2.5 Cell density and viability measurements
Cell counts and viability measurements were performed immediately post-sampling using an automated cell counting and viability measurement system i.e. Vi-cell XR Cell Viability Analyser (Beckman Coulter, Brea, California, United States). Briefly, a 0.5 – 1 mL of cell suspension was aliquoted into a Vi-Cell cup (Beckman Coulter, Brea, California, United States) which was then run on the Vi-Cell system to determine cell counts and viability measurements by trypan blue exclusion.