The Application Of Biphasic Calcium Phosphatesceramic Scaffold By 3D Printing In Bone Tissue Engineering

Objective:Bone defect caused by accidental injury,inflammation,tumor and congenital deformity is highly common in clinic.This kind of defect often affects the normal physiological function and morphology of patients,which seriously affects the normal life of the patients [1].At present,the traditional treatments of bone defect in clinic are autogenous bone grafts,allogeneic bone grafts,artificial bone substitute and so on.However,all these treatments have their own limitations [2].With the development of materials science,life science and engineering technology,more and more attention has been paid to tissue engineering.The tissue engineering technology has three basic elements: seed cells,biological scaffold and biological factors.As the important bridge between the cell and tissue,the main structure of the biological factors,the scaffold has an important influence on tissue engineering.Therefore,the choice of scaffold is very important.The scope of the study of ideal scaffold materials for bone tissue engineering is very extensive.The scaffold should have good biocompatibility,osteoinductivity,suitable biomechanical properties and reasonable biodegradable,sufficient porosity and pore size structure.At the same time,the scaffold material should have high plasticity,abundant source,simple processing,low price and so on in clinical application.In this study,we evaluate the application potential of hydroxyapatite(HA)/beta-tricalcium phosphate(?-TCP)composite calcium phosphate ceramic(BCP)scaffold by three-dimensional printing technologyin bone tissue engineering.Methods:The HA/ ?-TCP composite BCP scaffold with a mass ratio of 3:7 was prepared by three-dimensional printing technique.The morphology and mineral phase of thescaffold were observed by scanning electron microscopy(SEM)and X-ray diffraction(XRD).Rabbit bone marrow mesenchymal stem cells(BMSCs)were isolated and cultured.BMSCs were seeded on the scaffolds and cultured together.The biocompatibility of the scaffolds and the proliferation and differentiation of the seeded cells were detected by CCK-8 assay and alkaline phosphatase test.BCP cylinders were prepared by mold materials under pressure using the same shape with the scaffolds.Results:The BCP scaffolds fabricated by three-dimensional printing technique were cylindrical scaffolds with a height of 3mm and a diameter of 3mm and 10 mm respectively.The shape of the BCP cylinders by the mold pressure was as same as the scaffolds.The pore structure of scaffolds by three dimensional printing is uniform and interconnected,and the pore size is between 350-450 ?m.Many microporous structures could be seen on the pore wall surface.The results of CCK-8 showed that BMSCs could proliferate well on the scaffold,and the proliferation was better than that of the BCP cylinders by the mold pressure.ALP activity assay showed that the differentiation of BMSCs on the scaffold was superior to that of the cylinders.The results of CCK-8 showed that after 1,3 and 5 days of cell culture in vitro,the blank control group demonstrated significantly higher rates of cell proliferation than the experimental group and the control group(P<0.05).At the 1-day sampling point,the number of cells in the control group was higher than that in the experimental group(P<0.05),whereas there was no significant difference between the control group and the experimental group after the 3 and 5 days(P>0.05).Then,after 7 days,the number of cells in the control group was lower than that in the experimental group and the blank group(P<0.05),and no significant difference occurred between the experimental group and the blank control group.ALP activity test showed that the ALP activity of the experimental group was significantly higher than that of the control group(P<0.05)after 4,7 and 14 days cultured in vitro.At the 4-day sampling point,the activity of ALP in the control groupwas higher than that in the blank group(P<0.05).Then,there was no significant difference in ALP activity between the control group and the control group after 7 and14 days.Conclusion:The above experimental results showed that the HA/ ?-TCP composite calcium phosphate ceramic scaffold prepared by the three-dimensional printing technology had a good Stable structure and three-dimensional pore structure.The structure of the pores showed well mutual communication.The scaffolds have good biocompatibility.BMSCs could adhere,proliferate and differentiate well on the scaffold.Compared with the planar structure of BCP cylinders by the mold pressure,the threedimensional porous scaffold had the advantages of cell adhesion,proliferation and differentiation,which were contributed of the porous structure and larger surface area.In this study,the potential application of the three-dimensional printing biphasic calcium phosphate ceramic scaffold in bone tissue engineering had been proved,which also laid the early foundation for the following experiment and clinical application.