scholarly journals A model for adult organ resizing demonstrates stem cell scaling through a tunable commitment rate

2017 ◽  
Author(s):  
XinXin Du ◽  
Lucy Erin O’Brien ◽  
Ingmar Riedel-Kruse
Keyword(s):  
Stem Cell ◽  
Theoretical Models ◽  
Cell Number ◽  
Cellular Behaviors ◽  
Tissue Space ◽  
Physiological Demands ◽  
Kinetics Of ◽  
Cell Proportion ◽  
Adult Drosophila

AbstractMany adult organs grow or shrink to accommodate different physiological demands. Often, as total cell number changes, stem cell number changes proportionally in a phenomenon called ‘stem cell scaling’. The cellular behaviors that give rise to scaling are unknown. Here we study two complementary theoretical models of the adult Drosophila midgut, a stem cell-based organ with known resizing dynamics. First, we derive a differential equations model of midgut resizing and show that the in vivo kinetics of growth can be recapitulated if the rate of fate commitment depends on the tissue’s stem cell proportion. Second, we develop a twodimensional simulation of the midgut and find that proportion-dependent commitment rate and stem cell scaling can arise phenomenologically from the stem cells’ exploration of physical tissue space during its lifetime. Together, these models provide a biophysical understanding of how stem cell scaling is maintained during organ growth and shrinkage.

scholarly journals c-Myc inhibition is critical for HSC expansion and Rad51 expression

2018 ◽  
Author(s):  
Merve Aksoz ◽  
Esra Albayrak ◽  
Galip Servet Aslan ◽  
Raife Dilek Turan ◽  
Lamia Yazgi Alyazici ◽  
...  
Keyword(s):  
Gene Expression ◽  
Stem Cell ◽  
Kinase Inhibitor ◽  
Ex Vivo ◽  
Fold Increase ◽  
Hematopoietic Stem ◽  
Cyclin Dependent Kinase Inhibitor ◽  
Nos Inhibitor ◽  
Kinetics Of

c-Myc plays a major role in the maintenance of glycolytic metabolism and hematopoietic stem cell (HSC) quiescence. Targeting modulators of HSC quiescence and metabolism could lead to HSC cell cycle entry with concomitant expansion. Here we show that c-Myc inhibitor 10074-G5 treatment leads to 2-fold increase in murine LSKCD34low HSC compartment post 7 days. In addition, c-Myc inhibition increases CD34+ and CD133+ human HSC number. c-Myc inhibition leads to downregulation of glycolytic and cyclin-dependent kinase inhibitor (CDKI) gene expression ex vivo and in vivo. In addition, c-Myc inhibition upregulates major HDR modulator Rad51 expression in hematopoietic cells. Besides, c-Myc inhibition does not alter proliferation kinetics of endothelial cells, fibroblasts or adipose derived mesenchymal stem cells, however; it limits bone marrow derived mesenchymal stem cell proliferation. We further demonstrate that a cocktail of c-Myc inhibitor 10074-G5 along with tauroursodeoxycholic acid (TUDCA) and i-NOS inhibitor L-NIL provides a robust HSC maintenance and expansion ex vivo as evident by induction of all stem cell antigens analyzed. Intriguingly, the cocktail of c-Myc inhibitor 10074-G5, TUDCA and L-NIL improves HDR related gene expression. These findings provide tools to improve ex vivo HSC maintenance and expansion, autologous HSC transplantation and gene editing through modulation of HSC glycolytic and HDR pathways.

Cellular and molecular basis of haematopoiesis

2020 ◽  
pp. 5172-5181
Author(s):  
Paresh Vyas ◽  
N. Asger Jakobsen
Keyword(s):  
Stem Cells ◽  
Bone Marrow ◽  
Stem Cell ◽  
Progenitor Cells ◽  
Cell Number ◽  
Stages Of Development ◽  
Self Renewal ◽  
Haematopoietic System

