scholarly journals Novel Pituitary Organoid Model as Powerful Tool to Unravel Pituitary Stem Cell Biology Across Ages and Disease

2021 ◽  
Vol 5 (Supplement_1) ◽  
pp. A652-A652
Author(s):  
Hugo E J Vankelecom ◽  
Emma Laporte ◽  
Florian Hermans ◽  
Charlotte Nys ◽  
Annelies Vennekens
Keyword(s):  
Stem Cells ◽  
Stem Cell ◽  
Cell Biology ◽  
Cell Activation ◽  
Stem Cell Biology ◽  
Cell Compartment ◽  
Organoid Culture ◽  
Stem Cell Compartment

Abstract The pituitary gland harbors a population of stem cells. However, role and regulation of these cells remain poorly understood. We recently established organoids from mouse pituitary as a novel research tool to explore pituitary stem cell biology (Cox et al., J. Endocrinol. 2019; 240:287-308). In general, organoids represent 3D in vitro cell configurations that develop and self-organize from (single) tissue stem cells under well-defined culture conditions that typically mirror the stem cell niche and/or embryogenic processes. Organoids reliably recapitulate key aspects of the original organ, including of its stem cell compartment. Moreover, organoids are long-term expandable while retaining these properties. We demonstrated that pituitary organoids originate from the resident (SOX2+) stem cells, largely phenocopy these cells and retain the stemness phenotype during expansive culture. Interestingly, the organoids show confident in vivo translatability and, when developed from transgenically damaged gland, recapitulate the activation status of the stem cells as observed in situ following injury. Now, we found that the organoids also mirror the stem cells’ phenotype and biology in physiological conditions in which the stem cell compartment is either activated or compromised. Organoids from the neonatal maturing pituitary reproduce phenotypical and functional aspects of its activated stem cells, whereas organoids from aging gland mimic the declined functional state of the stem cells in old pituitary. Interestingly, this functional decay was found to be reverted during organoid culture, indicating that the old pituitary stem cells retain intrinsic functionality but are in vivo restrained by an obstructive microenvironment, not present in the organoid culture. Indeed, using single-cell transcriptomics and in vivo analysis, we found that the aging pituitary suffers from a prevailing inflammatory state (inflammaging) which appears to raise the threshold for stem cell activation. Interestingly, comparison of young and old pituitary led us to the discovery of pituitary stem cell activators. Finally, we found that activated parameters of organoid formation are also observed when tumorigenesis takes place in the gland, again mimicking the in situ stem cell activation that is occurring in this perturbed, pathological condition. Taken together, we identified, and applied, our new pituitary organoid model as advanced and powerful tool to gain profound insight into pituitary stem cell behavior across life and disease, which is expected to eventually translate into restorative and rejuvenative tactics when pituitary function is compromised by damage or age. In this context, our single-cell transcriptome database has strong potential to unveil appealing targets.

The Role of Nucleophosmin In Hematopoietic Stem Cells and the Pathogenesis of Myelodysplastic Syndrome

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 95-95 ◽  
Author(s):  
Keisuke Ito ◽  
Paolo Sportoletti ◽  
John G Clohessy ◽  
Grisendi Silvia ◽  
Pier Paolo Pandolfi
Keyword(s):  
Stem Cells ◽  
Stem Cell ◽  
Myelodysplastic Syndrome ◽  
Cell Biology ◽  
De Novo ◽  
Stem Cell Biology ◽  
Hematopoietic Stem

