Cellularized hydrogel-interfaced cantilever (CHIC) biosensors for monitoring 3D cell culture mechanical properties

Sensors that employ and interface with cell-laden hydrogels can be used to identify novel cell signal transduction mechanisms, detect novel analytes, and test the effects of environmental perturbations on cell behavior, such as microgravity and drug exposure. Here, we report a novel cellularized hydrogel-interfaced cantilever (CHIC) biosensor for continuously monitoring the mechanical properties of 3D cell co-cultures in hydrogels. CHIC biosensors interfaced with 3D microporous annealed particle hydrogels laden with co-cultured fibroblasts and endothelial cells enabled monitoring of changes in the culture stiffness and the response to TGF-β1 stimulation over time via a mechanobiological transduction mechanism. 3D cell culture responses to the growth factor TGF-β1 (10 ng/mL) were associated with a change in the biosensor phase angle at resonance (ϕ). Long-term studies using CHIC biosensor arrays in a 3D co-culture assay over three weeks showed that TGF-β1 stimulation-induced changes in biosensor ϕ were consistent with changes in compressive modulus measured by an independent destructive testing method. The biosensor response and results of independent destructive mechanical characterization were corroborated by gene and protein expression analysis. The decrease in ϕ following TGF-β1 stimulation was correlated with upregulation of ACTA2, IL6, COL4A1, CXCL10, downregulation of MMP1, IL1R1, and CXCL8 in fibroblasts and endothelial cells. Meanwhile, expressions of PDGF-BB and IFN-γ remained elevated compared to the unstimulated control throughout the time course. This work establishes a new biosensor that enables mechanical property sensing of hydrogel-based 3D cell co-culture models.