Inducing Neurite Outgrowth by Mechanical Cell Stretch

Abstract

Establishing extracellular milieus to stimulate neuronal regeneration is a critical need in neuronal tissue engineering. Many studies have used a soluble factor (such as nerve growth factor or retinoic acid [RA]), micropatterned substrate, and electrical stimulation to induce enhanced neurogenesis in neuronal precursor cells. However, little attention has been paid to mechanical stimulation because neuronal cells are not generally recognized as being mechanically functional, a characteristic of mechanoresponsive cells such as osteoblasts, chondrocytes, and muscle cells. In this study, we performed proof-of-concept experiments to demonstrate the potential anabolic effects of mechanical stretch to enhance cellular neurogenesis. We cultured human neuroblastoma (SH-SY5Y) cells on collagen-coated membrane and applied 10% equibiaxial dynamic stretch (0.25 Hz, 120 min/d for 7 days) using a Flexcell device. Interestingly, cell stretch alone, even without a soluble neurogenic stimulatory factor (RA), produced significantly more and longer neurites than the non–RA-treated, static control. Specific neuronal differentiation and cytoskeletal markers (e.g., microtubule-associated protein 2 and neurofilament light chain) displayed compatible variations with respect to stretch stimulation.

Device-Based In Vitro Techniques for Mechanical Stimulation of Vascular Cells: A Review

“…Systems may be modified to provide additional device features, such as live-cell imaging, protein analysis, and higher throughput [98,[114][115][116][117]119]. Also of note are commercially available systems that use a vacuum to stretch the membrane (Flexcell International, Hillsborough, NC), which can be used for equiaxial strain studies [120][121][122]. Recently, Lau et al implemented a system using the Flexcell equiaxial device that was computer-controlled to generate arbitrary stretch waveforms based on physiologically relevant data [123].…”

Engineering Approaches for Creating Skeletal Muscle

“…70 Stretch also tended to increase the expression of neurofilament light chain (NFL), which is an important part of the neural cytoskeleton, but this change was not statistically significant. 70 This cyclic stretching is more relevant to skeletal muscle tissue than the axonal stretch growth, however, both studies demonstrate that carefully applied forces are able to improve outcomes for neuron cultures.…”

“…Other researchers have found that neurite outgrowth is increased by cyclic equibiaxial stretching. 70 Human neuroblastoma (SH-SY5Y) cells were cultured on BioFlex culture plates and mechanically stimulated to 10% at 0.25 Hz. 70 This culture was performed either with or without the addition of retinoic acid (RA), a well-known mediator of neurite outgrowth.…”

“…70 Human neuroblastoma (SH-SY5Y) cells were cultured on BioFlex culture plates and mechanically stimulated to 10% at 0.25 Hz. 70 This culture was performed either with or without the addition of retinoic acid (RA), a well-known mediator of neurite outgrowth. 70 It was found that by simply applying this biaxial strain, neurite length and numbers per cell was significantly increased.…”

“…70 This culture was performed either with or without the addition of retinoic acid (RA), a well-known mediator of neurite outgrowth. 70 It was found that by simply applying this biaxial strain, neurite length and numbers per cell was significantly increased. 70 Stretch also tended to increase the expression of neurofilament light chain (NFL), which is an important part of the neural cytoskeleton, but this change was not statistically significant.…”