Fig. 4

Design strategies of hydrogel encapsulation systems for HSC culture. (a) Confocal microscopy images of HSPC on 2D/3D collagen hydrogel constructs via cytoskeleton (F-actin) and nucleus (DAPI) staining. Yellow arrows at the lower right indicate the thin filopodial protrusions from cells are extending into the surrounding hydrogel. Scale bar, 5 μm [73]. (b) GAG-rich 3D starPEG-heparin hydrogel system. Gel stiffness can be controlled by the molar ratio of starPEG to heparinmaleimide [123]. (c) Scanning electron micrograph image of cocultured MSC-BM (purple) and HSPCs within porous PEG hydrogels. Scale bar, 20 μm [124]. (d) Mechanical stretching induces the morphological changes in BM-derived progenitor cells within 3D fibrin hydrogels. Stress or strain induces the organization of the surrounding matrix. Cells (nuclei, blue) and F-actin filaments (green) are randomly organized in unconstrained control group (left), while cells in the static stress group (center) and the cyclic strain group (right) are aligned parallel to the direction of the stress or strain (magnification × 40, insets × 100; scale bar,10 μm) [125]