We’re staring a new series of posts “Not Lost in Translation“. In this series, we will try to bridge the translational gaps between scientific discovery in research labs and clinical cell applications for therapies. We will look at challenges in translation of cell product development and manufacturing in academic and industry settings. I’d like to invite professionals to support or/ and contribute by writing a problematic post for this series. Please contact us!
Today I’d like to talk about “clinical grade” conditions for cell culture. From research cell culture to therapeutic cell product. How can we get there?
If you’re researcher, I’d like to ask you: “Have you ever thought about potential clinical application of your cells?” If so, do you know how to get there? Is there any guidance and written protocol? The problem is that we don’t have this kind of information, available right now in simple and accessible form. These kind of issues have been discussed among professional on conferences and meetings. I’d like to highlight some considerations, which should be taken in account for translation of research cell culture protocol to potential clinical application. So, how can you get clinical grade?
1. Animal products-free cell culture
This is the first and the most important principal of clinical grade cell culture. Almost all research labs are using variety of animal products for cell culture – serum, feeder (supporting) cells, proteins and supplements. Once you start to think about potential clinical application of your cells, you have to test “animal (xeno)-free conditions”. Try animal- serum-free, feeder-free and supplements-free condition. You can try to replace animal serum and supplements by human analogs or by completely synthetic components. Try to replace feeder cells by extracellular matrix (ECM) mimetic. You have to test multiple xeno-free condition and pick the one, which is not affecting your critical cell culture characteristics.
Some benefits of xeno-free clinical cell culture:
- no risk of animal pathogenes (including infectious agents) transfer;
- minimizing a risk of immune reactions;
- avoiding the problem of limited availability of animal components (ex: “peak serum“);
- avoiding batch-to-batch variability and, therefore increasing robustness and reproducibility.
Despite the fact, that animal serum is still not prohibited by regulatory agencies for clinical cell culture, the trend toward completely animal-free settings is very strong and the era of xeno-free culture is inevitable.
2. Reagents and devices for human/ clinical use
Cell culture media, reagents (including growth factors, enzymes, cell separation reagents…), supplements and devices should be approved and labeled “for clinical use“. Alternatively, labels could be the following:
- “for human use”
- “clinical grade”
- “USP” and “pharmaceutical grade”
- “for clinical cell processing”
- “for infusions”/ “for injections”
If you maintain your cells in culture with recombinant cytokines and growth factors in research lab, you should find out if there is any analogs of these reagents, approved for use in human and try it. Some reagents may not be approved for clinical use and you may look for alternatives. You have to be prepared for these kind of challenges.
3. Scalability and full characterization of cell culture
This principle means “knowing everything about your cells“. Phenotype, genotype, function, growth kinetics. For the cell growth kinetics, you have to know the following variables:
- Scalability / expansion – how much cells can multiple in your culture;
- Population doubling level (PDL) – number of times your cells have doubled since primary isolation for culture;
- Passage number – how many times you can subculture (remove cells from one culture vessel and seed in another) your cells without exhaustion;
- Viability (and apoptosis) in dynamics.
Scalability is essential, because even for personal clinical use (autologous therapy) you will need to get much more cells than you used to grow in research lab. Critical cell culture characteristics (phenotype, function, cell number, viability) should be assessed with every passage or daily or at certain time points.
4. Reproducibility and robustness of cell culture protocol
If you want to translate your research culture to clinical use, you have to make sure that your protocol is easily reproduced by few (or many) people in few (or multiple) labs. Robustness means minimizing a heterogeneity and variability of cell culture from day-to-day and from one batch/ lot of reagents to another. So, your cell culture protocol should be robust and highly reproducible.
These were 4 major principles, which you can implement in order to translate your research cell culture to future clinical use. Please share your thoughts and experience with us!