The effects of splenectomy in murine models of ischemic stroke: a systematic review and meta-analysis

Background The spleen, a substantial reservoir of non-differentiated monocytes, may play a crucial role in the pathophysiology of post-ischemic inflammation and influence outcomes after ischemic stroke. Aim of the study To analyze splenectomy as a preclinical intervention in murine models of ischemic stroke. Methods Following systematic searches of PubMed, Scopus and Web of Science, a qualitative synthesis of study characteristics was performed, and the effect of splenectomy estimated by a three-level random-effects meta-analysis of infarct volumes and a conventional two-level random-effects meta-analysis of neurological deficit scores. Results Database searches identified a total of 14 studies, 13 of which were used for meta-analysis. The ischemic lesion volumes were reduced in splenectomized animals compared to the control groups (difference in standardized mean differences: - 1.42; 95% CI [- 1.98, - 0.85]; 95% PI [- 2.03, - 0.80]; I-(2)(2) = 19.04%; 95% CI [0.00%, 65.49%]; I-(3)(2) = 47.24%; 95% CI [0.00%, 85.23%]) and neurological deficit scores were improved (- 1.20; 95% CI [- 2.20, - 0.20]; 95% PI [- 4.58, 2.18]; I-2 = 77.5%; 95% CI [50.0%, 89.9%]). A subgroup analysis for infarct volumes showed that splenectomy performed prior to ischemia achieved a higher reduction of the ischemic lesion than when splenectomy was performed immediately prior or after stroke. Although the overall effect size of splenectomy could be classified as large, there was a significant presence of risks of bias, study heterogeneity, and a potential presence of publication bias. Conclusion Despite limitations related to heterogeneity, risks of bias, and potential publication bias, this meta-analysis points to the spleen and its functional cell populations as promising targets for the therapeutic modulation of post-stroke inflammation.

Automated summary

This study analyzed the effect of splenectomy as a preclinical intervention in murine models of ischemic stroke. The results showed that splenectomy reduced the ischemic lesion volumes and improved neurological deficit scores. Despite limitations related to bias, study heterogeneity, and potential publication bias, this meta-analysis suggests that the spleen and its functional cell populations are promising targets for the therapeutic modulation of post-stroke inflammation.