Haematopoiesis involves a regulated set of developmental stages from haematopoietic stem cells (HSCs) that produce haematopoietic progenitor cells that then differentiate into more mature haematopoietic lineages, which provide all the key functions of the haematopoietic system. Definitive HSCs first develop within the embryo in specialized regions of the dorsal aorta and umbilical arteries and then seed the fetal liver and bone marrow. At the single-cell level, HSCs have the ability to reconstitute and maintain a functional haematopoietic system over extended periods of time in vivo. They (1) have a self-renewing capacity during the life of an organism, or even after transplantation; (2) are multipotent, with the ability to make all types of blood cells; and (3) are relatively quiescent, with the ability to serve as a deep reserve of cells to replenish short-lived, rapidly proliferation progenitors. Haematopoietic progenitor cells are unable to maintain long-term haematopoiesis in vivo due to limited or absent self-renewal. Rapid proliferation and cytokine responsiveness enables increased blood cell production under conditions of stress. Lineage commitment means limited cell type production. The haematopoietic stem cell niche is an anatomically and functionally defined regulatory environment for stem cells modulates self-renewal, differentiation, and proliferative activity of stem cells, thereby regulating stem cell number. Haematopoietic reconstitution during bone marrow transplantation is mediated by a succession of cells at various stages of development. More mature cells contribute to repopulation immediately following transplantation. With time, cells at progressively earlier stages of development are involved, with the final stable repopulation being provided by long-lived, multipotent HSCs. Long-term haematopoiesis is sustained by a relatively small number of HSCs.

c-Myc Inhibitor 10074-G5 Induces Murine and Human Hematopoietic Stem and Progenitor Cell Expansion and HDR Modulator Rad51 Expression

2019 ◽  
Vol 19 (6) ◽  
pp. 479-494 ◽  
Author(s):  
Merve Aksoz ◽  
Esra Albayrak ◽  
Galip Servet Aslan ◽  
Raife Dilek Turan ◽  
Lamia Yazgi Alyazici ◽  
...  
Keyword(s):  
Gene Expression ◽  
Stem Cell ◽  
Kinase Inhibitor ◽  
Ex Vivo ◽  
Fold Increase ◽  
Hematopoietic Stem ◽  
Cell Cycle Entry ◽  
Nos Inhibitor ◽  
Kinetics Of

Background:c-Myc plays a major role in the maintenance of glycolytic metabolism and hematopoietic stem cell (HSC) quiescence.Objective:Targeting modulators of HSC quiescence and metabolism could lead to HSC cell cycle entry with concomitant expansion.Methods and Results:Here we show that c-Myc inhibitor 10074-G5 treatment leads to 2-fold increase in murine LSKCD34low HSC compartment post 7 days. In addition, c-Myc inhibition increases CD34+ and CD133+ human HSC number. c-Myc inhibition leads to downregulation of glycolytic and cyclindependent kinase inhibitor (CDKI) gene expression ex vivo and in vivo. In addition, c-Myc inhibition upregulates major HDR modulator Rad51 expression in hematopoietic cells. Besides, c-Myc inhibition does not alter proliferation kinetics of endothelial cells, fibroblasts or adipose-derived mesenchymal stem cells, however, it limits bone marrow derived mesenchymal stem cell proliferation. We further demonstrate that a cocktail of c-Myc inhibitor 10074-G5 along with tauroursodeoxycholic acid (TUDCA) and i-NOS inhibitor L-NIL provides a robust HSC maintenance and expansion ex vivo as evident by induction of all stem cell antigens analyzed. Intriguingly, the cocktail of c-Myc inhibitor 10074-G5, TUDCA and L-NIL improves HDR related gene expression.Conclusion:These findings provide tools to improve ex vivo HSC maintenance and expansion, autologous HSC transplantation and gene editing through modulation of HSC glycolytic and HDR pathways.

Tracking Differential Repopulation Kinetics of Human Hematopoietic Progenitor Cells Using MRI Detection of Nanoparticles.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 1274-1274
Author(s):  
Todd E. Meyerrose ◽  
Andrew J. Hope ◽  
Shao P. Lin ◽  
Phillip E. Herrbrich ◽  
Michael H. Creer ◽  
...  
Keyword(s):  
Stem Cell ◽  
Human Cell ◽  
Hematopoietic Progenitor Cells ◽  
Hematopoietic Progenitor ◽  
Short Term ◽  
Post Transplant ◽  
Cell Engraftment ◽  
Cd34 Cells ◽  
Kinetics Of

