Aging hematopoietic stem cells decline in function and exhibit epigenetic dysregulation Chambers, S.M. et al. PLoS Biol. 5, e201 (2007) This article by Margaret Goodell and others finds that blood stem cells are not protected from aging and argues that aging is driven partly by loss of proper epigenetic regulation.

Long-term propagation of distinct hematopoietic differentiation programs in vivo Dykstra, B. et al. Cell Stem Cell 1, 218–229 (2007). This article by Connie Eaves and colleagues describes distinct sub-populations of blood stem cells, previously considered to be more uniform in function.

Host defense linked to hematopoietic stem cell proliferation Feng, C. et al. Cell Stem Cell (in the press). In this forthcoming article in Cell Stem Cell, Goodell and others show how the enzyme p47 GTPase Lrg-47 (Irgm1) connects immunity and stem cell proliferation.

Genome-wide maps of chromatin state in pluripotent and lineage-committed cells Mikkelson, T.S. et al. Nature 448, 553–560 (2007). A technical tour-de-force from Eric Lander and Bradley Bernstein maps histone modifications in embryonic stem cells and in differentiated cells and allows some fascinating observations.

Adult human cells reprogrammed to pluripotency Baker, M. Nat. Rep. Stem Cells; published online 6 December 2007; A series of papers describes how introduced genes can send cells back in development.

The molecular anatomy of spontaneous germline mutations in human testes Qin, J. et al. PLoS Biol. 5, e224 (2007). This article from Norman Arnheim and others shows that positive selection for mutations in germ line stem cells can be selected for in the testes and have deleterious effects on offspring.