Immune -suppression effect of fetal-originated human bone marrow mesenchymal stem cells on peripheral blood mononuclear cells in vitro and tumor necrosis factor-a expression at cerebral infarct site in vivo in rats

Abstract

Objective To investigate whether human bone marrow mesenchymal stem cells (hBC-MSCs) have the immune-suppression ability on the proliferation of peripheral blood mononuclear cells (PBMCs) and their pro-inflammatory cytokine production in rats, to explore what kinds of human cytokines are required for the induction of hBM-MSCs to become immune-suppressive, and to observe the effect of intravenous delivery of hBM-MSCs on tumor necrosis factor (TNF)-α transcription and expression in the core infarct areas of rats after cerebral ischemia. Methods The fetal-originated hBC-MSCs and rat PBMCs were extracted; the rat PBMCs were activated by adding 10 μg/mL concanavalin A (ConA). (1) The first experiment was divided into hBM-MSCs+PBMCs group, hBM-MSCs+PBMCs+ConA group, PBMCs group and hBM-MSCs group; CCK-8 assay was employed to detect the proliferation of these cells. (2) The second experiment was divided into hBM-MSCs+PBMCs+ConA group, PBMCs+ConA group; ELISA was used to detect the TNF-α, interferon-γ (IFN-γ) and interleukin (IL)-10 expressions. (3) The third experiment was divided into hBM-MSCs+PBMCs (IFN-γ+IL-1α) group, hBM-MSCs+PBMCs (IFN-γ+IL-1β) group, hBM-MSCs+PBMCs (IFN-γ+TNF-α) group and hBM-MSCs+PBMCs group; CCK-8 assay was used to detect the proliferation of these cells. (4) Thirty SD rats were randomly divided sham-operated group, control group (giving normal saline after ischemia) and hBM-MSCs group (giving hBM-MSCs after ischemia, n=10); on the third d of ischemia, the TNF-α mRNA and protein expressions at the infarct areas was detected by real time PCR and Western blotting, respectively. Results (1) The optical density (OD) in the hBM-MSCs+PBMCs group was significantly increased as compared with that in the PBMCs group and hBM-MSCs group (P<0.05); OD in the hBM-MSCs+PBMCs group was significantly increased as compared with that in the hBM-MSCs+PBMCs+ConA group (P<0.05). (2) The TNF-α, IFN-γ and IL-10 levels in the PBMCs+ConA group were (1030±196) pg/mL, (2880±250) pg/mL and (330±45) pg/mL; the TNF-α and IFN-γ levels in hBM-MSCs+PBMCs+ConA group were (160±10) pg/mL and (240±55) pg/mL, which were significantly lower than those in the PBMCs+ConA group (P<0.05); the IL-10 level in hBM-MSCs+PBMCs+ConA group was (750±110) pg/mL, which was significantly higher than that in the PBMCs+ConA group (P<0.05). (3) The OD in the hBM-MSCs+PBMCs(IFN-γ+IL-1α) group, hBM-MSCs+PBMCs(IFN-γ+IL-1β) group and hBM-MSCs+PBMCs(IFN-γ+TNF-α) group was significantly decreased as compared with that in the hBM-MSCs+PBMCs group (P<0.05). (4) The TNF-α mRNA expression in the sham-operated group, control group and hBM-MSCs group was 0.490±0.128, 2.369±0.788 and 1.002±0.408; the TNF-α protein expression in the sham-operated group, control group and hBM-MSCs group was 0.144±0.028, 0.314±0.029, 0.240±0.029; the TNF-α protein and mRNA expressions in the hBM-MSCs group were significantly decreased as compared with those in the control group (P<0.05). Conclusions The allogeneic transplantation of hBC-MSCs is competent in suppressing the inflammation of rats in vitro and in vivo. Furthermore, this immune-suppression ability is not innate, but cytokine stimulation dependent. The immune-suppression ability of hBM-MSCs on rat PBMCs are at least partly responsible for the therapeutic effect of hBM-MSCs transplantation into the rat models, such as ischemia stroke. Key words: Cerebral ischemia; Human bone marrow mesenchymal stem cell; Mononuclear cell; Inflammation factor; Immune-suppression