2022, Vol. 26 ›› Issue (34): 5425-5429

Modified coaxial 3D-printed akermanite scaffold with hollow-pipe structure

Liu Chang, Xu Ling   

Abstract: BACKGROUND: With the continuous development of three-dimensional (3D) printing technology and bone tissue engineering, more and more 3D printed scaffolds have applied in study of bone tissue engineering. The 3D printed scaffold with hollow pipe structure has the advantages of vascular growth and nutrient delivery, which is worthy of further study.
OBJECTIVE: To investigate the effect of ionic components released by akermanite on osteogenic differentiation of rat bone marrow mesenchymal stem cells and migration of human umbilical vein endothelial cells and fabricate the 3D-printed akermanite scaffold with hollow-pipe structure with coaxial 3D printing technology.   
METHODS: The rat bone marrow mesenchymal stem cells and human umbilical vein endothelial cells were cultured with different concentrations of akermanite extracts (1/4, 1/8 and 1/16). The proliferation of rat bone marrow mesenchymal stem cells was detected by CCK-8 assay. Osteogenic differentiation of human umbilical vein endothelial cells was investigated by alkaline phosphatase staining and RT-qPCR. Transwell assay was used to observe the migration of human umbilical vein endothelial cells in response to different concentrations of akermanite extracts. The akermanite scaffold with hollow-pipe structure was prepared using a modified printer nozzle with a core/shell structure with the printing system. The scaffolds were immersed into deionized water and the extracts were collected at set time points. The concentration of ionic products was detected with inductively coupled plasma atomic emission spectrometry.
RESULTS AND CONCLUSIOIN: (1) CCK-8 assay indicated that the akermanite extracts had a concentration and time-related effect on promoting the proliferation of bone marrow mesenchymal stem cells. (2) Alkaline phosphatase staining showed that the akermanite extracts had a concentration-related effect on the alkaline phosphatase activity of rat bone marrow mesenchymal stem cells. RT-qPCR indicated that the extracts had a concentration-related effect on the mRNA expression of alkaline phosphatase, collagen-1 and Runx2 of bone marrow mesenchymal stem cells. (3) The akermanite extracts had a concentration-related effect on the migration of human umbilical vein endothelial cells. (4) The scaffolds would continuously release the Ca, Mg and Si ions during immersion into deionized water for 30 days. The akermanite scaffold with hollow pipes was conducive to the release of biologically active ions and had high concentration. (5) The result showed that the akermanite scaffolds with hollow pipes were successfully prepared with the modified 3D printer. The ionic products released by scaffolds had an obvious effect on osteogenesis of rat bone marrow mesenchymal stem cells and promoted migration of human umbilical vein endothelial cells, thereby accelerating vascular regeneration.
Key words: 3D printing, akermanite, bio-ceramic, scaffold, hollow-pipe structure, vascularization bone regeneration