Search

The interventional therapy of vascular stent implantation is a popular treatment method for cardiovascular stenosis and blockage. However, traditional stent manufacturing methods such as laser cutting are complex and cannot easily manufacture complex structures such as bifurcated stents, while three-dimensional (3D) printing technology provides a new method for manufacturing stents with complex structure and personalized designs. In this paper, a cardiovascular stent was designed, and printed using selective laser melting technology and 316L stainless steel powder of 0-10 µm size. Electrolytic polishing was performed to improve the surface quality of the printed vascular stent, and the expansion behavior of the polished stent was assessed by balloon inflation. The results showed that the newly designed cardiovascular stent could be manufactured by 3D printing technology. Electrolytic polishing removed the attached powder and reduced the surface roughness Ra from 1.36 µm to 0.82 µm. The axial shortening rate of the polished bracket was 4.23% when the outside diameter was expanded from 2.42 mm to 3.63 mm under the pressure of the balloon, and the radial rebound rate was 2.48% after unloading. The radial force of polished stent was 8.32 N. The 3D printed vascular stent can remove the surface powder through electrolytic polishing to improve the surface quality, and show good dilatation performance and radial support performance, which provides a reference for the practical application of 3D printed vascular stent.

Objective: The aim of this study was to clarify whether the fusion of bone marrow mesenchymal stem cells (MSCs) with tumor cells can promote tumor angiogensis., Methods: Human glioma stem/progenitor cells (GSPCs) (SU3 cells) were transfected with red fluorescent protein (RFP) gene. Bone marrow mesenchymal stem cells (MSCs) were harvested from nude mice with whole-body green fluorescent protein (GFP) gene expression. Then the two kinds of cells were co-cultured in vitro. At the same time SU3-RFP was transplanted into the brain of GFP-expressing nude mice to establish xenograft tumors. The co-cultured cells, GFP/RFP double positive (yellow) cells and blood vessels obtained from the xenograft tumors were observed under fluorescent microscope and laser scanning confocal microscope., Results: After five passages in vitro, MSCs maintained the proliferative activity and highly expressed CD105. CD105 was also expressed in the femurs of GFP-expressing nude mice, tumor cells, blood vessels of SU3 xenograft tumors, and clinical malignant gliomas. When MSCs were co-cultured with SU3-RFP, the ratio of yellow cells co-expressing RFP and GFP was significantly increased after extended time and continuous passages. According to the flow cytometry, yellow cells co-expressing RFP and GFP were 83.7% of the cultured cells. In tissue slices of the xenograft tumors, bundles of yellow vessel-like structure and cross-sectioned yellow vascular wall structures including vascular wall stroma cells were observed with RFP and GFP expression, and were identified as de novo formed vessels derived from fusion of MSCs with SU3-RFP cells., Conclusion: Cell fusion occurs between tumor cells and host MSCs and it promotes tumor angiogenesis.

Background: Nowadays the secondary resistance of gefitinib in the treatment of lung adenocarcinoma is an outstanding problem. This research is to explore whether the gefitinib secondary resistance can be induced by gefitinib, to explore whether epidermal growth factor receptor (EGFR) promotor methylation correlate with the gefitinib-resistance in PC9/GR cell lines and to find a new therapeutic target to overcome the gefitinib secondary resistance in lung adenocarcinoma., Methods: In vitro cultivation of lung adenocarcinoma PC9 cell lines, apply gefitinib on lung adenocarcinoma PC9 cell lines, and improve drug concentration. MTT for test of gefitinib resistance index in PC9 cell and PC9/GR cell. Bisulfite sequencing polymerase chain reaction (BSP) and Reverse transcription-polymerase chain reaction (RT-PCR) for detection of EGFR promoter methylation status and mRNA expression. In vitro cultivation of lung adenocarcinoma PC9 cell lines, apply 1 μmol/L 5-Aza-dc on lung adenocarcinoma PC9/GR cell lines for 72 h. MTT method for test of gefitinib resistance index in PC9/GR cell., Results: After improving the gefitinib concentration, MTT results showed that half maximal inhibitory concentration (IC50) of PC9 cell lines increase from (0.01 ± 0.002) μmol/L to (3.95 ± 0.23) μmol/L (P<0.05). BSP results showed that abnormal methylation sites compared the degree of methylation change: PC9: 59%; PC9/GR: 74% (P<0.05). RT-PCR results showed in PC9/GR cell lines, EGFR mRNA expression quantity increased (P<0.05). After applying 5-Aza-dc on PC9 cell lines, IC50 of PC9/GR decrease from (3.87 ± 0.034) μmol/L to (2.55 ± 0.14) μmol/L., Conclusions: The PC9 cell line which is induced by improving gefitinib concentration will be resistant to gefitinib, and the gefitinib-resistant cell line PC9/GR could be built. EGFR gene promoter methylation may be one of the mechanisms for the secondary resistance to gefitinib.