[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.