Hematopoiesis is the process where the body's blood and immune cells are generated from a small number of hematopoietic stem cells (HSCs). These events take place in, and are regulated by, unique parts of the bone marrow termed niches. And while HSCs are responsible for producing nearly one trillion hematopoietic cells a day, mutations in this process can lead to a range of pathologies such as leukemia and bone marrow failure. Further, deficits in homing and engraftment in hematologic disease and during HSC transplant procedures used to treat these diseases significantly reduce patient survival. Previous in vivo and in vitro investigations have identified putative niche components and modes of action, yet culture platforms to predict HSC engraftment, maintain quiescence or direct differentiation do not exist. A major bottleneck is that it remains unclear how the diversit of microenvironmental signals that exist in close spatial and temporal order across the marrow impact HSC response. The goal of this proposal is to use a biomaterial approach to investigate the impact of spatially-organized biophysical signals and marrow-derived niche cells on HSC fate. We will use an engineered bone marrow (EBM) platform to test and revise biophysical hypotheses related to niche regulation of HSC quiescence and activation. To accomplish this goal, we have integrated microfluidic forming tools and orthogonal hydrogel chemistries to generate libraries of optically-translucent 3D biomaterials. Each EBM contains overlapping patterns of marrow-inspired matrix, biomolecule, and cell cues. This approach allows us to isolate small numbers of HSCs from the marrow, establish then manipulate niche signals surrounding these cells in defined increments, and track their response. Uniquely, this system allows selective, stepwise addition of multiple niche-inspired signals in order to reveal their individual versus coordinated impact.
Our aims are three-fold.
AIM 1 : Dissect how overlapping patterns of niche-inspired biophysical signals shape HSC fate.
AIM 2 : Define the contribution of bone marrow niche cells on quiescence vs. activation.
AIM 3 : Resolve defects in engraftment and self-renewal for Pcl2-/- HSCs. Leveraging the well-characterized murine hematopoietic system, this approach offers the potential for mechanistic insight regarding native marrow niches, whose rarity and complexity limit direct in vivo examination. This project will generate essential information to aid development of a biomaterial rheostat to control human HSC homeostasis. Such a system would be invaluable for personalized-medicine approaches. As the marrow is the site of leukemogenesis and the target for donor HSC engraftment, EBMs could facilitate more accurate investigations of the etiology, progression, and treatment of hematopoietic diseases. Predictions realized by this approach may also suggest patient-specific improvements in HSC transplant regimens to reduce patient mortality, such as expanding HSCs pre- transplantation vs. pre-conditioning donor niche cells to improve engraftment post-transplantation.
The bone marrow provides instructive signals that regulate hematopoiesis, though defects in hematopoietic stem cell (HSC) engraftment within the marrow contribute significantly to patient mortality in diseases such as leukemia, myelodysplasia, and bone marrow failure. This project will develop an engineered bone marrow to dissect the coordinated impact of marrow-inspired biophysical signals on HSC quiescence versus activation. Identifying biophysical mechanisms underlying these processes is essential for optimizing artificial bone marrow systems to study the onset and growth of hematologic disease as well as to test and revise treatment protocols to improve patient survival.
|Offeddu, G S; Axpe, E; Harley, B A C et al. (2018) Relationship between permeability and diffusivity in polyethylene glycol hydrogels. AIP Adv 8:105006|
|Chen, Jee-Wei E; Pedron, Sara; Shyu, Peter et al. (2018) Influence of Hyaluronic Acid Transitions in Tumor Microenvironment on Glioblastoma Malignancy and Invasive Behavior. Front Mater 5:|
|Zhuo, Yue; Choi, Ji Sun; Marin, Thibault et al. (2018) Quantitative analysis of focal adhesion dynamics using photonic resonator outcoupler microscopy (PROM). Light Sci Appl 7:|
|Choi, Ji Sun; Harley, Brendan A C (2017) Marrow-inspired matrix cues rapidly affect early fate decisions of hematopoietic stem and progenitor cells. Sci Adv 3:e1600455|
|Mahadik, Bhushan P; Bharadwaj, Narayanan A K; Ewoldt, Randy H et al. (2017) Regulating dynamic signaling between hematopoietic stem cells and niche cells via a hydrogel matrix. Biomaterials 125:54-64|
|Pedron, Sara; Pritchard, Amanda M; Vincil, Gretchen A et al. (2017) Patterning Three-Dimensional Hydrogel Microenvironments Using Hyperbranched Polyglycerols for Independent Control of Mesh Size and Stiffness. Biomacromolecules 18:1393-1400|
|Rahil, Zainab; Pedron, Sara; Wang, Xuefeng et al. (2016) Nanoscale mechanics guides cellular decision making. Integr Biol (Camb) 8:929-35|
|Zhuo, Yue; Choi, Ji Sun; Marin, Thibault et al. (2016) Quantitative Imaging of Cell Membrane-associated Effective Mass Density Using Photonic Crystal Enhanced Microscopy (PCEM). Prog Quantum Electron 50:1-18|
|Choi, Ji Sun; Harley, Brendan A C (2016) Challenges and Opportunities to Harnessing the (Hematopoietic) Stem Cell Niche. Curr Stem Cell Rep 2:85-94|
|Choi, Ji Sun; Mahadik, Bhushan P; Harley, Brendan A C (2015) Engineering the hematopoietic stem cell niche: Frontiers in biomaterial science. Biotechnol J 10:1529-45|
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