Fig. 7

Endothelial differentiation of MSCs in vivo and its association with graft endothelial integrity. a Endothelial differentiation of MSCs homed to neointima (green fluorescent protein (GFP)-labeled cells) was assessed by immunofluorescence for CD31. The percentage of neointimal GFP⁺ cells expressing CD31 (marked with yellow arrows) was significantly higher in the pLV-HMGB1 group than in the pLV-control group. b α-Smooth muscle actin (αSMA) was selected as the cell maker for MSCs differentiated to SMCs. The fraction of αSMA in neointimal GFP-labeled cells was significantly lower in the pLV-HMGB1 group than in the pLV-control group (marked with yellow arrows). Thus, pLV-HMGB1-transfected MSCs preferably differentiated to the endothelial lineage in vivo. Five random high-power fields were examined in the sections of graft vessels for each rat, and the neointimal cell number was counted to determine the percentage of CD31-positive cells and αSMA-positive cells in the total GFP-labeled cell population. The average percentage was calculated from eight rats for each group. c Aortic endothelial barrier integrity was assessed by Evans blue staining in the graft vessels. The area of impaired endothelium was stained with dark blue. Isograft and allograft groups served as negative and positive staining control, respectively. The unstained area was normalized to the total intraluminal surface area of the graft aorta and expressed as a percentage. Compared with the pLV-control group, the percentage of unstained area was significantly increased in the pLV-HMGB1 group. This suggested that infusion of pLV-HMGB1-transfected MSCs had more protective effects on the graft endothelial barrier, which was associated with preferential endothelial differentiation of the cells in vivo. Eight rats were examined for each group. Group comparisons were made using the Mann-Whitney test. **P < 0.05. DAPI 4′,6-diamidino-2-phenylindole, HMGB1 high mobility group box 1, RAGE receptor for advanced glycation end-product