Immunohistochemical and Electron Microscopic Study of the Biodegradation Processes of Chitin and Chitosan Implanted in Rat Alveolar Bone

Abstract

The present study was designed to investigate histochemically the biodegradation processes of chitin and chitosan implanted in rat alveolar bone. Lysozyme was immunohistochemically detected using postembedding immunogold labeling. The degradation process was ultrastructurally observed using the lectin-colloidal gold technique with electron microscopy. Three groups of chitin were specially prepared according to their degree of deacetylation: 100% deacetylated chitin (DDAC 100); 50% (DDAC 50); and 0% (DDAC 0). The present immunohistochemical study indicated that lysozyme expression was not detected in the DDAC 100 group. Furthermore, electron microscopy clearly demonstrated that the contour of implanted chitosan changed over time, and that chitosan-like fragments were present in the phagosomes in the DDAC 50 and 100 groups. These findings strongly suggest that phagocytes, such as multinuclear cells, are easily supplied in bone tissue and that the phagocytosis is more effective than enzymatic digestion for chitin and chitosan biodegradation in bone tissue. DDAC 100 should be a suitable biomaterial for bone surgery and bone regeneration therapy.