Figure 6.

IL-33/ST2 is essential for MSC-Exo’s neuroprotective effects in vitro.

(A) MTT assay after 3-hour OGD/24-hour reoxygenation. (B, C) Expression of IL-33 (B) and ST2 (C) (normalized by siRNA-NC group) were determined by quantitative reverse transcription-polymerase chain reaction. *P < 0.05, vs. siRNA-NC group (Student’s t-test). (D, E) The results of MTT (D) and LDH (E) assays showed IL-33-CM significantly increased neuronal survival, but ST2 siRNA could block the IL-33-condition medium-induced neuroprotective effect. (F, G) The results of MTT (F) and LDH (G) assays showed MSC-Exo-CM significantly increased neuronal survival, but IL-33 siRNA or ST2 siRNA could block the MSC-Exo-CM-induced neuroprotective effect. Data are expressed as mean ± SD (n = 5 per group). *P < 0.05, vs. normoxia group; #P < 0.05, vs. OGD group; &P < 0.05, vs. MSC-Exo-CM group (one-way analysis of variance followed by the Tukey’s post hoc test). CM: Conditioned medium; IL-33: interleukin-33; LDH: lactate dehydrogenase; MSC-Exo: exosomes derived from bone marrow mesenchymal stem cells; MTT: thiazolyl blue tetrazolium bromide; siRNA: small interfering RNA; ST2: suppression of tumorigenicity 2.