| Objective:1.To scan the lumbar vertebrae of Wistar rats with three-dimensional CT in advance,and to measure the size of the implant site.According to CT scan parameters,composite scaffords were made using the 3D printing and CAD software and bone defect models were established using Wistar rats.2.The Polycaprolactone / ?-Tricalcium Phosphate / Carbon Nanotube scaffold(PCL / ?-TCP / CNT)and Polycaprolactone / ?-Tricalcium Phosphate(PCL /?-TCP)scaffold were implanted into bone defect site of the rat model and osteogenic effects were compared for two diffferent materials.Method:1.Length,width and height of scaffords materials was 15 mm,10mm and 5mm respectively.Height,and diameter of pinting parameters was 0.5mm,and 0.1mm respectively and required graphics were drawn using CAD software,program was exported and saved.2.The printed composites were tested for mechanical strength,SEM analysis,porosity calculation,systemic toxicity test and hemolytic rate.3.The effect of composite scaffolds on the proliferation of adipose-derived stem cells(ADSC)was detected by CCK-8 assay.4.The establishment of bone defect model of Wistar rats: the incision of Wistar rats was made to expose L4-5 transverse process bone after general anesthesia.The cortex of transverse process bone was polished with a high-speed magic drill to achieve the explosion of cancellous bone.The sterilized composite material was implanted into the surface of transverse process bone,and the surrounding muscles were sutured so that the scaffold material and transverse process residual end were closely integrated.5.Rats were sacrificed at different time after surgery.The scaffolds were taken out for three-dimensional CT scanning? HE?and Masson staining.The results were statistically analyzed.Results:1.Composite material scaffolds with 15 mm length,10 mm width and 5mm height were manufactured with the help of CAD software and 3D printer.2.The scan of electron microscopy showed that the internal pore size of the scaffold was appropriate and the pores were interconnected with each other.The mechanical strength matched the strength of human cancellous bone,and the porosity of the scaffold was calculated to be 60% with non-toxic and non-hemolytic.3.The proliferation activity of ADSC with co-cultured different scaffold materials was as follows: Polycaprolactone / ?-tricalcium phosphate / 0.2% carbon nanotube scaffolds > Polycaprolactone / ?-tricalcium phosphate / 0.1% carbon nanotube scaffolds > Polycaprolactone / ?-tricalcium phosphate / 0.3% carbon Nanotube scaffolds> polycaprolactone / ?-tricalcium phosphate scaffolds(P<0.05).The results showed that polycaprolactone/tricalcium anphosphate /0.2%carbon nanotube scaffolds had more advantages in promoting the adhesion and proliferation of ADSC.4.1)The one month postoperative observation of the gross specimen with scaffold showed that there was a small amounts of fibrous tissue around the scaffold in the experimental group and the control group but no obvious new bone grew into the scaffold.At 2 months after the operation,the surface aperture of the scaffold with growing into new bone tissue in the experimental group were more obviously than that in the control group.2)At one month after surgery,three-dimensional CT scan of the experimental group and the control group showed that the density of the scaffold was lower than the bone density and obvious space was found between the scaffold and the transverse process bone.With the extension of time,CT scan showed that the scaffold density in the experimental group was closed to the bone density and even some of the scaffold were almost completely fused with the transverse process bone.Two months after the operation,the BV/TV value of the experimental group was higher than that of the control group,and the OD value of the middle-dose experimental group(PCL / ?-TCP / 0.2% CNT scaffold group)was significantly higher than the other two experimental groups(P <0.05).With the increoff time of implantation,the PCL / ?-TCP / 0.2% CNT scaffold group effectively promoted new bone formation.3)HE staining and Masson staining: a small amounts of new bone tissue were both observed in the experimental group and the control group at one month after the operation.Blue staining of new bone tissue was higher in the experimental group than in the control group.At two months after the operation,collagen fibers and new bone tissue increased,and some areas in the experimental group contained large amounts of collagen fibers,dense muscle fiber tissue and rich capillaries.With the increasing time of implantation,no matter the HE staining or Masson staining,the amount of new bone in the experimental group(containing CNT material)was more than that in the control group,which was significantly different(p<0.05).The optical density values in the middle-dose experimental group(PCL /?-TCP / 0.2% CNT scaffold group)were significantly higher than those in the other two experimental groups(P <0.05).This indicated that the scaffold group containing0.2%CNT was more conducive to promoting the growth of bone tissue,which could quickly and effectively repair bone defects.Conclusion:1.The combination of 3D printing technology and CAD software can print individualized composite scaffolds with repeatability,high precision and low cost.With the assist of 3D printing technology,a variety of materials can be combined with each other to take the greatest advantages of materials meanwhile avoid the waste of resources.2.The polycaprolactone/?-tricalcalcium phosphate /0.2% carbon nanotube scaffolds preparation in this study has good pore structure and mechanical properties compatible with human spongy bone.The scaffolds are significantly better than other scaffold materials in promoting ADSC proliferation and bone property,and are expected to be a promising substitute for bone defect repair. |
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