Extracellular matrix cues modulate Schwann cell morphology, proliferation, and protein expression

Abstract

Peripheral nerve injuries require a complex set of signals from cells, macrophages, and the extracellular matrix (ECM) to induce regeneration across injury sites and achieve functional recovery. Schwann cells (SCs), the major glial cell in the peripheral nervous system (PNS), are critical to nerve regeneration due to their inherent capacity for altering phenotype postinjury to facilitate wound healing. The ECM plays a vital role in wound healing as well as regulating cell phenotype during tissue repair. To examine the underlying mechanisms between the ECM and SCs, this work sought to determine how specific ECM cues regulate the phenotype of SCs. To address this, SCs were cultured on polydimethylsiloxane substrates of a variable Young's modulus coated with ECM proteins. Cells were analyzed for spreading area, proliferation, cell and nuclear shape, and c‐Jun expression. It was found that substrates with a stiffness of 8.67 kPa coated with laminin promoted the highest expression of c‐Jun, a marker signifying a “regenerative” SC. Microcontact printed, cell adhesive areas were then utilized to precisely control the geometry and spreading of SCs and by controlling spreading area and cellular elongation; expression of c‐Jun was either promoted or downregulated. These results begin to address the significant interplay between ECM cues and phenotype of SCs, while offering a potential means to enhance PNS regeneration through cellular therapies.

Development of a Piezoelectric PVDF‐TrFE Fibrous Scaffold to Guide Cell Adhesion, Proliferation, and Alignment

“…[45][46][47][48] For instance, it has been previously demonstrated that polydimethylsiloxane (PDMS) substrates can be fabricated over a broad range of physiologically relevant Young's Moduli to promote durotaxis and phenotype change of Schwann cells. [24,41] It was also shown that an intermediate substrate stiffness promotes the proliferation of Schwann cells and expression of the dedifferentiated Schwann cell marker c-jun. [24] In broader applications, the extracellular matrix has received a renewed interest in relation to rheological mediation of cell behavior during development, disease, and regeneration.…”

“…[24,41] It was also shown that an intermediate substrate stiffness promotes the proliferation of Schwann cells and expression of the dedifferentiated Schwann cell marker c-jun. [24] In broader applications, the extracellular matrix has received a renewed interest in relation to rheological mediation of cell behavior during development, disease, and regeneration. For instance, ECM stiffening has been directly linked to tumor progression for various cancers.…”

“…While prior work observed a maximum induced current of 40 nA for fibrous scaffolds, the vast difference is likely attributable to our smaller scaffold thickness (where a thicker scaffold produces higher currents). [58] A piezoelectric response of the PVDF-TrFE scaffolds may be able to provide a significant electric stimulation due to the deformations caused by cell attachment and migration, where cells have notably been shown to contract their matrices by 1 to 3 µm in vitro, [24] and the general locomotion of tissue and adjacent biological structures. To artificially promote the piezoelectric effect, alternative techniques such as noninvasive ultrasound can be used to incur polarization and subsequent differentiation of cells.…”

“…For instance, Schwann cells dedifferentiate into a regenerative phenotype that secretes extracellular matrix proteins and subsequently provides a template for axon growth. [23][24][25][26][27] Likewise, fibroblasts have been identified as crucial supportive cells that promote the alignment and migration of Schwann cells while simultaneously depositing additional ECM proteins and neurotrophic factors. [19,26] Therefore, this work aims to create tunable PVDF-TrFE scaffolds with extensive characterization of the parameters beneficial to a regenerative neurotrophic environment.…”

Tyrosine-Derived Polycarbonate Nerve Guidance Tubes Elicit Pro-Regenerative Extracellular Matrix Deposition When Used to Bridge Segmental Nerve Defects in Swine

“…During regeneration, fibronectin is upregulated and increases Schwann cell spread and proliferation, and neurite outgrowth [35,36]. Besides from providing endogenous support, collagen, laminin, and fibronectin have been thoroughly investigated and shown to improve nerve regeneration in various rodent models as fillers for conduits [37][38][39][40], which has led to development of various biomimetic conduits [41].…”