Objective: To observe the prevention and treatment of acute graft-versus-host disease (aGVHD) by murine marrow mesenchymal stem cells (MSCs) in vivo.
Methods: Allogeneic aGVHD model was established with lethally irradiated BALB/c recipients receiving allogeneic BM (BMC) and spleen cells (SP) from C57BL/6 with or without mMSCs at different dose and different time posttransplantation. Six groups were set up, group 1 (irradiation control group); group 2 (i.v. BMC only); group 3 (i.v. SP+ BMC); group 4 (i.v. SP + BMC + 1 x 10(5) mMSC at day 0); group 5 (i.v. SP + BMC +5 x 10(5) mMSC at day 0); group 6 (i.v. SP + BMC +1 x 10(5) mMSC at day 7). The survival was monitored daily. mMSCs infected with adenoviral vector (Ad-GFP) were injected into aGVHD model to observe the distribution of MSCs in vivo.
Results: (1) Addition of donor mMSCs significantly controlled the lethal GVHD. The survival time (day) in group 1 was 13.5 +/- 2.6, group 3 11.1 +/- 4.0, group 4 26.4 +/- 7.7, group 5 22.7 +/- 9.2, group 6 22.9 +/- 8.2, respectively. The difference between groups 4-6 and group 3 was statistically significant (P < 0.01), but there was no difference among groups 4-6 (P = 0.28); There was less lymphocyte infiltration and architectural disruption in the intestine and spleen of groups 4-6 than that of group 3; (2) mMSCs significantly reduced IFN-gamma and TNF-alpha in the serum of recipient mouse; the levels of IFN-gamma in groups 3, 4, 5, 6 were (607.9 +/- 157.1), (143.6 +/- 37.5), (117.0 +/- 77.8), (131.4 +/- 63.4) ng/L, respectively. And of TNF-alpha were (52.31 +/- 17.95), (6.02 +/- 3.99), (5.21 +/- 0.28), (22.39 +/- 18.21) ng/L, respectively. mMSCs had no effect on allogeneic T cell proliferation in GVHD model but increased apoptosis of allogeneic T cells. The percentage of CD3(+) Annexin V(+)PI(-) in each group were (10.3 +/- 6.6)%, (13.5 +/- 13.8)%, (19.7 +/- 6.0)%, (16.6 +/- 7.3)%, respectively. (3) After intravenous infusion, large numbers of GFP-MSCs lodged in lungs and intestines while small numbers in the liver, spleen and kidney.
Conclusions: MSCs has no effect on proliferation but induce apoptosis of allo-reactive T cells; MSCs can inhibit the second activation of allogeneic T cells, significantly reduce the secretion of IFN-gamma and TNF-alpha; MSCs might be able to repair GVHD target tissues by extensive distribution to lungs, intestines, and liver of the animals.