LNPs, exosomes, extracellular vehicles: did evidence show early on that lipid nano particles (LNPs) exchange more easily in small diameter vessels with low flow rate i.e., capillaries & small vessels?

Yes! Chen et al. showed us this via how flow Rate Affects Nanoparticle Uptake into Endothelial Cells

https://onlinelibrary.wiley.com/doi/10.1002/adma.201906274

‘Injected nanoparticles travel within the blood and experience a wide range of flow velocities that induce varying shear rates to the blood vessels.

Endothelial cells line these vessels, and have been shown to uptake nanoparticles during circulation, but it is difficult to characterize the flow-dependence of this interaction in vivo.

Here, a microfluidic system is developed to control the flow rates of nanoparticles as they interact with endothelial cells. Gold nanoparticle uptake into endothelial cells is quantified at varying flow rates, and it is found that increased flow rates lead to decreased nanoparticle uptake.

Endothelial cells respond to increased flow shear with decreased ability to uptake the nanoparticles. If cells are sheared the same way, nanoparticle uptake decreases as their flow velocity increases. Modifying nanoparticle surfaces with endothelial-cell-binding ligands partially restores uptake to nonflow levels, suggesting that functionalizing nanoparticles to bind to endothelial cells enables nanoparticles to resist flow effects.’