within the G0 phase, because transplantation of CD34+cells residing in G0 (G0CD34+) resulted on average in a 16.6- ± 3.2-fold higher BM chimerism than infusion of equal numbers of CD34+ cells isolated in G1. We then investigated the effect of ex vivo cell cycle progression, in the absence of cell division, on engraftment capacity. Freshly isolated G0CD34+ cells were activated by interleukin-3 (IL-3), stem cell factor (SCF), and flt3-ligand (FL) for a 36-hour incubation period during which a fraction of cells progressed from G0 into G1 but did not complete a cell cycle. The repopulating capacity of stimulated cells was markedly diminished compared with that of unmanipulated G0CD34+ cells. Cells that remained in G0 during the 36-hour incubation period and those that traversed into G1 were sorted and assayed separately in NOD/SCID recipients. The repopulating ability of cells remaining in G0 was insignificantly reduced compared with that of unstimulated G0CD34+ cells. On the contrary, CD34+ cells traversing from G0 into G1 were largely depleted of repopulating capacity. Similar results were obtained when G0CD34+ cells were activated by the combination of thrombopoietin-SCF-FL. These studies provide direct evidence of the quiescent nature of cells capable of repopulating the BM of NOD/SCID mice. Furthermore, these data also demonstrate that G0-G1 progression in vitro is associated with a decrease in engraftment capacity. © 1998 by The American Society of Hematology.

scholarly journals Functional Heterogeneity of Human CD34+ Cells Isolated in Subcompartments of the G0 /G1 Phase of the Cell Cycle

Blood ◽  
1997 ◽  
Vol 90 (11) ◽  
pp. 4384-4393 ◽  
Author(s):  
André Gothot ◽  
Robert Pyatt ◽  
Jon McMahel ◽  
Susan Rice ◽  
Edward F. Srour
Keyword(s):  
Cell Cycle ◽  
Ex Vivo ◽  
G1 Phase ◽  
Dna And Rna ◽  
Human Cd34 ◽  
Rna Content ◽  
Cd34 Cells ◽  
Ex Vivo Culture

Abstract Using simultaneous Hoechst 33342 (Hst) and Pyronin Y (PY) staining for determination of DNA and RNA content, respectively, human CD34+ cells were isolated in subcompartments of the G0 /G1 phase of the cell cycle by flow cytometric cell sorting. In both bone marrow (BM) and mobilized peripheral blood (MPB) CD34+ cells, primitive long-term hematopoietic culture-initiating cell (LTHC-IC) activity was higher in CD34+ cells isolated in G0 (G0CD34+ cells) than in those residing in G1 (G1CD34+ cells). However, as MPB CD34+ cells displayed a more homogeneous cell-cycle status within the G0 /G1 phase and a relative absence of cells in late G1 , DNA/RNA fractionation was less effective in segregating LTHC-IC in MPB than in BM. BM CD34+ cells belonging to four subcompartments of increasing RNA content within the G0 /G1 phase were evaluated in functional assays. The persistence of CD34 expression in suspension culture was inversely correlated with the initial RNA content of test cells. Multipotential progenitors were present in G0 or early G1 subcompartments, while lineage-restricted granulomonocytic progenitors were more abundant in late G1 . In vitro hematopoiesis was maintained for up to 6 weeks with G0CD34+ cells, whereas production of clonogenic progenitors was more limited in cultures initiated with G1CD34+ cells. To test the hypothesis that primitive LTHC-ICs would reenter a state of relative quiescence after in vitro division, BM CD34+ cells proliferating in ex vivo cultures were identified from their quiescent counterparts by a relative loss of membrane intercalating dye PKH2, and were further fractionated with Hst and PY. The same functional hierarchy was documented within the PKH2dim population whereby LTHC-IC frequency was higher for CD34+ cells reselected in G0 after in vitro division than for CD34+ cells reisolated in G1 or in S/G2 + M. However, the highest LTHC-IC frequency was found in quiescent PKH2bright CD34+ cells. Together, these results support the concept that cells with distinct hematopoietic capabilities follow different pathways during the G0 /G1 phase of the cell cycle both in vivo and during ex vivo culture.

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