The extracellular matrix (ECM) controls keratinocyte proliferation, migration, and differentiation through β‐integrin signaling. Wound‐healing research requires expanding cells in vitro while maintaining replicative capacity; however, early terminal differentiation under traditional culture conditions limits expansion. Here, a design of experiments approach identifies poly(ethylene glycol)‐based hydrogel formulations with mechanical properties (elastic modulus,
This content will become publicly available on July 10, 2024
Integrin, as a mechanotransducer, establishes the mechanical reciprocity between the extracellular matrix (ECM) and cells at integrin-mediated adhesion sites. This study used steered molecular dynamics (SMD) simulations to investigate the mechanical responses of integrin
This article is part of a discussion meeting issue ‘Supercomputing simulations of advanced materials’.
more » « less- NSF-PAR ID:
- 10488277
- Publisher / Repository:
- Royal Society Publishing
- Date Published:
- Journal Name:
- Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences
- Volume:
- 381
- Issue:
- 2250
- ISSN:
- 1364-503X
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
more » « less
Abstract E = 20.9 ± 0.56 kPa) and bioactive peptide sequences that mimic the epidermal ECM. These hydrogels enable systematic investigation of the influence of cell‐binding domains from fibronectin (RGDS), laminin (YIGSR), and collagen IV (HepIII) on keratinocyte stemness and β1integrin expression. Quantification of 14‐day keratin protein expression shows four hydrogels improve stemness compared to standard techniques. Three hydrogels increase β1integrin expression, demonstrating a positive linear relationship between stemness and β1integrin expression. Multifactorial statistical analysis predicts an optimal peptide combination ([RGDS] = 0.67 mm , [YIGSR] = 0.13 mm , and [HepIII] = 0.02 mm ) for maintaining stemness in vitro. Best‐performing hydrogels exhibit no decrease in Ki‐67‐positive cells compared to standards (15% decrease, day 7 to 14;p < 0.05, Tukey Test). These data demonstrate that precisely designed hydrogel biomaterials direct integrin expression and promote proliferation, improving the regenerative capability of cultured keratinocytes for basic science and translational work. -
more » « less
The extracellular matrix (ECM) is a complex, hierarchical material containing structural and bioactive components. This complexity makes decoupling the effects of biomechanical properties and cell-matrix interactions difficult, especially when studying cellular processes in a 3D environment. Matrix mechanics and cell adhesion are both known regulators of specific cellular processes such as stem cell proliferation and differentiation. However, more information is required about how such variables impact various neural lineages that could, upon transplantation, therapeutically improve neural function after a central nervous system injury or disease. Rapidly Assembling Pentapeptides for Injectable Delivery (RAPID) hydrogels are one biomaterial approach to meet these goals, consisting of a family of peptide sequences that assemble into physical hydrogels in physiological media. In this study, we studied our previously reported supramolecularly-assembling RAPID hydrogels functionalized with the ECM-derived cell-adhesive peptide ligands RGD, IKVAV, and YIGSR. Using molecular dynamics simulations and experimental rheology, we demonstrated that these integrin-binding ligands at physiological concentrations (3–12 m
m ) did not impact the assembly of the KYFIL peptide system. In simulations, molecular measures of assembly such as hydrogen bonding and pi-pi interactions appeared unaffected by cell-adhesion sequence or concentration. Visualizations of clustering and analysis of solvent-accessible surface area indicated that the integrin-binding domains remained exposed. KYFIL or AYFIL hydrogels containing 3 mm of integrin-binding domains resulted in mechanical properties consistent with their non-functionalized equivalents. This strategy of doping RAPID gels with cell-adhesion sequences allows for the precise tuning of peptide ligand concentration, independent of the rheological properties. The controllability of the RAPID hydrogel system provides an opportunity to investigate the effect of integrin-binding interactions on encapsulated neural cells to discern how hydrogel microenvironment impacts growth, maturation, or differentiation. -
more » « less
