Phenotypic and functional evidence that embryonic and adult HSCs express α4 integrin. (A) Adult and embryonic tissues have been analyzed for α4 integrin expression in their respective HSC-enriched populations. (Isotype control = filled curve; α4 integrin = empty curve.) (Ai) The CD45+VE-cadherin+ population, enriched with HSCs in the E11.5 AGM region,42,44 is α4 integrin+. (Aii) The lineage– c-Kit+Sca-1+CD11b+ population, enriched with HSCs in the fetal liver,45 is α4 integrin+. (Aiii) The lineage– c-Kit+Sca-1+ fraction, enriched with HSCs in the adult BM,29 is α4 integrin+. (B) α4 integrin+ (▦) and α4 integrin– (▴) fractions were isolated by flow sorting based on staining with anti–α4 integrin antibody and transplanted into irradiated recipient mice. Dead cells were excluded using 7-AAD. The percentage of mice repopulated out of the total number receiving transplants is indicated (for actual numbers of mice, see Table S1). ee indicates embryo equivalent; HSCe, bone marrow hematopoietic stem cell equivalent. (Bi) Uncultured embryonic tissues. (Bii) Cultured E11.5 AGM region. (Biii) Adult BM (unlysed erythrocytes were gated out).
