Chapter 28 – Multipotent Adult Progenitor Cells

Publisher Summary This chapter aims to provide updated information regarding a rare cell population named multipotent adult progenitor cells (MAPC). While attempting to select and culture mesenchymal stem cells (MSC) from human and subsequently mouse and rat bone marrow (BM), a rare population of cells that has characteristics unlike most adult somatic stem cells in that they appear to proliferate without senescence and have broad differentiation ability in vitro and in vivo, was identified. MAPC can be cultured from mouse, rat, swine, and human bone marrow (BM). MAPC from all species are significantly smaller than their mesenchymal stem cell (MSC) counterpart, and differ phenotypically from MSC. Unlike most adult somatic stem cells, MAPC proliferate without obvious signs of senescence, and have active telomerase. In humans, the length of MAPC telomeres is 3–5 kB longer than in neutrophils and lymphocytes, which suggests that MAPC are derived from a population of cells that either has active telomerase in vivo, or that is highly quiescent in vivo, and therefore have not yet incurred telomere shortening in vivo. The challenge in MAPC isolation is that cells with morphological and phenotypic features of MAPC can only be detected in bone marrow cultures after several population doublings. It is still not determined whether MAPC exist as such in the freshly isolated bone marrow, or whether this cell phenotype is acquired via the culture process.