Authors:
Adlen Foudi, Konrad Hochedlinger, Denille Van Buren, Jeffrey W Schindler, Rudolf Jaenisch, Vincent Carey, & Hanno Hock
Summary:
Hematopoietic stem cells (HSCs) are thought to divide infrequently based on their resistance to cytotoxic injury targeted at rapidly cycling cells1, 2 and have been presumed to retain labels such as the thymidine analog 5-bromodeoxyuridine (BrdU). However, BrdU retention is neither a sensitive nor specific marker for HSCs3. Here we show that transient, transgenic expression of a histone 2B (H2B)–green fluorescent protein (GFP) fusion protein in mice has several advantages for label-retention studies over BrdU, including rapid induction of H2B-GFP in virtually all HSCs, higher labeling intensity and the ability to prospectively study label-retaining cells, which together permit a more precise analysis of division history. Mathematical modeling of H2B-GFP dilution in HSCs, identified with a stringent marker combination (L-K+S+CD48-CD150+)4, revealed unexpected heterogeneity in their proliferation rates and showed that 20% of HSCs divide at an extremely low rate ( 0.8–1.8% per day).
Source:
Nature Biotechnology; 27, 84-90 (12/05/08)