The cancer cells and stromal cells in tumor microenvironment secrete cytokines and recruit “homing” cells (macrophage, lymphocytes, platelets, etc.). Platelets can interact with tumor microenvironment and specifically aggregate at tumor sites. Surprising, we observed different “homing” effects of activated platelets in breast cancer model and pancreatic cancer model which is highly related with the blood supply of tumors. Besides, platelets targeting magnetic nanoparticles (MNPs) can home to breast cancer but be repelled from pancreatic cancer. We observed the targeting effect of MNPs is highly related with the expressions of collagen Ⅰ (marker of extracellular matrix) and CD34 (marker of tumor neovascularization). The homing nanoparticles such as platelets targeting MNPs could realize the tumor targeting ability, photo-thermal effect and tumor immunotherapeutic ability in the accessible tumor (e.g. breast cancer) but not the hypovascular tumor (e.g. pancreatic cancer).

肿瘤微环境中的癌细胞和基质细胞分泌细胞因子并募集“归巢”细胞（巨噬细胞，淋巴细胞，血小板等）。血小板可以与肿瘤微环境相互作用，并在肿瘤部位特异性聚集。令人惊讶的是，我们在乳腺癌模型和胰腺癌模型中观察到了活化血小板的不同“归巢”效应，这与肿瘤的血液供应高度相关。此外，靶向磁性纳米颗粒（MNPs）的血小板可能会成为乳腺癌的宿主，但会被胰腺癌排斥。我们观察到MNPs的靶向作用与Ⅰ型胶原（细胞外基质的标志物）和CD34（肿瘤新血管形成的标志物）的表达高度相关。靶向MNPs的归巢纳米颗粒（如血小板）可以实现肿瘤靶向能力，