One common error with post thaw assesment
Question: We freeze hematopoietic stem cells and we getm uch higher viabilities than other centers that use the same protocol. Why are our number different?
Answer: In our experience post thaw assessment is performed incorrectly more than correctly. When preserving cells, please remember to measure yield (defined as the total number of viable cells post thaw divided by the total number of viable cells pre-freeze). During freezing, cells have three basic fates: (1) cells that are intact and viable; (2) cells that are intact but not viable; and (3) cells that are neiterh viable nor intact. Measurement of cell viability alone (typically defined as the number of viable cells post thaw divided by the total number of cells present) biases the measure of viability upward by failing to account for cells that have simply lysed and disappeared during the preservation process. Calculating both viability and yield helps to correct the bias and give you a more meaningful measure of post-thaw recovery of cells.
There are several other common erros that happen during post thaw assessment. We cover those common errors in our short course.
