In answer to your question, the cells don't need to be frozen down immediately. My understanding is that once the mesenchymal precursor cells (MPC's) are isolated from bone marrow donors, those cells are then expanded in cell culture without any differentiation into other lineage types. MSB can then use this pool of MPC's to derive their mesenchymal stem cells (MSC's), which can then be maipulated via MSB's "proprietary methods" (which I suspect is a cocktail of specific growth factors, cytokines, and/or monoclonals used to differentiate the MSC's into mesenchymal lineage cells (MLC's)). All of this is done in cell culture, and depending on demand at the time, the various MLC's can either be re-suspended immediately into the final product for clinical use, or if they have an excess of cells, those can be frozen away for storage until needed.
As for the actual shelf life once the cells have been harvested from culture and prepared for clinical use, I'm afraid I don't have any real experience with that side of things. Someone else on here mentioned 48 hours, which seems about right. I imagine the shelf life would be comparable to other nucleated cells such as white blood cells, which are generally used within 24 hours. So 24-48 hours seems reasonable.
But basically, its actually quite easy and relatively cheap to maintain and expand cell stocks. One of the advantages to cell-based therapies in comparison to conventional drugs is that unlike synthetic drugs, cells manufacture themselves (through cell division) in an incredibly efficient manner. Imagine if you designed a drug that could replicate itself ad infinitum. That's basically what we are looking at here. There are some limitations of course. You still have to provide the appropriate growth medium, antibiotics (to prevent microbial contamination of the culture), and nutrients, some of which can be expensive, especially the fetal calf serum (FCS). MSB also apparently utilizes monoclonal antibodies during the culturing process in order to isolate/purify their MPC's. Monoclonal antibodies are notoriously expensive. A single 1mg vial of antibody can cost anywhere between $5000 and $10000 AUD. A standard 1L bottle of FCS can cost around $3000 AUD. So while the cells themselves are relatively easy and cheap to acquire and maintain, the reagents required to do so can be very expensive.
I suspect this is where at least some of the money from the recent CR went to.
One thing I'm not clear on is whether MSB has tried to immortalise their MSC stocks, which would enable them maintain a potentially infinite amount cell stocks at very little cost, which would mean they would no longer require bone marrow donors to replenish their inventory. This would provide them with a huge manufacturing advantage and help cut down production time and cost significantly. I strongly suspect they have avoided this due to concerns about genetic drift, hence why they are sticking to Primary Cell Culture methods for now.
I'd be very interested to know if MSB has made any efforts at trying to move towards a secondary culture system, and looking at the degree of genetic drift between primary and secondary cells, and whether or not this would have any clinical impact. This issue could potentially be mitigated by keeping the passage number (the number of times a cell culture has been subcultured) as low as possible.
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