Via1 Cassettes are the standard medium to perform “Viability and cell count Assays” in the NC-200 instruments. The cassettes are pre-loaded with a defined amount of lyophilized fluorescent dyes for staining live cells (acridine orange), as well as dead cells (DAPI). The staining of dead cells is accomplished by acidophilic binding of DAPI to AT rich regions in the DNA. In certain cell types and their associated treatments (CHO cells in long term reactor processes; T cells that have been frozen and thawed), staining of DNA can be tricky, due to partial degradation/disintegration of nuclear material. Therefore, viability readings can be inaccurate or inconsistent, and complaints about the issue have been reported by customers. To compensate for this, Via2 cassettes have been created, which contain a significantly higher amount (x3) of DAPI, thus increasing the sensitivity for staining DNA.
-To run the “Viability and cell count Assay” for Via2, the associated protocol must be imported in NV.
-The Via2 system on the NC-200 is only relevant for customers with this specific problem.
-The Via2 cassette is standard for the NC-202, as Bioprocessing units often encounter these problems.
How to explain the difference between Via1- and Via2 Cassettes
In order to avoid confusion in the customer base about when to use the Via2 system, it is important to clearly communicate its purpose. Via2 is not for everyone. Ask your clients about the problems they see in their viability readings, if you are approached. Scan for key words as described above (CHO, frozen T cells, long term cultures). Only mention Via2 yourself, when the key words check the box. If approached by customers directly about Via2, stick to the internal communication guide, which states: