Biomedical Engineering Reference
In-Depth Information
5.1 Introduction
To restore functionality of bones or repair any defects caused by trauma,
tumors, infections or congenital defi ciencies, or damaged by accident is a
most desired but clinically challenging procedure. Traditionally, autograft
and allograft procedures are used for repairing bone defects, both of these
have serious limitations [1, 2]. Although autografts are still considered as
the gold standard in bone transplantation, their inherent problems, such
as limited availability, donor site morbidity and risk of disease transmis-
sion from donor to recipient and immune rejection, have limited their clin-
ical application [3, 4]. Allograft procedures are now considered attractive
alternatives to autografts, and there have been a spate of research activi-
ties in fi nding and developing alternative procedures for tissue engineer-
ing both in academia and industry.
Tissue engineering has many complementary facets and research in this
fi eld is multidisciplinary with the aim of developing a new therapeutic phi-
losophy encompassing aspects of replacement, restoration, maintenance and
enhancement of tissue and organ functions. Research in this fi eld started in
the 1990s and since then signifi cant progress has been made. Currently, tis-
sue engineering is one of the most infl uential domains within new strategies
for the treatment of diseased tissues and organs. Bone tissue engineering,
however, is a new and emerging area of research with clinical applications
in orthopaedic defects, bone tumors, repairing spinal injuries, maxillofacial,
craniofacial, neck and head surgery. In recent years, a variety of biomateri-
als, derived from biological or synthetic materials, have been designed to
provide extracellular matrix (ECM) scaffolds for new bone formation [5].
Such scaffolds are three-dimensional (3D) constructions that are implanted
into the human body, leading to host integration without immune rejection.
In bone tissue engineering, the design and fabrication of 3D architecture
scaffolds are a key requirement, because scaffolds can mimic the structure
and function of the extracellular matrix (ECM) and support cell adhesion,
proliferation and differentiation [6]. There are various fabrication tech-
niques for constructing scaffolds, including conventional chemical engi-
neering methods as well as advanced manufacturing technologies [7-10].
In recent years much attention has been given to advanced techniques in
the tissue engineering fi eld because they can control the external and inter-
nal structure of tissue engineering scaffolds and overcome some inherent
limitations of conventional methods, such as manual intervention, incon-
sistent and infl exible processing procedures, and shape limitations [9, 10].
A variety of synthetic materials such as polymers and nanomaterials have
been investigated for bone regeneration. These were derived from ceramics,
glasses and other inorganic materials, nanotubes, and their composites, and
were studied with or without cells and growth factors. In an ideal scenario,
the synthetic biomaterials should have excellent biocompatibility, the ability
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