Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.; Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
Sci Adv. 2017 Jan 6;3(1):e1600455. doi: 10.1126/sciadv.1600455. eCollection 2017 Jan.
Hematopoiesis is the physiological process where hematopoietic stem cells (HSCs) continuously generate the body's complement of blood and immune cells within unique regions of the bone marrow termed niches. Although previous investigations have revealed gradients in cellular and extracellular matrix (ECM) content across the marrow, and matrix elasticity and ligand type are believed to be strong regulators of stem cell fate, the impact of biophysical signals on HSC response is poorly understood. Using marrow-inspired ECM ligand-coated polyacrylamide substrates that present defined stiffness and matrix ligand cues, we demonstrate that the interplay between integrin engagement and myosin II activation processes affects the morphology, proliferation, and myeloid lineage specification of primary murine HSCs within 24 hours ex vivo. Notably, the impact of discrete biophysical signals on HSC fate decisions appears to be correlated to known microenvironmental transitions across the marrow. The combination of fibronectin and marrow matrix-associated stiffness was sufficient to maintain hematopoietic progenitor populations, whereas collagen and laminin enhanced proliferation and myeloid differentiation, respectively. Inhibiting myosin II-mediated contraction or adhesion to fibronectin via specific integrins (αβ and αβ) selectively abrogated the impact of the matrix environment on HSC fate decisions. Together, these findings indicate that adhesive interactions and matrix biophysical properties are critical design considerations in the development of biomaterials to direct HSC behavior in vitro.
造血是指造血干细胞（HSCs）在骨髓的特定区域（称为龛位）中不断生成体内血液和免疫细胞的生理过程。尽管先前的研究已经揭示了骨髓中细胞和细胞外基质（ECM）含量的梯度，并且认为基质弹性和配体类型是干细胞命运的强大调节剂，但生物物理信号对 HSC 反应的影响还知之甚少。本研究使用受骨髓启发的 ECM 配体涂层聚丙烯酰胺底物，这些底物具有明确的刚度和基质配体线索，我们证明了整合素结合和肌球蛋白 II 激活过程之间的相互作用会影响原代小鼠 HSC 的形态、增殖和髓系细胞分化，这一过程在 24 小时内发生。值得注意的是，离散生物物理信号对 HSC 命运决定的影响似乎与骨髓中的已知微环境转变相关。纤维连接蛋白和骨髓基质相关刚度的组合足以维持造血祖细胞群体，而胶原蛋白和层粘连蛋白分别增强增殖和髓系分化。通过特定整合素（αβ和 αβ）抑制肌球蛋白 II 介导的黏附或对纤维连接蛋白的黏附，选择性地消除了基质环境对 HSC 命运决定的影响。总之，这些发现表明，黏附相互作用和基质生物物理特性是开发生物材料以指导体外 HSC 行为的关键设计考虑因素。
