Credit: Graham Paterson, Children's Hospital Boston
Innate Sca-1 Protein Concentration in a Population of Stem Cells: (A) The concentration Sca-1 protein, a marker of "stemness," varies greatly in a population of stem cells, though the most common concentration is toward the middle of the range. (B) If the population of stem cells is divided into three groups (low, medium and high Sca-1 level), and those cells are allowed to divide and grow, (C) each group of descendents will reproduce the original range of Sca-1 concentrations. This suggests that populations of stem cells, though genetically identical, have an innate variability that may provide the basis for stem-cell differentiation. This variability could be tapped to increase the efficiency of stem-cell differentiation for therapeutic purposes.