Abstract Even within cell populations enriched for hematopoietic stem cells, there exists phenotypic and functional heterogeneity, with subsets of progenitors differentially contributing to the total character of the transplant. Here, we have used a dynamic in vivo imaging technology to track the differential homing kinetics of such subsets, within a well defined stem cell pool, and identified patterns of short term homing unique to CD31 versus CD34 cells. Human umbilical cord blood derived (hUCB) hematopoietic progenitor cells (HPC) were isolated on high expression of aldehyde dehydrogenase (ALDH) to yield a population of cells we have previously reported to be enriched for stem cell activity by phenotypic and functional parameters. Cells were plated 12 hours on fibronectin in X-Vivo15 supplemented with SCF, flt-3, and TPO. During incubation, cells were labeled with Bang’s Laboratories 0.9um SPIO nanoparticles containing the Dragon Green fluorescent dye at a ratio of approximately 10:1 beads to cells. Positively loaded cells were immunomagnetically selected and transplanted into sublethally irradiated NOD/SCID/MPS7 mice. The MPS7 mouse model is highly permissive of human cell engraftment, and allows easy identification of donor cells by virtue of a genetic defect in beta-glucuronidase production. Post-transplant, animals underwent MRI every 30 minutes for 12 hours to develop a dynamic, real-time survey of donor migration between organs, and then sacrificed at optimal times for analysis by flow cytometry. The utility of this approach was validated by quantitative PCR for human beta-globin versus murine rapsyn to correlate loss of MR signal intensity to human cell engraftment. At 12 hours, MR signal intensity had decreased by 29% relative to time 0, with internal standardization against a water control. In contrast, repetitive imaging of a non-transplanted animal resulted in deviation of only +/− 4% from the mean. This loss of MR signal correlated to a spleen engraftment of as few as 10,000 cells (homing efficiency of ~2.5%) in some cohorts. This demonstrates the efficacy and resolution of this paradigm for real time analysis and manipulation of homing in vivo. We have noted a preferential affinity of CD31+ ALDH high HPC that highly co-express markers for CD117 and CD133 to the splenic vasculature as early as 1 hour post-transplant and peaking at 12 hours post-transplant. Alternatively, we observed initial marrow seeding to contain almost exclusively CD34+ cells with little co-expression of CD31 or even CD133. Additionally, we found that the spleen-homed fractions of cells also express classical markers of activation such as CD71 and CD38, whereas the marrow homed fraction does not. From a functional standpoint, we believe these two subsets comprise two facets of contribution to the total graft, providing short-term radioprotection and cytokine delivery from the spleen-homed compartment, and long term durable engraftment and self-renewal from the marrow-homed compartment.

Pilot Study Of Regulatory T Cell Depletion In The Setting Of Autologous Stem Cell Transplantation For Multiple Myeloma

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 4607-4607 ◽  
Author(s):  
Gottfried von Keudell ◽  
Cara A Rosenbaum ◽  
Todd M. Zimmerman ◽  
Michael Bishop ◽  
Koen van Besien ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
T Cells ◽  
Stem Cell ◽  
Pilot Study ◽  
Stem Cell Transplantation ◽  
Ex Vivo ◽  
Treg Depletion ◽  
Before And After ◽  
Kinetics Of

Although autologous stem cell transplantation (ASCT) is effective for patients with multiple myeloma (MM), disease relapse remains problematic. Despite significant advances in therapeutics for MM, it remains mostly incurable. Following ASCT, a majority of MM patients are in a minimal residual disease state, at which time delivery of immunotherapy may be most effective. Regulatory T cells (Tregs) are a naturally-suppressive CD4+ T cell population (CD4+CD25+FoxP3+ T cells) that expand in MM patients, and strongly inhibit anti-tumor immune responses. In pre-clinical models Treg depletion enhanced the function of tumor antigen-specific T cells. Effective strategies to deplete Tregs in humans are being investigated. We initiated pilot study to test 2 methods of Treg depletion in MM patients undergoing ASCT. In the first approach, an anti-CD25 monoclonal antibody (basiliximab) was administered day +1 following ASCT (in vivo Treg depletion). The second method involved depleting CD4+CD25+ Tregs from autologous stem cell (ASC) grafts with clinical-grade anti-CD25 microbeads and the CliniMACS device (Miltenyi) (ex vivo Treg depletion). A control arm consisted of patients in which no Treg-depleting maneuver was performed. To date, 10 patients with symptomatic MM have been enrolled and randomly assigned to 1 of 3 study arms (arm 1 – standard ASCT; arm 2 – in vivo Treg depletion; arm 3 – ex vivo Treg depletion). Primary endpoints included: a) efficacy of ex vivo Treg depletion from ASC grafts, b) kinetics of Treg depletion and recovery in each study arm, and c) assessment of toxicity associated with Treg depletion. Secondary endpoints included time to engraftment following ASCT and disease response. The overall goal of the study was to identify a superior strategy with regard to depth and durability of Treg depletion. Ten patients (median age 59; range 46-68) have been enrolled. 4 were enrolled onto arm 1, 3 onto arm 2 and 3 onto arm 3. One patient enrolled on arm 2 was removed from study due to ASC mobilization failure. ASC were collected following neupogen and plexifor, and conditioning for ASCT consisted of melphalan (200mg/m2). Typical serious adverse events associated with ASCT were observed in all study arms, with neutropenic fever being the most common (n=2 arm 1, n=1 arm 2 and n=2 arm 3). Autoimmune complications, such as autologous graft-versus-host disease, were not observed. All patients engrafted post-ASCT with normal kinetics. Too few patients have been treated to make conclusions regarding clinical efficacy. Depletion of CD4+CD25+ Tregs from ASC grafts in arm 3 (ex vivo Treg depletion) was effective. As shown in Figure 1, 90.1% +/- 6% of CD4+25+ Tregs were depleted from 3 ASC grafts following the procedure. Baseline frequencies of peripheral blood (PB) CD4+FoxP3+ Tregs were similar between patients in all arms (p = n.s.). At least a 2-fold reduction in PB Treg frequency was observed at days +28 and + 60 following ASCT (Figure 2). At day +28, mean numbers (+/- SD) of CD4+FoxP3+ PB Tregs were 8.58% +/- 4.52%, 2.48% +/- 1.77%, and 3.28% +/- 1.12% in arms 1, 2 and 3, respectively (p = 0.08 arm 1 vs arm 2; p = 0.05 arm 1 vs arm 3; p = .57 arm 2 vs arm 3). These data suggest that both the in vivo and ex vivo Treg depletion may be effective at mediating effective and durable Treg depletion.Figure 1Treg are effectively depleted ex vivo with CD25 microbeads and the Clinimacs device. A FACS plots showing frequency of CD4 +CD25 + Tregs before (left) and after (right) ex vivo Treg depletion procedure (arm 3). B Mean CD4+CD25+ Treg frequencies before and after ex vivo Treg depletion (*p= 0.05).Figure 1. Treg are effectively depleted ex vivo with CD25 microbeads and the Clinimacs device. A FACS plots showing frequency of CD4 +CD25 + Tregs before (left) and after (right) ex vivo Treg depletion procedure (arm 3). B Mean CD4+CD25+ Treg frequencies before and after ex vivo Treg depletion (*p= 0.05).Figure 2Kinetics of Treg depletion following ASCT. Mean (+/- SD) frequency of CD4+FoxP3+ Tregs before and after ASCT in each study arm are displayed.Figure 2. Kinetics of Treg depletion following ASCT. Mean (+/- SD) frequency of CD4+FoxP3+ Tregs before and after ASCT in each study arm are displayed. In conclusion, both the in vivo or ex vivo method of Treg depletion appear to be effective based on small patient numbers. Treg depletion in MM patients undergoing ASCT is safe and does not delay engraftment. Additional patients will need to be treated to make conclusions regarding clinical efficacy. Future studies of Treg depletion in combination with other immunotherapeutic strategies are being considered. Disclosures: No relevant conflicts of interest to declare.