Abstract Abstract 95 Myelodysplastic syndrome (MDS) is an incurable stem cell disorder characterized by ineffective hematopoiesis and an increased risk of leukemia transformation. Nucleophosmin (NPM) is directly implicated in primitive hematopoiesis, the pathogenesis of hematopoietic malignancies and more recently of MDS. However, little is known regarding the molecular role and function of NPM in MDS pathogenesis and in stem cell biology. Here we present data demonstrating that NPM plays a critical role in the maintenance of hematopoietic stem cells (HSCs) and the transformation of MDS into leukemia. NPM is located on chromosome 5q and is frequently lost in therapy-related and de novo MDS. We have previously shown that Npm1 acts as a haploinsufficient tumor suppressor in the hematopoietic compartment and Npm1+/− mice develop a hematologic syndrome with features of human MDS, including increased susceptibility to leukemogenesis. As HSCs have been demonstrated to be the target of the primary neoplastic event in MDS, a functional analysis of the HSC compartment is essential to understand the molecular mechanisms in MDS pathogenesis. However, the role of NPM in adult hematopoiesis remains largely unknown as Npm1-deficiency leads to embryonic lethality. To investigate NPM function in adult hematopoiesis, we have generated conditional knockout mice of Npm1, using the Cre-loxP system. Analysis of Npm1 conditional mutants crossed with Mx1-Cre transgenic mice reveals that Npm1 plays a crucial role in adult hematopoiesis and ablation of Npm1 in adult HSCs leads to aberrant cycling and followed by apoptosis. Analysis of cell cycle status revealed that HSCs are impaired in their ability to maintain quiescence after Npm1-deletion and are rapidly depleted in vivo as well as in vitro. Competitive reconstitution assay revealed that Npm1 acts cell-autonomously to maintain HSCs. Conditional inactivation of Npm1 leads to an MDS phenotype including a profoundly impaired ability to differentiate into cells of the erythroid lineage, megakaryocyte dyspoiesis and centrosome amplification. Furthermore, Npm1 loss evokes a p53-dependent response and Npm1-deleted HSCs undergo apoptosis in vivo and in vitro. Strikingly, transfer of the Npm1 mutation into a p53-null background rescued the apoptosis of Npm1-ablated HSCs and resulted in accelerated transformation to an aggressive and lethal form of acute myeloid leukemia. Our findings highlight the crucial role of NPM in stem cell biology and identify a new mechanism by which MDS can progress to leukemia. This has important therapeutic implications for de novo MDS as well as therapy-related MDS, which is known to rapidly evolve to leukemia with frequent loss or mutation of TRP53. Disclosures: No relevant conflicts of interest to declare.

scholarly journals The kinetics of murine hematopoietic stem cells in vivo in response to prolonged increased mature blood cell production induced by granulocyte colony-stimulating factor

Blood ◽  
1995 ◽  
Vol 86 (8) ◽  
pp. 2986-2992 ◽  
Author(s):  
G de Haan ◽  
B Dontje ◽  
C Engel ◽  
M Loeffler ◽  
W Nijhof
Keyword(s):  
Stem Cells ◽  
Stem Cell ◽  
Blood Cells ◽  
Granulocyte Colony Stimulating Factor ◽  
Cell Compartment ◽  
Hematopoietic Stem ◽  
Cell Numbers ◽  
Stem Cell Compartment ◽  
Stimulating Factor

Abstract Because of the complexity of appropriate stem cell assays, little information on the in vivo regulation of murine stem cell biology or stemmatopoiesis is available. It is unknown whether and how in vivo the primitive hematopoietic stem cell compartment is affected during a continued increased production of mature blood cells. In this study, we present data showing that prolonged (3 weeks) administration of granulocyte colony-stimulating factor (G-CSF), which is a major regulator of mature granulocyte production, has a substantial impact on both the size and the location of various stem cell subset pools in mice. We have used the novel cobblestone area forming cell (CAFC) assay to assess the effects of G-CSF on the stem cell compartment (CAFC days 7, 14, 21, and 28). In marrow, in which normally 99% of the total number of stem cells can be found, G-CSF induced a severe depletion of particularly the most primitive stem cells to 5% to 10% of normal values. The response after 7 days of G-CSF treatment was an increased amplification between CAFC day 14 and 7. However, this response occurred at the expense of the number of CAFC day 14. It is likely that the resulting gap of CAFC day 14 cell numbers was subsequently replenished from the more primitive CAFC day 21 and 28 compartments, because these cell numbers remained low during the entire treatment period. In the spleen, the number of stem cells increased, likely caused by a migration from the marrow via the blood, leading to an accumulation in the spleen. The increased number of stem cells in the spleen overcompensated for the loss in the marrow. When total body (marrow and spleen) stem cell numbers were calculated, it appeared that a continued increased production of mature granulocytes resulted in the establishment of a higher, new steady state of the stem cell compartment; most committed stem cells (CAFC day 7) were increased threefold, CAFC day 14 were increased 2.3-fold, CAFC-day 21 were increased 1.8-fold, and the most primitive stem cells evaluated, CAFC day 28, were not different from normal, although now 95% of these cells were located in the spleen. Four weeks after discontinuation of the G-CSF treatment, the stem cell reserve in the spleen had returned to a normal level, whereas stem cell numbers in marrow had recovered to values above normal. This study shows that the primitive stem cell compartment is seriously perturbed during an increased stimulation of the production of mature blood cells.(ABSTRACT TRUNCATED AT 400 WORDS)

