Roche Cedex HiRes, Руководство оператора

Страница: 27 / 166

21
Overview
A
A
2 The Measurement Procedure
The determination of the number of viable cells (cells/ml) and viability of cell suspensions (the percentage
of viable cells from the total cell sample) is a fully automated, standardized procedure based on the manual
Trypan Blue Exclusion Method. A defi ned volume of Trypan Blue is added by the syringe to the Cedex Sample
Cup containing the cell suspension. The cell suspension and dye are optimally mixed between the syringe and
Cedex Sample Cup by controlled pump actions and then incubated for exactly the same amount of time for
each measurement. This minimizes effects on the viability measurements that might be caused by the toxicity
of the Trypan Blue.
After the incubation period, the stained cell suspension in the syringe is then transported in one portion via
the capillary tubes and the 8-way valve into the precision fl ow chamber, an image of which is scanned with the
scanner. The scanned image of the fl ow chamber is then cut up into smaller images for evaluation.
Once the measurement procedure is completed, a cleaning routine is automatically per formed by the Liquid
Management system. It is only possible to begin a new measurement after the cleaning routine has fi nished.
The Trypan Blue Exclusion Method
The Trypan Blue Exclusion Method is based on the principle that viable cells will not take up the dye, while
dead or dying cells have a compromised membrane that allows for the up take of the dye. Thus, dead cells will
appear darkly stained.
Trypan Blue has a greater affi nity for serum proteins than cellular proteins. If the image has a dark
background due to high quantities of stained serum proteins, centrifuge the cell sample and resuspended it in
a protein-free medium or physiological saline solution prior to counting.
The Measurement Procedure