Distribution of TmDOTP5− in rat tissues: TmDOTP5− vs. CoEDTA− as markers of extracellular tissue space

1998 ◽  
Vol 85 (5) ◽  
pp. 1800-1805 ◽  
Author(s):  
J. D. Makos ◽  
C. R. Malloy ◽  
A. D. Sherry
Keyword(s):  
Extracellular Space ◽  
Rat Tissues ◽  
Anionic Complex ◽  
Anionic Complexes ◽  
Tissue Space ◽  
Rat Tissue ◽  
Tissue Compartments ◽  
Tissue Contents ◽  
Kinetics Of

The distribution of TmDOTP5− in rat tissue was compared with CoEDTA−, an anionic complex previously used as a marker of extracellular space. Heart, liver, muscle, blood, and urine were collected from rats after infusion of either complex and were quantitatively analyzed by atomic absorption spectroscopy. Although total TmDOTP5− in blood and tissue was consistently lower (0.88 ± 0.04; n = 6) than CoEDTA− after an identical infusion protocol (presumably because of some association of the phosphonate complex with bone), a comparison of blood and tissue contents indicated that the two anionic complexes distributed into identical extracellular spaces. Relative extracellular space in the in vivo liver, as determined by TmDOTP5− and CoEDTA−, was 0.18 ± 0.02 and 0.15 ± 0.01, respectively. The corresponding relative extracellular space values for the in vivo heart reported by the two agents were identical (0.11 ± 0.02). Experiments were also performed to evaluate the washout kinetics of TmDOTP5− from anesthesized rats. In rats given a total dose of 0.16 mmol TmDOTP5−, 81% appeared in urine by 180 min, <2% was found in all remaining soft tissue, leaving ∼18% undetected. The rate of Tm appearance in urine was fit to a standard pharmacokinetic model that included four tissue compartments: plasma, one fast equilbrating space, one slow equilibrating space, and one very slow equilibrating space (presumably bone). The best fit result suggests that the highly charged TmDOTP5− complex is cleared from plasma more rapidly than is the typical lower charged Gd-based contrast agents and that release from bone is slow compared with renal clearance.

scholarly journals Maintenance of Proper Germline Stem Cell Number Requires Adipocyte Collagen in Adult Drosophila Females

Genetics ◽  
2018 ◽  
Vol 209 (4) ◽  
pp. 1155-1166 ◽  
Author(s):  
Lesley N. Weaver ◽  
Daniela Drummond-Barbosa
Keyword(s):  
Stem Cell ◽  
Cell Number ◽  
Germline Stem Cell ◽  
Adult Drosophila

scholarly journals Rb1 Gene Inactivation Expands Satellite Cell and Postnatal Myoblast Pools

2011 ◽  
Vol 286 (22) ◽  
pp. 19556-19564 ◽  
Author(s):  
Tohru Hosoyama ◽  
Koichi Nishijo ◽  
Suresh I. Prajapati ◽  
Guangheng Li ◽  
Charles Keller
Keyword(s):  
Cell Cycle ◽  
Stem Cell ◽  
Satellite Cell ◽  
Muscle Fiber ◽  
Satellite Cells ◽  
Cell Activation ◽  
Cell Lineage ◽  
Cell Number ◽  
Fiber Formation

Satellite cells are well known as a postnatal skeletal muscle stem cell reservoir that under injury conditions participate in repair. However, mechanisms controlling satellite cell quiescence and activation are the topic of ongoing inquiry by many laboratories. In this study, we investigated whether loss of the cell cycle regulatory factor, pRb, is associated with the re-entry of quiescent satellite cells into replication and subsequent stem cell expansion. By ablation of Rb1 using a Pax7CreER,Rb1 conditional mouse line, satellite cell number was increased 5-fold over 6 months. Furthermore, myoblasts originating from satellite cells lacking Rb1 were also increased 3-fold over 6 months, while terminal differentiation was greatly diminished. Similarly, Pax7CreER,Rb1 mice exhibited muscle fiber hypotrophy in vivo under steady state conditions as well as a delay of muscle regeneration following cardiotoxin-mediated injury. These results suggest that cell cycle re-entry of quiescent satellite cells is accelerated by lack of Rb1, resulting in the expansion of both satellite cells and their progeny in adolescent muscle. Conversely, that sustained Rb1 loss in the satellite cell lineage causes a deficit of muscle fiber formation. However, we also show that pharmacological inhibition of protein phosphatase 1 activity, which will result in pRb inactivation accelerates satellite cell activation and/or expansion in a transient manner. Together, our results raise the possibility that reversible pRb inactivation in satellite cells and inhibition of protein phosphorylation may provide a new therapeutic tool for muscle atrophy by short term expansion of the muscle stem cells and myoblast pool.

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