Schwann cell migration is important for both spinal cord and peripheral nerve injuries, as Schwann cells are responsible for remyelinating the regenerated axons as well as providing guidance for regrowing axons. However, although numerous studies have focused on designing transplantable scaffolds for bridging the damaged nerve, few have taken into consideration the migration of Schwann cells required for remyelination. Evidence suggests that filaments and channels hold promise in enhancing the directionality and efficiency of Schwann cell migration . To date, studies have monitored single cell migration on grooved surfaces, however the migration speed of a single cell differs from a collection of cells, and given that cells in vivo migrate not as discrete cells but rather as cell populations , the latter would better inform on the scaffold design for tissue repair. Therefore to better optimize the design of transplantable scaffolds, we studied the influence of channel diameter on the migration behavior of large populations of Schwann cells.
Micropatterned polydimethylsiloxane (PDMS) channel surfaces with different channel sizes (50μm, 100μm, and 150μm) were prepared through photolithography, which served to mimic the varying channel sizes of transplantable scaffolds in vitro. Schwann cells were seeded onto PDMS substrates and monitored daily for cell migration. The average cell migration speeds were quantified and normalized. We hypothesize that the smaller channel size induces higher degree of contact guidance causing the cells to align in the channel direction and migrate faster. The experimental results support higher Schwann cell migration speeds on PDMS channels with decreasing channel sizes, which was most prominent in the 50μm channels with migration speeds of 2.3 times greater than on the 150μm channels. In conclusion, the data suggest that Schwann cell migration into the scaffold, required for nerve repair, could be manipulated by controlling the scaffold channel size.
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