Controlling the Stem Cell Compartment and Regeneration In Vivo: The Role of Pluripotency Pathways

2012 ◽  
Vol 92 (1) ◽  
pp. 75-99 ◽  
Author(s):  
Kirsty Greenow ◽  
Alan R. Clarke
Keyword(s):  
Stem Cells ◽  
Stem Cell ◽  
Embryonic Stem ◽  
Cell Types ◽  
Dark Side ◽  
Cell Compartment ◽  
Pluripotent State ◽  
Stem Cell Compartment

Since the realization that embryonic stem cells are maintained in a pluripotent state through the interplay of a number of key signal transduction pathways, it is becoming increasingly clear that stemness and pluripotency are defined by the complex molecular convergence of these pathways. Perhaps this has most clearly been demonstrated by the capacity to induce pluripotency in differentiated cell types, so termed iPS cells. We are therefore building an understanding of how cells may be maintained in a pluripotent state, and how we may manipulate cells to drive them between committed and pluripotent compartments. However, it is less clear how cells normally pass in and out of the stem cell compartment under normal and diseased physiological states in vivo, and indeed, how important these pathways are in these settings. It is also clear that there is a potential “dark side” to manipulating the stem cell compartment, as deregulation of somatic stem cells is being increasingly implicated in carcinogenesis and the generation of “cancer stem cells.” This review explores these relationships, with a particular focus on the role played by key molecular regulators of stemness in tissue repair, and the possibility that a better understanding of this control may open the door to novel repair strategies in vivo. The successful development of such strategies has the potential to replace or augment intervention-based strategies (cell replacement therapies), although it is clear they must be developed with a full understanding of how such approaches might also influence tumorigenesis.

Paving the road for lung stem cell biology: bronchioalveolar stem cells and other putative distal lung stem cells

2007 ◽  
Vol 293 (5) ◽  
pp. L1092-L1098 ◽  
Author(s):  
Carla F. Kim
Keyword(s):  
Stem Cells ◽  
Stem Cell ◽  
Cell Biology ◽  
The United States ◽  
Chronic Obstructive ◽  
Stem Cell Biology ◽  
Adult Lung ◽  
Cell Functions ◽  
Isolation And Characterization

New discoveries in stem cell biology are making the biology of solid tissues increasingly complex. Important seminal studies demonstrating the presence of damage-resistant cell populations together with new isolation and characterization techniques suggest that stem cells exist in the adult lung. More detailed in vivo molecular and cellular characterization of bronchioalveolar stem cells (BASCs), other putative lung stem and progenitor cells, and differentiated cells is needed to determine the lineage relationships in adult lung. Lung diseases such as cystic fibrosis or chronic obstructive pulmonary disease, as well as the most common form of lung cancer in the United States, all involve apparent bronchiolar and alveolar cell defects. It is likely that the delicate balance of stem, progenitor, and differentiated cell functions in the lung is critically affected in patients with these devastating diseases. Thus the discovery of BASCs and other putative lung stem cells will lay the foundation for new inroads to understanding lung biology related to lung disease.

scholarly journals Studies of hematopoietic stem cells spared by 5-fluorouracil.

1984 ◽  
Vol 159 (3) ◽  
pp. 679-690 ◽  
Author(s):  
G Van Zant
Keyword(s):  
Stem Cells ◽  
Bone Marrow ◽  
Stem Cell ◽  
Cell Compartment ◽  
Hematopoietic Stem ◽  
Stem Cell Compartment ◽  
Developmental Maturation ◽  
Marrow Cells

