High-Throughput, Time-Resolved Mechanical Phenotyping of Prostate Cancer Cells.

Worldwide, prostate cancer sits only behind lung cancer as the most commonly diagnosed form of the disease in men. Even the best diagnostic standards lack precision, presenting issues with false positives and unneeded surgical intervention for patients. This lack of clear cut early diagnostic tools is a significant problem. We present a microfluidic platform, the Time-Resolved Hydrodynamic Stretcher (TR-HS), which allows the investigation of the dynamic mechanical response of thousands of cells per second to a non-destructive stress. The TR-HS integrates high-speed imaging and computer vision to automatically detect and track single cells suspended in a fluid and enables cell classification based on their mechanical properties. We demonstrate the discrimination of healthy and cancerous prostate cell lines based on the whole-cell, time-resolved mechanical response to a hydrodynamic load. Additionally, we implement a finite element method (FEM) model to characterise the forces responsible for the cell deformation in our device. Finally, we report the classification of the two different cell groups based on their time-resolved roundness using a decision tree classifier. This approach introduces a modality for high-throughput assessments of cellular suspensions and may represent a viable application for the development of innovative diagnostic devices.

Detection of biliverdin reductase activity.

The conversion of biliverdin to the bile pigment bilirubin is catalyzed by biliverdin reductase, a cytosolic enzyme with two pH optima with different cofactors. The enzyme is assayed at pH 8.7 with NADPH as a cofactor and at 6.75 with NADH. The production of bilirubin is detected as described in this unit with a spectrophotometric assay. The enzyme can be qualitatively assayed by immunoblotting and changes in reductase isoform expression can be detected by two-dimensional electrophoresis.