Hybrid pulmonary surfactant-coated nanogels mediate efficient in vivo delivery of siRNA to murine alveolar macrophages

Abstract

The local delivery of small interfering RNA (siRNA) to the lungs may provide a therapeutic solution to a range of pulmonary disorders. Resident alveolar macrophages (rAM) in the bronchoalveolar lumen play a critical role in lung inflammatory responses and therefore constitute a particularly attractive target for siRNA therapeutics. However, achieving efficient gene silencing in the lung while avoiding pulmonary toxicity requires appropriate formulation of siRNA in functional nanocarriers. In this study, we evaluated pulmonary surfactant-coated dextran nanogels for the delivery of siRNA to rAM upon pharyngeal aspiration in BALB/c mice. Both the surfactant-coated and uncoated nanogels achieved high levels of siRNA uptake in rAM, yet only the surfactant-coated formulation could significantly reduce gene expression on the protein level. Surfactant-coated nanogels induced a profound downregulation of target mRNA levels, reaching 70% knockdown with ~1 mg kg -1 siRNA dose. In addition, only mild acute pro-inflammatory cytokine and chemokine responses were detected one day after nanoparticle aspiration, accompanied by a moderate neutrophil infiltration in the bronchoalveolar lumen. The latter could be substantially reduced by removal of excess surfactant from the formulation. Overall, our hybrid core-shell nanoparticles have demonstrated safe and effective siRNA delivery to rAM, providing a new therapeutic approach for treatment of inflammatory pathologies in the lung.

Surfactant protein B (SP-B) enhances the cellular siRNA delivery of proteolipid coated nanogels for inhalation therapy

“…We recently reported on the unanticipated finding that the decoration of siRNA-loaded dextran nanogels (siNGs) with a clinically used pulmonary surfactant (PS) from porcine origin (Curosurf  ) substantially enhanced cellular siRNA delivery both in vitro [9] and in vivo. [10] Comparable to native human PS, the most abundant component of the (phospho)lipid fraction in To evaluate the contribution of the remaining hydrophobic SPs to the PS-enhanced siRNA delivery, siNGs were initially coated with a mixture of abundant PS phospholipids, i.e. DPPC, 1-palmitoyl-2-oleoylsn-glycero-3-phosphocholine (POPC) and L-α-phosphatidylglycerol (eggPG) in a 50:35:15 weight ratio.…”

“…In this context, we recently reported on hybrid NPs composed of an siRNA-loaded polymeric matrix core that is coated with a proteolipid shell of Curosurf ® , a clinical pulmonary surfactant (PS). [9], [10] The core of these NPs consists of a cationic polysaccharide hydrogel nanoparticle (nanogel; NG), which has a high loading capacity for siRNA (~0.4 µg/µg) and a proven delivery potential in various cell types. [11][12][13] PS is an endogenous surface-active material that covers the alveolar surface to maintain a low surface tension upon expiration and prevent alveolar collapse.…”

“…However, the molecular determinants for this delivery-promoting effect remain elusive. [9], [10] Native PS is composed of various lipids (~90 wt%) and specialized surfactant proteins (SPs, ~10 wt%). [16] The lipid fraction mainly consists of phosphatidylcholine (PC) (~60-70 wt%) and anionic phospholipids such as phosphatidylglycerol (PG) and phosphatidylinositol (~10-15 wt%) species.…”

Bio-inspired materials in drug delivery: Exploring the role of pulmonary surfactant in siRNA inhalation therapy

“…mucins) [103]. Because of its promising features, this NP platform was subsequently evaluated in vivo for siRNA delivery to murine resident alveolar macrophages (rAM) [104]. Of note, already more than fifteen years ago, a first in vivo experiment on the co-delivery of animal-derived PS and DNA-loaded polymeric NPs was conducted [105].…”

Nucleic Acid-Based Therapeutics for Pulmonary Diseases

“…Th e use of en dogenou s pho sp holipids, su ch as dipalmitoylphosphatidylcholine, can be considered a valid approach to increase the compatibility of nanoparticles with the lung environment (46). Researchers combined a naturalderived pulmonary surfactant shell with a siRNA-loaded dextran nanogel to achieve effective siRNA delivery to murine alveolar macrophages, which are difficult to transfect, resulting in a substantial gene knockdown with a relatively low dose (47)(48)(49). Diverse surface modifications and conjugation of targeting agents attached to the vectors could render them desirable properties and enhance the therapeutic efficiency of nucleic acid therapy.…”