Distribution and differentiation of myeloid-derived suppressor cells after fluid resuscitation in mice with hemorrhagic shock.

Objective: To investigate the distribution and differentiation of myeloid-derived suppressor cells (MDSCs) in hemorrhagic shock mice, which are resuscitated with normal saline (NS), hypertonic saline (HTS), and hydroxyethyl starch (HES).

Methods: BALB/c mice were randomly divided into control, NS, HTS, and HES resuscitation groups. Three subgroups (n=8) in each resuscitation group were marked as 2, 24, and 72 h. Flow cytometry was used to detect the MDSCs, monocytic MDSCs (M-MDSCs), and granulocytic/neutrophilic MDSCs (G-MDSCs) in peripheral blood nucleated cells (PBNCs), spleen single-cell suspension, and bone marrow nucleated cells (BMNCs).

Results: The MDSCs in BMNCs among three resuscitation groups were lower 2 h after shock, in PBNCs of the HTS group were higher, and in spleen of the NS group were lower (all P<0.05 vs. control). The M-MDSC/G-MDSC ratios in PBNCs of the HTS and HES groups were lower (both P<0.05 vs. control). At 24 h, the MDSCs in PBNCs of the NS and HTS groups were higher, while the spleen MDSCs in the HTS group were higher (all P<0.05 vs. control). The M-MDSC/G-MDSC ratios were all less in PBNCs, spleen, and BMNCs of the NS and HTS groups, and were lower in BMNCs of the HES group (all P<0.05 vs. control). At 72 h, the elevated MDSCs in PBNCs were presented in the HTS and HES groups, and in spleen the augment turned up in three resuscitation groups (all P<0.05 vs. control). The inclined ratios to M-MDSC were exhibited in spleen of the NS and HTS groups, and in PBNCs of the NS group; the inclination to G-MDSC in BMNCs was shown in the HES group (all P<0.05 vs. control).

Conclusions: HTS induces the earlier elevation of MDSCs in peripheral blood and spleen, and influences its distribution and differentiation, while HES has a less effect on the distribution but a stronger impact on the differentiation of MDSCs, especially in bone marrow.