Age-dependent depletion of human skin-derived progenitor cells.

A major unanswered question in autologous cell therapy is the appropriate timing for cell isolation. Many of the putative target diseases arise with old age and previous evidence, mainly from animal models, suggests that the stem/progenitor cell pool decreases steadily with age. Studies with human cells have been generally hampered to date by poor sample availability. In recent years, several laboratories have reported on the existence, both in rodents and humans, of skin-derived precursor (SKP) cells with the capacity to generate neural and mesodermal progenies. This easily obtainable multipotent cell population has raised expectations for their potential use in cell therapy of neurodegeneration. However, we still lack a clear understanding of the spatiotemporal abundance and phenotype of human SKPs. Here we show an analysis of human SKP abundance and in vitro differentiation potential, by using SKPs isolated from four distinct anatomic sites (abdomen, breast, foreskin, and scalp) from 102 healthy subjects aged 8 months to 85 years. Human SKP abundance and differentiation potential decrease sharply with age, being extremely difficult to isolate, expand, and differentiate when obtained from the elderly. Our data suggest preserving human SKP cell banks early in life would be desirable for use in clinical protocols in the aging population.