Ito A, Nomura S, Hirota S, Suda J, Suda T, Kitamura Y
Department of Pathology, Osaka University Medical School, Japan.
Lab Invest. 1995 May;72(5):532-8.
Immunohistochemical studies have demonstrated that CD34 antigen is present on the surface of vascular endothelial cells and hematopoietic cells. Roles of CD34 for angiogenesis and its function as a homophilic adhesion molecule between endothelial and hematopoietic cells have been speculated.
Northern blotting was used to examine the expression levels of CD34 mRNA, and in situ hybridization was used to localize CD34 mRNA. First, we investigated changes in CD34 mRNA expression in developmental processes of mice. Second, we investigated the changes in skin tissues of adult mice in the process of wound healing and tumor growth.
CD34 mRNA was strongly expressed by most of the vascular endothelial cells in developing organs. The magnitude of the expression decreased after birth but increased again in the process of wound healing and tumor growth. Although CD34 mRNA signals were observed in hematopoietic cells in the yolk sac and fetal liver, the endothelial cells of these tissues did not express CD34 mRNA signals. CD34 mRNA signals were detectable in neither hematopoietic nor endothelial cells of the bone marrow. In tissues other than hematopoietic ones, however, blood cells within the vessels did not express CD34 mRNA, although the endothelial cells expressed CD34 mRNA.
The expression pattern of CD34 mRNA suggested its significant role in development of blood vessels not only in embryos but also in adults. Although CD34 mRNA was expressed both by endothelial cells and hematopoietic cells, the expression did not occur within the same organ, suggesting that the CD34 molecule may not be used as a homophilic adhesion molecule between endothelial and hematopoietic cells.
免疫组织化学研究表明，CD34抗原存在于血管内皮细胞和造血细胞表面。人们推测了CD34在血管生成中的作用及其作为内皮细胞和造血细胞之间的同种嗜性黏附分子的功能。
采用Northern印迹法检测CD34 mRNA的表达水平，采用原位杂交法对CD34 mRNA进行定位。首先，我们研究了小鼠发育过程中CD34 mRNA表达的变化。其次，我们研究了成年小鼠皮肤组织在伤口愈合和肿瘤生长过程中的变化。
发育器官中的大多数血管内皮细胞强烈表达CD34 mRNA。出生后表达量下降，但在伤口愈合和肿瘤生长过程中再次升高。虽然在卵黄囊和胎肝的造血细胞中观察到CD34 mRNA信号，但这些组织的内皮细胞不表达CD34 mRNA信号。骨髓的造血细胞和内皮细胞中均未检测到CD34 mRNA信号。然而，在造血组织以外的组织中，血管内的血细胞不表达CD34 mRNA，而内皮细胞表达CD34 mRNA。
CD34 mRNA的表达模式表明其不仅在胚胎血管发育中，而且在成体血管发育中均发挥重要作用。虽然CD34 mRNA在内皮细胞和造血细胞中均有表达，但在同一器官内不表达，提示CD34分子可能不作为内皮细胞和造血细胞之间的同种嗜性黏附分子。
