2. Flow Cytometry
A flow cytometer is used to determine the identify and size of specific cell populations in the product.
Example: CD34 Enumeration
The CD34 molecule is a cell surface antigen which exclusively identifies stem cells of the hematopoietic
system. The flow cytometeris used to enumerate this CD34 marker and identify the size of the stem cell
population in order to calculate the target dose.
3. Determining Cell Viability
Viability (proportion of living and dead cells) is an important indicator of the overall potency of the stem cell product.
Two methodologies are used to determine viability.
• Trypan Blue Dye Exclusion: Dead cells appear blue under the microscope as their damaged membranes allow
trypanbluedye to pass through, while live cells are colorless.
• Flow Cytometry: Fluorescent compounds penetrate dying and dead cell membranes and insert into the DNA.
The flow cytometer is able to accurately identify these dyed cells, and determine the viability of specific cell populations.
4. ABO / RH Typing
In order to help confirm identity, units are blood typed prior to processing.
5. Determining the Total Viable Nucleated Cell Count
An automated hematological analyzer is utilized to measure and differentiate cell types
in the stem cell product. This information is used to assess the processing efficacy and
quality of the product. The white blood cell count is often used as a release criteria, or
component of the cell dose calculation.
6. 14 Day Product Sterilities
An automated microbial detection system is used to monitor product
sterilities. Microorganisms present in the cultures release carbon
dioxide, triggering the instrument to alert the user that there is a positive
sample.
