The Innovation

This patent application concerns an automated image-based method for determining whether particular cells in a sample are live or dead. It’s based on the trypan blue dye exclusion test, used in cytometry to count and characterize biological cells. The method involves tagging cells with Trypan blue dye, taking a series of digital images at different focus planes, and using a specially programmed computer to identify and analyze cells in these images to characterize them as live or dead.

Technical Contribution

The application’s method automates the cell characterization process using a series of steps. These steps include tagging cells with Trypan blue dye, forming a series of digital images, and automatically identifying a digital image at the plane of best focus by evaluating a contrast metric. The application improves accuracy by determining the live or dead status of cells not necessarily at the plane of best focus for each cell. It also considers cell drift in the imaging process, assigning scores to objects in the images to identify the cells. The method is noted for improving the accuracy of determining whether particular cells are live or dead, exploiting multiple available images in a computationally efficient manner, and allowing for the use of low-cost imaging options. This approach addresses the challenge where no single digital image is accurate for both total cell counting and live cell characterization (“Reasons no. 11”).

Key Findings

• Tagging cells with Trypan blue dye – technical
• Forming a series of digital images at different focus planes – technical
• Automatically identifying a digital image at the plane of best focus – technical
• Evaluating a contrast metric for identifying the best focus image – technical
• Automatically analyzing images to characterize cells as live or dead – technical
• Considering cell drift and assigning scores to objects in images – technical

Read the full decision here: T 0302/19 (Cell characterization/BIO-RAD) 21-12-2023