Oxygen is an important environmental factor, which has received rather little attention in culturing stem cells and other progenitor cells. In November Journal of Cellular Physiology, Marie Csete and colleagues from University of Michigan Medical School, Ann Arbor, US, show that too much oxygen can kill stem cells, slow growth and even trigger an alternate developmental pathway that converts pre-muscle stem cells into fat cells.

Csete et al. examined the effects of O₂ levels on the adult skeletal muscle fiber progenitors (satellite cells), and cell lines that model multipotential embryonic paraxial mesoderm from which skeletal muscle develops. They found that both satellite cell proliferation and survival of mature fibers increased in physiologic (6%) O₂ compared to non-physiologic 20% O₂ — used in most traditional cell culture systems. In addition, satellite cells gained a significant adipocyte phenotype in the 20% O₂ environment, a phenomenon not...