Comparative analysis of gene expression in CD34⁺ subpopulations from adult BM, cord blood (CB), and fetal liver (FL).

Panel A shows a representative Southern blot analysis of cDNAs for 7 genes expressed in the matching CD34⁺CD38⁻ and CD34⁺CD38⁺ subpopulations isolated from 2 different samples of each tissue. Panel B shows the results of a quantitative comparison of the different levels of transcripts in the CD38⁻ and CD38⁺ subsets of CD34⁺cells obtained from a total of 3 samples of each different tissue. In each case the value shown is the mean ± SEM of the normalized gene-specific transcript levels in the CD34⁺CD38⁺ subset expressed as a fraction of the levels measured in the matching CD34⁺CD38⁻population (set = 1.0) as described in the “Materials and methods.” Panel C shows a quantitative analysis of the relative levels of expression of the same genes as shown in panel B but, in this case, comparing the results for the CD34⁺CD38⁻ subset in CB and FL with the CD34⁺CD38⁻ data from adult BM examined on the same filter. The result for the CD34⁺CD38⁻cells from each sample (panel B) was thus first normalized and then expressed as a proportion of the average value obtained for all adult BM CD34⁺CD38⁻ samples analyzed using the same probe (average value set = 1.0, n = 5). In panels B and C, significant differences between the test and the reference population (P < .05) are indicated by an asterisk (*).