# Open-Top Patterned Hydrogel-Laden 3D Glioma Cell Cultures for Creation of Dynamic Chemotactic Gradients to Direct Cell Migration

## TL;DR

A new open fluidic system using hydrogels creates controlled chemical gradients to study glioma cell migration in 3D cultures.

## Contribution

A PDMS-free open fluidic system is developed to create dynamic chemotactic gradients in 3D glioma cultures.

## Key findings

- The open fluidic system maintains uniformity across millimeter-scale depths for better cell-biomaterial interactions.
- CXCL12 chemotactic gradients successfully induce U87 glioma cell migration across the hydrogel width.
- AMD3100 inhibition of CXCL12 is validated in the system, confirming its chemotactic functionality.

## Abstract

The laminar flow profiles in microfluidic systems coupled
to rapid
diffusion at flow streamlines have been widely utilized to create
well-controlled chemical gradients in cell cultures for spatially
directing cell migration. However, within hydrogel-based closed microfluidic
systems of limited depth (≤0.1 mm), the biomechanical cues
for the cell culture are dominated by cell interactions with channel
surfaces rather than with the hydrogel microenvironment. Also, leaching
of poly(dimethylsiloxane) (PDMS) constituents in closed systems and
the adsorption of small molecules to PDMS alter chemotactic profiles.
To address these limitations, we present the patterning and integration
of a PDMS-free open fluidic system, wherein the cell-laden hydrogel
directly adjoins longitudinal channels that are designed to create
chemotactic gradients across the 3D culture width, while maintaining
uniformity across its ∼1 mm depth to enhance cell–biomaterial
interactions. This hydrogel-based open fluidic system is assessed
for its ability to direct migration of U87 glioma cells using a hybrid
hydrogel that includes hyaluronic acid (HA) to mimic the brain tumor
microenvironment and gelatin methacrylate (GelMA) to offer the adhesion
motifs for promoting cell migration. Chemotactic gradients to induce
cell migration across the hydrogel width are assessed using the chemokine
CXCL12, and its inhibition by AMD3100 is validated. This open-top
hydrogel-based fluidic system to deliver chemoattractant cues over
square-centimeter-scale areas and millimeter-scale depths can potentially
serve as a robust screening platform to assess emerging glioma models
and chemotherapeutic agents to eradicate them.