Figure 1: Identification, immunogenicity and immunomodulation of huMSCs. (A) The huMSCs cultured in our experiment. The huMSCs were spindle-shaped and grew in a whorl pattern. Original magnification 100×, scale bars: 200 μm. (B) Flow cytometry detection of CD29, CD44, CD73 and CD105. The rate of positive expression for all factors was greater than 95%. (C) Detection of huMSC HLAII expression in PBMCs and huMSCs by western blot. No HLAII expression band was detected in the huMSCs. (D) Relative expression of HLAII in PBMCs and huMSCs. The bar graph shows no HLAII expression in huMSCs. (E) PCR amplification curves of HLA-DPA1, HLA-DQA1 and HLA-DRA1 genes in PBMCs and huMSCs. (F) Relative expression of HLA-DPA1, HLA-DQA1 and HLA-DRA1 genes in PBMCs and huMSCs. PCR results showed no expression of HLA-DPA1, HLA-DQA1 or HLA-DRA1 genes in huMSCs. (G) Expression curves of serum IL-6, IL-10, IL-12, TGF-β, and TNF-α detected by ELISA method (n = 5 rats per group). Compared with the TBI group, the serum pro-inflammatory cytokines IL-6, IL-12 and TNF-α in the Tail Vein and In Situ group were lower (###P < 0.001), whereas the inflammation inhibiting factors IL-10 and TGF-β were much higher (###P < 0.001), indicating that huMSCs exert good immunoregulatory effects. Data are expressed as the mean ± SD. ***P < 0.001, vs. PBMCs (one-way analysis of variance followed by least significant difference test). ELISA: Enzyme-linked immunosorbent assay; GAPDH: glyceraldehyde 3-phosphate dehydrogenase; HLAII: human leukocyte antigen II; huMSCs: human umbilical cord mesenchymal stem cells; IL: interleukin; PBMCs: peripheral blood mononuclear cells; PCR: polymerase chain reaction; TBI: traumatic brain injury; TGF-β: transforming growth factor beta; TNF-α: tumor necrosis factor alpha.