Background: The marrow niche contains haematopoietic stem cells (HSCs) and
mesenchymal stromal cells (MSCs), which interact with each
other, as well as with soluble and matrix-associated factors in an
environment with diverse mechanical properties. MSCs respond to the mechanical properties of their environment and also play a
vital role in HSC maintenance through the expression of soluble
factors, but how this complex homeostatic process is affected
by age-related disease remains poorly understood. During ageing, the
mechanical environment of the marrow changes, with
increased production of adipose tissue and changes to
the physical loads experienced by ageing bones. Misregulation of mechanical stress has been linked to pathologies such as osteoporosis, leading to aberrant cellular regulation, increased apoptosis and production of inflammatory mediators.
Hypothesis: Misregulation of the mechanical properties of the marrow niche during ageing and disease perturbs communication between MSC and HSC populations and thus contributes to pathology.
Objectives: To understand how MSCs interpret chemical and mechanical signals from the surrounding marrow niche, and how they respond by secreting proteins that (i) modify the surrounding matrix, contributing to pathological changes in the tissue; (ii) signal to other cells. Parallel studies will quantify how HSC sub-populations respond to pathologically-induced soluble factor signalling and could thus cause system-wide immunological consequences.
Methods: MSCs will be characterized in vitro by high-content microscopy; and secreted proteins analyzed by mass spectrometry proteomics. MSCs and HSCs in co-culture will be analyzed by single-cell cytometry and CyTOF methods. Primary tissues will be characterized by histology and atomic force microscopy.
Outcome and impact: The project will contribute to excellent primary (cell biology) and translational (understanding disease mechanisms) research, and will provide training in new methods and the application of emerging technologies (instruments for proteomics and single-cell studies).
Swift, J., Ivanovska, I., Buxboim, A., Harada, T., Dingal, P., Pinter, J., Pajerowski, J., Spinler, K., Shin, J., Tewari, M. & Discher, D.E. Nuclear lamin-A scales with tissue stiffness and enhances matrix-directed differentiation. Science. (2013).
Shin, J., Spinler, K., Swift, J., Chasis, J., Mohandas, N. & Discher, D.E. Lamins regulate cell trafficking and lineage maturation of adult human hematopoietic cells. PNAS. (2013).
Shin, J., Buxboim, A., Spinler, K., Swift, J., Christian, D., Hunter, C., Léon, C., Gachet, C., Dingal, P., Ivanovska, I. & Discher, D.E. Contractile forces sustain and polarize hematopoiesis from stem and progenitor cells. Cell Stem Cell. (2014).
Askenase, M.H., Han, S., Byrd, A.L., Morais da Fonseca, D., Bouladoux, N., Wilhelm, C., Konkel, J.E., Hand, T.W., Lacerda-Queiroz, N., Su, X., Trinchieri, G., Grainger, J.R. & Belkaid, Y. Bone-marrow-resident NK cells prime monocytes for regulatory function during infection. Immunity. (2015).
Clarke, L., McConnell, J., Sherratt, M., Derby, B., Richardson, S. & Hoyland, J. Growth differentiation factor 6 and transforming growth factor-beta differentially mediate mesenchymal stem cell differentiation, composition and micromechanical properties of nucleus pulposus constructs. Arthritis Res Ther. (2014).