Rapamycin-Loaded Biomimetic Nanoparticles Reverse Vascular Inflammation

Abstract

Rationale: Through localized delivery of rapamycin via a biomimetic drug delivery system, it is possible to reduce vascular inflammation and thus the progression of vascular disease. Objective: Use biomimetic nanoparticles to deliver rapamycin to the vessel wall to reduce inflammation in an in vivo model of atherosclerosis after a short dosing schedule. Methods and Results: Biomimetic nanoparticles (leukosomes) were synthesized using membrane proteins purified from activated J774 macrophages. Rapamycin-loaded nanoparticles were characterized using dynamic light scattering and were found to have a diameter of 108±2.3 nm, a surface charge of −15.4±14.4 mV, and a polydispersity index of 0.11 +/ 0.2. For in vivo studies, ApoE −/− mice were fed a high-fat diet for 12 weeks. Mice were injected with either PBS, free rapamycin (5 mg/kg), or rapamycin-loaded leukosomes (Leuko-Rapa; 5 mg/kg) once daily for 7 days. In mice treated with Leuko-Rapa, flow cytometry of disaggregated aortic tissue revealed fewer proliferating macrophages in the aorta (15.6±9.79 %) compared with untreated mice (30.2±13.34 %) and rapamycin alone (26.8±9.87 %). Decreased macrophage proliferation correlated with decreased levels of MCP (monocyte chemoattractant protein)-1 and IL (interleukin)-b1 in mice treated with Leuko-Rapa. Furthermore, Leuko-Rapa–treated mice also displayed significantly decreased MMP (matrix metalloproteinases) activity in the aorta (mean difference 2554±363.9, P =9.95122×10 −6 ). No significant changes in metabolic or inflammation markers observed in liver metabolic assays. Histological analysis showed improvements in lung morphology, with no alterations in heart, spleen, lung, or liver in Leuko-Rapa–treated mice. Conclusions: We showed that our biomimetic nanoparticles showed a decrease in proliferating macrophage population that was accompanied by the reduction of key proinflammatory cytokines and changes in plaque morphology. This proof-of-concept showed that our platform was capable of suppressing macrophage proliferation within the aorta after a short dosing schedule (7 days) and with a favorable toxicity profile. This treatment could be a promising intervention for the acute stabilization of late-stage plaques.

Inhibition of macrophage proliferation dominates plaque regression in response to cholesterol lowering

“…While oral atorvastatin inhibits macrophage proliferation indirectly via systemic cholesterol and ApoB-lipoprotein reductions, direct targeting of macrophage proliferation may emerge as a potent add-on therapy to support plaque regression. Anti-proliferative drugs such as paclitaxel and methotrexate or mTOR-inhibitor rapamycin, incorporated into a lipid nanoparticle LDE resembling low-density lipoproteins or biomimetic nanoparticles, induced plaque regression and loss of plaque macrophages in murine and rabbit models of atherosclerosis with limited systemic toxicity [4,7,11]. More recently, LDE-paclitaxel was injected into eight patients with aortic atherosclerosis six times every 3 weeks, and computer tomography images of the atherosclerotic aortas were compared before and after 1-2 months of treatment with those obtained in untreated patients.…”

Advanced nanomedicines for the treatment of inflammatory diseases

“…In another study, biomimetic nanoparticles were synthesized using membrane proteins purified from activated J774 macrophages and loaded with rapamycine. In a model of ApoE-/-mice with atherosclerotic plaques, it was observed that systemic injection of these hybrid NPs was able to suppress cell proliferation within the aorta [104].…”

The Limitless Future of RNA Therapeutics

“…In a lipopolysaccharide (LPS) induced murine model of sepsis, administration of biomimetic nanoparticles derived from macrophages decreased pro-inflammatory genes (IL-6, IL-1b, and TNF-α), and increased anti-inflammatory genes (IL-10 and TGF-β) (Molinaro et al, 2019). The intrinsic anti-inflammatory effects of these biomimetic leukosomes have been demonstrated in other disease models including inflammatory bowel disease (IBD) (Corbo et al, 2017), atherosclerosis (Martinez et al, 2018;Boada et al, 2020), and cancer (Martinez et al, 2018). Most recently, we have shown the capability of leukosomes to home to sites of vascular inflammation in the apo E deficient hypercholesterolemic mouse.…”

“…In this model, the elevated levels of cholesterol cause the accumulation of lipid and macrophages in the aorta. Leukosomes were more efficient than standard LNPs at delivering rapamycin to the aorta, where the rapamycin inhibited macrophage proliferation and generation of inflammatory cytokines (Boada et al, 2020). While significant work remains to be done testing the efficacy of this platform in larger animal models, there is great promise for biomimetic nanoparticles to create new mRNA therapeutics that has the potential to selectively target all the inflammatory-based conditions.…”