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Brian Reid, Jing Gao, Vijaykrishna Raghuanthan, Paul Russell, Christopher Murphy, Min Zhao; Substrate topography enhances corneal epithelial cell electrotaxis. Invest. Ophthalmol. Vis. Sci. 2013;54(15):3896.
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© ARVO (1962-2015); The Authors (2016-present)
Corneal epithelial cells (CECs) attach to the underlying stroma via a 3D extracellular matrix basement membrane (BM) that possesses intrinsic biophysical (topography, stiffness) and biochemical cues (chemoattractants, growth factors, soluble factors). Cellular behavior can be significantly modulated by these factors during wound healing. An important yet grossly under-studied factor in corneal wound healing is the role of electric fields (EFs). Cornea wounds generate significant EFs which cells respond to by directional migration. Here, for the first time, we investigated the impact of simultaneous presentation of topographic cues and EFs on CEC migration.
Immortalized human CECs were cultured on unpatterned, stochastically patterned (mimicking the stochastic arrangement on the BM) or anisotropically patterned polymeric substrates (biomimetic scale 400 to 4000nm pitches; pitch = ridge width + groove width) coated with fibronectin. EFs (0-150 mV/mm) were applied to cells across an electrotaxis chamber for 3h. Single cell migration, cell migration as a monolayer across a simulated wound, and alterations in the gene expression of focal adhesion kinase (FAK), and cytoskeletal regulator ROCK1 were determined.
In the absence of an EF, cells migrated faster on stochastic substrates than on flat surfaces (21.14µm/h vs. 18.44µm/h respectively, P<0.05). With EFs of 25 to 150 mV/mm cell migration was more rapid (28.8µm/h vs. 21.9µm/h respectively at 150mV, P<0.001), although the directionality was not altered. With EF applied perpendicular to the grooves, cells migrated faster on 400nm pitch substrates than on 4000nm ones (P<0.05; directionality unchanged). After application of an EF for 3h, no alterations to FAK or ROCK1 mRNA expression were observed in the cells.
Human corneal epithelial cells migrated to the cathode in the presence of an EF on both unpatterned and nano-patterned surfaces. Because cells migrated significantly faster on stochastically patterned surfaces mimicking the BM without altering directionality, this finding may be exploited for engineering novel strategies to promote corneal wound healing. While the molecular mechanisms responsible for the interaction between EFs and topographic cues are not yet clear, our study highlights the importance of presentation of simultaneous yet biologically relevant cues to study corneal wound healing processes.
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