TABLE V.

Advantages and drawbacks of motorized platforms to study glial mechanotransduction.

Substrate	Material	Surface coating	Device/Mechanical stimulation	Stiffness and specific features	Cells tested	Biological outcomes	Limits	References
Biological hydrogel	Stretched silicon sheets	Matrigel	Cell-shortening device/Compression–space restriction	Stiffness non communicated (NC)	Mouse oligodendrocyte progenitor cell (OPC)	Stimulation promotes OL differentiation by heterochromatin formation through Syne1 (LINC) mechanotransduction	Comparable to microsphere space constraint	133
	Polystyrene Thick ACLAR 33 C film	Matrigel Collagen I	Custom-built mechanobioreactors with extension chamber/Stretch-growth Long process outgrowth	Stiffness NC	Rat astrocyte	Living scaffold emulating developmental conditions	Mimic radial glia	137
						More robust stretched processes at 12.5 μm/h	Result robustness is coating-dependent
						The applied displacement rate is different than stretched-injury models	Required astrocyte processes network with sufficient resilience and growth capacity
							Heterogeneous stretch within cultures with the most robust stretch seen near the corners of the towing membranes Changes in astrocyte processes thickness underscore the heterogeenous effect of the mechanical tension
Synthetic hydrogel	PDMS plates fabricated from Sylgard 184 silicone	Fibonectin	Tensile strain device/10% static tensile strain for 48h	Stiffness NC	Rat primary OPC	Early differentiation in OL investigated under mechanical stimulus shows reduction in cell migration and microtubule network reorganization	Only tested tensile strain, which may not encompass the complexity of mechanical stresses encountered in vivo	67
		PDL Laminin Fibonectin	Tensile strain device (1) Biaxial static tensile strain of 15% for 24 h (Proliferation) (2) 10% static tensile strain for 3–5 Day (Differentiation)	Stiffness NC	Rat primary OPC	Sustained tensile strain inhibits OPC proliferation and promoted OL differentiation through chromatine reorganization and nucleus shape changes	Only tested tensile strain, which may not encompass the complexity of mechanical stresses encountered in vivo	134
Synthetic substrate	Teflon disk with silicon membrane	Laminin Fibronectin	Tensile Strain/10% static equibiaxial stretch	Stiffness Unstretched 10 kPa Stretched 1.6 Mpa	Mouse cortical neural stem/progenitor cell (NSPC)	Stretch impacts NSPC differentiation into OL, but not neurons or astrocytes, and is dependent on ECM-integrin linkages	The stiffness range is high and does not mimic a physiological range	135
					Rat hippocampal NSPC	Generation of OL decreased on laminin
Synthetic substrate ?	Silicon chamber	Laminin	Cell stretching Shear stress (1) Computer-controlled stepping motor machine	Stiffness NC	Rat OPC	YAP regulates OL morphology and interactions with neuronal axons Mechanical stretching induces	Suitable only for early differentiation step but does not encompass topographical cues to study OL maturation and myelination	10
			(2) Shear stress by flask rotation
						nuclear YAP translocation and focal adhesion assembly
						Shear stress decreased the number of OL processes
Synthetic Hydrogel and substrate	PAA PDMS Silicone sheets	Sulfo-SANPAH PLL Laminin 211	Cell density Substrate stiffness Uniaxial stretching	0.5 kPa to 40 kPa (PAA) 4 Mpa (PDMS)	Primary rat Schwann cells (SC)	YAP/Taz remains nuclear in low cell density and relocates in the cytoplasm under blebbistatin treatment	Not suitable for complexes and topography-directed morphological study Short term stimulation and	9
						YAP/Taz is nuclear on very stiff substrate but cytopasmic on more compliant ones in presence of laminin 211. YAP/Taz nuclear localization is promoted by mechanical stretching
							culture
Modified biological hydrogel	Methacrylamide chitosan	Laminin	Mach 1 micromechanical testing system/Uniaxial stress-relaxation Substrate stiffness	Stiffness 1–30 kPa	Rat NSPC	Used for mechanical testing of the gels, not assessed for cells	Not suitable for complexes and topography-directed morphological study	84
				Porous network slightly varying across stiffness
Synthetic substrate	Bioflex Plates	Collagen I	biaxial stretch	Stiffness NC	Adult astrocytes	Mechanical stress activates stretched-activated ion channels and regulates the expression of endothelin and endothelin receptors in astrocytes	Not suitable for complexes and topography-directed morphological study	136