Biomedical Engineering Reference
In-Depth Information
1970s, “biomimetic chemistry” came along aiming at molecular-level
modeling of enzymes and biomembranes [6].
The emergence of biomimetic materials into tissue engineering came
after sequential stages of material development. While “fi rst generation”
materials were intended to be bioinert, they were required to achieve a
suitable combination of physical properties to match those of the replaced
tissue with a minimal toxic response in the host [7, 8]. In “second genera-
tion” materials this concept evolved into one where materials were bioac-
tive and resorbable and elicited a controlled reaction with physiological
environment.
As characterization tools and techniques continued to advance, the
understanding of how tissues work and form improved. Developments in
the creation of engineered surfaces and bulk architecture of scaffold materi-
als showed that the design of biomimetic materials is basic messages learnt
from studies of cell behavior in the extracellular matrix. Indeed, “third gen-
eration” materials were produced to be an extension of the second genera-
tion but designed and tailored to stimulate specifi c cellular responses at the
molecular level and to elicit specifi c interactions with cell surface receptors
that direct cell differentiation, proliferation and extracellular matrix pro-
duction and organization [9]. A key concept is that biomimetic materials
can imitate the extracellular matrix chemically and structurally to stimulate
tissue formation in a manner analogous to cell-cell communication.
6.2.2
Concept of Duplicating Nature
One important aspect of tissue engineering is the development of new bio-
materials to facilitate cell-material interactions, which can be achieved by
mimicking certain advantageous features of natural extracellular matrix
(ECM) [10]. Since the concept of tissue engineering emerged two decades
ago, scientifi c advances in biomaterials, biology, and medicine have cre-
ated unique opportunities to fabricate tissues in the laboratory by combin-
ing scaffolds (artifi cial extracellular matrices), cells, and biologically active
molecules. In an ideal situation, scaffolds would incorporate the functions
of natural extracellular matrix (ECM), specifi cally, they would provide sup-
port for cell attachment and proliferation, deliver and retain biochemical
factors, enable diffusion of nutrients for cells, and exert suitable mechani-
cal and other stimuli for cell function. For these reasons, scaffolds should
mimic the natural ECM in order to provide the optimal physiological envi-
ronment for cells to guide tissue development and regeneration [11, 12].
6.2.3
Strategies to Achieve Biomimetic Engineering
Initial approaches aimed at improving the adhesiveness of biomaterial
surfaces to increase the bioactivity of biomaterials by coating them with
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