Objective To use the new technique of seeding cells labeled with fluorescent protein for monitoring the construction process of tissue-engineering bone in vitro.Methods Human bone marrow stromal cells(BMSCs)were isolated and culture-expanded from femoral marrow.BMSCs were transfected with the recombinant retrovirus pLEGFP-Nl containing enhanced green fluorescent protein(EGFP).Those expressing EGFP were cultured in the experiment groups,and the unmarked BMSCs were in the control groups.The cell-scaffold complexes were constructed with BMSCs and hydroxyapatite in vitro.Some complexes were used to assess the adhesion efficiency and the others were cultured and observed under fluorescence microscope for four weeks.Results EGFP was successfully expressed after BMSCs were transfected with the retroviral vector pLEGFP-N1.The labeled cells were easy to observe while the cell-scaffold complexes were constructed and cultured.The adhesion efficiency was(90.3?2.1)%for the group of labeled BMSCs and(92.0?1.5)%for the control group,so there was no significant difference between the two groups(P=0.236).Conclusions After BMSCs are transfected with the recombinant retrovirus containing EGFP,the adhesion of cells will hardly be affected so that seeding cells labeled with fluorescent protein can well be used for monitoring the construction and culture of tissue-engineering bone in vitro.