The Importance of Stem Cell Toxicity Testing
In the adult, the stem cells make up 0.01% or less of the total number of cells in the bone marrow. The stem cells that give rise to the 8 primary blood cell lineages (red blood cells, platelets, neutrophils, basophils, eosinophils, macrophages, T- and B-lymphocytes) are the most important because they are responsible for producing all of these functionally mature cells throughout our lifetime. Without the stem cells, blood production would not occur and we would die.
The blood stem cells are responsible for producing about 1 million red blood cells and 200,000 white blood cells every second of our lives. Stem cells can only exhibit this incredible feat because of their amazing ability to proliferative. Indeed, the stem cells have the greatest ability to proliferate.
However, there are different types of stem cells. Some are very primitive, while others are much more mature and are ready to enter into one or other of the different blood-forming lineages. Those stem cells that are primitive are in a state of quiescence; they are not proliferating or dividing. And of the mature stem cells, only a small proportion of them are actually in a state of proliferation. This saves the blood-forming system from using all of its capability at once, because it must be stretched out over the lifetime of the person or animal.
Once a stem cell has decided, or is induced, to begin the process of proliferation, it becomes very accessible to agents that can either modify it or kill it. Some agents do not even need cells to be in proliferation in order to damage them. If the function of the stem cell is modified, the DNA of the cell can be changed and it is possible that the cell may enter a state of tumorigenesis that eventually can lead to a malignant state. If the stem cell and others like it are killed by an agent, the effect will eventually be amplified in a negative manner so that insufficient circulating cells will be produced leading to various clinical deficiencies, such as anemia, neutropenia and thrombocytopenia.
The stem cells, together with their immediate progeny, the progenitor cells, are the most sensitive to toxic agents. For this reason, testing the effects of compounds and other agents on stem and progenitor cells is the best way to detect potential toxicity to the lympho-hematopoietic system.
At HemoGenix®, we specialize in in vitro stem cell hemotoxicity testing and have developed a number of validated assays that can predict various aspects of toxicity to the blood-forming system. We provide both a Full Contract Service and an extensive Assay Kit Product Line for this purpose. The in vitro platform capable of providing you with this information is called HALO® or Hemotoxicity Assays via Luminescence Output.
