Lipid membrane coated nanoparticles as model system to investigate glycoprotein-independent targeting of human immune cells and mimic viral uptake and trafficking
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Nanoparticles (NPs) are becoming increasingly popular as a new tool for the investigation of virus trafficking pathways and the delivery of therapeutic agents into targeted recipient cells. However, one general challenge for applications of NPs in the biological context is that a broad variety of different proteins can adsorb to the NP surface. The resulting formation of a so-called “corona” around NPs impacts the fate and distribution of NPs both in vitro and in vivo due to nonspecific opsonization and scavenging. Inspired by the surface compositions of living cells and enveloped viruses, here in this dissertation, a NP passivation strategy based on a self-assembled lipid membrane containing phospholipids such as 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) and 1,2-dioleoyl-sn-glycero-3-phospho-L-serine (DOPS) is developed and evaluated. The effect of the DPPC / DOPS ratio on corona formation is systematically analyzed. After inclusion of monosialoldihexosyl-ganglioside GM3, which binds selectively to CD169 (Siglec-1) expressed by myeloid cells such as macrophages and dendritic cells, into the membrane coating, NPs are found to target CD169 expressing macrophages in mouse lymph nodes in vivo. Combined in vitro and in vivo studies show that lipid-wrapped NPs represent a versatile platform for utilizing specific lipid–receptor interactions for targeting purposes. Presentation of GM3 on NPs achieves a recapitulation of the intracellular distribution observed for human immunodeficiency virus type 1 (HIV-1) in CD169 expressing macrophages and dendritic cells. Therefore, membrane-wrapped NPs are referred to as artificial virus nanoparticles (AVN). We demonstrate that AVN can accumulate in virus containing compartments (VCC), which are deep plasma membrane invaginations in macrophages that provide evasion for HIV-1 from the immune system and anti-viral therapeutics. Intriguingly, the ability to target VCC depended exquisitely on the GM3/DOPS ratio in the AVN membrane. Exchange of gold NPs with mesoporous silica NPs provides a new class of AVN whose core can serve as matrix and also carry therapeutic agents. We show using rilpivirine (RPV), a FDA approved second-generation non-nucleoside reverse transcriptase inhibitor of HIV-1 infection, that AVN with mesoporous NP core achieve significantly enhanced HIV-inhibition effects compared with soluble RPV or long-acting nanocrystalline formulation of RPV.