Mechanical Characterization of 3D Ovarian Cancer Nodules Using Brillouin Confocal Microscopy



The mechanical interaction between cells and their microenvironment is emerging as an important determinant of cancer progression and sensitivity to treatment, including in ovarian cancer (OvCa). However, current technologies limit mechanical analysis in 3D culture systems. Brillouin Confocal Microscopy is an optical non-contact method to assess the mechanical properties of biological materials. Here, we validate the ability of this technology to assess the mechanical properties of 3D tumor nodules.


OvCa cells were cultured in 3D using two established methods: (1) overlay cultures on Matrigel; (2) spheroids in ultra-low attachment plates. To alter the mechanical state of these tumors, nodules were immersed in PBS with varying levels of sucrose to induce osmotic stress. Next, nodule mechanical properties were measured by Brillouin microscopy and validated with standard stress–strain tests: Atomic Force Microscopy (AFM) and a parallel plate compression device (Microsquisher). Finally, the nodules were treated with a chemotherapeutic commonly used to manage OvCa, carboplatin, to determine treatment-induced effects on tumor mechanical properties.


Brillouin microscopy allows mechanical analysis with limited penetration depth (~ 92 µm for Matrigel method; ~ 54 µm for low attachment method). Brillouin microscopy metrics displayed the same trends as the corresponding “gold-standard” Young’s moduli measured with stress–strain methods when the osmolality of the medium was increased. Nodules treated with carboplatin showed a decrease in Brillouin frequency shift.


This validation study paves the way to evaluate the mechanics of 3D nodules, with micron-scale three-dimensional resolution and without contact, thus extending the experimental possibilities.

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This work is supported in part by the National Institutes of Health (R00 CA175292, R33CA204582 and U01CA202177), National Science Foundation (CMMI-1537027). The authors also acknowledge funding from the Burroughs Wellcome Career Award at the Scientific Interface (to KMS).

Conflict of interest

The authors, Christina Conrad, Kelsey M. Gray, Kimberly M. Stroka, Imran Rizvi, and Giuliano Scarcelli declare that they have no conflict of interest.

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No animal or human studies were carried out by the authors for this article.

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Correspondence to Imran Rizvi or Giuliano Scarcelli.

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Conrad, C., Gray, K.M., Stroka, K.M. et al. Mechanical Characterization of 3D Ovarian Cancer Nodules Using Brillouin Confocal Microscopy. Cel. Mol. Bioeng. 12, 215–226 (2019).

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  • Tumors
  • Osmolality
  • Young’s modulus
  • Stiffness
  • Spheroids
  • Optics
  • Atomic force microscopy
  • MicroSquisher