In some tissues like the skin, there are numerous stem cells and progenitor cells unlike cardiac tissue with rare stem cells.
Also in the repair situation the count of progenitor cells (and maybe stem cells) become more.
How can we know the percent of stem cells and progenitor cells count (which involve cell cycle and mitosis process ) in each tissues in the normal condition?
The only way I see - as in almost all tissues apart from bone marrow there is no specific stem cell marker - the only way is to establish a cell culture procedure and look for clonogenic, i.e colony-forming cells. They may not reflect the true number of stem cells, but will allow for the estimation of relative changes.
W.
I would add to Wolfgang Doerr's answer that for colony-forming cells (clonogenic) one must set the minimum number of divisions reasonably above 7, e.g., maybe 10. This is to avoid including Amplifying Transit Cells (ATCs) in the supposed Stem Cell count. Above 7 because this is the number of divisions done by an erythroblast, the post-hematological-stem cell lineage-committed progenitor cell. In my Hybrid Spheroid Assay for Cancer Stem Cells (CSCs), we look for colonies representing at least 10 divisions as putative CSCs, and those usually do 15 divisions before exhausting the well nutrients.
Dear Christopher,
I agree. But ... in the usual clonogenic assay, as I am sure you know, we count colonies with >50 cells as a progeny of a clonogenic, i.e. "stem" cell, which means 5-6 divisions. This is the rule at least in radiation biology, for most of the "expected" tissue stem cells. We measured what we call abortive divisions of already dead cells in oral mucosa in vivo, and came to a number of 3-4 maximum.
Open for further discussions.
Best Wolfgang
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