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

A BIOREATOR TO BIOMECHANICAL AND BIOCHEMICAL
CHARACTERIZATION OF ENGINEERED CARTILAGE
1. ABSTRACT
A. Completo 1 , J. Pereira 1 , C. Relvas 1 , A. Ramos 1 , J. Simoes 1 ,
Osteoarthritis is a degenerative joint disease characterized by pain and disability. Severe
osteoarthritis is the prime cause for joint replacement surgery [1]. The substitution of
tissues with allograft materials includes the risk of infections or a graft rejection [2].
Artificial implants have limitations and insufficient bonding to the bone. New therapy
concepts for practical medical applications are required. To this end, tissue engineered
substitutes generated in vitro could open new strategies for the restoration of damaged
tissues. Many of the tissues for which one may desire to engineer a replacement have a
biomechanical function. However, the mechanical properties of many tissues
engineered to date are inferior to those of native tissues [2], a finding that clearly
highlights two important key issues in biomechanics. The first is related to the relevance
of the mechanical properties of the engineered tissues to their function in-vivo. The
second, assuming that the mechanical properties will be important, concerns the control
of these properties. Some investigators had concluded that the mechanical properties of
artificial cartilage can be improved by appropriate mechanical stimulation [2]. These
indications are promising, but the properties of these engineered cartilages remain
inferior of native [1]. Much more investigation is required in what concerns new devices
for tissue culture namely the bioreactors in order to identify the types of required
stimulation to improve the mechanical properties of engineered cartilage tissue [2].
Together with biomechanical characterization, bioreactors could thus help in defining
when engineered tissues have a sufficient mechanical integrity and biological
responsiveness to be implanted [2]. Large part of the actually bioreactors cannot
accommodate the differentiated mechanical stimulations and don’t allow following in
real time its biomechanical and biochemists properties [1]. In order to answer at the
limitations of the actual bioreactors concepts a new bioreactor concept was developed.
2. METHODS
The general functions of the bioreactor (Figure 1) are the control and delivery accurate
and reproducible compression, tension, shear, bending and/or electric and/or magnetic
stimulation patterns, and the generation of a biochemical environment suitable for
growth and differentiation. In order to achieve this aim, the first design principle is high
versatile both of the actuator and culture chamber, so the device can be used with 3D
cell constructs or 2D cell constructs. Deriving from these general design criteria, the
most constraint and requirements are: Cytocompatibility of the materials in contact with
culture mean, Easy sterilization and sterility maintenance, Easy of use, Can be used in a
standard incubator, Comparative biomechanical and biochemical characterization
between mechanical stimuled and static cell constructs without interrupt cell culture and
1 Biomechanics Research Group, Mechanical Engineering Department, University of Aveiro, Campus de
Santiago, Aveiro, Portugal.