Biomedical Engineering Reference
In-Depth Information
Contents
1 Introduction .................................................................................. 168
2 Cell Adhesion to a Model Biomaterial Surface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 169
2.1 Self-Assembled Monolayer as a Model Surface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 169
2.2 Cell Adhesion on Material Surfaces .................................................. 170
2.3 Effect of Protein Adsorption on Cell Adhesion ...................................... 173
3 Cell Culture Substrates for Specific Cell Proliferation .................................... 178
3.1 Strategy for Adherent Cultures of Neural Stem Cells ............................... 179
3.2 Oriented Immobilization of Engineered EGF ........................................ 179
3.3 Proliferation of Rat NSCs on EGF-His-Immobilized Surface ....................... 181
3.4 Structural Integrity and Stability of Immobilized EGF-His ......................... 184
3.5 Spontaneous Dimerization of EGF . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 184
3.6 Modules for Culturing NSCs in a Closed System . .................................. 185
4 Cell Surface Modifications .................................................................. 187
4.1 Cell Surface Modifications with Amphiphilic Polymers . . . . . . . . . . . . . . . . . . . . . . . . . . . . 187
4.2 Immobilization of Bioactive Substances on an Islet Surface . . ...................... 189
4.3 Encapsulation of Islets with Living Cells . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 192
5 Summary . . . .................................................................................. 193
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 194
1
Introduction
Much effort has been devoted to understanding biological responses to artificial
materials [
1
,
2
] in order to facilitate the development of medical devices and
artificial organs. However, many issues remain to be fully understood. Furthermore,
these studies require overcoming various difficulties because biological responses are
affected by many factors, including surface energy, surface electrostatic properties,
macro- and microsurface morphology, surface heterogeneity, different functional
groups, and the mobility of functional groups on surfaces. Systematic studies of
biological responses to artificial materials require surfaces with well-controlled
properties; however, there is a lack of methods for systematically controlling
surface properties. Surface chemistry approaches have employed the use of model
surfaces, like self-assembled monolayers (SAMs) of alkanethiols, HS(CH
2
)
n
X, where
X denotes various functional groups [
3
-
6
]. SAMs are also suitable for studying
correlations between biological responses and surface properties.
It has been shown that cell adhesion highly depends on the outermost functional
groups on SAMs; however, cells do not directly interact with the SAMs. Instead,
they interact with proteins adsorbed on SAMs. Cell adherence requires an interac-
tion between integrin molecules in the cell membrane and glycoproteins specialized
for cell adhesion, like fibronectin (Fn) and vitronectin (Vn), which are adsorbed on
the artificial material. Thus, the presence of glycoproteins in serum plays a crucial
role in cell adherence to artificial materials. In the first part of this review (Sect.
2
),
we will briefly survey recent studies of cell adhesion on SAMs with different
functional groups and discuss the mechanisms involved.
