High ALDH activity: A novel functional marker of murine prostate stem/progenitor cells

We have shown previously that prostatic stem/progenitor cells can be purified from isolated prostate ducts, based on their high expression of the Sca-1 surface antigen. We now report that high levels of aldehyde dehydrogenase (ALDH) activity are present in a subset of prostate epithelial cells that co-express a number of antigens found on stem/progenitor cells of other origins (CD9, Bcl-2, CD200, CD24, prominin, Oct 3/4, ABCG2 and nestin). Almost all of these ALDH hi cells also express Sca-1 and a third of them express high levels of this antigen. The ALDH hi cells have greater in vitro proliferative potential than cells with low ALDH activity. Importantly, in an in vivo prostate reconstitution assay, the ALDH hi expressing cell population was much more effective in generating prostatic tissue than a population of cells with low enzymatic activity. Thus, high levels of ALDH activity can be considered a functional marker of prostate stem/progenitor cells and allows for simple, efficient isolation of cells with primitive features. The elucidation of the role of ALDH in prostate stem/progenitor cells may lead to the development of rational therapies for treating prostate cancer and benign prostatic hyperplasia.