Properties Of Decellularized Native Cartilage-loading Photocrosslinked Gelatin Hydroges And Investigation Of Its Effect On Cartilage Repair In Vivo

Background and objectiveArticular cartilage injury is one of the most common diseases in clinical orthopedics.Cartilage injury is highly likely to develop to osteoarthritis,which causes joint pain and inconvenience to the patient.As a chronic disease,the pain and deformity caused by osteoarthritis not only affect the quality of life,but also may lead to psychological problem like depression.At the same time,the economic burden caused by long-term treatment can not be underestimated.How to treat the cartilage injury at early stage has been a hot spot in medical research.None of the existing clinical treatments are satisfied.In recent years,the rapid development and application of tissue engineering and regeneration medicine have brought new hopes and ideas for cartilage repair.The application of scaffold in tissue engineering is particularly important to rebuild cartilage construct.Hydrogels have become one of the most popular materials for tissue engineering because they mimic the extracellular microenvironment.Gelatin is a hydrolysate of collagen,which is the main component of cartilage matrix,and an ingredient of gelatin Methacryloyl hydrogel(GelMA)which has tunable mechanical properties and excellent biocompatibility.GelMA hydrogels can provide a suitable microenvironment for the migration,adhesion,proliferation and chondrogenic differentiation of chondrocytes and mesenchymal stem cells(MSCs).However,GelMA hydrogels are no bioactivities and chondroinductive.The decellularized native cartilage(DCC)is derived from natural cartilage which is decellularized to eliminate the immunogenicity by chemical and physical treatments.DCC possesses bioactivity cause retaining the glycosaminoglycans and multiple bioactive factors.However,pore size and porosity are difficult to control when fabricating DCC scaffolds.In this study,we explore to fabricate DCC-loading photocrosslinked GelMA hydrogel by embedding DCC into GelMA solution.The hybrid hydrogel can not only highly simulate the native extracellular matrix but also contains bioactive factors.We hope the application of GelMA/DCC hydrogel can guide the regeneration of cartilage.Part ? Study on the bio-inks of methacrylamide-basedgelatin containing decellularized native cartilage and itspropertiesObjective: To fabricate GelMA/DCC bioink,and investigate its physicochemical properties and cell compatibility.Method: Fistly prepared DCC powder and GelMA solution and then mixed them together in proportions;the mixed solution was photocrosslinked into hydrogels by UV light;the mechanical properties were measured by tensile test;after the cells were implanted into bioink and cultivated for 0,3,5,and 7 days,observed the cell activity under the fluorescence microscope.Result: Bioink with 15%(w/v)GelMA + 1 %(w/v)DCC was prepared.The Young's modulus of the tensile test was significantly greater than that of the control group.The cell viability was 90.32~96.79% after cell culture.Conclusion: The addition of DCC makes hydrogels have better mechanical properties.GelMA/DCC bioink has good biocompatibility.Part ? Exploring the printability and performancecharacterization of GelMA/DCC bio-inkObjective: To test the printability of GelMA/DCC bioink.Method: The bioinks were printed to scaffolds by 3D printer;the structure of the scaffold was observed by microscope;the compression strength and the survival rate of the cells in the scaffold were examined.Results: The formability of GelMA/DCC hydrogel was great after 3D print,and its multi-layer mesh structure was completely interconnected;the compression modulus reached more than 100kPa;the survival rate of cells in the scaffold was >90%.Conclusion: GelMA/DCC bioink had superior printability and high cell survival rate after printing.In the future,the scaffold ccan be made into a customized shape to generate a specific tissue or implanted in vivo.Part ? Investigation of the GelMA/DCC hydrogelpromoting cartilage injury repair in vivoObjective: To investigate the effect of GelMA/DCC hydrogel on repairing cartilage defects repair in experimental animals.Method: Nine male New Zealand white rabbits were randomly selected and divided into 3 groups: Group A: GelMA/DCC scaffold group,Group B: GelMA scaffold group,and Group C: Control group.After established articular cartilage injury models,the bioink was implanted in the defect area and crosslinked by UV light.Gross observation,HE staining,safranin O staining,and type II collagen immunohistochemistry were performed after 12 weeks.Result: ICRS scores: group A:(10.2 ± 1.0),group B:(7.5 ± 1.0),and group C:(5.0 ± 0.9).The score in group A was significant higher than that in group B and C(P<0.05).O'Driscoll histology score: group A:(15.2 ± 0.8).Group B:(9.5 ± 1.0)and Group C:(7.2 ± 1.2.The score in group A was significantly higher than that in group B and C(P<0.05).Conclusion: GelMA/DCC hydrogel can promote the repair of cartilage injury in vivo and the regeneration tissue resembles natural cartilage.