Hematopoietic stem cells (HSCs) have self-renewal capacity and
multilineage developmental potentials. The molecular mechanisms
that control the self-renewal of HSCs are still largely unknown.
Here, a systematic approach using bioinformatics and array hybridization
techniques to analyze gene expression profiles in HSCs is described.
To enrich mRNAs predominantly expressed in uncommitted cell lineages,
54 000 cDNA clones generated from a highly enriched population
of HSCs and a mixed population of stem and early multipotent progenitor
(MPP) cells were arrayed on nylon membranes (macroarray or high-density
array), and subtracted with cDNA probes derived from mature lineage
cells including spleen, thymus, and bone marrow. Five thousand
cDNA clones with very low hybridization signals were selected
for sequencing and further analysis using microarrays on glass
slides. Two populations of cells, HSCs and MPP cells, were compared
for differential gene expression using microarray analysis. HSCs
have the ability to self-renew, while MPP cells have lost the
capacity for self-renewal. A large number of genes that were differentially
expressed by enriched populations of HSCs and MPP cells were identified.
These included transcription factors, signaling molecules, and
previously unknown genes.