2D or 3D cells or cell models users often complain about the lack of reproducibility of their models, and therefore the lack of confidence in results from one batch to another. This recurrent drawback is inherent to either manufacturing or elaboration of models. However, it would be in the supplier’s interest to control and limit this variability.
Beneath is an example of twelve samples of the same batch of a reconstituted skin 3D model that we had to analyze. For each of the parameters tested, we highlighted in yellow the 3 highest values and in brown the 3 lowest values.
Result is largely visual, no need to be an experienced metabolicist to understand it. These twelve samples from the same batch highly differ metabolically from each other. However, based on the classical quality control he used, the manufacturer had judged them suitable for sale according to its acceptability criteria. It is therefore easy to understand that, depending on what he receives, the customer may observed different results when using these models.
This happens within the same batch. Anyone can easily imagine what can be observed from one batch to another.
So, for the manufacturer, there is a urgent need to improve its production processes to correctly satisfy its customers. If this is not possible, to keep customers happy, it is necessary to largely modify conformity criteria to avoid saling too different cells.
Cell suppliers must therefore get to know how his cells behave. To do this, samples from several production batches must be analyzed, establishing metabolic profiles of tested samples. From that measurements, production usual values are defined. Acceptable values (e.g. mean +/- 2 SD) for each of the parameters tested are determined. The peak analysis gives quantitative criteria that serve as a reference. The supplier can try to improve his processes and has now objective criteria for comparison. The aim is to reduce the observed deviations, showing a more homogeneous production.
If this is not possible, he may not sell batches with too large deviations.
The newly defined quality criteria become a guarantee of quality for its customers.
This analysis should become an integral part of the quality control of each production batch.
In liquid chromatography (HPLC), recurrent problems of reproducibility from one column to another are constantly found. Every manufacturer set up a quality criterion on an essential parameter, which is called theoretical column tray numbers. For each column, they now guarantee, with experimental proof, this number. Unsatisfactory columns are not sold. Since then, thanks to this approach, they have considerably improved their manufacturing processes. Users now buy a more reliable product, they have confidence.
For cellular models, the ideal virtuous circle may be close to that of HPLC. Supplier will sells cells, whose quality has been checked and found to be in line with usual manufacturing values. He gives to customer cell metabolic profile of what he sells, showing its conformity to the usual manufacturing values. The user will buy a more reliable product.
This is what we call « cell metabolic passport« .
Suppliers can then go further and verify how long or how many times the cell lines they sell will keep the metabolic profile they certify.
By purchasing his cell line, the client receives its metabolic passport. If he wants to keep his cell lineage for a long time, he will have to check its metabolic profile. If metabolic profile remains constant, results should remain homogeneous. If not, he cannot ascertain whether his results are homogeneous if the profile is very modified.