Biocompatibility Of Chitosan / BMP - 2 Plasmid Thermosensitive Hydrogel Complex And Study Of Alveolar Bone Regeneration In

Objective: The aim of this study was to prepared the injectable CS/CSn(p DNA-BMP2)-GP thermosensitive hydrogel scaffold system,and evaluate the histocompatibility of the injectable CS/CSn(p DNA-BMP2)-GP thermosensitive hydrogel scaffold system and its regenerative effects on the endogenous repair of alveolar bone.Methods: 1. Preparation and characterization of CS/CSn-GP and CS/CSn(p DNA-BMP2)-GP hydrogel.Morphology of CS/CSn-GP and CS/CSn(p DNA-BMP2)-GP thermosensitive hydrogel was observed by SEM, and temperature sensitivity of CS/CSn-GP and CS/CSn(p DNA-BMP2)-GP thermosensitive hydrogel was identified using invert tube method. 2. In vivo histocompatibility study of the CS/CSn-GP hydrogel. In vivo histocompatibility testing of the CS/CSn-GP hydrogel was performed by injecting room-temperature aqueous CS/CSn-GP into 18 male SD rats. At day 3 and at weeks 1, 2, 4, 6, and 9, the rats were sacrificed and the surrounding tissues where the hydrogels were injected were isolated. Tissue sections were stained with hematoxylin-eosin(HE), and examined using a light microscope. 3. The efficiency of CS/CSn-GP and CS/CSn(p DNA-BMP2)-GP hydrogel in noninflammatory bone defect for endogenous regeneration. To investigate the ability of p DNA-BMP2 to partake in bone regeneration, a rat calvarial defect model was used. Five-millimeter-diameter defects were generated in the left and right parietal bones, then animals were divided into two groups:(1) CS/CSn(p DNA-BMP2)-GP thermosensitive hydrogel;(2) CS/CSn-GP thermosensitive hydrogel. The left side defects remained empty(sham control) and the right side defects were filled with CS/CSn-GP or CS/CSn(p DNABMP2)-GP thermosensitive hydrogels. At 4 and 8 weeks, animals were sacrificed and calvarial specimens were processed with HE staining. 4. The capacity of CS/CSn-GP and CS/CSn(p DNA-BMP2)-GP hydrogel for endogenous repair of alveolar bone. The second and third premolars in each of four beagle dogs were selected to establish periodontitis model. After the periodontitis model was established, the teeth were randomly allocated into three groups:(1) CS/CSn(p DNA-BMP2)-GP thermosensitive hydrogel group;(2) CS/CSn-GP thermosensitive hydrogel group;(3) negative control group. The dogs were euthanized 8 weeks post-surgery, and the maxilla and mandibles were processed with Masson’s trichrome staining the Gomori calciumcobalt method.Result: 1.Preparation and characterization of CS/CSn-GP and CS/CSn(p DNA-BMP2)-GP hydrogel.(1).SEM showed after the CS/CSn-GP and CS/CSn(p DNA-BMP2)-GP solution turned into a hydrogel, regular holes and a porous structure formed into a crosslinked network.(2).They both remained in a liquid phase when the temperature was below 25°C and turned into a gel state after 3 min at 37°C. 2. In vivo histocompatibility study of the CS/CSn-GP hydrogel. HE staining showed that all of the inflammation and repair processes described above were physiologically normal reactions. 3. The efficiency of CS/CSn-GP and CS/CSn(p DNA-BMP2)-GP hydrogel in noninflammatory bone defect for endogenous regeneration.The injectable thermosensitive CS/CSn-GP complex system therefore demonstrated good potentiality in promoting regeneration of rat calvarial defects. When loaded with p DNA-BMP2, however, the capacity for regeneration was enhanced. 4.The capacity of CS/CSn-GP and CS/CSn(p DNA-BMP2)-GP hydrogel for endogenous repair of alveolar bone.(1). Masson’sstaining showed that CS/CSn-GP and CS/CSn(p DNA-BMP2)-GP group have different degree of alveolar bone regeneration compared with the negative control group. While statistical differences were also found between the CS/CSn(p DNA-BMP2)-GP and CS/CSn-GP groups.(2). Gomori calciumcobalt method showed that ALP activity in the periodontal tissues of the CS/CSn(p DNABMP2)-GP) and CS/CSn-GP groups was much higher than in the negative control group. While statistical differences were also found between the CS/CSn(p DNA-BMP2)-GP and CS/CSn-GP groups.Conclution: 1. The CS/CSn-GP thermosensitive hydrogel demonstrated good biocompatibility and thermosensitivity. This finding supports that the CS/CSn-GP complex system is a highly potential candidate gene delivery carrier. 2. The CS/CSn-GP thermosensitive hydrogel showed a greater capacity for endogenous repair of alveolar bone and this regeneration ability was strengthened when conjugated with p DNA-BMP2.