The blood vessel growth inhibitor bevacizumab targets vascular endothelial growth factor (VEGF), a crucial regulator of angiogenesis. Recently, small extracellular vesicles (sEVs) have been demonstrated to be important vehicles in the transport of growth factors to target cells. In this study, we isolated primary carcinoma-associated fibroblasts (CAFs) from four human oral squamous cell carcinoma (OSCC) specimens. Compared with other non-extracellular vesicle components, CAF-derived sEVs were found to be the main regulators of angiogenesis. The ability of CAF sEVs to activate VEGF receptor 2 (VEGFR2) signaling in human umbilical vein endothelial cells (HUVEC) was dependent on the association between sEVs and VEGF. In addition, sEV-bound VEGF secreted by CAFs further activated VEGFR2 signaling in HUVEC in a bevacizumab-resistant manner. VEGF was found to interact with heparan sulfate proteoglycans on the CAF sEV surface and could be released by heparinase I/III. The bioactivity of the dissociated VEGF was retained in vitro and in vivo and could be neutralized by bevacizumab. These findings suggest that the combined use of heparinase and bevacizumab might inhibit angiogenesis in patients with high levels of sEV-bound VEGF.

血管生长抑制剂贝伐单抗靶向血管内皮生长因子（VEGF），这是血管生成的关键调节剂。近来，小细胞外囊泡（sEVs）已被证明是将生长因子转运至靶细胞的重要载体。在这项研究中，我们从四个人类口腔鳞状细胞癌（OSCC）标本中分离了原发癌相关的成纤维细胞（CAF）。与其他非细胞外囊泡成分相比，CAF衍生的sEVs是血管生成的主要调节因子。CAF sEV激活人脐静脉内皮细胞（HUVEC）中的VEGF受体2（VEGFR2）信号传导的能力取决于sEV和VEGF之间的关联。此外，CAF分泌的与sEV结合的VEGF以抗贝伐单抗的方式进一步激活HUVEC中的VEGFR2信号传导。发现VEGF与CAF sEV表面的硫酸乙酰肝素蛋白聚糖发生相互作用，并可能被肝素酶I / III释放。分离的VEGF的生物活性得以保留在体外和体内均可被贝伐单抗中和。这些发现表明，肝素酶和贝伐单抗的联合使用可能抑制高水平与sEV结合的VEGF患者的血管生成。