Introduction: Lipid nanoparticles (LNPs) are a well-established mRNA-delivery system [1] and their public health significance through mRNA vaccines is now well-recognized. However, precise delivery of mRNA-therapeutics to pathological areas remains a key bottleneck in translating this breakthrough technology beyond Covid-19 [2]. Our approach to organ-specific mRNA delivery leverages small-molecule ligands with high binding affinity to Fibroblast Activation Protein (FAP) to functionalize LNPs. This strategy offers a promising approach to direct RNA-therapeutics specifically to activated cardiac myofibroblasts and cancer-associated fibroblasts (CAFs), with the potential to respectively enable cardiac regeneration in heart failure (HF) and enhance cancer immunotherapy in desmoplastic tumours such as pancreatic ductal adenocarcinoma (PDAC).
Aims: To engineer mRNA-LNPs with small-molecule ligands against FAP towards advancing mRNA-based therapies for cardiac tissue regeneration and cancer immunotherapy.
Methods: The highly potent and selective inhibitor of FAP UAMC-1110 was conjugated to DSPE-PEG through carbodiimide chemistry. LNPs were prepared using a custom-made microfluidic nanoprecipitation device using various amounts of DSPE-PEG-FAPi. The FAP-positive cell line was used to assess binding affinity and specificity in vitro. In vivo performance was assessed in well-established murine HF model.
Results: Physicochemical characterization demonstrated excellent particle sizes for both targeted (86 ± 0.4 nm) and non-targeted (85 ± 0.6 nm) LNPs. In vitro studies confirmed that the FAPi-LNPs exhibited significantly higher binding affinity and mCherry mRNA expression in FAP-positive cells compared with non-targeted LNPs. Moreover, in vivo biodistribution analysis in HF model revealed enhanced accumulation of FAPi-LNPs and higher mCherry expression in the fibrotic area of the heart, validating their targeting capability.
Discussion: This proof-of-concept study establishes a promising foundation for advancing mRNA-based therapies for cardiac tissue regeneration and cardiac reprogramming. Ongoing studies will assess in vivo mRNA expression in murine model of pancreatic cancer to further explore their applications in cancer immunotherapy.