Optimization of Schwann Cell Adhesion in Response to Shear Stress in an in Vitro Model for Peripheral Nerve Tissue Engineering

Abstract

The design of nerve guidance channels (NGCs) is evolving to produce a favorable environment for neural regeneration. We created an in vitro model to evaluate the interactions between three centrally important components of this altered host environment: (1). Schwann cells, (2). substrate, and (3). sustained mechanical stimulus in the form of shear stress with laminar fluid flow. Preconfluent Schwann cells were plated on slides coated either with laminin, poly-D-lysine, type IV collagen, or fibronectin. These slides were placed into custom-designed, parallel-plate, flow chambers and were administered laminar fluid flow at a rate of 15 mL/min for 2 h. Schwann cell adhesion assays demonstrated that laminin (mean, 86.1%; SEM, 4.47%) and fibronectin (mean, 81.7%; SEM, 3.24%) were statistically superior to collagen type IV (mean, 57.7%; SEM, 3.96%) and poly-D-lysine (mean, 58.0%; SEM, 4.97%) (p < 0.001). Fibronectin (mean, 12.20%; SEM, 0.374%) induced statistically greater Schwann cell proliferation than did laminin (mean, 8.14%; SEM, 0.682%) (p < 0.001). Therefore, we recommend that fibronectin should be used as an important component of NGCs with further in vivo studies. As mechanical stress is an integral part of the host environment, our study is the first to incorporate this factor into an in vitro model for peripheral nerve tissue engineering.

Inhibition of N‐cadherin and β‐catenin function reduces axon‐induced Schwann cell proliferation

“…Scramble‐transfected SCs showed 11.5% BrdU‐positive cells (Fig. 4a,c), comparable to previously reported rates (Chafik et al,2003). In contrast, β‐catenin knockdown SC cultures had significantly fewer dividing cells, showing only 5% BrdU‐positive nuclei (Fig.…”

Demyelination secondary to chronic nerve compression injury alters Schmidt–Lanterman incisures

“…1995). Furthermore, it has been shown that when Schwann cells are subjected to shear stress in vitro , stress that mimics the mechanical stress that occurs with CNC injury, they down‐regulate mRNA and protein expression of MBP and of myelin‐associated glycoprotein (MAG) (Chafik et al. 2003; Gupta et al.…”

“…Animals with a knockout gene mutation for myelin basic protein (MBP) showed an increase in the number of SLIs per internode if both copies of the MBP gene were knocked-out (Gould et al 1995). Furthermore, it has been shown that when Schwann cells are subjected to shear stress in vitro , stress that mimics the mechanical stress that occurs with CNC injury, they down-regulate mRNA and protein expression of MBP and of myelinassociated glycoprotein (MAG) (Chafik et al 2003;Gupta et al 2005). MAG is a promyelinogenic marker in Schwann cells that is located in SLIs, as well as periaxonal cytoplasm and nodes of Ranvier (Xu et al 2000).…”

Artificial nerve conduits in peripheral‐nerve repair

“…In order to discover the most suitable linking substance, Chafik et al [89] assessed SC adhesion in vitro in response to shear stress (13.3 dyn/cm 2 ; 1 dyn=10 −5 N) in a laminar‐flow model. This is within the shear stress range known to elicit a biological response.…”