[Comparative study of differentially expressed genes in mouse bone marrow and fetal liver cells]

Hematopoiesis undergoes several migrations from yolk sac to liver and spleen, and finally bone marrow until the end of life. A number of investigations have demonstrated that the hematopoietic microenvironment plays very important role in this process. However, the exact mechanisms remain unknown. In order to systematically analyze and understand the role of hematopoietic microenvironment in the regulation and control of hematopoiesis, a microarray containing 588 complementary DNAs was used to compare the gene expressions between those in murine fetal liver and bone marrow cells. The results obtained from array hybridization were analyzed and reconfirmed by using bioinformatics and RT-PCR as well as Northern blot. The results showed that 65 and 131 genes were relatively high expressed in bone marrow and fetal liver cells respectively among 588 known genes in the array-membrane. According to the survey in the PubMed, 39 out of bone-marrow-expressed genes and 71 in fetal-liver-expressed genes were closely related to the hematopoiesis. Further reconfirmation by RT-PCR or Northern blot has demonstrated that CD18, CD44 an d PSGL-1 genes chosen for analysis were highly expressed in adult bone marrow, but unexpressed or lower expressed in fetal liver cells, resulting in high similarity to the array results. Moreover, the expressions of CD18 and CD44 in fetal liver were down-regulated with the increment of gestational age. In conclusion, the gene expressions in bone marrow and fetal liver cells are obviously different, some of the genes are down-regulated at the different stages of ontogeny. The different gene expression levels between bone marrow and fetal liver, especially those genes closely related to the hematopoiesis, may be the molecular basis for the explanation of why hematopoietic stem cells derived from different tissues have different characterizations as well as the differences from the beginning and terminating of fetal liver hematopoiesis, and why hematopoietic stem cells derived from fetal liver is tremendously difficult to be grafted in bone marrow.