Dendronized Polymeric Biomaterial for Loading, Stabilization, and Targeted Cytosolic Delivery of microRNA in Cancer Cells

MicroRNAs (miRNAs) are small non-coding RNAs involved in the fine-tuning of gene regulation. Anti-miRNA is a promising RNA-interference (RNAi) agent that potently regulates post-transcriptional expression of an abnormal gene by inhibiting its target mRNAs. To date, ONPATTRO and Leqvio are the only first-in-dass USFDA-approved RNAi-therapeutics available in clinic. The deficiency of a fitting delivery carrier remains a primary hindrance to their clinical translation. To address this issue, this investigation reports the development of a dendronized polymeric nanobiomaterial involving a USFDA-approved biopolymer (hyaluronic acid, also called hyaluronan; HA) for the selective delivery of anti-miRNA into the cytosolic compartment of cancer cells. Dendrons are synthesized for focal cationization of HA to produce a cationic dendronized HA polymer (dCHA) using a ligated dendron motif approach. The synthesized dCHA is inert toward blood cells, as observed in the hemolysis assay. It also depicts a strong binding affinity for the CD44-receptor protein and is found to be neutral toward macrophages and albumin proteins (human origin; molecular simulation and docking tool: GROMACS). The developed approach is simple in application, offers high anti-miR21 loading, and avoids RNase enzymatic degradation of loaded anti-miRNA. The dCHA could efficiently escape the lysoendosomal compartment to mediate cytosolic delivery of the loaded anti-miRNA, ascribed to the proton sponge effect offered by weak basic groups of ligated dendron motifs in the dCHA architecture. The dCHA-loaded anti-miR21 upregulates the mRNA levels of Bax and CASP3 and downregulates the levels of Bcl2, accompanied by significant miR21 gene downregulation. Furthermore, under the influence of CD44-receptor blockade, a reduction in the cellular uptake of FAM-labeled anti-miR21 is observed compared to the control, inferring receptor-mediated uptake of dCHA. The conclusive outcome of this research advocates the use of dCHA to be a fit-to-purpose modality to load, preserve, and selectively deliver anti-miRNA-therapeutics to the cytosolic compartment of cancer cells. The developed approach has been tested using anti-miR21 as a model RNAi-therapeutic; however, the knowledge developed in this fundamental research can also be extended to other gene therapeutics, including DNA, siRNA, miRNA mimics, plasmid oligonucleotides, and so forth.