血管生成素1在G-CSF诱导的造血干／祖细胞动员中的表达变化

OBJECTIVE: To investigate the changes and mechanism of angiopoietin1 (Ang1) in murine bone marrow during G-CSFinduced mobilization of hematopoietic stem/progenitor cell. METHODS: The proportion of Lin(−)Sca1(+)cKit(+)(LSK) cells in peripheral blood of C57BL/6 mice before and after G-CSF mobilization was detected by flow cytometry. Expression changes of Ang1 and osteocalcin (OCN) during HSC mobilization were determined by immunohistochemistry, enzyme linked immunosorbent assay (ELISA) and real-time fluorescence quantitative PCR. The number of osteoblasts in the bone marrow was counted under the microscope. RESULTS: After treated with G-CSF, the proportion of LSK cells in peripheral blood significantly increased from the controls (0.04±0.01)% to (0.61±0.05)% at day 5 (P< 0.05). Before G-CSF mobilization, the endosteum cells expressed higher level of OCN and Ang1 than that of bone marrow nucleated cells. The mRNA expression level of OCN was significantly reduced from 28.64±8.61 in the controls to 12.55±7.06 on day 3 and 4.75±1.62 on day 5, and the expression level of Ang1 also declined from 2.84±0.95 in the controls to 0.93±0.30 on day 3 and to 0.92±0.22 on day 5 after G-CSF mobilization. The number of endosteum osteoblasts was significantly decreased after mobilization (P< 0.05). The Ang1 expression was decreased in the BM after mobilization. The serum OCN was significantly reduced from (24.11±3.17) ng/ml in the controls to (9.96±2.16) ng/ml on day 3 and (8.43±2.62) ng/ml on day 5, and the Ang1 also declined from (2.24±0.52) ng/ml in the controls to (1.21±0.38) ng/ml on day 3 and (0.90±0.24) ng/ml on day 5. CONCLUSION: In G-CSFinduced HSPC mobilization, the bone marrow osteoblasts retraction causes reduction of Ang1, and the reduction of Ang1 may contribute to HSPC mobilization.