OBJECTIVETo observe the effect of Fn-TPO gene modification on human bone marrow mesenchymal stem cells (MSCs).

METHODSRetroviral vector containing Fn-TPO gene was constructed and bone marrow MSCs was modified by this vector. The transcription of Fn-TPO gene in MSCs was observed. The proliferation capacities, hematopoietic cells adhering capacities and TPO secretion capacities of gene modified MSCs were assayed respectively. Cord blood CD34 cells were seeded on the gene modified MSCs layers and several essential growth factors were added. After co-culturing in vitro for 7 days, the number of CD34 cells and their colony forming capacities were assayed by flow cytometry and semisolid culture assay.

RESULTSRetroviral vector containing Fn-TPO gene was successfully constructed and bone marrow MSCs were modified by this vector. Fn-TPO gene was expressed by bone marrow MSCs after gene modification. The viability of MSCs had no significant difference between pre- and post-gene-modification [(7.18 +/- 0.89) 10(4)/ml vs. (6.92 +/- 0.77) 10(4)/ml, P > 0.05]. The hematopoietic cells adhering ability of gene modified bone marrow MSCs was reinforced(0. 188 +/- 0.018 vs. 0.167 +/- 0.017, P < 0.01). The concentration of TPO in the MSCs culture supernatant raised from (5.58 +/- 0.37) ng/ml to (7.46 +/- 0.59) ng/ml (P < 0.01) and did not significantly decline in a short-time period, but influenced by the growth status of MSCs. After co-culturing with gene modified MSCs for 7 days, the absolute number of nucleated cells, the percentage of CD34+ cells and the colony numbers of BFU-E, CFU-GM, CFU-GEMM were (29.9 +/- 2.7) x 10(4), (33.3 +/- 2.8)% , 109.3 +/- 4.1, 163.7 +/- 7.1, 13.3 +/- 1.5, respectively, being significantly higher than that co-cultured with non-modified MSCs.

CONCLUSIONSFn-TPO gene modification can improve the capacity of human bone marrow MSCs for hematopoietic cells adhering, TPO secretion and cord blood CD34 cells amplification.