An in vivo model to study and manipulate the hematopoietic stem cell niche

Department of Biologic and Materials Sciences, University of Michigan School of Dentistry, Ann Arbor, MI, USA.
Blood (Impact Factor: 10.45). 04/2010; 115(13):2592-600. DOI: 10.1182/blood-2009-01-200071
Source: PubMed


Because the microenvironment that supports hematopoietic stem cell (HSC) proliferation and differentiation is not fully understood, we adapted a heterotopic bone formation model as a new approach for studying the HSC microenvironment in vivo. Endogenous HSCs homed to tissue-engineered ossicles and individually sorted HSCs from ossicles were able to reconstitute lethally irradiated mice. To further explore this model as a system to study the stem cell niche, ossicles were established with or without anabolic parathyroid hormone (PTH) treatment during the 4-week course of bone development. Histology and micro-computed tomography showed higher bone area-to-total area ratios, thicker cortical bone and trabecular bone, significantly higher bone mineral density and bone volume fraction in PTH-treated groups than in controls. By an in vivo competitive long-term reconstitution assay, HSC frequency in the ossicle marrow was 3 times greater in PTH groups than in controls. When whole bone marrow cells were directly injected into the ossicles after lethal irradiation, the PTH-treated groups showed an enhanced reconstitution rate compared with controls. These findings suggest the residence of HSCs in heterotopic bone marrow and support the future use of this ossicle model in elucidating the composition and regulation of the HSC niche.

Full-text preview

Available from:
  • Source
    • "Moreover, some of these studies show none or only small amounts of mineralized tissue formation e not a fully regenerated organ bone e and often the newly formed bone and marrow compartment is interspersed with large volumes of scaffold material, which interferes with the development of a coherent physiological tissue network [18] [19]. Importantly, most current models investigating hematopoietic niche physiology fail to recapitulate the processes seen in humans as they analyse the behaviour and function of murine e and not human e HSCs within their niches [16] [17] [20]. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Advances in tissue-engineering have resulted in a versatile tool-box to specifically design a tailored microenvironment for hematopoietic stem cells (HSCs) in order to study diseases that develop within this setting. However, most current in vivo models fail to recapitulate the biological processes seen in humans. Here we describe a highly reproducible method to engineer humanized bone constructs that are able to recapitulate the morphological features and biological functions of the HSC niches. Ectopic implantation of biodegradable composite scaffolds cultured for 4 weeks with human mesenchymal progenitor cells and loaded with rhBMP-7 resulted in the development of a chimeric bone organ including a large number of human mesenchymal cells which were shown to be metabolically active and capable of establishing a humanized microenvironment supportive of the homing and maintenance of human HSCs. A syngeneic mouse-to-mouse transplantation assay was used to prove the functionality of the tissue-engineered ossicles. We predict that the ability to tissue engineer a morphologically intact and functional large-volume bone organ with a humanized bone marrow compartment will help to further elucidate physiological or pathological interactions between human HSCs and their native niches. Copyright © 2015. Published by Elsevier Ltd.
    Full-text · Article · Aug 2015 · Biomaterials
  • Source
    • "Next, we analyzed gR expression on different cell subsets of the BM HSC niche. Therefore, we isolated primary ECs (CD45 À CD31 + ScaFigure S4A) and generated BM stromal cells in vitro according to Song et al. (2010). The functional gR consists of two subunits, the ligand binding a chain (gRa) and b chain (gRb), which is important for intracellular signaling (Bach et al., 1997 ). "
    [Show abstract] [Hide abstract]
    ABSTRACT: Cytotoxic CD8(+) T cells (CTLs) play a major role in host defense against intracellular pathogens, but a complete clearance of pathogens and return to homeostasis requires the regulated interplay of the innate and acquired immune systems. Here, we show that interferon γ (IFNγ) secreted by effector CTLs stimulates hematopoiesis at the level of early multipotent hematopoietic progenitor cells and induces myeloid differentiation. IFNγ did not primarily affect hematopoietic stem or progenitor cells directly. Instead, it promoted the release of hematopoietic cytokines, including interleukin 6 from bone marrow mesenchymal stromal cells (MSCs) in the hematopoietic stem cell niche, which in turn reduced the expression of the transcription factors Runx-1 and Cebpα in early hematopoietic progenitor cells and increased myeloid differentiation. Therefore, our study indicates that, during an acute viral infection, CTLs indirectly modulate early multipotent hematopoietic progenitors via MSCs in order to trigger the temporary activation of emergency myelopoiesis and promote clearance of the infection.
    Full-text · Article · Feb 2014 · Cell stem cell
  • Source
    • "With a better understanding of biomaterials and stem cells, a number of new ectopic transplant models have been proposed recently as useful tools to examine roles of microenvironment in stem cell biology. One study performed subcutaneous transplantation of mouse marrow stromal cells (MSCs) encapsulated in gelatin sponges to form an ossicle, but microvessel density, lineage number, and HSC/P number in the ossicle proves to be far lower than in the femur (Song et al., 2010 ). Interestingly, adipocyte number is 30- fold higher in the ossicle than the femur, consistent with a previous observation that marrow adipocytes negatively regulate HSC number and engraftment (Naveiras et al., 2009). "
    [Show abstract] [Hide abstract]
    ABSTRACT: Adult stem cells and progenitors are of great interest for their clinical application as well as their potential to reveal deep sensitivities to microenvironmental factors. The bone marrow is a niche for at least two types of stem cells, and the prototype is the hematopoietic stem cell/progenitors (HSC/Ps), which have saved many thousands of patients for several decades now. In bone marrow, HSC/Ps interact functionally with marrow stromal cells that are often referred to as mesenchymal stem cells (MSCs) or derivatives thereof. Myosin and matrix elasticity greatly affect MSC function, and these mechanobiological factors are now being explored with HSC/Ps both in vitro and in vivo. Also emerging is a role for the nucleus as a mechanically sensitive organelle that is semi-permeable to transcription factors which are modified for nuclear entry by cytoplasmic mechanobiological pathways. Since therapies envisioned with induced pluripotent stem cells and embryonic stem cells generally involve in vitro commitment to an adult stem cell or progenitor, a very deep understanding of stem cell mechanobiology is essential to progress with these multi-potent cells.
    Full-text · Article · Jun 2013 · Differentiation
Show more