2.2.4. Nanoparticles to Target Myeloid and Lymphoid Immune Cell-Enriched Tissues

Nanomedicine is well-known to be uptaken by the RES, and various strategies have been documented to overcome this major drawback [46]. RES is a part of the immune system composed of phagocytic cells found in the spleen, liver, lungs, bone marrow, and lymph nodes. So, it is important to consider that targeting immune cells also implies delivering drugs to these immune-cell-rich organs [27]. Nevertheless, this apparent drawback may be advantageous to target immune cell-enriched tissues for both diagnosis and therapy. Indeed, in various cancers, nanoparticles are administered subcutaneously to target lymph nodes for preoperative imaging and intraoperative detection (radioactivity, fluorescence, magnetism).

As an example, a novel mannose-labeled SPION was recently developed (maghemite iron oxide core) to target lymph node resident macrophages, making it possible to perform lymph node imaging in pigs with a substantial percentage of accumulated iron (83%) [47]. Moreover, it is also possible to target RES with NPs to elicit a personalized anti-cancer response through various lipid NP platforms, allowing the targeted delivery of mRNA or gene editing in a tissue-specific manner [27].
