Abstract:

Objective To discuss their effects of PLA （polylactic acid）/PTMC （polytrimethylene carbonate） and PLA/PTMC-calcium phosphate ［Ca?（PO?）?］ composite porous scaffolds prepared by 3D printing technology on bone marrow mesenchymal stem cells （BMSCs） of the rabbits， and to clarify their application values in bone defect repairment. Methods After mixing the materials， PLA/PTMC and PLA/PTMC-Ca₃（PO₄）₂ filaments were prepared by desktop filament extruder. The scaffolds were designed by CATIA V5-6R2019 modeling software and fabricated using CreatBot F430 3D printer. The chemical structure of the PLA/PTMC-Ca₃（PO₄）₂ scaffold was detected by infrared spectroscopy. In vitro degradation experiments were used to detect the degradation weight loss rates and pH values of the two scaffolds. A contact angle measuring instrument was used to detect the hydrophilicities of the two scaffolds. The BMSCs were extracted from three newborn New Zealand white rabbits （2-5-day-old）； CCK-8 method was used to detect the proliferation activities of the cells co-cultured with two scaffolds， and Alizarin red staining was used to observe the osteogenic differentiation of the cells co-cultured with two scaffolds. Results Infrared spectroscopy confirmed the successful preparation of composite scaffolds containing PLA， PTMC， and β-Ca?（PO?）?. During degradation for 6-14 weeks， compared with PLA/PTMC scaffold， the degradation rates of the PLA/PTMC-Ca₃（PO₄）₂ scaffold in lipase solution and phosphate-buffered saline （PBS） were significantly increased （P<0.05 or P<0.01）. During degradation for 8-14 weeks， compared with PLA/PTMC scaffold， the pH value of the PLA/PTMC-Ca?（PO?）? scaffold in lipase solution was significantly increased （P<0.01）. Compared with PLA/PTMC scaffold， the contact angle of the PLA/PTMC-Ca?（PO?）? scaffold was significantly decreased （P<0.01）. On days 5 and 7 of cell co-culture， compared with PLA/PTMC scaffold， the proliferation activity of the cells co-cultured with PLA/PTMC-Ca₃（PO₄）₂ scaffold was significantly increased （P<0.05 or P<0.01）. After 21 d of co-culture， both scaffolds overlapped with BMSCs and locally formed calcified nodules， which were stained orange by Alizarin red. Compared with PLA/PTMC scaffold， the number of mineralized calcium nodules in the cells co-cultured with PLA/PTMC-Ca?（PO?）? scaffold was increased， with greater density and deeper color. Conclusion The PLA/PTMC-Ca₃（PO₄）₂ composite porous scaffolds containing PLA， PTMC， and β-Ca₃（PO₄）₂ are successfully prepared by 3D printing technology. These scaffolds exhibit good degradation properties and show advantages in biocompatibility， hydrophilicity， and osteogenic induction； they are excellent materials for the bone defect repairment.

Key words: Bone defect, Bone regeneration, 3D printing, Polylactic acid, Polytrimethylene carbonate