Biocompatibility and toxicity of poly(vinyl alcohol)/N,O-carboxymethyl chitosan scaffold

Abstract

The in vivo biocompatibility and toxicity of PVA/NOCC scaffold were tested by comparing them with those of a biocompatible inert material HAM in a rat model. On Day 5, changes in the blood parameters of the PVA/NOCC-implanted rats were significantly higher than those of the control. The levels of potassium, creatinine, total protein, A/G, hemoglobulin, erythrocytes, WBC, and platelets were not significantly altered in the HAM-implanted rats, when compared with those in the control. On Day 10, an increase in potassium, urea, and GGT levels and a decrease in ALP, platelet, and eosinophil levels were noted in the PVA/NOCC-implanted rats, when compared with control. These changes were almost similar to those noted in the HAM-implanted rats, except for the unaltered potassium and increased neutrophil levels. On Day 15, the total protein, A/G, lymphocyte, monocyte, and eosinophil levels remained unaltered in the PVA/NOCC-implanted rats, whereas urea, A/G, WBC, lymphocyte, and monocyte levels remained unchanged in the HAM-implanted rats. Histology and immunohistochemistry analyses revealed inflammatory infiltration in the PVA/NOCC-implanted rats, but not in the HAM-implanted rats. Although a low toxic tissue response was observed in the PVA/NOCC-implanted rats, further studies are necessary to justify the use of this material in tissue engineering applications.

Figure 1

(a) Hydrogel and silicone discs. (b) The fur is cleared and marked incision area indicated by arrow. (c) Arrow indicates the representative animal and site of material implanted. (d) Representative photograph for site of implantation after suturing (arrow).

Figure 2

Histological sections and H&E staining of the PVA hydrogel and HAM after 5, 10, and 15 days of subcutaneous implantation. “M” indicates the implantation sites, 100x (low) and 400x (high). The high magnification photograph indicates the inflammatory infiltrates after implantation at variable time points.

Figure 3

Immunohistology staining for CD 68 of the PVA hydrogel and HAM after 5, 10, and 15 days of subcutaneous implantation, 400x. Briefly, the samples were rinsed with phosphate buffered saline (PBS) and fixed with methanol for 15 min. Then, the samples were treated with 0.03% hydrogen peroxide for 5 min and incubated with mouse anti-rabbit anti-CD 68 antibody for 30 min at 1 : 100 dilutions and then with peroxidase-labeled polymer conjugated to goat anti-mouse immunoglobulin for another 30 min. The expression of CD 68 has been indicated by arrow (100x).