[Todos] charla "Dynamics of Nano Particles in Drug Delivery Simulations"

[Esteban Mocskos]

El laboratorio de sistemas complejos (lsc.dc.uba.ar) tiene el agrado de 
invitar al seminario especial "Dynamics of Nano Particles in Drug Delivery 
Simulations" el día 30/12/2008 a las 15:00hs en el aula E-24 del pabellón 1 

Será dictado por Dr Victor M. Calo, Visiting Fellow, Institute for 
Computational Engineering and Sciences (ICES), University of Texas at Austin 
(http://www.ices.utexas.edu/~victor) and Assistant Professor, Earth and 
Environmental Science and  Engineering, King Abdullah University of Science 
and Technology (KAUST) and Assistant Professor, Applied Mathematics and 
Computational Science, King Abdullah University of Science and Technology 
(KAUST)

Abstract
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In the treatment and imaging of diseases, as such cancer and cardiovascular, 
nano-sized delivery vehicles (particulate system) are emerging as powerful 
tools. These are made up of a central core, carrying drug molecules or 
imaging contrast agents, and an external coating with precise physicochemical 
properties, and are injected within the blood stream at the systemic level. 
The great advantage of particulate systems over freely administered molecules 
is their “engineerability:” their size, shape and surface properties can be 
optimized to increase the probability of reaching the desired biological 
target. An “optimally” designed particulate system should be able to
navigate into the circulatory system, recognize preferentially the target 
vasculature and there adhere firmly to the vessel walls resisting to the 
hydrodynamic dislodging forces or, if sufficiently small, leave spontaneously 
the vasculature and diffuse into the extravascular space. The dynamics of a 
particulate system within the blood vessels, however, is not only influenced 
by its intrinsic properties (size, shape and surface properties) but it is 
also dramatically affected by (i) the hydrodynamic conditions at the
site of adhesion or extravasation, (ii) the authentic structure and (iii) 
physiological properties of the vasculature and (iv) the rheology of blood. 
Notably, the points (i)-(iv) are disease specific, patient specific and would 
change over time as the disease progresses.

Recently, the Isogeometric Analysis concept has been extended to simulate 
fluid-structure interaction problems with biomedical applications. 
Isogeometric analysis encompasses and generalizes the finite element method, 
simplifying mesh refinement and improving the functional representation of 
the geometry and the solution. The increased geometrical flexibility obtained 
with isogeometric methodology, as well as the smoothness of the geometrical 
description, allows for the accurate representation of patient-specific 
vascular geometries with fewer degrees of freedom. An efficient 
parallel-solution strategy has been implemented and thoroughly tested in the 
Texas Advanced Computing Center (TACC) high-performance computing systems. 
This efficiency, combined with the robustness and accuracy of the numerical 
procedures, permits the inclusion of several non-linear physical phenomena in 
a single simulation framework. This combination has allowed more realistic 
simulation of relevant biomedical problems, such as drug delivery [4], the 
analysis of flow patterns in cerebral and abdominal aneurysms and the 
growth-and-remodeling process by which healthy arterial-wall tissue 
degenerates into an aneurysm.

A multiphysics mathematical model to simulate drug delivery in idealized and
patient- specific coronary arteries is presented. Blood is modeled as an 
incompressible Navier- Stokes fluid, the arterial wall as a linear 
poroelastic medium, and the drug transport is described by a scalar 
advection-diffusion equation. The drug compound is released into the 
bloodstream, carried by the flow, deposited onto the endothelium, penetrates 
into the wall, and is transported within the arterial wall. NURBS-based 
isogeometric analysis is employed to describe the geometry and discretize the 
fluid-solid interaction equations. The aim of this work is to extend this 
model to analyze (i) the distribution of particulate systems, treated as 
diffusing/advecting scalars, within authentically complex (patient specific) 
vascular systems; and (ii) their adhesive interaction with the walls of the 
vessels. The effect of the permeability of the vessels to both the 
particulate systems and the plasma will be addressed.