ABSTRACT
Mesenchymal stem cells, also known as multipotential stromal cells, are progenitor cells for mesenchymal lineages and may be isolated from several sources. MSCs have been isolated from many species, from mouse through humans, including rat, guinea pig, rabbit, dog, goat, pig, horse, macaque, and baboon; all have similar properties. Most of the information in this chapter applies to MSCs from rat through humans. Unfortunately, the mouse and all its attractive mutant strains have proven to be the most dif‹cult species to work with as mouse MSC proliferation is always accompanied by hematopoietic cells, and ‹nal puri‹cation by immunoselection is needed. The human MSCs have been routinely isolated from bone marrow as it is thought this tissue is a renewable source that can be harvested with limited tissue trauma (unlike bone, skin, muscle, etc.). MSCs are rarer than HSCs in bone marrow; for comparison, HSCs constitute about 0.1% of the nucleated cells in bone marrow, while MSCs are present at 0.01-0.001%. However, MSCs expand readily in proper culture conditions, while HSCs are more dif‹cult to expand by in vitro culture.
