Influenza A virus mimetic nanoparticles trigger selective cell uptake

Abstract

Poor target cell specificity is currently a major shortcoming of nanoparticles (NPs) used for biomedical applications. It causes significant material loss to off-target sites and poor availability at the intended delivery site. To overcome this limitation, we designed particles that identify cells in a virus-like manner. As a blueprint, we chose a mechanism typical of influenza A virus particles in which ectoenzymatic hemagglutinin activation by target cells is a mandatory prerequisite for binding to a secondary target structure that finally confirms cell identity and allows for uptake of the virus. We developed NPs that probe mesangial cells for the presence of angiotensin-converting enzyme on their surface using angiotensin I (Ang-I) as a proligand. This initial interaction enzymatically transforms Ang-I to a secondary ligand angiotensin II (Ang-II) that has the potential to bind in a second stage to Ang-II type-1 receptor (AT1R). The presence of the receptor confirms the target cell identity and triggers NP uptake via endocytosis. Our virus-mimetic NPs showed outstanding target-cell affinity with picomolar avidities and were able to selectively identify these cells in the presence of 90% off-target cells that carried only the AT1R. Our results demonstrate that the design of virus-mimetic cell interactive NPs is a valuable strategy to enhance NP specificity for therapeutic and diagnostic applications. Our set of primary and secondary targets is particularly suited for the identification of mesangial cells that play a pivotal role in diabetic nephropathy, one of the leading causes of renal failure, for which currently no treatment exists.

The Effect of Ligand Mobility on the Cellular Interaction of Multivalent Nanoparticles

“…[ 25 ] Ang‐I is a substrate for ACE, [ 26 ] which we recently used to develop highly specific virus‐mimetic NPs. [ 22 ] The binding of Ang‐I‐decorated NPs to the cell membrane‐bound ACE results in the excision of the last two amino acids of the peptide, generating Ang‐II‐carrying NPs that are internalized through AT1R‐mediated endocytosis. To minimize any possible interference on the NP–cell interaction, [ 27 ] the polymers were chosen to keep the particles in a narrow size range (60–80 nm) (Figure 1b,e).…”

“…To determine the effect that ligand mobility exerts on the AT1R interaction and the NP's overall avidity, NP 2/510 and NP 5/510 functionalized with Ang‐II (NP 2/510 Ang‐II and NP 5/510 Ang‐II, respectively) carrying 20%, 40%, or 80% ligand densities were prepared. The affinities of the particle‐bound ligands and avidities of the resulting formulations toward the AT1R after a short NP–cell contact were evaluated using a calcium mobilization assay ( Figure 2 ) with AT1R‐expressing rat mesangial cells (rMCs), [ 22 ] as previously described by our group. [ 22,28 ] Under normal conditions, rMCs express high levels of the AT1R, of about 1185 ± 83 fmol mg −1 protein.…”

“…More so, they are biocompatible and biodegradable and are fitted for the use as drug carriers. To endow particles with targeting capacities we used angiotensin derivative ligands, which we previously used for highly specific cell identification, [ 22 ] and sought to further improve the system by adjusting its flexibility. To that end, we coupled angiotensin‐I (Ang‐I) or angiotensin‐II (Ang‐II), targeting cell membrane‐bound angiotensin converting enzyme (ACE) or angiotensin‐II type 1 receptor (AT1R), respectively, to long PEG 5k ‐PLA 10k chains and kept the remaining nonmodified polymers (NMPs) shorter by using a PEG 2k –PLA 10k to allow higher conformational freedom to the ligand‐carrying polymers (LMPs) ( Figure 1 a).…”

Nanoparticles Mimicking Viral Cell Recognition Strategies Are Superior Transporters into Mesangial Cells

“…The particle specificity in co‐culture of target and off‐target cells was investigated through CLSM and flow cytometry analysis as previously described. [ 9 ]…”

Is Nanotechnology Helping in the Fight Against COVID-19?

“…Similarly, angiotensin ligands-loaded copolymer structures bind to angiotensin enzymes, ensuring treatment specificity in ACE2 + cells for future drug delivery studies (Figueroa et al, 2019). Therefore, the ability of NPs to prevent viral binding at ACE2 appears to be promising against CoVs infection.…”