SUPPRESSION OF INFLAMMATORY REACTIONS ON MPC POLYMER SURFACES - Intelligent Scaffolds for Tissue Engineering and Regenerative Medicine - page 374

as soft tissue, a characteristic that minimizes their potential for irri-
tating surrounding tissue. Some recent trends in hydrogel research
for tissue engineering include macromolecular drug delivery and
cell entrapment. 37 , 38 We have synthesized a novel biodegradable
hydrogel consisting of MPC units with polyphosphates as macro-
cross-linkers. 39 Polyphosphates appear interesting for biological
and pharmaceutical applications because of their biocompatibility
and structural similarities to naturally occurring nucleic and echoic
acids. Recently, polyphosphates have been proposed for use in the
field of tissue engineeringas scaffoldsand as genecarriers. 40 - 42
We have previously investigated the in vitro biocompatibility
of biodegradable poly(MPC) hydrogel (PCPG). 39 Poly(2-i-propyl-
2-oxo-1,3,2-dioxaphospholane [IPP]-co-2-[2-oxo-1,3,2-dioxaphosp-
horoyloxyethyl methacrylate] [OPEMA]) (PIOP) was synthesized by
the method previously described. 43 The MPC was polymerized with
PIOP as a macro-cross-linker to form a hydrogel. Instead of MPC,
PEGMA was used to make a reference hydrogel (PEPG), as shown
in Fig. 19.8. Table 19.1 lists the degrees of hydration and the water
fraction of the hydrogels cross-linked with the PIOP. The Heq value
changed depending on the concentration of the PIOP. In this study,
hydrogels that had 1.0 mol% PIOP as a cross-linker were used for
the biocompatibilitytest.
Figure 19.9a shows optical micrographs of the subcutaneous
tissue in contact with the hydrogels for seven days. Many inflam-
matory cells were observed around the PEPG. In contrast, such
cells did not accumulate in the region of the tissue in contact with
Figure 19.8. Chemicalstructuresofmacro-cross-linker(PIOP)andwater-
soluble monomers.