Research On Injectable Poly(amino Acid)/Glycosaminoglycan Thermo-sensitive Hydrogel For The Treatment Of Periodontitis

Background:Periodontitis is a chronic inflammatory disease with bacteria as the initiating factor,which is one of the most common chronic diseases in the world.Periodontitis leads to periodontal tissue destruction and even tooth loss,seriously affecting the qualit y of life of patients.At present,the clinical treatment of periodontitis mainly includes scaling and root-planing and surgery.However,the long-term effect of using scaling and rootplaning alone is not satisfactory,and periodontitis is easy to relapse.The surgical treatment is traumatic and not easy to be accepted by patients.Because bacteria and plaque play a direct role in the occurrence and development of periodontitis,systemic or local antimicrobial agents are often used as an auxiliary means for the treatment of periodontitis,but th e existing adjuvant drugs for periodontitis are mainly antibiotics,of which long-term use is easy to cause bacterial drug resistance and oral flora imbalance.Therefore,the development of drugs to avoid the risk of antibiotic resistance has become a hotspot in the field of periodontitis researches.In addition,recent studies have shown that the imbalance of host immune system are also the key to the occurrence of periodontitis,and the regulation of immune microenvironment has also attracted the attention of researchers.L-methionine is a natural antioxidant in the human body,which can scavenge excess reactive oxygen specie s,which can reduce the tissue damage caused by oxidative stress in the treatment of periodontitis.ε-PolyL-lysine is a natural antimicrobial peptide with good antibacterial activity and biocompatibility.Some studies have shown that it has inhibitory effe ct on Porphyromonas gingivalis,the main pathogen of periodontitis.Chondroitin sulfate is a kind of glycosaminoglycan widely found in the extracellular matrix of periodontal tissue,which has the effects of anti-inflammation,anti-oxidation and regulating bone metabolism,and has the potential to regulate periodontal immune microenvironment.It has good application potential to combine the above materials with different biological activities to construct a new type of adjuvant therapy for periodontitis with antibacterial,ant ioxidant and anti-inflammatory effects.Objective:Preparing a thermosensitive hydrogel composed of Polyethylene glycol,L-methionine,ε-Poly-L-lysine and Chondroitin sulfate,exploring its antibacterial properties and the ability to regulate immune microenvironment,and evaluating its therapeutic effect on rat periodontitis model.Methods:1.The thermo-sensitive Poly(amino acid)-glycosaminoglycan hydrogel system was designed and prepared by synthesize polyamino acids and aldehyde polysaccharides,and the ratio of them was screened.The temperature sensitivity,injectability,self-healing ability,secondary structure,microstructure and in vitro degradation of the hydrogel were characterized.2.Porphyromonas gingivalis were selected to determine the antibacterial activity of Poly(amino acid)-glycosaminoglycan hydrogel by microbroth dilution method.3.L929 cell line was selected to determine the biocompatibility of Poly(amino acid)-glycosaminoglycan hydrogel and its protective effect on cells in reactive oxygen specie s environment by Cell Counting Kit-8 method.4.The rat periodontitis model was established by ligation method and treated with Poly(amino acid)-glycosaminoglycan hydrogel.The degree of periodontal tissue destruction and bone resorption were evaluated by micro computed tomography and hematoxylin-eosin staining,and the content of cytokines in periodontal tissue was detected by ELISA kit.Results:Poly(amino acid)-glycosaminoglycan thermosensitive hydrogel was successfully prepared.The hydrogel has good temperature sensitivity,injectability,self-healing ability,reactive oxygen specie s responsiveness,loose and porous structure and stable properties.The in vitro antibacterial experiment showed that the hydrogel had good antibacterial properties.In vitro Cell experiments showed that hydrogel had good biocompatibility and good protective effect on cells in reactive oxygen specie s environment.The results of rat periodontitis experiment showed that the periodontal tissue loss and the levels of Interleukin-1β and tumor necrosis factor-α in the Poly(amino acid)-glycosaminoglycan hydrogel group were lower than those in the periodontitis group,indicating that hydrogel has a good therapeutic effect on periodontitis in rats.Conclusion:The developed poly(amino acid)/ glycosaminoglycan thermosensitive hydrogel can inhibit the progression of periodontitis and reduces periodontal tissue destruction by eliminating excessive reactive oxygen species,inhibiting the growth of periodontitis-related pathogens and regulating immune inflammatory response,and has a good application prospect.