Biomedical Engineering Reference
In-Depth Information
was observed on the PEPG, that is, a fibrous capsule had developed.
In contrast, no fibrous layer was observed around the PCPG. These
micrographs indicate that the PCPG did not induce an inflammatory
response in the host and that there was a high degree of in vivo
biocompatibility.
PEGMA has short ethylene glycol (EG) chains in the side chain.
Although poly(ethylene oxide) (PEG) is believed to be a promising
polymer for reducing nonspecific interaction with biomolecules, 45
the molecular weight and density of the chain might influence the
degree of biocompatibility. In addition, PEG is susceptible to autox-
idation in the presence of dioxygen and transition metal ions, 46 , 47
and the terminal hydroxyl group of PEG can be oxidized by alcohol
dehydrogenasetoanaldehyde.Thereissomeconcernthatthisalde-
hydemightreactwithproteins in vivo andwithothermoleculeshav-
ingaminegroups.Thealdehydecanbeoxidizedfurtherbyaldehyde
dehydrogenase. 48 , 49
In addition, it has been reported that PEGlation is not su cient
to reduce capsulation on a Teflon plate. 50 In this study, we observed
the same phenomenon in a hydrogel havingthe EG chain.
Interactions with protein strongly relate to the biocompatibility
of a matrix because the interaction may work as a trigger for host
responses, especially foreign body reactions. We have clarified that
PCPG does not have an adverse effect on the enzymatic activity of
trypsin as aprobe protein. 39
After implantation for 28 days, PEPG and PCPG were allowed
to remain in the subcutaneous tissue. The in vivo degradation of
the hydrogel is now being investigated. Moreover, no cytotoxity was
observed in the substances that degraded from the PCPG39. Very
recently, three-dimensional (3D) cultivation of osteoblast cells has
been performed in the PCPG. 51
19.5 Newly Extracellular Matrices Generated
from MPC Polymers
Recent cell engineering has progressed toward regenerated medi-
cineandcells.Soon,cellswithhighfunctionsshouldbeobtainedand
treated by extensively developed nano- and biotechnology. Polymer
 
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