[Effect of human bone marrow mesenchymal stem cell on cord blood T lymphocyte transformation]

To study the effect of mesenchymal stem cell (MSC) on immune function, MSCs were isolated and cultured from human bone marrow cells. The purity of MSCs were identified with the spindle-fibroblastic morphology characterization by microphotograph and the phenotypes were tested by flow cytometry. MSCs were plated in 96-well plates (2,000/well and 1,000/well), and cocultured for 3 days with T cells isolated from cord blood. Cord blood T cells non-cocultured with MSC acted as control group. After cord blood T cells stimulated by PHA for 60 hours, [(3)H]-thymidine was added to each well and T cell proliferation was assessed by [(3)H] thymidine incorporation. The results showed that cord blood T cell proliferation was suppressed when 2,000 MSCs were plated each well and cord blood T cell proliferation was activated when 1,000 MSCs were plated. Our results suggested that the immunomodulatory function of MSC seemed dependent on cell dose. High concentration of MSC most often resulted in inhibition, while low concentration resulted in stimulation.