Fig. 1

Donor, supplement of the cell culture medium and PL-batch affect HLA-DR expression by primary MSCs. A HLA-DR expression by MSCs, which were generated from the bone marrow of 23 donors, in DMEM supplemented with 10% FBS for 13 days (P0). Spearman correlation analysis showed no correlation between the age of MSC donors and HLA-DR expression (r = 0.21). B Primary MSCs (P0) were generated from bone marrow mononuclear cells of seven donors after thirteen days in culture with DMEM supplemented either with FBS (10%) or PL (5%). The median percentage of HLA-DR + MSCs/FBS was 1.1% (range 0.29–22%), whereas that of MSCs in PL was 28.4% (range 3.34–73.7%). The difference between the groups was statistically significant (p < 0.02; Wilcoxon signed-rank test). C Primary MSCs (P0) were generated from bone marrow mononuclear cells of eight donors after thirteen days in culture with DMEM supplemented with 5% of two different PLs: PL-19 and PL-A. The median percentage of HLA-DR + MSCs in PL-19 was 15.43% (range 2.7–71.4%), and that in PL-A was 5.6% (range 1.5–47.5%). The difference between the groups was statistically significant (p < 0.04; Wilcoxon signed-rank test). PL-19 and PL-A are labels for different PL batches. In panels B and C, each donor is represented with one colored square