Mannose‐Modified Serum Exosomes for the Elevated Uptake to Murine Dendritic Cells and Lymphatic Accumulation

Abstract

The surface of bovine serum‐derived exosomes (EXOs) are modified with α‐d‐mannose for facile interaction with mannose receptors on dendritic cells (DCs) and for efficient delivery of immune stimulators to the DCs. The surface of the EXOs is modified with polyethylene glycol (PEG) without particle aggregation (≈50 nm) via the incorporation of 1,2‐distearoyl‐sn‐glycero‐3‐phosphoethanolamine (DSPE) into the lipid layer of the EXO, compared to chemical conjugation by N‐hydroxysuccinimide activated PEG (NHS‐PEG). PEG modification onto the exosomal surface significantly decreases the non‐specific cellular uptake of the EXOs into the DCs. However, the EXOs with mannose‐conjugated PEG‐DSPE (EXO‐PEG‐man) exhibit excellent intracellular uptake into the DCs and boost the immune response by the incorporation of adjuvant, monophosphoryl lipid A (MPLA) within the EXO. After an intradermal injection, a higher retention of EXO‐PEG‐man is observed in the lymph nodes, which could be used for the efficient delivery of immune stimulators and antigens to the lymph nodes in vivo.

EVs and Bioengineering: From Cellular Products to Engineered Nanomachines

“…In particular, for what concerns the functionalization, it is important to find the proper molecule for the desired purpose, and a variety of functionalizations are reported in the literature, as mentioned above. As for the indirect methods, the use of DSPE-PEG [ 88 , 89 , 100 ] or DMPE-PEG [ 87 ], as spacer to expose the functionalization, is a commonly used strategy. Finally, for both in vitro and in vivo testing steps, the biological challenges are the same listed above and analyzed for the indirect methods in terms of choice of the best cell line and/or animal model.…”

Engineered Extracellular Vesicles as a Reliable Tool in Cancer Nanomedicine

“…The further functionalization of distal end of PEG chain with appropriate targeting ligands, as already described for synthetic particles [53], can easily overcome this drawback and create a promising tool for drug delivery with stealth properties and targeting abilities. A very recent study [54] described how modify EVs' surface with the active targeting ligand mannose. Exosomes' surface was successfully modified with PEG, avoiding particle aggregation, through the incorporation of 1,2-distearoyl-sn-glycero-3-phosphoethanolamine (DSPE) into the lipid layer of the exosome.…”

“…Exosomes' surface was successfully modified with PEG, avoiding particle aggregation, through the incorporation of 1,2-distearoyl-sn-glycero-3-phosphoethanolamine (DSPE) into the lipid layer of the exosome. For targeting purposes, the PEG's distal end, functionalized with amine groups, was further conjugated with mannose-isothiocyanate, guaranteeing a better accumulation of functional exosomes in lymph-nodes [54].…”

Exploiting Manipulated Small Extracellular Vesicles to Subvert Immunosuppression at the Tumor Microenvironment through Mannose Receptor/CD206 Targeting

“…On the other hand, also cell-secreted sEVs can be considered attractive candidates to specifically target M2-like macrophages via the MR, since they expose high mannose and other classes of N-linked oligosaccharides on their surface [ 115 , 116 ].…”

“…Glycomic studies conducted to date demonstrate that surface glycoprofiles of sEVs contain high amounts of mannose and other classes of N-linked oligosaccharides [ 27 , 34 , 128 , 129 ] making them suitable ligands for the MR. Recently, it has also been shown that mannose-modified serum sEVs display elevated uptake by murine DCs [ 116 ]. This evidence, together with a number of studies showing that mannosylation of both liposomes [ 102 ] and synthetic nanocarriers [ 130 , 131 ] enhance cellular uptake by M2 macrophages, inducing stimulation and polarization of macrophages toward the M1 phenotype, point to sEVs as powerful ligands of M2 macrophages.…”