Figure 1

Mesenchymal stem cells induce endothelial cell quiescence. (A) The relative gene expression of ANG-1 and ANG-2 from mono- and co-cultured constructs after one week dynamic culture in vitro was altered by co-seeding endothelial cells (ECs) with mesenchymal stem cells (MSC). An up-regulation of ANG-1 and a down-regulation of ANG-2 was detected. (B) Also, cell proliferation markers PCNA and ki67 were both down-regulated in EC/MSC-constructs. (C) In a two-dimensional co-culture system, which allowed separation of cells, the number of viable ECs was reduced in the presence of MSCs after five days culture. After seven days the difference was not statistically significant (P = 0.07), whereas after nine days the number of viable ECs was significantly reduced in the presence of MSCs. (D) UEA-1 staining (red) demonstrated a quiescent phenotype of ECs in co-culture with CD90-positive MSCs (green) (10x). Nuclei were stained with DAPI. Scale bar = 20 μm. * = P <0.05, ** = P <0.01. ANG-1, angiopoietin-1; ANG-2, angiopoietin-2; DAPI, 4',6-diamidino-2-phenylindole; PCNA, proliferating cell nuclear antigen.