Transferrin Functionization Elevates Transcytosis of Nanogranules across Epithelium by Triggering Polarity-Associated Transport Flow and Positive Cellular Feedback Loop

Abstract

Overcoming the epithelial barriers to enhance drug transport is a focused topic for gastrointestinal, intratracheal, intranasal, vaginal, and intrauterine delivery. Nanomedicines with targeting functionization promote such a process owing to specific ligand–receptor interaction. However, compared to the cell uptake of targeting nanotherapies, currently few studies concentrate on their transcytosis including endocytosis for “in” and exocytosis for “out”. In fact, the cellular regulatory mechanism for these pathways as well as the principle of ligand’s effect on the transcytosis are almost ignored. Here, we fabricated transferrin (Tf) functionalized nanogranules (Tf-NG) as the nanomedicine model and confirmed the difference in polar distributions of Tf receptors (TfRs) between two epithelium models (bipolarity for Caco-2 and unipolarity for MDCK cells). Compared to the nonspecific reference, Tf-conjugation boosted the endocytosis by different pathways in two cell models and transformed the intracellular route of Tf-NG in both cells differently, affecting exocytosis, recycling, and degradation but not the secretion pathway. Only bipolar cells could establish a complete transport flow from “in” to “out”, leading to the enhanced transcytosis of Tf-NG. Importantly, epithelia could make responses to Tf-NG transcytosis. Based on the quantitative proteomics, the intracellular trafficking of Tf-NG altered the protein expression profiles, in which the endocytosis- and transcytosis-related proteins were specifically upregulated. Particularly, only bipolar cells could positively feed back to such trafficking via accelerating the subsequent Tf-NG transcytosis. Here, all the cell transport of Tf-NG was polarity associated. In summary, Tf modification elevated the transcytosis of Tf-NG across the epithelium by triggering the polarity-associated transport flow and positive cell feedback loop. These findings provided an insight into the targeting nanodelivery for efficient transport through epithelial barriers.

<p>Endocytosis and Organelle Targeting of Nanomedicines in Cancer Therapy</p>

“…Early endosomes act as a sorting machine and can carry the cargos to specific subcellular organelles, to recycling endosomes for apical recycle recycled, to basolateral compartment for releasing. [16][17][18] Besides, early endosomes can mature to late endosomes (also called multivesicular body). NMs that failed to escape from the endosomes face degradation in the lysosome.…”

“…NMs that failed to escape from the endosomes face degradation in the lysosome. [16][17][18] According to the proteins involved, endocytosis pathways are generally classified into phagocytosis and pinocytosis. 19 Pinocytosis is ubiquitous in almost any eukaryotic cell and is employed by NMs when entering into the tumor cell.…”

Delivery of Nanoparticles across the Intestinal Epithelium via the Transferrin Transport Pathway

“…There are however reports of TfR-mediated transcytosis being explored for oral delivery of biologics via a Tf recombinant fusion protein approach [15] or Tf conjugation to therapeutic macromolecule [16]—both these approaches have shown evidence and potential for the use of TfR-mediated transport as a strategy to enhance the intestinal absorption (i.e., in the apical-to-basolateral direction) of biologics. Importantly, a recent landmark study clearly showed a complete and enhanced apical-to-basolateral transcytosis of Tf-functionalised nanogranules in Caco-2 cells, with Tf modification upregulating the expression of trafficking-related (endocytosis and transcytosis) proteins [17].…”

“…A fundamental study of this nature is imperative to assess the possibility that TfR-mediated transcytosis may be utilised to facilitate intestinal translocation of nanomedicines. This is important as, with the exception of two studies [17,18], TfR-mediated transcytosis has not been investigated for intestinal delivery of nanosystems. We show here that TfR targeting of NP significantly improves their uptake into intestinal epithelial cells (Caco-2), as well as translocation across cell monolayers serving as an in vitro intestinal model.…”

Polymeric Nanoparticles-Based Brain Delivery with Improved Therapeutic Efficacy of Ginkgolide B in Parkinson’s Disease

“…To that end, we explored the endocytic mechanisms of NPs in Madin-Darby canine kidney (MDCK) cells, as these cells represent an ideal in vitro epithelial model owing to their polarity, tight junction formation, and relatively thin mucus layer. 17 Moreover, the neuroprotective effects of NPs were evaluated using human neuroblastoma SH-SY5Y cells, a neuron-like cell model that has been widely used to evaluate intracellular events linked to neurotoxic insults. To extend this work, we then employed a zebrafish model system in order to explore the ability of coumarin 6 (C6)-labeled NPs (C6-NPs) to cross specific biological barriers in vivo.…”