Biomedical Engineering Reference
In-Depth Information
Our recent work shows the potential of galectins and glycans in the preparation of
biomaterial surfaces (figure 4). The assembly of an artificial extracellular matrix consisting of
immobilised glycans, galectins and other extracellular matrix components was proven with
a fungal model lectin (CGL2) (Sauerzapfe et al., 2009). In this approach poly-
N
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acetyllactosamine structures which are well known ligands for galectins (see chapter 3.2) are
enzymatically produced. Those structures can be immobilised to different functionalised
materials by a free amino group coupled to the reducing sugar. Concentration dependent
binding of lectins to immobilised glycans was proven showing differences for specific
glycan ligands. Lectin-mediated crosslinking of the surface with ECM-glycoproteins was
also shown (Sauerzapfe et al., 2009). This galectin-mediated binding of ECM-glycoproteins
leads to a natural presentation of these structures for subsequent adhesion of cells.
Our ongoing work focuses on the transfer of this set-up to applicable biomaterial surfaces.
On the one hand recombinant human galectins are used instead of the fungal lectin to
provide a more natural set-up (unpublished data). On the other hand the assembly of this
artificial extracellular matrix is transferred to a special hydrogel surface. Star shaped
NCO-sP(EO-stat-PO) is used as inert biomaterial which prevents unspecific protein
adsorption and can be further functionalised with specific structures such as sugar
molecules (Bruellhoff et al., 2010; Grafahrend et al., 2011). On the basis of these glycans an
artificial extracellular matrix composed of galectins and ECM-glycoproteins can be built up.
Fibroblasts show excellent adhesion and cell spreading on these surfaces (Rech, Beer, Elling,
Groll, manuscript in preparation).
7. Conclusion
The importance of galectins in cell adhesion and signal transduction has been shown in
several investigations. Therefore a possible application of galectins in the assembly of a
biomaterial surface mimicking the natural microenvironment seems to be obvious. Anyhow
only few articles regarding the use of galectins in biomaterial research have been published.
This might be explained by the fact that the fine regulation of galectin mediated cell
adhesion and signalling is still not fully understood yet. Therefore it is important to evaluate
galectin function under specified conditions to reduce or exclude the risk of unwanted
inflammatory or carcinogenic effects.
Taking the presented literature and our own work regarding the biofunctionalisation of
surfaces with glycans and galectins together, there is clear evidence that galectins play an
important role in cell adhesion and proliferation on specifically functionalised biomaterial
surfaces. However, further research has to be done to adopt the fundamental understanding
of galectin-glycan mediated cell adhesion processes to an applicable biomaterial surface.
8. Acknowledgements
The authors acknowledge financial support by the DFG (Deutsche Forschungsgemeinschaft)
within the Research Training Group 1035 “Biointerface”, by the DFG (project EL 135/10-1),
and by the excellence initiative of the German federal and state governments through
ERS@RWTH Aachen University.
9. References
Abbott, W. M. & Feizi, T. (1991). Soluble 14-kDa beta-galactoside-specific bovine lectin -
evidence from mutagenesis and proteolysis that almost the complete polypeptide-
