Mechanosensitivity of Embryonic Neurites Promotes Their Directional Extension and Schwann Cells Progenitors Migration.

Migration of Schwann cells (SCs) progenitors and neurite outgrowth from embryonic dorsal root ganglions (DRGs) are two central events during the development of the peripheral nervous system (PNS). How these two enthralling events preceding myelination are promoted is of great relevance from basic research and clinical aspects alike. Recent evidence demonstrates that biophysical cues (extracellular matrix stiffness) and biochemical signaling act in concert to regulate PNS myelination. Microenvironment stiffness of SCs progenitors and embryonic neurites dynamically changes during development. DRG explants were isolated from day 12.5 to 13.5 mice embryos and plated on laminin-coated substrates with varied stiffness values. After 4 days in culture and immunostaining with specific markers, neurite outgrowth pattern, SCs progenitors migration, and growth cone shape and advance were analyzed with confocal fluorescence microscopy. We found out that growing substrate stiffness promotes directional neurite outgrowth, SCs progenitors migration, growth cone advance and presumably axons fasciculation. DRG explants are in vitro models for the research of PNS development, myelination and regeneration. Consequently, we conclude the following: Our observations point out the importance of mechanosensitivity for the PNS. At the same time, they prompt the investigation of the important yet unclear links between PNS biomechanics and inherited neuropathies with myelination disorders such as Charcot-Marie-Tooth 1A and hereditary neuropathy with liability to pressure palsies. Finally, they encourage the consideration of mechanosensitivity in bioengineering of scaffolds to aid nerve regeneration after injury.