Evaluation of Liposome-Loaded Microbubbles as a Theranostic Tool in a Murine Collagen-Induced Arthritis Model

Michel Versluis,Heleen Dewitte,Silke Roovers,Julie Coudenys,Dirk Elewaut,Stefaan C De Smedt,Christian Vanhove,Ine Lentacker,Tine Decruy,Guillaume Lajoinie,Benedicte Descamps,Peggy Jacques,Joke Deprez

doi:10.3390/scipharm90010017

Abstract

Rheumatoid arthritis (RA) is an autoimmune disease characterized by severe inflammation of the synovial tissue. Here, we assess the feasibility of liposome-loaded microbubbles as theranostic agents in a murine arthritis model. First, contrast-enhanced ultrasound (CEUS) was used to quantify neovascularization in this model since CEUS is well-established for RA diagnosis in humans. Next, the potential of liposome-loaded microbubbles and ultrasound (US) to selectively enhance liposome delivery to the synovium was evaluated with in vivo fluorescence imaging. This procedure is made very challenging by the presence of hard joints and by the limited lifetime of the microbubbles. The inflamed knee joints were exposed to therapeutic US after intravenous injection of liposome-loaded microbubbles. Loaded microbubbles were found to be quickly captured by the liver. This resulted in fast clearance of attached liposomes while free and long-circulating liposomes were able to accumulate over time in the inflamed joints. Our observations show that murine arthritis models are not well-suited for evaluating the potential of microbubble-mediated drug delivery in joints given: (i) restricted microbubble passage in murine synovial vasculature and (ii) limited control over the exact ultrasound conditions in situ given the much shorter length scale of the murine joints as compared to the therapeutic wavelength.

Highlights

Rheumatoid arthritis (RA) is an auto-immune disease characterized by persistent joint inflammation resulting in irreversible cartilage degradation and bone erosion when left untreated [1,2]
We observed some non-specific interaction between liposomes and microbubbles in the absence of avidin, avidin-biotin coupling was required to allow efficient liposome loading of the microbubbles (Supplementary Figure S3)
The liposome-loading was conserved in serum as both the histogram shape as well as the Mean Fluorescence Intensity (MFI) of the bubbles completely overlap with the histograms of HEPES-diluted liposomeloaded microbubbles

Summary

Introduction

Rheumatoid arthritis (RA) is an auto-immune disease characterized by persistent joint inflammation resulting in irreversible cartilage degradation and bone erosion when left untreated [1,2]. About 0.5–1% of the population in developed countries is affected by the disease, mostly middle-aged patients. Incidence and prevalence rates are twice as high in women than in men [1,3,4]. The synovial lining expands dramatically in affected joints as a result of massive immune cell infiltration [2]. During the inflammatory process, uncontrolled neovascularization occurs to provide a constant transport of oxygen and nutrients to the hypertrophic site of inflammation. This neovasculature facilitates the transport of leukocytes to the synovial lining, leading to tissue remodelling and additional damage [5,6]

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Results

Discussion

Conclusion