Engineering Dendrimers for Targeted Drug Delivery to Injured Renal Proximal Tubules

Background: Acute kidney injury (AKI) is a common and sometimes severe clinical condition lacking effective therapeutic options. Impediments to the development of effective treatments include the glomerular filtration barrier, which can hinder therapeutic agents’ ability to reach injured tubular epithelial cells, and off-target effects of potent drugs on non-renal tissues. Therefore, developing targeted delivery systems holds significant potential for minimizing off-target side effects and enhancing the efficacy of AKI treatments. Methods: Single cell-RNA sequencing, immunofluorescence staining, and quantitative PCR were used to identify the folate receptor as a potential molecular target on proximal tubule (PT) cells. Acetylated polyamidoamine (PAMAM) dendrimers conjugated to folate [FA-G4(-Ac10)] were synthesized and characterized by DLS, 1H NMR and HPLC. Biodistribution evaluation was conducted 24 hours after intravenous injection of FA-G4(-Ac10) [FA-G4(-Ac10)-Cy3]. Lastly, the PPARα agonist Wy-14643 was loaded into FA-G4(-Ac10) nanoparticles and administered to mice 7 days after ischemia/reperfusion injury to assess therapeutic delivery and efficacy. Results: Folate receptor (FOLR1) expression was found to be high in both LTL-positive healthy and KIM-1-positive injured PT cells. FA-G4(-Ac10) nanoparticles were successfully synthesized and shown to pass the glomerular filtration barrier, specifically targeting FOLR1-expressing PT cells. Following intravenous injection, FA-G4(-Ac10) demonstrated a 2.9-fold and 9.1-fold increased uptake in PT cells compared to FA-G4 and G4 nanoparticles, respectively. A single dose injection of Wy-14643-loaded FA-G4(-Ac10) significantly increased the expression of PPARα target genes in both healthy and injured kidneys, while reducing the expression of inflammatory (Tnf) and injury (Vcam1) markers in injured kidneys. Mice treated with Wy@FA-G4(-Ac10) on day 7 post-injury showed a significantly reduction in both BUN and serum creatinine levels on day 8. Conclusion: This study demonstrates that folate-modified, acetylated PAMAM dendrimers can effectively deliver therapeutic agents to both healthy and injured PT cells, offering a promising strategy for enhancing drug delivery and therapeutic outcomes in AKI.