Abstract Since the most recent outbreak, the Ebola virus (EBOV) epidemic remains one of the world’s public health and safety concerns. EBOV is a negative-sense RNA virus that can infect humans and non-human primates, and causes hemorrhagic fever. It has been proposed that the T-cell immunoglobulin and mucin domain (TIM) family proteins act as cell surface receptors for EBOV, and that the interaction between TIM and phosphatidylserine (PS) on the surface of EBOV mediates the EBOV–host cell attachment. Despite these initial findings, the biophysical properties of the TIM-EBOV interaction, such as the mechanical strength of the TIM-PS bond that allows the virus-cell interaction to resist external mechanical perturbations, have not yet been characterized. This study utilizes single-molecule force spectroscopy to quantify the specific interaction forces between TIM-1 or TIM-4 and the following binding partners: PS, EBOV virus-like particle, and EBOV glycoprotein/vesicular stomatitis virus pseudovirion. Depending on the loading rates, the unbinding forces between TIM and ligands ranged from 40 to 100 pN, suggesting that TIM-EBOV interactions are mechanically comparable to previously reported adhesion molecule–ligand interactions. The TIM-4–PS interaction is more resistant to mechanical force than the TIM-1–PS interaction. We have developed a simple model for virus–host cell interaction that is driven by its adhesion to cell surface receptors and resisted by membrane bending (or tension). Our model identifies critical dimensionless parameters representing the ratio of deformation and adhesion energies, showing how single-molecule adhesion measurements relate quantitatively to the mechanics of virus adhesion to the cell.
-
more » « less
Abstract Strain gradients widely exist in development and physiological activities. The directional movement of cells is essential for proper cell localization, and directional cell migration in responses to gradients of chemicals, rigidity, density, and topography of extracellular matrices have been well‐established. However; it is unclear whether strain gradients imposed on cells are sufficient to drive directional cell migration. In this work, a programmable uniaxial cell stretch device is developed that creates controllable strain gradients without changing substrate stiffness or ligand distributions. It is demonstrated that over 60% of the single rat embryonic fibroblasts migrate toward the lower strain side in static and the 0.1 Hz cyclic stretch conditions at ≈4% per mm strain gradients. It is confirmed that such responses are distinct from durotaxis or haptotaxis. Focal adhesion analysis confirms higher rates of contact area and protrusion formation on the lower strain side of the cell. A 2D extended motor‐clutch model is developed to demonstrate that the strain‐introduced traction force determines integrin fibronectin pairs' catch‐release dynamics, which drives such directional migration. Together, these results establish strain gradient as a novel cue to regulate directional cell migration and may provide new insights in development and tissue repairs.
-
more » « less
Abstract Native extracellular matrix (ECM) can exhibit cyclic nanoscale stretching and shrinking of ligands to regulate complex cell–material interactions. Designing materials that allow cyclic control of changes in intrinsic ligand‐presenting nanostructures in situ can emulate ECM dynamicity to regulate cellular adhesion. Unprecedented remote control of rapid, cyclic, and mechanical stretching (“ON”) and shrinking (“OFF”) of cell‐adhesive RGD ligand‐presenting magnetic nanocoils on a material surface in five repeated cycles are reported, thereby independently increasing and decreasing ligand pitch in nanocoils, respectively, without modulating ligand‐presenting surface area per nanocoil. It is demonstrated that cyclic switching “ON” (ligand nanostretching) facilitates time‐regulated integrin ligation, focal adhesion, spreading, YAP/TAZ mechanosensing, and differentiation of viable stem cells, both in vitro and in vivo. Fluorescence resonance energy transfer (FRET) imaging reveals magnetic switching “ON” (stretching) and “OFF” (shrinking) of the nanocoils inside animals. Versatile tuning of physical dimensions and elements of nanocoils by regulating electrodeposition conditions is also demonstrated. The study sheds novel insight into designing materials with connected ligand nanostructures that exhibit nanocoil‐specific nano‐spaced declustering, which is ineffective in nanowires, to facilitate cell adhesion. This unprecedented, independent, remote, and cytocompatible control of ligand nanopitch is promising for regulating the mechanosensing‐mediated differentiation of stem cells in vivo.
