The balance between hematopoietic stem cell (HSC) self-renewal and differentiation directly impacts hematopoietic homeostasis. We hypothesize that signals from the bone marrow microenvironment (or ?niche?), together with cues from cell-intrinsic networks, contribute to fine-tuning this balance. However, our understanding of the niche has been limited by the current approach relying on sequential deletion of individual regulatory factors from candidate cells in available mouse models, and analysis of individual HSCs and their in vivo interactions with the niche has also been hindered by the heterogeneity of available HSC-enriched fractions and the technical challenges of imaging HSC fate in vivo. To illuminate the behavior of individual HSCs in vivo, we have established a new technical regimen which includes prospective isolation of HSCs with high purity based on Tie2 positivity, a local transplantation technique which delivers a single HSC under multiphoton microscopy guidance into the bone marrow of a live mouse, and micropipette aspiration to extract single cells after division directly from the marrow for transcriptomic assay. Our project will utilize these advances to describe the molecular basis of HSC fate choice in the niche. This in turn will facilitate novel therapeutic strategies for cell- fate manipulation which could accelerate hematopoietic recovery after transplantation, and possibly contribute to improved transplantation efficiency for non-malignant blood diseases. Thus, the goals of this proposal are three-fold: (1) to identify molecular mechanisms which enhance symmetric self-renewing division of HSCs, (2) to understand the niche factors governing HSC division balance, and (3) to assess the HSC niche under non- genotoxic conditioning. If successful, the proposed research will positively impact the HSC field by identifying molecular targets that will improve hematopoietic recovery after transplantation, and enable improvements in the ex vivo engineering of niche models.
Stem cell division results in either self-renewal or differentiation, with the balance between the two options directly impacting homeostasis, but precisely how the bone marrow microenvironment governing hematopoietic stem cell (HSC) fates remains unclear. This project utilizes single-cell approaches, including a new transplantation system and non-genotoxic conditioning, to identity molecular targets that will improve hematopoietic recovery after transplantation and enable ex vivo engineering of niche models for HSC expansion, while also analyzing the physiological bone marrow microenvironment. The resulting insights into the stem cell niche will have a major impact on HSC research as well as current clinical practice for hematological diseases.
| Guarnerio, Jlenia; Mendez, Lourdes Maria; Asada, Noboru et al. (2018) A non-cell-autonomous role for Pml in the maintenance of leukemia from the niche. Nat Commun 9:66 |
| Ito, Kyoko; Ito, Keisuke (2018) Hematopoietic stem cell fate through metabolic control. Exp Hematol 64:1-11 |
| Bonora, Massimo; Ito, Kyoko; Morganti, Claudia et al. (2018) Membrane-potential compensation reveals mitochondrial volume expansion during HSC commitment. Exp Hematol 68:30-37.e1 |
| Turcotte, Raphaël; Alt, Clemens; Runnels, Judith M et al. (2017) Image-guided transplantation of single cells in the bone marrow of live animals. Sci Rep 7:3875 |
