Viability testing

What is cord blood viability testing?

Once extracted from the body, all cells including blood begin to degrade in such a way that the cells comprising it start to die over time. This is also true of umbilical cord blood. Studies have shown that at room temperature a sample will degrade exponentially over time, with the first 24 hours having the slowest level of degradation, increasing as time progresses. Please see the graphs below for an explanation. 

A living cell is also referred to as a viable cell. Measurement of the viability of a blood sample gives us an insight into the relative proportion of cells (in our case we are only interested in measuring the white or nucleated cells) which remain viable at that moment in time.

Thus, to ensure the highest possible number of viable cells present in a cord blood sample, we insist that all umbilical cord blood samples are processed within a 24 hour period from collection to storage. By performing cell viability studies at the time of processing we can provide our customers with clear evidence that the sample arrived with us in a satisfactory condition.

How is The Viability Testing Carried Out?

We use a relatively new type of Personal Cell Analyser (PCA) which allows the examination of whole blood rather than isolated cells.

To perform the test, a tiny quantity of cord blood is mixed with a staining solution containing two specialised dyes. One dye is taken up by dead cells, the other by living (or viable) cells. After a few minutes, the mixture is loaded into the machine and a laser is used to count the actual numbers of dead and viable cells. With these counted, the apparatus can determine with a high degree of accuracy the percentage viability of the nucleated cells in the cord blood sample and provide a hardcopy record of this data.

The viability testing machine produces the following graphs after scanning the sample. It gives a visual representation of the alive and dead cells. This is then calculated into a percentage.

Cells4Life are the only company to use a dedicated medical courier service who works 24 hours a day, 365 days a year ensuring that your sample is collected and processed within 12 - 24 hours. This is vital to avoid deterioration in sample quality which is highlighted in the example viability test results shown below.

Graph B shows that 83.9% of the cells are viable after 24 hours, Graph C chows that 70.9% of the cells are viable after 48 hours and Graph D shows that only 56.6% of the cells are viable after 72 hours.

The results of this example viability test are displayed in the form of a linear graph below. Viability testing is performed before freezing process to ensure sample quality.

There is always some level of deterioration in quality due to the freezing process which again highlights the necessity to collect and store the sample as quickly as possible to ensure a high level of initial viability before the freezing process.