Preparation And Performance Study Of Bionic Osteochondral Integrated Scaffold

Articular cartilage has a very limited ability to repair itself due to the lack of vascular,lymphatic and nerve tissue.When a large defect occurs in cartilage and the defect exceeds a certain threshold,the articular cartilage is unable to repair itself and requires external intervention to facilitate the repair of the defect.There are numerous clinical approaches to cartilage defect repair,but they are generally unsatisfactory.With the development of tissue engineering technology,cartilage tissue engineering provides a new option for cartilage defect repair.The development of bionic tissue engineering scaffolds is the key to the successful repair of cartilage defects by cartilage tissue engineering,and is the focus of this paper.In this paper,an integrated osteochondral scaffold containing both cartilage-mimicking layer,calcification-mimicking layer and inferior bone layer was prepared by combining four materials,namely,type I collagen,silk protein,hyaluronic acid and nano-hydroxyapatite,and the structure,physicochemical properties,mechanical properties and biocompatibility of the scaffold were investigated by using freeze-drying technique.The results showed that the structure of the upper and lower surfaces of the scaffold was different,with a uniform pore structure on the upper surface and a flat and smooth lower surface,and no obvious pore structure was observed;the scaffold as a whole had a high porosity and good water absorption performance.The stent has good mechanical properties and can provide certain mechanical support in the body.Different layers of the stent had different Young’s modulus due to different material ratios;with the cyclic loading,its stress-strain hysteresis loop curve was not closed,which produced an obvious cyclic strain accumulation.The biocompatibility test results of the scaffold showed that the scaffold was not toxic to chondrocytes,and the cells had good activity and significant cell proliferation when cultured under the scaffold dip solution.When cells were cultured after inoculation into the scaffold,chondrocytes were found to adhere to the scaffold,grow and proliferate,and the cells were more active under certain mechanical stimulation.The mechanical properties of the synthetic integrated stent were simulated by finite element method.First,the mechanical properties of the synthetic stent under quasi-static loading were simulated,and the deformation and stress fields of different layers of the stent under compressive loading were analyzed,and it was found that the maximum deformation occurred in the cartilage layer of the stent and the minimum deformation occurred in the inferior bone layer;the maximum stress occurred in the inferior bone layer of the stent and the minimum stress occurred in the cartilage layer of the stent.This is related to the different material properties of each layer of the stent.This was verified by extracting software calculation data with real experimental data.The mechanical response of the synthetic stent under dynamic cyclic compression was also simulated.In this study,we also prepared a decalcified bone scaffold using cancellous bone as the raw material.By decellularization and decalcification of cancellous bone,an osteochondral integrated scaffold with both cartilage-like layer,calcified layer and inferior bone layer was prepared.The structure,physicochemical properties,mechanical properties and biocompatibility of the scaffolds were also investigated.The structural characterization of the scaffold showed that the surface of the scaffold had obvious pore structure,and the porosity of the scaffold reached 74.08% with a large pore size of 0.63 mm.mechanical experiments showed that the scaffold had excellent mechanical properties.In the cyclic compression experiments,the stent strain changes from a sharp increase to a slow increase and finally leveled off with the accumulation of cycles,with an obvious strain accumulation phenomenon.The biocompatibility test results of the scaffold showed that the scaffold material was non-toxic,and the histocultural results showed that chondrocytes could adhere and grow on the scaffold,and the pore structure of the scaffold provided space for cell growth,where the cells could grow in a colony.By analyzing and comparing the physicochemical properties,mechanical properties,biocompatibility and histoculture of the two scaffolds,it was found that the natural decalcified osteochondral integrated scaffold has better mechanical and physicochemical properties,and its good pore structure provides space for chondrocyte adhesion and growth,and chondrocytes have better cellular activity,more obvious cell proliferation and good cellular morphology on this scaffold.The results of this study are expected to provide some reference for the clinical application of tissue engineering.