Interaction of glia with a compliant, microstructured silicone surface

Area of Science:

• Biomaterials Science
• Neuroscience
• Cell Biology

Background:

• Chronic implantation of devices can lead to adverse tissue responses, such as glial scarring.
• Soft bioengineered surfaces offer a potential strategy to modulate these responses and improve device functionality.
• Neural interfaces require biocompatible materials that minimize foreign body reactions.

Purpose of the Study:

• To fabricate and characterize microtopographically rich, mechanically compliant silicone surfaces for soft neural interfaces.
• To investigate the in vitro interaction of glial cells (microglia and astroglia) with polydimethylsiloxane (PDMS) micropillar arrays of varying heights.
• To assess the effects of these micropillar surfaces on glial cell behavior, including migration, spreading, and proliferation.

Main Methods:

• Fabrication of polydimethylsiloxane (PDMS) surfaces with arrays of tall (4.7 μm) and short (0.5 μm) vertically oriented micropillars, alongside a flat PDMS control.
• In vitro co-culture of primary rat microglia and astroglia with the fabricated PDMS surfaces.
• Microscopic observation of cell morphology, cytoskeletal organization (actin staining), and cell-cell interactions.
• Quantification of cell migration, spreading, and proliferation rates on different surface topographies.

Main Results:

• Glial cells were observed to engulf and bend tall PDMS micropillars.
• Cells on tall pillar arrays exhibited altered cytoskeletal organization, with actin ring formations around pillars instead of stress fibers.
• Tall, but not short, micropillar arrays significantly inhibited glial cell migration and spreading.
• Proliferation rates of both microglia and astrocytes were reduced by approximately twofold on tall micropillar arrays compared to flat or short pillar surfaces.

Conclusions:

• Microtopographically structured PDMS surfaces, particularly tall micropillars, significantly influence glial cell behavior.
• The observed inhibition of migration, spreading, and proliferation suggests that tall micropillar arrays possess antimitotic properties.
• These findings indicate that soft, microstructured surfaces could be a valuable strategy for reducing glial encapsulation around chronically implanted neural devices, potentially improving their long-term performance.