Lot qualification is required because of the difference in enzymatic/biochemical compositions between different lots of poorly defined, crude or enriched collagenase products. Replacing poorly defined collagenase with defined collagenase usually requires a single set of lot qualification experiments. Once the enzyme composition and dose is defined, then the same product and dose can be used in future cell isolations using different lots of the same product. Tight control over the collagenase and protease activity for these products allows different lots to be used with pre-qualification.
The above statements assume inbred strains of animals of same age, weight, sex, diet, etc… are used as a source of cells. This assumption does not apply when using humans or other outbred animals.