Magnetic Alignment of Electrospun Fiber Segments Within a Hydrogel Composite Guides Cell Spreading and Migration Phenotype Switching

Abstract

Fibrous extracellular matrix (ECM) proteins provide mechanical structure and adhesive scaffolding to resident cells within stromal tissues. Aligned ECM fibers play an important role in directing morphogenetic processes, supporting mechanical loads, and facilitating cell migration. Various methods have been developed to align matrix fibers in purified biopolymer hydrogels, such as type I collagen, including flow-induced alignment, uniaxial tensile deformation, and magnetic particles. However, purified biopolymers have limited orthogonal tunability of biophysical cues including stiffness, fiber density, and fiber alignment. Here, we generate synthetic, cell-adhesive fiber segments of the same length-scale as stromal fibrous proteins through electrospinning. Superparamagnetic iron oxide nanoparticles (SPIONs) embedded in synthetic fiber segments enable magnetic field induced alignment of fibers within an amorphous bulk hydrogel. We find that SPION density and magnetic field strength jointly influence fiber alignment and identify conditions to control the degree of alignment. Tuning fiber length allowed the alignment of dense fibrous hydrogel composites without fiber entanglement or regional variation in the degree of alignment. Functionalization of fiber segments with cell adhesive peptides induced tendon fibroblasts to adopt a uniaxial morphology akin to within native tendon. Furthermore, we demonstrate the utility of this hydrogel composite to direct multicellular migration from MCF10A spheroids and find that fiber alignment prompts invading multicellular strands to separate into disconnected single cells and multicellular clusters. These magnetic fiber segments can be readily incorporated into other natural and synthetic hydrogels and aligned with inexpensive and easily accessible rare earth magnets, without the need for specialized equipment. 3D hydrogel composites where stiffness/crosslinking, fiber density, and fiber alignment can be orthogonally tuned may provide insights into morphogenetic and pathogenic processes that involve matrix fiber alignment and can enable systematic investigation of the individual contribution of each biophysical cue to cell behavior.

Collagen Alignment via Electro-Compaction for Biofabrication Applications: A Review

“…Since its first use, the technique has been modified to use stronger magnets (12 T) [ 81 ] and, most recently, in 2021, further modified to include a superconductor magnet (13 T) [ 66 ]. The use of stronger magnetic fields induces quicker and more dense alignment [ 84 ]. Mechanical characterisation of collagen-based magnetic alignment demonstrated a linear compressive modulus between 7–21 kPa and storage modulus between 26–75 Pa.…”

In Vitro Cellular Strain Models of Tendon Biology and Tenogenic Differentiation

“…In addition to cellmediated matrix remodeling, various methods have been developed to align matrix fibers within hydrogels. One such method includes embedding magnetic particles to provide cells with aligned contact points (Guo and Kaufman, 2007;Hiraki et al, 2021;Xu et al, 2021Xu et al, , 2021. Further development of 3D printing techniques later allowed for printing of multilayered scaffolds that improve upon the mechanical strength of hydrogels and support greater matrix organization (Rinoldi et al, 2019;Ciardulli et al, 2020).…”

“…Synthetic hydrogels (e.g., polyethylene glycol, methacrylated gelatin) provide higher control of the gels’ physical properties, but fibrous architecture is lacking in these substrates without additional processing. ( Hiraki et al, 2021 ). Seeding in hydrogels induced longitudinal arrangement of cells, increased tenogenic gene expression, and increased ECM production, with and without additional growth factors.…”

“…In addition to cell-mediated matrix remodeling, various methods have been developed to align matrix fibers within hydrogels. One such method includes embedding magnetic particles to provide cells with aligned contact points ( Guo and Kaufman, 2007 ; Hiraki et al, 2021 ; Xu et al, 2021 , 2021 ).…”

ECM-LSE: Prediction of Extracellular Matrix Proteins Using Deep Latent Space Encoding of k-Spaced Amino Acid Pairs

“…It is significant for cell functionality and plays an important role in the physiological dynamics. ECMs are also responsible for the promotion of vital cellular processes, including differentiation, adhesion, proliferation, apoptosis, and migration ( Klavert and van der Eerden, 2021 ; Hiraki et al, 2021 ; Mathews et al, 2012 ; Endo et al, 2012 ; Kim et al, 2011 ). The chemical composition of ECM mainly consists of minerals, proteoglycans, proteins, and water.…”