The microcirculation presents functional organic structures in the range of 1-100 micrometers, commensurate with the upper
end of nanotechnology constructs. When devices are designed and deployed to deliver treatment via the circulation they ultimately contend
with the smallest dimensions of both healthy and impaired microvessels, particularly the capillary system whose ability to sustain
the tissue is assessed by measuring “functional capillary density” (FCD). FCD is directly determined by hydrostatic and osmotic pressures
and indirectly by the effect of cardiovascular regulators, particularly the bioavailability of nitric oxide (NO) resulting from fluid
mechanical effects and transport in the submicroscopic cell free plasma layer (CFL) located between blood and microvascular wall. Macromolecules
using colloids as templates that are surface decorated with polyethylene glycol (PEG) become immuno-invisible and can be
introduced into the circulation to manipulate the NO environment in blood and the endothelium. PEG-albumin is a class of molecules
with novel plasma expansion properties that directly interacts with the microcirculation via CFL related effects. The principal application
of this technology is in transfusion medicine and the plasma expanders used to treat blood losses and concomitant effects on microvascular
function due to related acute inflammatory conditions and ischemia.
Keywords: Microcirculation, cell free layer, functional capillary density, PEG-albumin, plasma expanders.
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