脐血CD34+细胞体外扩增时HOXB4基因表达的变化

同源盒基因家族成员HOXIM反映原始造血干／祖细胞（PHSC／PHPC）的自我更新和增殖能力。本研究采用实时定量RT—PCR的方法在mRNA水平上检测HOXIM基因的表达，以观察体外扩增脐血CD34^＋细胞自我更新的水平。结果显示：随着体外培养时间的延长，虽然CD34^＋细胞数增加，但HOXB4表达下降；周后，HOXB4几乎检测不到，与成熟外周血淋巴细胞表达HOXIM的水平相同；CD34^＋细胞与骨髓间充质干细胞（BM—MSC）共培养可以减缓CD34^＋细胞HOXIM表达的下降。结论：脐血CD34^＋细胞体外扩增过程中自我更新能力逐渐下降。CD34^＋与BM—MSC共培养有助于减缓体外扩增的CD34^＋细胞自我更新能力的丧失。

Expression of HOXB4 in Cord Blood Progenitor Cells Expanded in vitro

HOXB4, a member of homeobox gene family, is closely related to the self-renewing and proliferative ability of primitive hematopoietic stem/progenitor cells(PHSC/PHPC). This study was aimed to investigate the self-renewing level of cord blood progenitor cells (CBPC) expanded in vitro. The HOXB4 expression at mRNA level was assayed by using real time RT-PCR. The results indicated that as culture prolonged, the total cells, CD34~+ cells greatly increased, however the HOXB4 expression gradually declined, even down to undetectable level similar to that of mature lymphocytes. Meanwhile, it was shown that CD34~+ cells co-cultured with bone marrow mesenchymal stem cells (BM-MSC) could abate the decline of HOXB4 expression. It is concluded that the self-renewing potential of CD34~+ cells gradually decreased during expansion in vitro, co-culture with BM-MSC was helpful to CD34~+ cell expansion and slowed the loss trend of its self-renewal.