Study On Osteogenic Effect Of 3D Printed Loaded 20(S)-propananediol Plga/PLGA/β-TCP Composite Scaffold

Objective:The repair of large area bone defect is still a great challenge,and bone tissue engineering is one of the most promising methods to solve this problem.Autogenous bone transplantation has been regarded as the gold standard for reconstruction of maxillofacial defects due to its excellent characteristics of osteogenesis,bone conduction and bone induction.However,its disadvantages include the need to open up a second surgical area,limited donor pool,immune rejection and the complex shape of the surgical area defect which cannot be accurately restored,thus limiting its application.Tissue engineering can increase the adhesion of osteoblasts and bone progenitor cells and promote cell migration and differentiation by using the morphology and structure of scaffolds.3D printing is an emerging technology that can finely print the delicate structure of the stent and meet the specific needs of the patient.Traditional skull repair materials such as hydroxyapatite,although it is the main component of natural bone,has good biocompatibility,but its bone induction ability is generally poor.Adding bioactive compounds,including growth factors,drugs,extracellular matrix and peptides,is a method to improve the osteogenic induction ability of bone defect repair scaffolds.In this paper,a Chinese herbal extract,20(S)-propananediol(PPD),was studied and its osteogenic bioactivity was studied in vitro,and then loaded into a 3D printed scaffold.The material properties,biocompatibility and osteogenic effects in vitro and in vivo of the extract were evaluated.Method:1.Alkalinephosphatase(ALP)staining and alizarin red staining(ARS),fluorescence quantitative PCR(q RT-PCR)and immunofluorescence staining on osteogenesis effect and mechanism of PPD were studied.2.In order to further study the osteogenic effects of PPD and scaffolds,we loaded the bioactive PPD into 3D-printed PLGA/β-TCP(PTP)composite scaffolds.The scaffolds were characterized by scanning electron microscopy,universal testing machine,porosity detection,in vitro degradation behavior and fourier infrared spectroscopy.The release behavior of PPD from PTP scaffolds was detected by High performance liquid chromatography(HPLC).3.Through cell adhesion,live-dead staining and the evaluation of the cytoskeleton staining method for composite scaffold for bone marrow mesenchymal stem cells(BMSCs)between the biocompatibility and toxicity;The in vitro osteogenic effect of PTP scaffold on BMSCs was detected by ALP quantification and q RT-PCR.4.The effect of PLGA/β-TCP(PTP)composite scaffolds loaded with PPD on skull defects in rats was studied in vivo.Results and conclusions:In this study,we first demonstrated the osteogenic effect of PPD and then successfully loaded it into 3D-printed PLGA/β-TCP to prepare scaffolds with high porosity and controllable morphology.It is obvious from SEM observation that the prepared 3D-printed scaffold forms a rough and highly porous surface,and the pores of the scaffold are highly interconnected,which will be very conducive to cell adhesion and growth.Mechanical tests and porosity results showed no statistical significance between PT and PTP scaffolds.HPLC results showed that PPD could be sustainably released in PTP scaffold for 30 days.Live-dead staining and cytoskeleton staining showed that both scaffolds had good biocompatibility,and the cells could unfold well and extend the pseudopods close to the scaffolds or other cell surfaces.ALP quantification and q RT-PCR results showed that PTP scaffolds promoted osteogenic differentiation of BMSCs,and in vivo experiments showed that PTP scaffolds could significantly promote the repair of skull defects in rats.In conclusion,our results suggest that this PPD-loaded bone scaffold has the potential to repair critical-size bone defects with better osteogenic bioactivity.