Fibrous Structure and Stiffness of Designer Protein Hydrogels Synergize to Regulate Endothelial Differentiation of Bone Marrow Mesenchymal Stem Cells

Abstract

Matrix stiffness and fibrous structure provided by the native extracellular matrix have been increasingly appreciated as important cues in regulating cell behaviors. Recapitulating these physical cues for cell fate regulation remains a challenge due to the inherent difficulties in making mimetic hydrogels with well-defined compositions, tunable stiffness, and structures. Here, we present two series of fibrous and porous hydrogels with tunable stiffness based on genetically engineered resilin-silk-like and resilin-like protein polymers. Using these hydrogels as substrates, the mechanoresponses of bone marrow mesenchymal stem cells to stiffness and fibrous structure were systematically studied. For both hydrogel series, increasing compression modulus from 8.5 to 14.5 and 23 kPa consistently promoted cell proliferation and differentiation. Nonetheless, the promoting effects were more pronounced on the fibrous gels than their porous counterparts at all three stiffness levels. More interestingly, even the softest fibrous gel (8.5 kPa) allowed the stem cells to exhibit higher endothelial differentiation capability than the toughest porous gel (23 kPa). The predominant role of fibrous structure on the synergistic regulation of endothelial differentiation was further explored. It was found that the stiffness signal activated Yes-associated protein (YAP), the main regulator of endothelial differentiation, via spreading of focal adhesions, whereas fibrous structure reinforced YAP activation by promoting the maturation of focal adhesions and associated F-actin alignment. Therefore, our results shed light on the interplay of physical cues in regulating stem cells and may guide the fabrication of designer proteinaceous matrices toward regenerative medicine.

Hyaluronic-Acid-Nanomedicine Hydrogel for Enhanced Treatment of Rheumatoid Arthritis by Mediating Macrophage–Synovial Fibroblast Cross-Talk

“…4 A and E, compared with the control group and the CEL group, the collagen secretion determined by sirius red staining of BMSCs treated with P@CEL or HP@CEL were significantly increased. These colorimetric analyses demonstrated that coincubation with the hydrogel facilitated the proliferation and differentiation of BMSCs, which may be attributed to the HA components and ECM-like 3-dimensional microstructure of the hydrogel [ 30 , 31 ].…”

Angiogenic Potential of Human Adipose-Derived Mesenchymal Stromal Cells in Nanofibrillated Cellulose Hydrogel

“…Lou et al [ 76 ] showed that human pluripotent stem cells changed their spheroid formation behavior when different fiber concentrations of NFC hydrogel were applied. Regarding endothelial differentiation, studies have shown differing differentiation potential of mesenchymal stromal cells depending on the scaffold stiffness [ 77 , 78 , 79 ]. With respect to stiffness control, NFC hydrogel could become a highly beneficial material since it has a fiber concentration directly proportional to the mechanical properties [ 25 ] that can easily be adjusted when needed by diluting the hydrogel or concentrating the dried form of NFC, as explained in our previous studies [ 80 ].…”

Mechanical Signal‐Tailored Hydrogel Microspheres Recruit and Train Stem Cells for Precise Differentiation

“…Many in vitro experiments have demonstrated that substrates mimicking tissue-specific moduli can promote the differentiation of stem cells to specific tissue lineages. [16] For example, the soft matrix (<5 Kpa) inhibits cytoskeleton organization and induces differentiation of stem cells to adipocytes and endothelial cells. [17] However, current mechanobiological training studies have only been applied to enhance exogenous cell transplantation, and its potential to improve endogenous regeneration needs to be further explored.…”