ARUP; ISBN: 978-0-9562121-5-3 - CMBBE 2012 - Cardiff University

CELL SEEDING OPTIMIZATION IN 3D SCAFFOLD UNDER
DYNAMIC CONDITION: COMPUTATIONAL AND EXPERIMENTAL
METHODS
1. ABSTRACT
A. L. Olivares 1 , C.M. Perrault 2 and D. Lacroix 3
Proper cell density and spatial distribution in a 3D scaffold are essential to
morphogenetic development of an engineered tissue. The aim of this study was to
combine computational and experimental techniques to study cell seeding under
dynamic conditions. Rapid prototyped poly-caprolactone scaffolds, 5 mm in diameter
and 1.5 mm in height, were used in a custom-made microfluidic chamber, thus enabling
live visualization of the seeding process. The scaffold morphologies were reconstructed
from micro CT images and the fluid volume was created similar to the microfluidic
chamber. Computationally cell motion was represented as spherical particles in a fluid
medium using a multiphase Lagrangian formulation implemented in Ansys Fluent. Cells
were dragged by the fluid flow and adhesion was quantified using wall film theory.
Experimentally, fluorescent microspheres, 10 um in diameter, were used, and fluid flow
was controlled with a syringe pump. Inlet fluid flow was applied at 0.15 mm/s, identical
to the model condition. Live imaging of the seeding process in the microfluidic chamber
enables to record particle trajectory and velocity and possible zone of cell adhesion. The
computational simulation shows velocities (≈0.6mm/s) in agreement with the particles
experiment. Particles distributions was similar and can be highlighted the scaffold
design in fluid accessibility.
2. INTRODUCTION
Development of in vitro tissue involves cell seeding onto a biodegradable scaffold and
culture through a bioreactor system [1,2]. Cell density and spatial distribution in a 3D
scaffold are critical to morphogenetic development of an engineered tissue [3]. A high
number and even distribution of cells in a scaffold are associated with reduced culture
time and with increased formation of tissue (e.g. increase of bone mineralization [4] or
cartilage formation [5]). In addition, initial cell distribution in a scaffold is strongly
related with the final tissue properties [6,7]. Since human cells are often available in
short supply [8], maximization of the cell seeding process is necessary. Dynamic cell
seeding with bioreactors have proven to provide a higher efficiency and more even
distribution of cells [9], more particularly within 3D scaffolds, where perfusion systems
were reported to lead to greater efficiency (40% to 90%) [2, 10-12] and better cell
distribution [13]. The main challenge of dynamic cell seeding is the proper selection and
optimization of parameters [8,14].
1
Postdoctoral researcher, Biomechanics and Mechanobiology, Institute for Bioengineering of Catalonia,
Baldiri Reixac, 4;Torre I, 08028 Barcelona, Spain
2
Lecturer, Department of Mechanical Engineering, University of Sheffield, Mappin Street, Sheffield, S1
3JD, UK
3
Professor, Department of Mechanical Engineering, University of Sheffield, Mappin Street, Sheffield,
S1 3JD, UK