Mouse marrow cells were exposed to 5-fluorouracil (FU) either in vivo or in vitro and the effects on the hematopoietic stem cell compartment were studied. The drug was highly toxic to bone marrow cells including the spleen colony-forming unit (CFU-S) population. The small population of stem cells surviving FU, however, caused a different pattern of spleen colony growth when injected into lethally irradiated mice. Whereas numbers of spleen colonies caused by normal marrow cells remained constant during an 8-14 d period after transplantation, spleen colonies derived from FU-treated marrow cells increased by as much as 100-fold during this time. This effect on stem cells was dose dependent both in vitro and in vivo. When FU was given in vivo, the day 14/day 8 ratio of colonies was greatest 1 d after injection and, over the next 7 d, returned to a near-normal value, that is, unity. A number of studies have shown that the stem cell compartment is heterogeneous with respect to self-replicative capacity and developmental potential. An age structure for the stem cell compartment has been proposed wherein cells with a short mitotic history are more likely to self-replicate than they are to differentiate; hence they are more primitive. 'Older' stem cells with a longer mitotic history are, according to the hypothesis, more likely to differentiate. 5-fluorouracil may be toxic to the older stem cells and selectively spare the more primitive subpopulation. Although the surviving cells may not themselves be able to form spleen colonies, they may give rise to an older cohort of cells more likely to differentiate and form spleen colonies. It is the requisite developmental maturation within the stem cell compartment that may be responsible for the delay in appearance of spleen colonies derived from FU-treated marrow. Our results support this explanation and identify the locus of at least part of this activity as the bone marrow. We found that the FU-treated marrow did not cause an increase in spleen colony numbers between 8 and 14 d in hosts with a long-standing marrow aplasia, due to the incorporation of 89Sr into bone. I propose that the delayed spleen colony appearance in normal hosts is the result of developmental maturation of the primitive stem cell compartment that survives FU and is responsible for spleen colonies arising around day 14. This maturation, at least initially, occurs in the marrow and leads to the replenishment of the more differentiated CFU-S subsets ablated by FU, which are normally responsible for spleen colonies appearing earlier after transplantation.

scholarly journals The kinetics of murine hematopoietic stem cells in vivo in response to prolonged increased mature blood cell production induced by granulocyte colony-stimulating factor

Blood ◽  
1995 ◽  
Vol 86 (8) ◽  
pp. 2986-2992 ◽  
Author(s):  
G de Haan ◽  
B Dontje ◽  
C Engel ◽  
M Loeffler ◽  
W Nijhof
Keyword(s):  
Stem Cells ◽  
Stem Cell ◽  
Blood Cells ◽  
Granulocyte Colony Stimulating Factor ◽  
Cell Compartment ◽  
Hematopoietic Stem ◽  
Cell Numbers ◽  
Stem Cell Compartment ◽  
Stimulating Factor

Because of the complexity of appropriate stem cell assays, little information on the in vivo regulation of murine stem cell biology or stemmatopoiesis is available. It is unknown whether and how in vivo the primitive hematopoietic stem cell compartment is affected during a continued increased production of mature blood cells. In this study, we present data showing that prolonged (3 weeks) administration of granulocyte colony-stimulating factor (G-CSF), which is a major regulator of mature granulocyte production, has a substantial impact on both the size and the location of various stem cell subset pools in mice. We have used the novel cobblestone area forming cell (CAFC) assay to assess the effects of G-CSF on the stem cell compartment (CAFC days 7, 14, 21, and 28). In marrow, in which normally 99% of the total number of stem cells can be found, G-CSF induced a severe depletion of particularly the most primitive stem cells to 5% to 10% of normal values. The response after 7 days of G-CSF treatment was an increased amplification between CAFC day 14 and 7. However, this response occurred at the expense of the number of CAFC day 14. It is likely that the resulting gap of CAFC day 14 cell numbers was subsequently replenished from the more primitive CAFC day 21 and 28 compartments, because these cell numbers remained low during the entire treatment period. In the spleen, the number of stem cells increased, likely caused by a migration from the marrow via the blood, leading to an accumulation in the spleen. The increased number of stem cells in the spleen overcompensated for the loss in the marrow. When total body (marrow and spleen) stem cell numbers were calculated, it appeared that a continued increased production of mature granulocytes resulted in the establishment of a higher, new steady state of the stem cell compartment; most committed stem cells (CAFC day 7) were increased threefold, CAFC day 14 were increased 2.3-fold, CAFC-day 21 were increased 1.8-fold, and the most primitive stem cells evaluated, CAFC day 28, were not different from normal, although now 95% of these cells were located in the spleen. Four weeks after discontinuation of the G-CSF treatment, the stem cell reserve in the spleen had returned to a normal level, whereas stem cell numbers in marrow had recovered to values above normal. This study shows that the primitive stem cell compartment is seriously perturbed during an increased stimulation of the production of mature blood cells.(ABSTRACT TRUNCATED AT 400 WORDS)

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