Metabolic Glycan Labelling based approach for Highly Selective Gastrointestinal Delivery
Metabolic glycan labelling is a technique where unnatural sugar analogues are used to decorate cell surfaces with specific functional groups. This allows for targeted delivery of complimentary probes through bioorthogonal targeting, a strategy common for cancer treatment and the concept won a Nobel Prize in 2022. While this approach has been used for tumours, its use in intestinal tissues via oral administration has been unexplored. This study investigated using DBCO-sugar to modify intestinal surfaces for attaching 'clickable' particles. Potentially extend their stay in the gastrointestinal tract. Cells dominating the intestinal layer, like enterocytes and goblet cells, were targeted. Tests on different cell lines showed efficient labelling of mucus-secreting cells. Experiments on rat tissues and oral administration in rats showed successful labelling, showing potential for targeted drug delivery in intestines.
01
In vitro labelling
Caco-2 and HT29-MTX cell lines were labelled with the DBCO functional groups after 24 h of incubation with Ac4ManNDBCO at 100 µM, proving that Ac4ManNDBCO could be incorporated into the sugar processing machinery of the cells and thereby enabling the labelling of intestinal cells.
02
Ex vivo labelling
Duodenal tissue was labelled with Ac4ManNDBCO after 4 h of sugar perfusion and targeted specifically by Cy5-N3 dye, represented by a strong punctate Cy5 signal located at the periphery of the villi.
03
In vivo labelling
The innovative and novel approach had evidently increased Cy5-N3 targeting in duodenal tissues after in situ perfusion and in vivo oral administration of Ac4ManNDBCO. Co-incident staining of Cy5 and MUC2 in vivo was observed, indicating the labelling of the mucous layer in the intestine after 4 h of Ac4ManNDBCO treatment.
04
Particles targeting
Therefore, different azide-functionalised particles such as liposomes and E. coli, were treated to the modified cells as nanoparticle and probiotic models. The preliminary study showed that azide-functionalised E-coli could specifically target labelled Caco-2 cells.
