[The effect of semimature dendritic cell and the levels of Treg on transplantation tolerance of hepatocytes differentiated from mouse embryonic stem cell]

Objective: To investigate the inducing effect and mechanism of semimature dendritic cell (smDCs) on transplantation tolerance of hepatocytes differentiated from mouse embryonic stem cells (ESCs), and to study the connections between smDCs and regulatory dendritic cells (regDCs). Methods: ESCs of 129 mouse labelled green fluorescent protein (GFP) were induced to hepatocytes by using previous methods. Meanwhile, bone marrow mononuclear cells of 129 mouse were induced to smDCs and regDCs. Moreover, the hepatocytes differentiated from 129 mouse ESCs were transplanted into liver of BALB/c mouse 3 days after infusing smDCs and regDCs suspension of 129 mouse into BALB/c mouse by tail vein respectively. After that, the growth status and survival time of transplanted cells in the recipient and infiltration of lymphocytes in transplant sites were observed. Furthermore, Foxp3 expression of peripheral blood CD4+ T cells was also tested. Results: In the control group, the transplanted cells in liver of BALB/c mouse survived only about 1 week. In contrast, the transplanted cells of smDC groups and regDCs groups survived about 4 weeks and the transplant sites of smDC groups also had less CD3(+) T cells. The morphology of smDCs were similar with regDCs. The expression of MHC-Ⅱ, CD40, CD80 and CD86 on smDCs and regDCs were moderate. Moreover, the Foxp3 expression of peripheral blood CD4+ T cells in smDC groups was higher than that in the control groups, from 1.11% up to 5.38%. The Foxp3 expression in regDC groups rose to 3.87%. Conclusion: The smDCs could induce transplantation tolerance of hepatocytes differentiated from 129 mouse ESCs in the recipient. The mechanism was associated with high level of Foxp3(+) Tregs, which could be increased by means of smDCs appropriate expression of MHC-Ⅱ, CD40, CD80 and CD86. The smDCs and regDCs were the same type of tolerance dendritic cells.

The similarities between smDCs and regDCs in alleviating the immune injury caused by transplantation of hepatocytes differentiated from ESCs

Background

This study aimed to investigate the tolerogenic mechanisms induced by semimature dendritic cells (smDCs) and regulatory dendritic cells (regDCs) after transplantation of hepatocytes differentiated from mouse embryonic stem cells (ESCs) and to confirm the low immunogenicity of hepatocytes differentiated from ESCs.

Methods

Green fluorescent protein-labeled ESCs collected from 129 mice were cultured to differentiate into hepatocytes. smDCs and regDCs were cultured in vitro. The hepatocytes were cultured after being extracted from the livers of 129 mice. After injecting smDCs or regDCs 3 days in advance, these differentiated hepatocytes and normal hepatocytes were transplanted into the livers of BALB/c mice separately. Subsequently, the histopathological features and cytokines in transplant tissues as well as the Foxp3 expression in peripheral blood CD4⁺ T cells of the recipients were examined.

Results

The morphological phenotypes of smDCs and regDCs were similar. They both expressed medium levels of MHC-II, CD40, CD80, and CD86, high levels of TGF-β and IL-10, and low levels of IL-2. The survival of differentiated hepatocytes was prolonged and inflammatory infiltration in transplant tissues was reduced in both the smDC and regDC groups. Foxp3 expression in peripheral blood CD4⁺ T cells of the smDC group increased to 5.38% and that of the regDC group also rose to 3.87%. Moreover, the inflammatory infiltration in the tissues receiving transplanted hepatocytes was more obvious.

Conclusions

smDCs and regDCs were similar tolerogenic dendritic cells. They both could alleviate the immune injury by inducing CD4⁺CD25⁺Foxp3⁺ regulatory T cells through the medium expression of MHC-II, CD40, CD80, and CD86 and the appropriate secretion of cytokines. Hepatocytes differentiated from ESCs displayed low immunogenicity.