Tumor exosome-based nanoparticles are efficient drug carriers for chemotherapy
Authors: Hélder A Santos
Tuying Yong
Abdul Hakeem
Nana Bie
Xiangliang Yang
Xuting Zhang
Jun Hu
Fuying Li
Hongbo Zhang
Lu Gan
Xiaoqiong Zhang
Journal: Nature Communications (2019)
Discipline: Multidisciplinary
Keywords: biomimetic nanoparticles; cancer chemotherapy; exosome-biomimetic; porous silicon nanoparticles; drug carrier
Affiliations: National Engineering Research Center for Nanomedicine, College of Life Science and Technology, Huazhong University of Science and Technology, 430074, Wuhan, China., Hubei Key Laboratory of Bioinorganic Chemistry and Materia Medica, Huazhong University of Science and Technology, 430074, Wuhan, China., Pharmaceutical Sciences Laboratory and Turku Center for Biotechnology, Åbo Akademi University, 20520, Turku, Finland., National Engineering Research Center for Nanomedicine, College of Life Science and Technology, Huazhong University of Science and Technology, 430074, Wuhan, China. ., Hubei Key Laboratory of Bioinorganic Chemistry and Materia Medica, Huazhong University of Science and Technology, 430074, Wuhan, China. ., Drug Research Program, Division of Pharmaceutical Chemistry and Technology, University of Helsinki, FI-00014, Helsinki, Finland. ., Helsinki Institute of Life Science, University of Helsinki, FI-00014, Helsinki, Finland. .

Abstract:  Developing biomimetic nanoparticles without loss of the integrity of proteins remains a major challenge in cancer chemotherapy. Here, we develop a biocompatible tumor-cell-exocytosed exosome-biomimetic porous silicon nanoparticles (PSiNPs) as drug carrier for targeted cancer chemotherapy. Exosome-sheathed doxorubicin-loaded PSiNPs (DOX@E-PSiNPs), generated by exocytosis of the endocytosed DOX-loaded PSiNPs from tumor cells, exhibit enhanced tumor accumulation, extravasation from blood vessels and penetration into deep tumor parenchyma following intravenous administration. In addition, DOX@E-PSiNPs, regardless of their origin, possess significant cellular uptake and cytotoxicity in both bulk cancer cells and cancer stem cells (CSCs). These properties endow DOX@E-PSiNPs with great in vivo enrichment in total tumor cells and side population cells with features of CSCs, resulting in anticancer activity and CSCs reduction in subcutaneous, orthotopic and metastatic tumor models. These results provide a proof-of-concept for the use of exosome-biomimetic nanoparticles exocytosed from tumor cells as a promising drug carrier for efficient cancer chemotherapy. 

Retracted: No

PubPeer comments:
 In many of the measurements, the variation is very low and the data points in one single experiement or across several differnet experiments are very similar. Examples from Figure 2c, 3 and 6d,e are shown. In Figure 3e, a Western immunoblot of CD63 is shown. Anti-CD63 always gives a smeared band, and not around 25 kDa, so I am questioning that your are actually showing the CD63 protein. The electron microscopy images (TEM) in Figure 3b look odd. The ultrastructure of the nanoparticles is strange and the background noise is absent. I don t understand the micrographs presented in Figure 4, where you claim to show co-localization in nanoparticles exocytosed. The single  drop can be anything. ![file] , 
 In Figure 3e the Western immunoblot of CD63 shows a straight band with no smear. In all the CD63 immunoblots I have seen, from different cell types, anti-CD63 always shows a typical smeared appearance. The MW is also very low to be CD63. The appearance of nanoparticles in Figure 3b is unusual, both in shape and ultrastructure, and the background is without debris. The E-NPsiEs particles have an area which is very dense (appears black). Why? Which contrast agent has been used to obtain this images? The micrographs in Figure 4a shows one single area with colocalization, but it is difficult to understand what this is and interpret. , 
 ![file] , 
 #3 Dear Dr. Tanganyikensis, Thank you very much for your interest in our work. CD63 contains four transmembrane domains, one small (EC1) and one large (EC2) extracellular domains, and short cytoplasmic N- and C-termini. It is a highly glycosylated protein containing three N-linked glycosylation sites. The molecular weight of non-glycosylated CD63 is about 25 kDa, while the glycosylation produces diverse CD63 molecules with different molecular weights. Depending on the antigenic determinant recognized, western blot analysis revealed CD63 bands with different molecular weights using different CD63 antibodies, as we can see from different product company websites. In our experiments, we used CD63 antibody from Abcam (catalog number ab216130) to detect the CD63 expression as an exosome marker. The official website from Abcam showed that this antibody recognizes CD63 at less than 28 kDa (please see the below image downloaded from this official website), which is consistent with our data. We have already indicated the CD63 antibody information (including the company and catalog) in the Reporting Summary of this paper. ![file] (downloaded from the https: www.abcam.cn cd63-antibody-late-endosome-marker-ab216130.html) To prepare PSiNPs, single crystal Si wafers were electrochemically etched, and the obtained PSi film was then fragmented by ultrasonication overnight and centrifuged. The morphology of PSiNPs was observed by high-resolution transmission electron microscopy (HRTEM, 300 kV) without contrast agent. Since the preparation of PSiNPs is a top-down process and the PSi film was fragmented randomly by ultrasonication, no particles with regular morphology were found routinely which can be confirmed by several PSiNPs-related papers (ACS Appl. Mater. Interfaces 2019, 11, 23926u221223937; Adv. Mater. 2018, 30, 1800512). E-PSiNPs were prepared by incubating the cells with PSiNPs and then collecting the exocytosed PSiNPs from the cell culture medium. To clearly observe that membrane (exosomes) was coated onto PSiNPs in E-PSiNPs by TEM at 100 kV, we used 2% phosphotungstic acid to stain E-PSiNPs. Since the intracellular process of assembling PSiNPs into exosomes is complicated, we did not know how exosomes sheathed PSiNPs and how many PSiNPs were sheathed by one exosome right now. The dense area shown in TEM image of E-PSiNPs in Figure 3b might be that several PSiNPs were coated into one exosome. On the other hand, phosphotungstic acid might be adsorbed in the pores of PSiNPs filling them, enhancing the particlesu2019 darkness (Adv. Mater. 2018, 30, 1800512). The intracellular assembly process of PSiNPs into exosomes needs to be further elucidated in the future research. Thank you very much for your kind remind. In the experiment of Figure 4a, we wanted to observe the overlay of exosomes labeled with DiO, DOX and PSiNPs in DOX@E-PSiNPs. To observe the overlay clearly, we zoomed in on a single area. Below is the large vision of this data. We are very sorry that we did not emphasize it in the paper. ![file] ,