Effects Of 3D Printed PLGA/HA Bioactive Scaffolds On The Repair Of Femoral Defect And Osteogenesis In Serum Of Rats

Objective: To study the effect of poly(lactic-co-glycolic acid)/ hydroxyapatite(PLGA /HA)made by 3D printing technology on the healing of bone tissue and the related factors of bone formation in serum of rats.Methods: 1.PLGA / HA scaffolds were prepared by 3D printing technology with PLA /PGA and HA as materials.2.The surface morphology and porosity of scaffolds were observed under electron microscope.3.60 6-week-old female SD rats were anesthetized with urethane chloral hydrate and then cut along the lateral skin of the femur.The skin,fascia and muscle were separated in turn,and the femur was fully exposed.A full-thickness bone defect about 4mm long was made near the head of the femur,reaching the medullary cavity.The operation was carried out on the left and right sides in turn.60 rats were randomly divided into experimental group and control group.PLGA /HA stent was implanted in the femoral defect of the experimental group,while no stent was implanted in the control group.Muscle and skin were sutured and plaster bandaged respectively.4.At the 3rd,1st,2nd,3rd,4th and 5th week after implantation,the femur samples and blood were collected.The healing of bone tissue at different stages of femoral defect were observed.5.The bone strength of femur was analyzed.6.The expression of BMP2 was detected by immunohistochemistry.7.Serum calcium(Ca),phosphorus(P),alkaline phosphatase(ALP)and acid phosphatase(TRAP)were measured with serum test kit.Results: 1.The scaffold of three-dimensional structure was prepared by 3D printing technology.2.The results of electron microscopy showed that there are many micro voids on the surface of the material,and the connectivity is good.3.The results of bone strength test showed that the bone tissue healing of the experimental group was better than that of the control group at the 4th week(P < 0.05),and the difference was more significant at the 5th week(P < 0.01).4.The results of immunohistochemistry showed that the expression of BMP2 in the experimental group was higher than that in the control group on the 1st,2nd and 4th weeks(P < 0.05).5.The serum ALP level of the experimental group was higher than that of the control group on the 1st,2nd and 3rd weeks(P < 0.05).The level of TRAP in the experimental group was lower than that in the control group on the 3rd day and the 1st,2nd and 3rd weeks(P < 0.05),especially on the 2nd week(P < 0.01).The calcium level of the experimental group was higher than that of the control group on the 1st,2nd and 3rd weeks(P < 0.05).There was no significant difference in phosphorus level between the two groups.Conclusion: 3D printing technology can print PLGA / HA scaffold with porous structure efficiently.After implantation,the scaffold can inhibit the expression of TRAP and stimulate the expression of ALP in serum,and promote the expression of BMP2 in bone healing area.PLGA / HA scaffolds can promote bone tissue formation and inhibit bone absorption,which is a good material for bone defect healing...