Impact of MSCs against Hepatic I/R Injury Figure 2. Characterization of BM-MSCs. BM-MSCs at passage 5 are induced to differentiate into adipocytes, osteoblasts, and chondrocytes-like cells. Cells analyzed by cytochemical staining with Oil Red-O, Alizarin red, or Safranin-O, respectively. doi:10.1371/journal.pone.0019195.g002 BM-MSC administration promotes the rate of liver regeneration After the operative procedure, all of the rats survived until sacrifice. Seven-two hours after reperfusion, H&E staining revealed significant morphological changes in Suzuki scores (1.461.3 vs. 3.961.7, p,0.03) and necrosis scores (0.360.5 vs. 1.561.2, p,0.05) in the MSC group compared with the Control group (Figure 6). As shown Figure 6A–B, the pathological findings revealed less vacuolar degeneration in the MSC group compared with the Control group. However, these pathological changes had almost completely improved 168 h after reperfu- sion, as the H&E-stained liver tissues were no longer morphologically distinguishable between the two groups (data not shown). Figure 3. Decrease of luciferase activity. The expression level of luciferase was postoperatively observed using a noninvasive living image acquisition IVIS system. Accumulation of MSCs in the remnant liver. A. Most of the MSCs became trapped in the remnant liver. Thereafter, the luciferase activity diminished with time. B. The largest level of luciferase was 1872726119507 photons/sec/cm2/sr (sr = units of solid angle or steradian). (24 h vs. 168 h: P,0.03; 24 h vs. 120 h: P,0.05; 72 h vs. 168 h: P,0.05). doi:10.1371/journal.pone.0019195.g003 PLoS ONE | www.plosone.org 3 April 2011 | Volume 6 | Issue 4 | e19195