[Three-dimensional printed Ti6Al4V-4Cu alloy promotes osteogenic gene expression through bone immune regulation].

OBJECTIVE: To investigate the effects of three-dimensional (3D) printed Ti6Al4V-4Cu alloy on inflammation and osteogenic gene expression in mouse bone marrow mesenchymal stem cells (BMSCs) and mouse mononuclear macrophage line RAW264.7. METHODS: Ti6Al4V and Ti6Al4V-4Cu alloys were prepared by selective laser melting, and the extracts of the two materials were prepared according to the biological evaluation standard of medical devices. The effects of two kinds of extracts on the proliferation of mouse BMSCs and mouse RAW264.7 cells were detected by cell counting kit 8 method. After co-cultured with mouse BMSCs for 3 days, the expression of osteogenesis- related genes [collagen type Ⅰ (Col-Ⅰ), alkaline phosphatase (ALP), Runx family transcription factor 2 (Runx-2), osteoprotegerin (OPG), and osteopontin (OPN)] were detected by real-time fluorescence quantitative PCR. After co-cultured with mouse RAW264.7 cells for 1 day, the expressions of inflammation-related genes [interleukin 4 (IL-4) and nitric oxide synthase 2 (iNOS)] were detected by real-time fluorescence quantitative PCR, and the supernatants of the two groups were collected to detect the secretion of vascular endothelial growth factor a (VEGF-a) and bone morphogenetic protein 2 (BMP-2) by ELISA. The osteogenic conditioned medium were prepared with the supernatants of the two groups and co-cultured with BMSCs for 3 days. The expressions of osteogenesis-related genes (Col-Ⅰ, ALP, Runx-2, OPG, and OPN) were detected by real-time fluorescence quantitative PCR. RESULTS: Compared with Ti6Al4V alloy extract, Ti6Al4V-4Cu alloy extract had no obvious effect on the proliferation of BMSCs and RAW264.7 cells, but it could promote the expression of OPG mRNA in BMSCs, reduce the expression of iNOS mRNA in RAW264.7 cells, and promote the expression of IL-4 mRNA. It could also promote the secretions of VEGF-a and BMP-2 in RAW264.7 cells. Ti6Al4V-4Cu osteogenic conditioned medium could promote the expressions of Col-Ⅰ, ALP, Runx-2, OPG, and OPN mRNAs in BMSCs. The differences were all significant ( P<0.05). CONCLUSION: 3D printed Ti6Al4V-4Cu alloy can promote RAW264.7 cells to secret VEGF-a and BMP-2 by releasing copper ions, thus promoting osteogenesis through bone immune regulation, which lays a theoretical foundation for the application of metal prosthesis.

Repair of flexor tendon defects of rabbit with tissue engineering method.

OBJECTIVE: To repair rabbit tendon defects with tissue engineering method. METHODS: The third passage of fetal skin fibroblast cells was labeled with 5-bromo-2' deoxyuridine (Brdu) and then seeded on human amnion extracellular matrix (HA-ECM). Using 1 cm-long-Achilles tendon defects as repairing models in the experimental group, tendon defects were core bridged with polydioxanone (PDS) and then capsulated with the complex of fibroblasts-HA-ECM. In the control group I, defective tendons were sutured with PDS following the former procedure and capsulated with HA-ECM (without fibroblasts). In the control group II, only PDS was applied to connect the defective tendons. Gross examination, light microscopy, scanning electronmicroscopy and biomechanical measurement of the repaired tendons were respectively performed at postoperative 1, 2, 3 month as well as immunohistochemical examination. RESULTS: The optimal cell concentration for seeding fibroblasts was 3.5 x 10(6) cells/ml. Cells grew well and radiated or paralleled on HA-ECM. Immunohistochemistry showed that the labeled seed fibroblasts played an important role in tendonization. The results of light microscopy, electron microscopy, and biomechanical assessment suggested that the rate and quality of tendonization in the experimental group was superior to those of the control group I and II. The tensile strength in the experimental group was the greatest, the next was in the control group I, and the worst in the control group II (P<0.05). CONCLUSIONS: HA-ECM is the excellent carrier for fibroblasts. Fibroblasts-HA-ECM complex has the capability to repair tendon defect and to tendonize with rapid rate and good performance three months after operation. Its tensile strength is 81.8% of that of normal tendon.

Congenital anterior midline cleft of the atlas and posterior atlanto-occipital fusion associated with symptomatic anterior atlantoaxial subluxation.

BACKGROUND: Congenital partial anterior arch defect of the atlas is extremely rare. It could be found as an incidental radiological finding or patients can present with neurological deficit after head or neck trauma. OBJECTIVE: To describe an extremely rare presentation of anterior midline cleft at the atlas and congenital posterior atlanto-occipital fusion with symptomatic anterior atlantoaxial subluxation. This report includes a feasible hypothesis for the development of this anomaly on the basis of previous hypotheses and surgical findings. METHODS: A 46-year-old female presented with a 6-day history of right limbs numb and left upper and lower extremities paraparesis (Frankel D). Radiographs of the cervical spine showed anterior atlantoaxial subluxation with congenital posterior atlanto-occipital fusion. Computed tomography subsequently revealed partial midline absence of the anterior arch of the atlas and the odontoid tip ahead of the anterior arch of the atlas. Magnetic resonance imaging showed that the cervical dura was compressed by the remnant of anterior arch of the atlas. The patient underwent Gardner-Wells tong traction and surgery of occipitocervical fusion with autogenous iliac bone graft because she had definite neurological symptom and congenital posterior atlanto-occipital fusion. RESULTS: Atlantoaxial reduction was confirmed with fluoroscopic X-ray evaluation by bed, her neurological deficit was resolved from Frankel D to E, and numb of right limbs completely disappeared 6 days postoperation. No instability has been observed during 2-year follow-up. CONCLUSION: We describe the association between compressive myelopathy and congenital defect of the anterior arch of the atlas with symptomatic anterior atlantoaxial subluxation. Both computed tomography and magnetic resonance image were required to demonstrate the bony configuration and cord compression. And Gardner-Wells tong traction and surgery of occipitocervical fusion with autogenous iliac bone graft were effective as a treatment for this compressive myelopathy caused by the remnant of anterior arch of the atlas.