The Different Proportions Of Chitosan Thermosensitive Hydrogel Biological Properties And Promotion On Periodontal Regeneration In Vitro And Vivo: A Preliminary Study

BackgroundPeriodontitis is an inflammation of oral disease with high incidence anddestroying periodontal tissue, which is the main cause of adult tooth loss. It isdifficult to make the loss of periodontal tissue regenerate and restore normalmorphology and function of the periodontal tissue. It will provide a new methodfor the treatment of periodontal disease when techniques and research findings oftissue engineering are applied to the study of periodontal treatment. Tissueengineering contains three factors that are seed cell, scaffold, signaling molecule,which will make periodontal regeneration as a possible with applying the threeindividually or jointly to the periodontal treatment. However, the source andconcentration of seed cells, the biocompatibility of scaffolds, the role ofsignaling molecules mechanism have not been thoroughly studied so far.In recent years, chitosan thermosensitive hydrogel as a biological scaffoldmaterials has drawn an increasing research attention, which is widely used asdrug carrier, scaffold, wound healing. The thermosensitive gel can turn into thegel at the person’s normal body temperature (37℃). It is biocompatibility andconducive to cell adhesion and proliferation. The volume ratio between chitosan and glycerophosphate in chitosan thermosensitive hydrogel is usually9:1, whileother study suggest that proportion is7:1. Because the pH is7.2, which is mostsuitable for cell proliferation and adhesion. Additionally, the gel time is10min at37℃, which is suitable as injectable scaffolds for cell survival and convenientfor operation.ObjectivePreparation of different ratios of chitosan gel to compare the physical andchemical properties. Comparing the biocompatibility of different proportion ofgel in vitro and in vivo and their ability of periodontal tissue regeneration. Topreliminarily evaluate the feasibility of the chitosan which promote periodontaland oral tissue regeneration from the perspective of the development of tissueengineering scaffolds.Methods and result1Preparation the different ratio of chitosan thermosensitive hydrogel andresearch the physiochemical properties1ml56%(m/v) β-GP was respectively added to9ml and7ml concentration ofchitosan hydrochloride solution by drop wise and stirred for10min. Both the9:1and7:1chitosan/β-GP solution were set at37°C water bath in order to turn intogel. The physiochemical properties of two groups were assessed by compared thegel time, viscosity, swelling ratio, degradation and microstructure.Result showed the gel time of9:1group was longer than the7:1ratio ofgroup’s;9:1group’s viscosity was higher than7:1group’s; The degradation rateof9:1group was lower than7:1group’s. There was no significant differencesbetween9:1and7:1group in swelling ratio and pore diameter.2The effect on the biocompatibility of human periodontal ligament cells withdifferent proportions of chitosanthe PDLCs were cultured in9:1and7:1chitosan gel to compare theirbiocompatibility and effect on adhesion and proliferation of PDLCs. DAPIstaining showed the adhesion and proliferation of cells in the surface and internalof chitosan. The effect of two groups’ extract on cell proliferation was compared by MTT assay.The results showed the9:1and7:1group could promote the adhesion andproliferation of human PDLCs. There was no significant difference between the9:1and7:1group. They had a good biocompatibility.3Comparison different proportions of chitosan with regenerative capacity of theperiodontal tissue in vivoTo observe and assess the biocompatibility and periodontal regenerationcapacity,9:1and7:1group were injected into the periodontal III furcationdefects of dogs which were at the second, third premolar and compared theireffect on periodontal tissue regeneration after12weeks by general observation,X-ray, CT, histological observation.Results showed the9:1and7:1could promote periodontal tissueregeneration and had good biocompatibility.ConclusionBoth the9:1group and7:1group had a good physical and chemicalproperties. They could provide a three-dimensional scaffold environment in vitro,which promoted PDLCs adhesion and proliferation. The experiments showedthat they were biocompatible, biodegradable and promoted repair andregeneration of periodontal defects in vivo. Both9:1and7:1group could beused as a new type of injectable scaffolds for periodontal regeneration andexpected for further research and clinical development.