Human umbilical cord blood-derived stromal cells suppress xenogeneic immune cell response in vitro.
OBJECTIVE
To explore immunological properties of human umbilical cord blood-derived stromal cells (hUCBDSC) and their effect on xenogeneic immune cells in vitro.


METHODS
Immunological phenotype of freshly isolated and cryopreserved hUCBDSCs was evaluated by flow cytometry. Xenogeneic splenic T-cells were stimulated by phytohemaglutinin A (PHA) or dendritic cells in the absence or presence of hUCBDSCs. T-cell proliferation was measured by cell counting kit-8 after 7-day incubation. The proportion of apoptotic cells and CD4+CD25+Foxp3+ regulatory T-cells (Tregs) was determined in T-cells activated by PHA in the absence or presence of hUCBDSCs by flow cytometry. Phenotype of dendritic cells, cultured alone or with hUCBDSCs, was analyzed by flow cytometry.


RESULTS
Levels of immune molecule expression on freshly isolated hUCBDSCs were as follows: human leukocyte antigen-I (HLA-I) (84.1+/-2.9%), HLA-II (1.6+/-0.3%), CD80 (0.8+/-0.1%), CD86 (0.8+/-0.1%), CD40 (0.6+/-0.1%), and CD40L (0.5+/-0.1%), which was not influenced by cryopreservation. T-cell proliferation in the presence of hUCBDSCs was significantly lower than that of positive control. The coculture led to a 10-fold increase (from 1.2+/-0.3% to 12.1+/-1.4%, P<0.001) in the proportion of CD4+CD25+Foxp3+ regulatory T-cells (Tregs) and a reversion of mature dendritic cells, as indicated by the down-regulation of major histocompatibility complex (MHC)-II molecule (49.3% vs 25.9%, P=0.001), CD80 (47.2% vs 23.3%, P=0.001), and CD86 (40.6% vs 25.1%, P=0.002). When subjected to annexin V binding and propidium iodide uptake assay, the hUCBDSCs did not show the ability to induce apoptosis of xenogeneic T-cells.


CONCLUSIONS
These results demonstrate low immunogenicity and immunomodulation effect of the hUCBDSCs. Reversion of mature dendritic cells and increase in Treg proportion, but not cell apoptosis, can possibly contribute to the suppression of xenogeneic T-cell proliferation by the hUCBDSCs.
Hao
Lei
L
Department of Hematology, Xinqiao Hospital, Third Military Medical University, Chongqing, PR China.
Zhang
Cheng
C
Chen
Xing-Hua
XH
Zou
Zhong-Min
ZM
Zhang
Xi
X
Kong
Pei-Yan
PY
Liang
Xue
X
Gao
Lei
L
Peng
Xian-Gui
XG
Sun
Ai-Hua
AH
Wang
Qing-Yu
QY
D015703:Antigens, CD / Q000276:immunology*; D003713:Dendritic Cells; D005312:Fetal Blood; D006801:Humans; D055261:Immunogenetic Phenomena; D007165:Immunosuppression Therapy; D013154:Spleen / Q000166:cytology; D017154:Stromal Cells / Q000276:immunology*
D015703:Antigens, CD