Effect of different fluid resuscitation of hemorrhagic shock on the number of myeloid-derived suppressor cells in rat bone marrow

Objective: To explore the number change of myeloid-derived suppressor cells(MDSCs) in rat bone marrow at different time-points after different fluid resuscitation of hemorrhagic shock.Methods: The rat model of hemorrhagic shock was established through femoral artery bleeding method.In early stage of fluid resuscitation,the rats were recovered with lactated Ringer solution(lactated Ringer solution group),crystal glue(crystal glue group) and 7.5% hypertonic sodium chloride(hypertonic sodium chloride group),then the rats were recovered with autologous blood transfusion.The rats were sacrificed after 12 h,24 h and 48 h of successful resuscitation,and the sham operation rat was set as the control group.The number changes of MDSCs in rat bone marrow were detected using flow cytometry.Results: The MAP in lactate Ringer solution group was higher than that in crystal glue group(P<0.05).Compared with the sham group,the proportion of MDSCs in rat bone marrow in lactate Ringer solution group,crystal glue group and hypertonic sodium chloride group at each time point were significantly lower(P<0.01).The proportion of MDSCs in rat bone marrow in hypertonic sodium chloride group at each time point were significantly lower than that in lactate Ringer solution group and crystal glue group(P<0.01).The differences of the MDSCs between lactate Ringer solution group and crystal glue group at 12 h and 24 h were not statistical significance(P>0.05),and the MDSCs in crystal glue group at 24 h was lower than that in lactate Ringer solution group(P>0.05).Conclusions: After the early fluid resuscitation of hemorrhagic shock,the number of MDSCs in bone marrow of rat increase at first,then decrease with the extend of time,which explains that the fluid resuscitation can moderately inhibit the number of MDSCs.Compared with the Ringer lactate fluid and crystal glue liquid,the hypertonic saline solution can effectively inhibit the number of MDSCs after the hypertonic saline solution resuscitation of hemorrhagic shock,which has strong immunoregulatory effects on hemorrhagic shock.