The future of mammary stem cell biology: the power of in vivo transplants

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.

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Preclinical Challenges and Clinical Target of Nanomaterials in Regenerative Medicine

Biomedical Engineering ◽

10.4018/978-1-5225-3158-6.ch059 ◽

2018 ◽

pp. 1402-1423

Author(s):

Martin Reinhardt ◽

Shibashish Giri ◽

Augustinus Bader

Keyword(s):

Tissue Engineering ◽

Stem Cell ◽

Cell Biology ◽

Stem Cell Biology ◽

Organ Engineering ◽

Cell Therapies ◽

Existing Problems ◽

Present Generation

Currently, practical application of nanotechnological approaches and stem cell therapies remains a challenge in both preclinical and clinical settings. Many existing problems in tissue engineering to organ engineering have been solved by the combined approaches of nanotechnology and stem cell biology, but significant barriers remain. Details about the role of various types of nanomaterial in preclinical and clinical research have been reviewed elsewhere, but scant information exists about the influence of nanomaterials on stem cell biology. Herein, the authors highlight the current advances of nanotechnological approaches for expansion, differentiations, harvesting, labeling, imagining, tissue engineering, and organ engineering of different types of stem cells. The preclinical outcome of in vitro and in vivo animal experimentations along with some examples of clinical outcomes of nanomaterials on stem cell research is the main focus of this chapter. This book chapter might be an impetus for the present generation of young scientists to revolutionize the coming generation of effective human healthcare.

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Live imaging of intracellular pH in planarians using the ratiometric fluorescent dye SNARF-5F-AM

Biology Methods and Protocols ◽

10.1093/biomethods/bpz005 ◽

2019 ◽

Vol 4 (1) ◽

Author(s):

Wendy Scott Beane ◽

Dany Spencer Adams ◽

Junji Morokuma ◽

Michael Levin

Keyword(s):

Stem Cell ◽

Cell Biology ◽

Cell Activity ◽

Tissue Level ◽

Model System ◽

Resting Potential ◽

Stem Cell Biology ◽

Ph Gradients ◽

Fluorescent Reporter

Abstract Physiological parameters such as resting potential and pH are increasingly recognized as important regulators of cell activity and tissue-level events in regeneration, development, and cancer. The availability of fluorescent reporter dyes has greatly increased the ability to track these properties in vivo. The planarian flatworm is an important and highly tractable model system for regeneration, stem cell biology, and neuroscience; however, no protocols have been published for investigating pH in this system. Here, we report a simple and effective protocol for imaging pH gradients in living planaria suitable for intact and regenerating flatworms.

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Distinct Embryonic Origin and Injury Response of Resident Stem Cells in Craniofacial Muscles

Frontiers in Physiology ◽

10.3389/fphys.2021.690248 ◽

2021 ◽

Vol 12 ◽

Author(s):

Xu Cheng ◽

Bing Shi ◽

Jingtao Li

Keyword(s):

Stem Cell ◽

Progenitor Cells ◽

Cell Biology ◽

Stem Cell Biology ◽

Injury Response ◽

Limb Muscles ◽

Resident Stem Cells ◽

Embryonic Origin

Craniofacial muscles emerge as a developmental novelty during the evolution from invertebrates to vertebrates, facilitating diversified modes of predation, feeding and communication. In contrast to the well-studied limb muscles, knowledge about craniofacial muscle stem cell biology has only recently starts to be gathered. Craniofacial muscles are distinct from their counterparts in other regions in terms of both their embryonic origin and their injury response. Compared with somite-derived limb muscles, pharyngeal arch-derived craniofacial muscles demonstrate delayed myofiber reconstitution and prolonged fibrosis during repair. The regeneration of muscle is orchestrated by a blended source of stem/progenitor cells, including myogenic muscle satellite cells (MuSCs), mesenchymal fibro-adipogenic progenitors (FAPs) and other interstitial progenitors. Limb muscles host MuSCs of the Pax3 lineage, and FAPs from the mesoderm, while craniofacial muscles have MuSCs of the Mesp1 lineage and FAPs from the ectoderm-derived neural crest. Both in vivo and in vitro data revealed distinct patterns of proliferation and differentiation in these craniofacial muscle stem/progenitor cells. Additionally, the proportion of cells of different embryonic origins changes throughout postnatal development in the craniofacial muscles, creating a more dynamic niche environment than in other muscles. In-depth comparative studies of the stem cell biology of craniofacial and limb muscles might inspire the development of novel therapeutics to improve the management of myopathic diseases. Based on the most up-to-date literature, we delineated the pivotal cell populations regulating craniofacial muscle repair and identified clues that might elucidate the distinct embryonic origin and injury response in craniofacial muscle cells.

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