Potency assays in cell products development

by Alexey Bersenev on March 21, 2012 · 2 comments

in cell product

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The potency is an ability of the product to effect a given therapeutic result. This is extremely important characteristic of the cellular product, which should be taken in consideration in development phase.

For example, the potency assay for mesenchymal stromal cell-based product in non-union fracture could be an ability to osteogenesis. This assay could indicate the mechanism of therapeutic action of cellular product and could be used for quality control (stability) throughout manufacturing process. The potency of the product should not be compromised by passaging cells during the culture, by cryopreservation procedure or storage. Development of potency assay for the cell product will allow to go smoothly through all stages of regulatory process during clinical trial.

Unfortunately, there is a lack of literature and data on potency assays in cell therapy. I was happy to see a very nice comprehensive review on this subject in the recent supplemental issue of BioProcess International journal.

Potency measurement is especially important for complex products such as cellular therapies (CTs). It is considered an essential aspect of the quality-control system for a CT drug substance and drug product. It is performed to assure identity, purity, potency (also called strength in FDA documents), and stability of products used during all phases of clinical study as well as for licensed products.

The authors overview FDA guidelines for potency of cell products:

For approval of a biologics license application (BLA), CT products must meet the requirements of safety, purity, and potency prescribed in the above regulations. However, as stated in FDA’s guidance on CGT potency testing, “FDA regulations allow for considerable flexibility in determining the appropriate measurement(s) of potency for each product.” As is typical, the FDA evaluates the adequacy of potency tests for such cutting-edge products case by case.

The authors offer 13 steps to succccessful potency assays. These are very useful recommendations! For example:

4. Start designing and developing two (or possibly more) potency assays early — as early as during preclinical development is desirable. Developing at least two different methods increases your chances that one of them will be suitable for both your company and the regulators.

You can find a possible solutions to the frequent problems associated with potency assay development. Also, they discuss specific challenges for potency in cellular products, such as:

  • multiple and heterogeneous cell populations;
  • unknown or complex a mechanism of action;
  • limited lot size;
  • donor-to-donor variability;
  • lot-to-lot variability…

Throughout method development, no matter how complex the MOA is for a CT product, it is critical to keep in mind that selected potency markers should be present in potent cells but missing in subpotent or undifferentiated cells.

This review is highly recommended for cell therapy products developers!

{ 2 comments… read them below or add one }

hank May 22, 2015 at 12:44 am

I am looking at CD24 antigen in the Leucocyte Typing III book from Oxford, England 1986 meeting run by world class Immunologist like Carl Milstien, and John Gurdon ……From that workshop CD24 is an early pre B cells but also on T cells and myeloid cells , low on RBCs …..This could be a pivot cell surface antigen for cradle to grave diagnostics related to hMSC ….Most important it is not on epithelium…. This antigen is lost as cells mature on MHC I like NK cells knowing what I know I would like to look at bone marrow with CD34/CD38/C24 cells I can only do this in my head since I do not have a lab to test this …..

If we think like Galileo and make the MSC the center of the immune system vs. what most researchers focus on are the bone marrow and T cells or subset of them and do not get the big picture …..All this fits……

If ….and this is a big if ….You put mesenchymal cells as the center of microenvironment at the nano level ….. like the sun ( so lets call the sun/MSC the center) and the planets that circle the sun are different systems like the earth and moon is in our system …….and you could have one big planet like Jupiter and her moons ( we will call this one the hematopoietic stem cells system ), this includes all the intermediates of T , B, NK lymphocytes , RBCs , platelets, PMNs, basophils , Eosinophils and monocytes / macrophages? ……Remember that the dendrictic cells controls the CTLA -4 antigen and CD28 on /off switch for T cell proliferation….DCs are the go between of the innate and acquired immune system.

The link is macrophages to Jupiter’s system (CD34+ bone marrow) and the sun ( mesenchymal) which comes from subset of pericytes according to Arnold Caplan and Mike West that turns into mesenchymal cells….. the rest of the solar system is what most do not understand or study as these are fat cells , epithelial, fixed Macrophages, fibroblasts, Osteoblasts, chrondroblasts, osteoclasts, mesothelial, mast cells …… meat and bones in humans for movement etc. etc. etc…..

Understand I did not get into the nervous systems and the brain /mind…for another time….

When you have Jupiter ‘s forces (cells ) mixing with the arrays of the sun you have the total solar system that is affect when you bring in an injection of the earliest cell hMSC to reboot , rescue and repair back to homeostasis ……Now if….. hMSc can migrate as Lanza has told us and I believe him…. until they anchor into one of the solar systems …..Mars, Venus, Earth whatever …

What happens next humans get old by forces and chronic inflammation that alter genes by SNP and the old adult MSC reverts back to the early hMSC like cells and the NK do not kill it off and they start to migrated and do not become apoptotic and die at the microenvironment sites… we get what us humans call cancer and the adult MSC (metastatic process) and auto immune diseases IMO ……and other scientist are calling these old migrating MSC, Cancer Stem Cells , but when you ask what they are…. they can not identify them by bioassays or bio-processes ….. The only thing that will kill cancer stem cells totally are cytotoxic T cells or NK directed by antigen presentation by dendritic cells …….Yes, chemo and radiation and surgery might work for some or indirect boost an immune response…..

flow assay to determine MSc potency CD10/ CD24/CD44/CD133/Stro-1

…LOL all IMO of course

Page 89 Figure 4.45 of Immunology : The science of Self-Nonself Discrimination by Jan Klien 1982…..Cell Type derived from undifferentiated or partially differentiated mesenchymal cells

This one here has a definition in the abstract and raises topics we’ve discussed here before, including MSCs and EMT: Cancer stem cells

“Cancer stem cells (CSCs) are a small subpopulation of cells within tumors with capabilities of self-renewal, differentiation, and tumorigenicity when transplanted into an animal host. A number of cell surface markers such as CD44, CD24, and CD133 are often used to identify and enrich CSCs. A regulatory network consisting of microRNAs and Wnt/β-catenin, Notch, and Hedgehog signaling pathways controls CSC properties. The clinical relevance of CSCs has been strengthened by emerging evidence, demonstrating that CSCs are resistant to conventional chemotherapy and radiation treatment and that CSCs are very likely to be the origin of cancer metastasis. CSCs are believed to be an important target for novel anti-cancer drug discovery. Herein we summarize the current understanding of CSCs, with a focus on the role of miRNA and epithelial–mesenchymal transition (EMT), and discuss the clinical application of targeting CSCs for cancer treatment.”

Int J Biochem Cell Biol. 2012 Dec;44(12):2144-51. doi: 10.1016/j.biocel.2012.08.022. Epub 2012 Sep 2.



Alex Brown May 28, 2015 at 2:30 pm

I like your analogy, placing MSCs as the center of a Mesenchymal-solar system is an interesting perspective.


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