Trypan blue stained cells. Dead (blue) and alive cells.
Testing viability of cells in a bioreactor with the traditional Trypan blue method is labour intensive, invasive and can’t be easily automated. The National Institute for Bioprocessing Research and Training (NIBRT) in Ireland has successfully tested two new techniques for monitoring cell health without the need for invasive procedures.
The researchers at the institute explored optical and dielectric techniques to track cell metabolism, finding them as effective as the commonly used industry methods. Michael Butler, a leading researcher in cell technology at NIBRT, stated that the results from J.M. Canty’s PHARMAFLOW™ and ABER Instruments’ Cell Capacitance Technology matched those of traditional approaches.
Trypan blue
A traditional method is to take a sample from a bioreactor, treat it with Trypan blue dye, and then analyze it using an instrument that differentiates between stained and unstained cells. However, this process has several drawbacks. It requires manual handling by technicians, is difficult to automate, and involves removing cells from the bioreactor and applying dye, making it invasive.
Digital images of cells
In contrast, Canty’s PHARMAFLOW, which NIBRT collaborated on, automatically takes digital images of cell samples. These images are processed by software that evaluates up to 40 morphological features, such as cell size, shape, and roundness. Using an AI-based approach, the system can identify which cells are alive and which are not. Butler mentioned that the PHARMAFLOW’s results are comparable to those obtained through the Trypan blue method. This collaboration even earned the Pharma Project of the Year award at the Irish Pharma Industry Awards.
Electrical capacitance
The second method involved measuring electrical capacitance using a sterile probe from ABER Instruments. This probe detects the number of cells in an electric field by measuring capacitance — the more cells present, the higher the capacitance. It can either be set to a single frequency or sweep through a range from 0.1 to 10 MHz, capturing a profile of the cell population. The curve that shows how capacitance declines at higher frequencies provides insights into the cells’ metabolic activity. According to Butler, this method can reveal changes in cell health sooner than the Trypan blue technique, allowing for earlier decisions about ending a production run.
Looking ahead, the NIBRT team plans to explore more advanced, less-established technologies for automated, noninvasive monitoring, such as Raman scattering. Traditionally used to analyze metabolites during bioprocessing, this method could further enhance the automation and accuracy of cell monitoring
Bron: GEN Edge