## 4 Discussion
Last but not least, it was indicated that TGF-\(\beta\)1 promoted angiogenesis through the regulation of immune cells in vivo. Hsa-miR-133a-5p may protect against hypoxia/reperfusion-induced or ischemia/reperfusion-induced hepatocyte injury by decreasing the expression of MARK6 [26], while upregulation of hsa-miR-10b-5p could inhibit caspase-3 activation, and, therefore, prevent cell apoptosis [27]. Conversely, hsa-miR-1469 was demonstrated to induce apoptosis in a series of cancer cells [28]. ECs-derived EVs affects recipient cells' function and modulates key events in the development of multiple disorders; the effect could be either beneficial or detrimental. It was also shown that capillary endothelial tip cells secrete EVs incorporating Delta-like 4 ligands, which are passed to the tip cells of the endothelial sprout, promote cell motility, and suppress their proliferation [29]. Senescent human ECs-derived EVs could knock down Frizled-3 of human MSCs and inhibit osteogenic differentiation [30]. Moreover, to systematically identify novel inflammatory cytokines related to the protective effect of icarini, we performed a screen among the Model group, Icarini-treated group and the control group by protein array assay. The present study found that 29 proteins were dysregulated in EVs secreted by BMECs after icarini intervention and most of these proteins were upregulated. Based on the PPI network, nine proteins (ICAM1, MMP3, BSG, LGALS3, CXCL9, CXCL16, MMP10, IL36 RN, and TNFRSF1B) with high connectivity were identified as playing essential roles in the protective effect of icarini to glucocorticoid-induced injury of BMECs. ICAM1 is a cell surface glycoprotein typically expressed on endothelial cells [31]. Meanwhile, ICAM1 might exert dual effects on bone homeostasis, especially in osteoclastogenesis [32]. MMP3 and MMP10 belong to the matrix metalloproteinase family and also participate in osteogenic differentiation [33]. LGALS3, which is widely expressed in various tissues including bone tissues, is considered as a marker of bone formation [34]. The cytokine-cytokine receptor interaction pathway is predicted to be significantly enriched by identified DEPs, which included CCL14, TNFRSF10C, CXCL9, IL36 RN, BMP7, TNFRSF1B, CXCL16, and GH1. By constructing a TF-miRNA-DEP interacted network, we selected multiple important miRNAs (e.g., hsa-miR-330-3p and hsa-miR-17) and transcription factors (e.g., MYC and SP1) that might be involved in the dysregulation of these proteins. In former studies, these molecules were demonstrated to be vital for vascular development and angiogenesis [35; 36]. MYC and SP1 could regulate the proliferation of endothelial cells after being stimulated by hyperoxia or hypoxia. Meanwhile, hsa-miR-17 is reported to affect the expression of these DEPs, and serves as a feasible strategy for the selective modulation of endothelialization and vascular remodeling [37]. It should be noted that these miRNAs and TFs were not differentially expressed in isolated EVs. In fact, they could interact with the identified DEPs in secretory cells or receipt cells, and therefore influence the cellular function. This study is not without limitations. First, extrapolation of the results from cell models to clinical practice should be performed with caution. It is needed to consider the impact of factors in vivo. Second, although hsa-miR-133a-5p and hsa-miR-10b-5p were enriched after icarini intervention, we did not perform a further experiment to test whether they could take effect on the reversion of glucocorticoid-induced cellular injury. Last but not least, the interaction of EVs secreted by BMECs and other cell types needs to be further investigated. It is well-acknowledged that icarini could affect multiple cell types existing in bones, for example, MSCs and osteocytes; meanwhile, EVs can modulate inflammation, regulate the activation and migration of monocytes, and affect the differentiation of MSCs.