Gene chip/PCR-array analysis of tissue response to 2-methacryloyloxyethyl phosphorylcholine (MPC) polymer surfaces in a mouse subcutaneous transplantation system

<div><p>To evaluate the <i>in vivo</i> foreign body reaction to bio-inert 2-methacryloyloxyethyl phosphorylcholine (MPC) polymers, MPC polymer-coated porous substrates, with large surface area, were implanted subcutaneously in mice for 7 and 28 days, and the surrounding tissue response and cells infiltrating into the porous structure were evaluated. The MPC polymer surface induced low angiogenesis and thin encapsulation around the porous substrate, and slightly suppressed cell infiltration into the porous substrate. M1-type macrophage specific gene (CCR7) expression was suppressed by the MPC polymer surface after 7 days, resulting in the suppression of inflammatory cytokine/chemokine gene expression. However, the expression of these genes on the MPC polymer surface was higher than on the non-coated surface after 28 days. These findings suggest that MPC polymer surfaces successfully inhibit inflammatory responses during the early stage of tissue response, and seem to retard its occurrence over time.</p></div

Global analysis of host body responses to PMB-coated and collagen-coated scaffolds.

<p>All genes having valid expression levels in non-coated, collagen-coated, and PMB-coated scaffolds were plotted.</p

Descriptions and expression levels of genes which were up-regulated in collagen and down-regulated in PMB.

<p>Numbers in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0085132#pone-0085132-g006" target="_blank">Fig. 6</a> correspond to those in the table. Plus and minus in this table indicate promotion and suppression, respectively.</p

Microscopic histological observations by HE staining (A, C, and E) and CD68 immunostaining (B, D, and F) of non-coat (A and B), PMB-coated (C and D), and collagen-coated (E and F) scaffolds at boundary between scaffold and tissue.

<p>Small vessels (arrow heads) and macrophages (arrows) were observed. The mean pore size of the scaffolds was 157 µm. Seven days after operation. Some scaffold skeletons (S) are detached from sliced samples. Bars  = 50 µm.</p

FTIR/ATR spectra of PMB- and collagen-coated PE films.

<p>FTIR/ATR spectra of PMB- and collagen-coated PE films.</p

Selected genes that were expressed differently between collagen-coated and PMB-coated and were related to tissue regeneration and inflammation.

<p>Closed circle, wound healing promotion factors; Open circle; inflammatory factors; Closed square, uncertain about tissue regeneration.</p

Descriptions and expression levels of genes which were down-regulated in collagen and up-regulated in PMB.

<p>Numbers in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0085132#pone-0085132-g006" target="_blank">Fig. 6</a> correspond to those in the table. Plus and minus in this table indicate promotion and suppression, respectively.</p

The appearance of scaffolds on day 7 after operation.

<p>All scaffolds were attached on the subcutaneous tissue. Scaffolds with a pore size of 157 µm (A, C, and E) and 32 µm (B, D, and F) were implanted. Angiogenesis (arrows) and fibrous tissue encapsulation were compared among non-coat (A and B), PMB-coated (C and D), and collagen-coated (E and F) scaffolds. All scaffold diameters are 6 mm.</p

Macroscopic observation of implanted scaffold with non-coat (A), PMB-coated (B), and collagen-coated (C) scaffold which were sliced and stained with HE.

<p>Scaffold mean pore size was 157 µm. Scaffolds were attached to rat dorsal skin and encapsulated with layer of fibrous tissue (arrows). Some scaffold skeletons (S) are detached from sliced sample. Bars  = 1 mm.</p

Morphological changes and viability of the islets cultured with or without MSCs.

<p>A: Morphological changes of the islets cultured with or without MSC at 4 d after starting the culture. Broken islets and cellular scattering appeared in Group A. Central necrosis (shown as darkness in the center of islets, arrow) was also seen in many residual round-shaped islets. In contrast, there was no cellular scattering caused by islet destruction in Group B. The shapes of the islets were round, and the central colors remained relatively clear. B1: Viability of the 1- and 4-d islets cultured with or without MSCs. Islets were stained with SYTO11 green (green for viable cells) and ethidium bromide (red for dead cells). B2: At 1 d of culture, the viability of Group A was 85.2% and that of Group B was 93% (p = 0.10). At 4 d of culture, the viability of Group A was 86.4% and that of Group B was 90.9% (p = 0.16). C: A glucose stimulation test was performed 4 d after starting the culture. In the resting state (low glucose stimulation), both groups of islets released a small volume of insulin, and there was no significant difference between the two groups (light gray bar). In contrast, the islets in Group B released a higher volume of insulin than those of Group A under high glucose stimulation (dark gray bar) (0.40 ng/islet/h vs. 1.38 ng/islet/h, p = 0.11). The stimulation index in Group B was also significantly higher than that in Group A (1.78 vs. 7.08, p = 0.0025).</p