Joan Lia, Justin Cooper-Whitea,b,c *

 

aAustralian Institute for Bioengineering & Nanotechnology, The University of Queensland, St. Lucia, QLD 4072, AUSTRALIA.
b
School of Chemical Engineering, The University of Queensland, St. Lucia, QLD 4072, AUSTRALIA.
cBiomedical Manufacturing, Manufacturing Flagship, CSIRO, Clayton, Victoria 3169, AUSTRALIA.

 

Background: MicroRNAs (miRNAs) are emerging as potential therapeutics for Chronic Kidney Disease (CKD) to reduce fibrosis, and myofibroblast proliferation. However, the lack of targeted delivery of miRNAs with sustained expression or suppression are major challenges in translating microRNA therapy to treat CKD. We have developed a novel self-assembled nanoparticle (SAnP) delivery system that, when functionalised with a specific cell-targeting ligand, is recognised by both interstitial fibroblasts and injured epithelial cells within the kidney, enabling cell-specific delivery of miRNA via receptor-mediated uptake.

Methods: In vitro Epithelial-to-mesenchymal transition (EMT) model was induced in cultured MDCK cells with TGF-β (10ng/ml) and treated with or without miR-29 (1nM) for 72 hours. Renal fibrosis model was created using Postn-Cre;Rosa26R-Zsgreen mice (~ 20 weeks), subjected to Unilateral Ureteral Obstruction (UUO). The miR-29 mimic (0.1mg/kg), either packaged into the SAnP system targeting receptor “X” or as “naked” microRNA, was directly delivered into the renal parenchyma of the UUO model, at the time of the obstruction. Mice were euthanized 7 days after UUO. Kidneys were collected and processed for histology analysis.

Results: To test the specificity of our SAnP delivery system, we packaged Cy3-labelled miR into the SAnP and infected cells expressing receptor “X”: MDCK cells. Uptake of Cy-3 was only detected in cells transfected with SAnP-Cy3-miR (97% vs 0.4% for Cy3-miR only), confirming receptor-mediated uptake. In cultured MDCK cells, TGF-β induced EMT was partially blocked by administration of the miR-29 mimic, as treated cells maintained the cobblestone-like morphology and preserved E-cadherin expression on the cell membrane. At 7 days post-UUO, our SAnP-delivered miR-29 mimic was able to reduce tubular dilatation and perivascular infiltration. Quantification of Picrosirius red staining indicated a 24% decrease in collage deposition. Delivery of “naked” miR-29 mimic did not show any beneficial effect in the UUO model.  

Conclusion: Our preliminary data demonstrate that whilst miR-29 alone can inhibit the EMT transition in vitro, “naked” miR-29 had no effect in vivo. Our SAnP system however could affect cell-specific targeted delivery of miR29, significantly reducing tubular dilatation, interstitial infiltration and collagen deposition in the UUO model.