Objective      To establish mesenchymal stem cells (MSCs) expressing SDF-1

HOXB4 and SDF-1/HOXB4 fusion gene respectively

and to compare their effects on the amplification and stemness main-tenance of umbilical cord blood CD34

+

cells in vitro.       Methods      The SDF-1/HOXB4 fusion gene was synthesized

based on whic

h SDF-1 and HOXB4 gene were obtained by PCR

and adenovirus vectors respectively expressing above gene fragments were constructed. Virus particles were packaged in 293A cells and the titer of the virus was determined. MSCs infected with different virus supernatants were divided into a SDF-1 group

a HOXB4 group and a SDF-1/HOXB4 fusion gene group (S-H group)

and MSCs infected with the adenovirus lack of target genes was used as control. The mRNA and protein expression of exogenous genes were detected. The 4 groups of MSCs were co-cultured with umbilical cord blood CD34

+

cells for 7 d

and then total cell counting and the ratio of CD34

+

cells were measured.       Results      The adenovirus vectors respectively expressing SDF-1

HOXB4 and SDF-1/HOXB4 were successfully constructed

and the MSCs infected with harvested virus supernatants stably and highly expressed the exogenous genes. The modified MSCs of the SDF-1 group (9.52±2.24) and S-H group (8.20±2.34)  could significantly increase the total number of hematopoietic cells as compared with the control group (4.85±2.53

P0.05)

and the S-H group (the proportion of CD34

+

cells 1.85%) showed better effect on stemness maintenance of umbilical cord blood CD34

+

cells as compared with the SDF-1 group (1.20%) and HOXB4 group (1.28%).       Conclusion      The SDF-1/HOXB4 fusion gene-modified MSCs can improve the amplification and stemness maintenance of HSCs in vitro.